# -*- coding: binary -*-
# rbreadline.rb -- a general facility for reading lines of input
#   with emacs style editing and completion.

#
#  Inspired by GNU Readline, translation to Ruby
#  Copyright (C) 2009 by Park Heesob phasis@gmail.com
#

=begin
Copyright (c) 2009, Park Heesob
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.
* Neither the name of Park Heesob nor the names of its contributors
  may be used to endorse or promote products derived from this software
  without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
=end


class Fixnum
   def ord; self; end
end

module RbReadline
   require 'etc'

   RL_LIBRARY_VERSION = "5.2"
   RL_READLINE_VERSION  = 0x0502
   RB_READLINE_VERSION = "0.2.2"

   EOF = "\xFF"
   ESC = "\C-["
   PAGE = "\C-L"
   SPACE = "\x20"
   RETURN = "\C-M"
   ABORT_CHAR = "\C-G"
   TAB = "\t"
   RUBOUT = "\x7f"
   NEWLINE = "\n"

   DEFAULT_BUFFER_SIZE = 256
   DEFAULT_MAX_KILLS = 10

   MB_FIND_NONZERO = 1
   MB_FIND_ANY = 0
   MB_LEN_MAX = 4

   DEFAULT_INPUTRC = "~/.inputrc"
   SYS_INPUTRC = "/etc/inputrc"

   UpCase = 1
   DownCase = 2
   CapCase = 3

   # Possible history errors passed to hist_error.
   EVENT_NOT_FOUND = 0
   BAD_WORD_SPEC  = 1
   SUBST_FAILED   = 2
   BAD_MODIFIER   = 3
   NO_PREV_SUBST  = 4

   # Possible definitions for history starting point specification.
   ANCHORED_SEARCH = 1
   NON_ANCHORED_SEARCH = 0

   # Possible definitions for what style of writing the history file we want.
   HISTORY_APPEND = 0
   HISTORY_OVERWRITE = 1

   # Input error; can be returned by (*rl_getc_function) if readline is reading
   #   a top-level command (RL_ISSTATE (RL_STATE_READCMD)).
   READERR = 0xFE.chr

   # Definitions available for use by readline clients.
   RL_PROMPT_START_IGNORE    = 1.chr
   RL_PROMPT_END_IGNORE    = 2.chr

   # Possible values for do_replace argument to rl_filename_quoting_function,
   #   called by rl_complete_internal.
   NO_MATCH      =  0
   SINGLE_MATCH  =  1
   MULT_MATCH    =  2

   # Callback data for reading numeric arguments
   NUM_SAWMINUS   = 0x01
   NUM_SAWDIGITS = 0x02
   NUM_READONE = 0x04

   # A context for reading key sequences longer than a single character when
   #   using the callback interface.
   KSEQ_DISPATCHED = 0x01
   KSEQ_SUBSEQ = 0x02
   KSEQ_RECURSIVE = 0x04

   # Possible state values for rl_readline_state
   RL_STATE_NONE        = 0x000000        # no state before first call

   RL_STATE_INITIALIZING =    0x000001    # initializing
   RL_STATE_INITIALIZED  =    0x000002    # initialization done
   RL_STATE_TERMPREPPED  =    0x000004    # terminal is prepped
   RL_STATE_READCMD =    0x000008    # reading a command key
   RL_STATE_METANEXT =    0x000010    # reading input after ESC
   RL_STATE_DISPATCHING =    0x000020    # dispatching to a command
   RL_STATE_MOREINPUT    = 0x000040    # reading more input in a command function
   RL_STATE_ISEARCH    = 0x000080    # doing incremental search
   RL_STATE_NSEARCH    = 0x000100    # doing non-inc search
   RL_STATE_SEARCH        = 0x000200    # doing a history search
   RL_STATE_NUMERICARG    = 0x000400    # reading numeric argument
   RL_STATE_MACROINPUT    = 0x000800    # getting input from a macro
   RL_STATE_MACRODEF    = 0x001000    # defining keyboard macro
   RL_STATE_OVERWRITE    = 0x002000    # overwrite mode
   RL_STATE_COMPLETING    = 0x004000    # doing completion
   RL_STATE_SIGHANDLER    = 0x008000    # in readline sighandler
   RL_STATE_UNDOING    = 0x010000    # doing an undo
   RL_STATE_INPUTPENDING =    0x020000    # rl_execute_next called
   RL_STATE_TTYCSAVED     = 0x040000    # tty special chars saved
   RL_STATE_CALLBACK     = 0x080000    # using the callback interface
   RL_STATE_VIMOTION     = 0x100000    # reading vi motion arg
   RL_STATE_MULTIKEY     = 0x200000    # reading multiple-key command
   RL_STATE_VICMDONCE     = 0x400000    # entered vi command mode at least once

   RL_STATE_DONE        = 0x800000    # done accepted line

   NO_BELL = 0
   AUDIBLE_BELL = 1
   VISIBLE_BELL = 2
   # The actions that undo knows how to undo.  Notice that UNDO_DELETE means
   #   to insert some text, and UNDO_INSERT means to delete some text.   I.e.,
   #   the code tells undo what to undo, not how to undo it.
   UNDO_DELETE, UNDO_INSERT, UNDO_BEGIN, UNDO_END  = 0,1,2,3

   # Definitions used when searching the line for characters.
   # NOTE: it is necessary that opposite directions are inverses
   FTO   =  1     # forward to
   BTO   = -1     # backward to
   FFIND =  2     # forward find
   BFIND = -2     # backward find

   # Possible values for the found_quote flags word used by the completion
   #   functions.  It says what kind of (shell-like) quoting we found anywhere
   #   in the line.
   RL_QF_SINGLE_QUOTE   = 0x01
   RL_QF_DOUBLE_QUOTE   = 0x02
   RL_QF_BACKSLASH      = 0x04
   RL_QF_OTHER_QUOTE = 0x08

   KEYMAP_SIZE = 257
   ANYOTHERKEY = KEYMAP_SIZE-1

   @hConsoleHandle = nil
   @MessageBeep = nil

   RL_IM_INSERT    = 1
   RL_IM_OVERWRITE    = 0
   RL_IM_DEFAULT    = RL_IM_INSERT
   @no_mode = -1
   @vi_mode = 0
   @emacs_mode = 1
   ISFUNC = 0
   ISKMAP = 1
   ISMACR = 2

   HISTORY_WORD_DELIMITERS    = " \t\n;&()|<>"
   HISTORY_QUOTE_CHARACTERS   = "\"'`"

   RL_SEARCH_ISEARCH = 0x01      # incremental search
   RL_SEARCH_NSEARCH = 0x02      # non-incremental search
   RL_SEARCH_CSEARCH = 0x04      # intra-line char search

   # search flags
   SF_REVERSE     = 0x01
   SF_FOUND    = 0x02
   SF_FAILED      = 0x04

   @slashify_in_quotes = "\\`\"$"

   @sigint_proc = nil
   @sigint_blocked = false

   @rl_prep_term_function = :rl_prep_terminal
   @rl_deprep_term_function = :rl_deprep_terminal

   @_rl_history_saved_point = -1

   @rl_max_kills =  DEFAULT_MAX_KILLS
   @rl_kill_ring = nil
   @rl_kill_index = 0
   @rl_kill_ring_length = 0

   @pending_bytes = ''
   @stored_count = 0

   @_rl_isearch_terminators = nil
   @_rl_iscxt = nil
   @last_isearch_string = nil
   @last_isearch_string_len = 0
   @default_isearch_terminators = "\033\012"
   @_rl_history_preserve_point = false
   @terminal_prepped = false
   @otio = nil

   @msg_saved_prompt = false

   @_rl_nscxt = nil
   @noninc_search_string = nil
   @noninc_history_pos = 0
   @prev_line_found = nil

   rl_history_search_len = 0
   rl_history_search_pos = 0
   history_search_string = nil
   history_string_size = 0

   @_rl_tty_chars = Struct.new(:t_eol,:t_eol2,:t_erase,:t_werase,:t_kill,:t_reprint,:t_intr,:t_eof,
   :t_quit,:t_susp,:t_dsusp,:t_start,:t_stop,:t_lnext,:t_flush,:t_status).new
   @_rl_last_tty_chars = nil

   @_keyboard_input_timeout = 0.01

   # Variables exported by this file.
   # The character that represents the start of a history expansion
   #   request.  This is usually `!'.
   @history_expansion_char = "!"

   # The character that invokes word substitution if found at the start of
   #   a line.  This is usually `^'.
   @history_subst_char = "^"

   # During tokenization, if this character is seen as the first character
   #   of a word, then it, and all subsequent characters upto a newline are
   #   ignored.  For a Bourne shell, this should be '#'.  Bash special cases
   #   the interactive comment character to not be a comment delimiter.
   @history_comment_char = 0.chr

   # The list of characters which inhibit the expansion of text if found
   #   immediately following history_expansion_char.
   @history_no_expand_chars = " \t\n\r="

   # If set to a non-zero value, single quotes inhibit history expansion.
   #   The default is 0.
   @history_quotes_inhibit_expansion = 0

   # Used to split words by history_tokenize_internal.
   @history_word_delimiters = HISTORY_WORD_DELIMITERS

   # If set, this points to a function that is called to verify that a
   #   particular history expansion should be performed.
   @history_inhibit_expansion_function = nil

   @rl_event_hook = nil
   # The visible cursor position.  If you print some text, adjust this.
   # NOTE: _rl_last_c_pos is used as a buffer index when not in a locale
   #   supporting multibyte characters, and an absolute cursor position when
   #   in such a locale.  This is an artifact of the donated multibyte support.
   #   Care must be taken when modifying its value.
   @_rl_last_c_pos = 0
   @_rl_last_v_pos = 0

   @cpos_adjusted = false
   @cpos_buffer_position = 0

   # Number of lines currently on screen minus 1.
   @_rl_vis_botlin = 0

   # Variables used only in this file.
   # The last left edge of text that was displayed.  This is used when
   #   doing horizontal scrolling.  It shifts in thirds of a screenwidth.
   @last_lmargin = 0

   # The line display buffers.  One is the line currently displayed on
   #   the screen.  The other is the line about to be displayed.
   @visible_line = nil
   @invisible_line = nil

   # A buffer for `modeline' messages.
   @msg_buf = 0.chr * 128

   # Non-zero forces the redisplay even if we thought it was unnecessary.
   @forced_display = false

   # Default and initial buffer size.  Can grow.
   @line_size = 1024

   # Variables to keep track of the expanded prompt string, which may
   #   include invisible characters.

   @local_prompt = nil
   @local_prompt_prefix = nil
   @local_prompt_len = 0
   @prompt_visible_length = 0
   @prompt_prefix_length = 0

   # The number of invisible characters in the line currently being
   #   displayed on the screen.
   @visible_wrap_offset = 0

   # The number of invisible characters in the prompt string.  Static so it
   #   can be shared between rl_redisplay and update_line
   @wrap_offset = 0

   @prompt_last_invisible = 0

   # The length (buffer offset) of the first line of the last (possibly
   #   multi-line) buffer displayed on the screen.
   @visible_first_line_len = 0

   # Number of invisible characters on the first physical line of the prompt.
   #   Only valid when the number of physical characters in the prompt exceeds
   #   (or is equal to) _rl_screenwidth.
   @prompt_invis_chars_first_line = 0

   @prompt_last_screen_line = 0

   @prompt_physical_chars = 0

   # Variables to save and restore prompt and display information.

   # These are getting numerous enough that it's time to create a struct.

   @saved_local_prompt = nil
   @saved_local_prefix = nil
   @saved_last_invisible =  0
   @saved_visible_length = 0
   @saved_prefix_length = 0
   @saved_local_length = 0
   @saved_invis_chars_first_line = 0
   @saved_physical_chars = 0

   @inv_lbreaks = nil
   @vis_lbreaks = nil
   @_rl_wrapped_line = nil

   @term_buffer = nil
   @term_string_buffer = nil

   @tcap_initialized = false

   # While we are editing the history, this is the saved
   #   version of the original line.
   @_rl_saved_line_for_history = nil

   # An array of HIST_ENTRY.  This is where we store the history.
   @the_history = nil
   @history_base = 1

   # Non-zero means that we have enforced a limit on the amount of
   #   history that we save.
   @history_stifled = false

   # If HISTORY_STIFLED is non-zero, then this is the maximum number of
   #   entries to remember.
   @history_max_entries = 0
   @max_input_history = 0  # backwards compatibility

   # The current location of the interactive history pointer.  Just makes
   #   life easier for outside callers.
   @history_offset = 0

   # The number of strings currently stored in the history list.
   @history_length = 0

   @_rl_vi_last_command = 'i' # default `.' puts you in insert mode

   # Non-zero means enter insertion mode.
   @_rl_vi_doing_insert = 0

   # Command keys which do movement for xxx_to commands.
   @vi_motion = " hl^$0ftFT;,%wbeWBE|"

   # Keymap used for vi replace characters.  Created dynamically since
   #   rarely used.
   @vi_replace_map = nil

   # The number of characters inserted in the last replace operation.
   @vi_replace_count = 0

   # If non-zero, we have text inserted after a c[motion] command that put
   #   us implicitly into insert mode.  Some people want this text to be
   #   attached to the command so that it is `redoable' with `.'.
   @vi_continued_command = false
   @vi_insert_buffer = nil
   @vi_insert_buffer_size = 0

   @_rl_vi_last_repeat = 1
   @_rl_vi_last_arg_sign = 1
   @_rl_vi_last_motion = 0
   @_rl_vi_last_search_char = 0
   @_rl_vi_last_replacement = 0

   @_rl_vi_last_key_before_insert = 0

   @vi_redoing = 0

   # Text modification commands.  These are the `redoable' commands.
   @vi_textmod = "_*\\AaIiCcDdPpYyRrSsXx~"

   # Arrays for the saved marks.
   @vi_mark_chars = Array.new(26,-1)

   @emacs_standard_keymap = {
      "\C-@" => :rl_set_mark  ,
      "\C-a" => :rl_beg_of_line  ,
      "\C-b" => :rl_backward_char  ,
      "\C-d" => :rl_delete  ,
      "\C-e" => :rl_end_of_line  ,
      "\C-f" => :rl_forward_char  ,
      "\C-g" => :rl_abort  ,
      "\C-h" => :rl_rubout  ,
      "\C-i" => :rl_complete  ,
      "\C-j" => :rl_newline  ,
      "\C-k" => :rl_kill_line  ,
      "\C-l" => :rl_clear_screen  ,
      "\C-m" => :rl_newline  ,
      "\C-n" => :rl_get_next_history  ,
      "\C-p" => :rl_get_previous_history  ,
      "\C-q" => :rl_quoted_insert  ,
      "\C-r" => :rl_reverse_search_history  ,
      "\C-s" => :rl_forward_search_history  ,
      "\C-t" => :rl_transpose_chars  ,
      "\C-u" => :rl_unix_line_discard  ,
      "\C-v" => :rl_quoted_insert  ,
      "\C-w" => :rl_unix_word_rubout  ,
      "\C-y" => :rl_yank  ,
      "\C-]" => :rl_char_search  ,
      "\C-_" => :rl_undo_command  ,
      "\x7F" => :rl_rubout ,
      "\e\C-g" => :rl_abort  ,
      "\e\C-h" => :rl_backward_kill_word  ,
      "\e\C-i" => :rl_tab_insert  ,
      "\e\C-j" => :rl_vi_editing_mode  ,
      "\e\C-m" => :rl_vi_editing_mode  ,
      "\e\C-r" => :rl_revert_line  ,
      "\e\C-y" => :rl_yank_nth_arg  ,
      "\e\C-[" => :rl_complete  ,
      "\e\C-]" => :rl_backward_char_search  ,
      "\e " => :rl_set_mark  ,
      "\e#" => :rl_insert_comment  ,
      "\e&" => :rl_tilde_expand  ,
      "\e*" => :rl_insert_completions  ,
      "\e-" => :rl_digit_argument  ,
      "\e." => :rl_yank_last_arg ,
      "\e0" => :rl_digit_argument  ,
      "\e1" => :rl_digit_argument  ,
      "\e2" => :rl_digit_argument  ,
      "\e3" => :rl_digit_argument  ,
      "\e4" => :rl_digit_argument  ,
      "\e5" => :rl_digit_argument  ,
      "\e6" => :rl_digit_argument  ,
      "\e7" => :rl_digit_argument  ,
      "\e8" => :rl_digit_argument  ,
      "\e9" => :rl_digit_argument  ,
      "\e<" => :rl_beginning_of_history  ,
      "\e=" => :rl_possible_completions  ,
      "\e>" => :rl_end_of_history  ,
      "\e?" => :rl_possible_completions  ,
      "\eB" => :rl_backward_word  ,
      "\eC" => :rl_capitalize_word  ,
      "\eD" => :rl_kill_word  ,
      "\eF" => :rl_forward_word  ,
      "\eL" => :rl_downcase_word  ,
      "\eN" => :rl_noninc_forward_search  ,
      "\eP" => :rl_noninc_reverse_search  ,
      "\eR" => :rl_revert_line  ,
      "\eT" => :rl_transpose_words  ,
      "\eU" => :rl_upcase_word  ,
      "\eY" => :rl_yank_pop  ,
      "\e\\" => :rl_delete_horizontal_space  ,
      "\e_" => :rl_yank_last_arg  ,
      "\eb" => :rl_backward_word  ,
      "\ec" => :rl_capitalize_word  ,
      "\ed" => :rl_kill_word  ,
      "\ef" => :rl_forward_word  ,
      "\el" => :rl_downcase_word  ,
      "\en" => :rl_noninc_forward_search  ,
      "\ep" => :rl_noninc_reverse_search  ,
      "\er" => :rl_revert_line  ,
      "\et" => :rl_transpose_words  ,
      "\eu" => :rl_upcase_word  ,
      "\ey" => :rl_yank_pop  ,
      "\e~" => :rl_tilde_expand  ,
      "\377" => :rl_backward_kill_word  ,

      "\C-x\C-g" => :rl_abort  ,
      "\C-x\C-r" => :rl_re_read_init_file  ,
      "\C-x\C-u" => :rl_undo_command  ,
      "\C-x\C-x" => :rl_exchange_point_and_mark  ,
      "\C-x(" => :rl_start_kbd_macro  ,
      "\C-x)" => :rl_end_kbd_macro   ,
      "\C-xE" => :rl_call_last_kbd_macro  ,
      "\C-xe" => :rl_call_last_kbd_macro  ,
      "\C-x\x7F" => :rl_backward_kill_line
   }

   @vi_movement_keymap = {
      "\C-d" => :rl_vi_eof_maybe ,
      "\C-e" => :rl_emacs_editing_mode ,
      "\C-g" => :rl_abort ,
      "\C-h" => :rl_backward_char ,
      "\C-j" => :rl_newline ,
      "\C-k" => :rl_kill_line ,
      "\C-l" => :rl_clear_screen ,
      "\C-m" => :rl_newline ,
      "\C-n" => :rl_get_next_history ,
      "\C-p" => :rl_get_previous_history ,
      "\C-q" => :rl_quoted_insert ,
      "\C-r" => :rl_reverse_search_history ,
      "\C-s" => :rl_forward_search_history ,
      "\C-t" => :rl_transpose_chars ,
      "\C-u" => :rl_unix_line_discard ,
      "\C-v" => :rl_quoted_insert ,
      "\C-w" => :rl_unix_word_rubout ,
      "\C-y" => :rl_yank ,
      "\C-_" => :rl_vi_undo ,
      " " => :rl_forward_char ,
      "#" => :rl_insert_comment ,
      "$" => :rl_end_of_line ,
      "%" => :rl_vi_match ,
      "&" => :rl_vi_tilde_expand ,
      "*" => :rl_vi_complete ,
      "+" => :rl_get_next_history ,
      "," => :rl_vi_char_search ,
      "-" => :rl_get_previous_history ,
      "." => :rl_vi_redo ,
      "/" => :rl_vi_search ,
      "0" => :rl_beg_of_line ,
      "1" => :rl_vi_arg_digit ,
      "2" => :rl_vi_arg_digit ,
      "3" => :rl_vi_arg_digit ,
      "4" => :rl_vi_arg_digit ,
      "5" => :rl_vi_arg_digit ,
      "6" => :rl_vi_arg_digit ,
      "7" => :rl_vi_arg_digit ,
      "8" => :rl_vi_arg_digit ,
      "9" => :rl_vi_arg_digit ,
      "" => :rl_vi_char_search ,
      "=" => :rl_vi_complete ,
      "?" => :rl_vi_search ,
      "A" => :rl_vi_append_eol ,
      "B" => :rl_vi_prev_word ,
      "C" => :rl_vi_change_to ,
      "D" => :rl_vi_delete_to ,
      "E" => :rl_vi_end_word ,
      "F" => :rl_vi_char_search ,
      "G" => :rl_vi_fetch_history ,
      "I" => :rl_vi_insert_beg ,
      "N" => :rl_vi_search_again ,
      "P" => :rl_vi_put ,
      "R" => :rl_vi_replace ,
      "S" => :rl_vi_subst ,
      "T" => :rl_vi_char_search ,
      "U" => :rl_revert_line ,
      "W" => :rl_vi_next_word ,
      "X" => :rl_vi_rubout ,
      "Y" => :rl_vi_yank_to ,
      "\\" => :rl_vi_complete ,
      "^" => :rl_vi_first_print ,
      "_" => :rl_vi_yank_arg ,
      "`" => :rl_vi_goto_mark ,
      "a" => :rl_vi_append_mode ,
      "b" => :rl_vi_prev_word ,
      "c" => :rl_vi_change_to ,
      "d" => :rl_vi_delete_to ,
      "e" => :rl_vi_end_word ,
      "f" => :rl_vi_char_search ,
      "h" => :rl_backward_char ,
      "i" => :rl_vi_insertion_mode ,
      "j" => :rl_get_next_history ,
      "k" => :rl_get_previous_history ,
      "l" => :rl_forward_char ,
      "m" => :rl_vi_set_mark ,
      "n" => :rl_vi_search_again ,
      "p" => :rl_vi_put ,
      "r" => :rl_vi_change_char ,
      "s" => :rl_vi_subst ,
      "t" => :rl_vi_char_search ,
      "u" => :rl_vi_undo ,
      "w" => :rl_vi_next_word ,
      "x" => :rl_vi_delete ,
      "y" => :rl_vi_yank_to ,
      "|" => :rl_vi_column ,
      "~" => :rl_vi_change_case
   }

   @vi_insertion_keymap = {
      "\C-a" => :rl_insert  ,
      "\C-b" => :rl_insert  ,
      "\C-c" => :rl_insert  ,
      "\C-d" => :rl_vi_eof_maybe  ,
      "\C-e" => :rl_insert  ,
      "\C-f" => :rl_insert  ,
      "\C-g" => :rl_insert  ,
      "\C-h" => :rl_rubout  ,
      "\C-i" => :rl_complete  ,
      "\C-j" => :rl_newline  ,
      "\C-k" => :rl_insert  ,
      "\C-l" => :rl_insert  ,
      "\C-m" => :rl_newline  ,
      "\C-n" => :rl_insert  ,
      "\C-o" => :rl_insert  ,
      "\C-p" => :rl_insert  ,
      "\C-q" => :rl_insert  ,
      "\C-r" => :rl_reverse_search_history  ,
      "\C-s" => :rl_forward_search_history  ,
      "\C-t" => :rl_transpose_chars  ,
      "\C-u" => :rl_unix_line_discard  ,
      "\C-v" => :rl_quoted_insert  ,
      "\C-w" => :rl_unix_word_rubout  ,
      "\C-x" => :rl_insert  ,
      "\C-y" => :rl_yank  ,
      "\C-z" => :rl_insert  ,
#      "\C-[" => :rl_vi_movement_mode,
# XXX: NOT IMPLEMENTED
      "\C-\\" => :rl_insert  ,
      "\C-]" => :rl_insert  ,
      "\C-^" => :rl_insert  ,
      "\C-_" => :rl_vi_undo  ,
      "\x7F" => :rl_rubout
   }

   @rl_library_version = RL_LIBRARY_VERSION

   @rl_readline_version = RL_READLINE_VERSION

   @rl_readline_name = "other"

   @rl_getc_function = :rl_getc

   # Non-zero tells rl_delete_text and rl_insert_text to not add to
   #   the undo list.
   @_rl_doing_an_undo = false

   # How many unclosed undo groups we currently have.
   @_rl_undo_group_level = 0

   # The current undo list for THE_LINE.
   @rl_undo_list = nil

   # Application-specific redisplay function.
   @rl_redisplay_function = :rl_redisplay

   # Global variables declared here.
   # What YOU turn on when you have handled all redisplay yourself.
   @rl_display_fixed = false

   @_rl_suppress_redisplay = 0
   @_rl_want_redisplay = false

   # The stuff that gets printed out before the actual text of the line.
   #   This is usually pointing to rl_prompt.
   @rl_display_prompt = nil

   # True if this is `real' readline as opposed to some stub substitute.
   @rl_gnu_readline_p = true

   for i in 32 .. 255
      @emacs_standard_keymap[i.chr] = :rl_insert unless @emacs_standard_keymap[i.chr]
      @vi_insertion_keymap[i.chr] = :rl_insert unless @vi_insertion_keymap[i.chr]
   end
   # A pointer to the keymap that is currently in use.
   #   By default, it is the standard emacs keymap.
   @_rl_keymap = @emacs_standard_keymap


   # The current style of editing.
   @rl_editing_mode = @emacs_mode

   # The current insert mode:  input (the default) or overwrite
   @rl_insert_mode = RL_IM_DEFAULT

   # Non-zero if we called this function from _rl_dispatch().  It's present
   #   so functions can find out whether they were called from a key binding
   #   or directly from an application.
   @rl_dispatching = false

   # Non-zero if the previous command was a kill command.
   @_rl_last_command_was_kill = false

   # The current value of the numeric argument specified by the user.
   @rl_numeric_arg = 1

   # Non-zero if an argument was typed.
   @rl_explicit_arg = false

   # Temporary value used while generating the argument.
   @rl_arg_sign = 1

   # Non-zero means we have been called at least once before.
   @rl_initialized = false

   # Flags word encapsulating the current readline state.
   @rl_readline_state = RL_STATE_NONE

   # The current offset in the current input line.
   @rl_point = 0

   # Mark in the current input line.
   @rl_mark = 0

   # Length of the current input line.
   @rl_end = 0

   # Make this non-zero to return the current input_line.
   @rl_done = false

   # The last function executed by readline.
   @rl_last_func = nil

   # Top level environment for readline_internal ().
   @readline_top_level = nil

   # The streams we interact with.
   @_rl_in_stream = nil
   @_rl_out_stream = nil

   # The names of the streams that we do input and output to.
   @rl_instream = nil
   @rl_outstream = nil

   @pop_index = 0
   @push_index = 0
   @ibuffer = 0.chr * 512
   @ibuffer_len = @ibuffer.length - 1


   # Non-zero means echo characters as they are read.  Defaults to no echo
   #   set to 1 if there is a controlling terminal, we can get its attributes,
   #   and the attributes include `echo'.  Look at rltty.c:prepare_terminal_settings
   #   for the code that sets it.
   @readline_echoing_p = false

   # Current prompt.
   @rl_prompt = nil
   @rl_visible_prompt_length = 0

   # Set to non-zero by calling application if it has already printed rl_prompt
   #   and does not want readline to do it the first time.
   @rl_already_prompted = false

   # The number of characters read in order to type this complete command.
   @rl_key_sequence_length = 0

   # If non-zero, then this is the address of a function to call just
   #   before readline_internal_setup () prints the first prompt.
   @rl_startup_hook = nil

   # If non-zero, this is the address of a function to call just before
   #   readline_internal_setup () returns and readline_internal starts
   #   reading input characters.
   @rl_pre_input_hook = nil

   # The character that can generate an EOF.  Really read from
   #   the terminal driver... just defaulted here.
   @_rl_eof_char = "\cD"

   # Non-zero makes this the next keystroke to read.
   @rl_pending_input = 0

   # Pointer to a useful terminal name.
   @rl_terminal_name = nil

   # Non-zero means to always use horizontal scrolling in line display.
   @_rl_horizontal_scroll_mode = false

   # Non-zero means to display an asterisk at the starts of history lines
   #   which have been modified.
   @_rl_mark_modified_lines = false

   # The style of `bell' notification preferred.  This can be set to NO_BELL,
   #   AUDIBLE_BELL, or VISIBLE_BELL.
   @_rl_bell_preference = AUDIBLE_BELL

   # String inserted into the line by rl_insert_comment ().
   @_rl_comment_begin = nil

   # Keymap holding the function currently being executed.
   @rl_executing_keymap = nil

   # Keymap we're currently using to dispatch.
   @_rl_dispatching_keymap = nil

   # Non-zero means to erase entire line, including prompt, on empty input lines.
   @rl_erase_empty_line = false

   # Non-zero means to read only this many characters rather than up to a
   #   character bound to accept-line.
   @rl_num_chars_to_read = 0

   # Line buffer and maintenence.
   @rl_line_buffer = nil

   # Key sequence `contexts'
   @_rl_kscxt = nil

   # Non-zero means do not parse any lines other than comments and
   #   parser directives.
   @_rl_parsing_conditionalized_out = false

   # Non-zero means to convert characters with the meta bit set to
   #   escape-prefixed characters so we can indirect through
   #   emacs_meta_keymap or vi_escape_keymap.
   @_rl_convert_meta_chars_to_ascii = true

   # Non-zero means to output characters with the meta bit set directly
   #   rather than as a meta-prefixed escape sequence.
   @_rl_output_meta_chars = false

   # Non-zero means to look at the termios special characters and bind
   #   them to equivalent readline functions at startup.
   @_rl_bind_stty_chars = true

   @rl_completion_display_matches_hook = nil

   XOK = 1

   @_rl_term_clreol = nil
   @_rl_term_clrpag = nil
   @_rl_term_cr = nil
   @_rl_term_backspace = nil
   @_rl_term_goto = nil
   @_rl_term_pc = nil

   # Non-zero if we determine that the terminal can do character insertion.
   @_rl_terminal_can_insert = false

   # How to insert characters.
   @_rl_term_im = nil
   @_rl_term_ei = nil
   @_rl_term_ic = nil
   @_rl_term_ip = nil
   @_rl_term_IC = nil

   # How to delete characters.
   @_rl_term_dc = nil
   @_rl_term_DC = nil

   @_rl_term_forward_char = nil

   # How to go up a line.
   @_rl_term_up = nil

   # A visible bell; char if the terminal can be made to flash the screen.
   @_rl_visible_bell = nil

   # Non-zero means the terminal can auto-wrap lines.
   @_rl_term_autowrap = true

   # Non-zero means that this terminal has a meta key.
   @term_has_meta = 0

   # The sequences to write to turn on and off the meta key, if this
   #   terminal has one.
   @_rl_term_mm = nil
   @_rl_term_mo = nil

   # The key sequences output by the arrow keys, if this terminal has any.
   @_rl_term_ku = nil
   @_rl_term_kd = nil
   @_rl_term_kr = nil
   @_rl_term_kl = nil

   # How to initialize and reset the arrow keys, if this terminal has any.
   @_rl_term_ks = nil
   @_rl_term_ke = nil

   # The key sequences sent by the Home and End keys, if any.
   @_rl_term_kh = nil
   @_rl_term_kH = nil
   @_rl_term_at7 = nil

   # Delete key
   @_rl_term_kD = nil

   # Insert key
   @_rl_term_kI = nil

   # Cursor control
   @_rl_term_vs = nil    # very visible
   @_rl_term_ve = nil    # normal

   # Variables that hold the screen dimensions, used by the display code.
   @_rl_screenwidth = @_rl_screenheight = @_rl_screenchars = 0

   # Non-zero means the user wants to enable the keypad.
   @_rl_enable_keypad = false

   # Non-zero means the user wants to enable a meta key.
   @_rl_enable_meta = true

   # ****************************************************************
   #
   #    Completion matching, from readline's point of view.
   #
   # ****************************************************************

   # Variables known only to the readline library.

   # If non-zero, non-unique completions always show the list of matches.
   @_rl_complete_show_all = false

   # If non-zero, non-unique completions show the list of matches, unless it
   #   is not possible to do partial completion and modify the line.
   @_rl_complete_show_unmodified = false

   # If non-zero, completed directory names have a slash appended.
   @_rl_complete_mark_directories = true

   # If non-zero, the symlinked directory completion behavior introduced in
   #   readline-4.2a is disabled, and symlinks that point to directories have
   #   a slash appended (subject to the value of _rl_complete_mark_directories).
   #   This is user-settable via the mark-symlinked-directories variable.
   @_rl_complete_mark_symlink_dirs = false

   # If non-zero, completions are printed horizontally in alphabetical order,
   #   like `ls -x'.
   @_rl_print_completions_horizontally = false

   @_rl_completion_case_fold = false

   # If non-zero, don't match hidden files (filenames beginning with a `.' on
   #   Unix) when doing filename completion.
   @_rl_match_hidden_files = true

   # Global variables available to applications using readline.

   # Non-zero means add an additional character to each filename displayed
   #   during listing completion iff rl_filename_completion_desired which helps
   #   to indicate the type of file being listed.
   @rl_visible_stats = false

   # If non-zero, then this is the address of a function to call when
   #   completing on a directory name.  The function is called with
   #   the address of a string (the current directory name) as an arg.
   @rl_directory_completion_hook = nil

   @rl_directory_rewrite_hook = nil

   # Non-zero means readline completion functions perform tilde expansion.
   @rl_complete_with_tilde_expansion = false

   # Pointer to the generator function for completion_matches ().
   #   NULL means to use rl_filename_completion_function (), the default filename
   #   completer.
   @rl_completion_entry_function = nil

   # Pointer to alternative function to create matches.
   #   Function is called with TEXT, START, and END.
   #   START and END are indices in RL_LINE_BUFFER saying what the boundaries
   #   of TEXT are.
   #   If this function exists and returns NULL then call the value of
   #   rl_completion_entry_function to try to match, otherwise use the
   #   array of strings returned.
   @rl_attempted_completion_function = nil

   # Non-zero means to suppress normal filename completion after the
   #   user-specified completion function has been called.
   @rl_attempted_completion_over = false

   # Set to a character indicating the type of completion being performed
   #   by rl_complete_internal, available for use by application completion
   #   functions.
   @rl_completion_type = 0

   # Up to this many items will be displayed in response to a
   #   possible-completions call.  After that, we ask the user if
   #   she is sure she wants to see them all.  A negative value means
   #   don't ask.
   @rl_completion_query_items = 100

   @_rl_page_completions = 1

   # The basic list of characters that signal a break between words for the
   #   completer routine.  The contents of this variable is what breaks words
   #   in the shell, i.e. " \t\n\"\\'`@$><="
   @rl_basic_word_break_characters = " \t\n\"\\'`@$><=|&{(" # })

   # List of basic quoting characters.
   @rl_basic_quote_characters = "\"'"

   # The list of characters that signal a break between words for
   #   rl_complete_internal.  The default list is the contents of
   #   rl_basic_word_break_characters.
   @rl_completer_word_break_characters = nil

   # Hook function to allow an application to set the completion word
   #   break characters before readline breaks up the line.  Allows
   #   position-dependent word break characters.
   @rl_completion_word_break_hook = nil

   # List of characters which can be used to quote a substring of the line.
   #   Completion occurs on the entire substring, and within the substring
   #   rl_completer_word_break_characters are treated as any other character,
   #   unless they also appear within this list.
   @rl_completer_quote_characters = nil

   # List of characters that should be quoted in filenames by the completer.
   @rl_filename_quote_characters = nil

   # List of characters that are word break characters, but should be left
   #   in TEXT when it is passed to the completion function.  The shell uses
   #   this to help determine what kind of completing to do.
   @rl_special_prefixes = nil

   # If non-zero, then disallow duplicates in the matches.
   @rl_ignore_completion_duplicates = true

   # Non-zero means that the results of the matches are to be treated
   #   as filenames.  This is ALWAYS zero on entry, and can only be changed
   #   within a completion entry finder function.
   @rl_filename_completion_desired = false

   # Non-zero means that the results of the matches are to be quoted using
   #   double quotes (or an application-specific quoting mechanism) if the
   #   filename contains any characters in rl_filename_quote_chars.  This is
   #   ALWAYS non-zero on entry, and can only be changed within a completion
   #   entry finder function.
   @rl_filename_quoting_desired = true

   # This function, if defined, is called by the completer when real
   #   filename completion is done, after all the matching names have been
   #   generated. It is passed a (char**) known as matches in the code below.
   #   It consists of a NULL-terminated array of pointers to potential
   #   matching strings.  The 1st element (matches[0]) is the maximal
   #   substring that is common to all matches. This function can re-arrange
   #   the list of matches as required, but all elements of the array must be
   #   free()'d if they are deleted. The main intent of this function is
   #   to implement FIGNORE a la SunOS csh.
   @rl_ignore_some_completions_function = nil

   # Set to a function to quote a filename in an application-specific fashion.
   #   Called with the text to quote, the type of match found (single or multiple)
   #   and a pointer to the quoting character to be used, which the function can
   #   reset if desired.
   #rl_filename_quoting_function = rl_quote_filename

   # Function to call to remove quoting characters from a filename.  Called
   #   before completion is attempted, so the embedded quotes do not interfere
   #   with matching names in the file system.  Readline doesn't do anything
   #   with this it's set only by applications.
   @rl_filename_dequoting_function = nil

   # Function to call to decide whether or not a word break character is
   #   quoted.  If a character is quoted, it does not break words for the
   #   completer.
   @rl_char_is_quoted_p = nil

   # If non-zero, the completion functions don't append anything except a
   #   possible closing quote.  This is set to 0 by rl_complete_internal and
   #   may be changed by an application-specific completion function.
   @rl_completion_suppress_append = false

   # Character appended to completed words when at the end of the line.  The
   #   default is a space.
   @rl_completion_append_character = ' '

   # If non-zero, the completion functions don't append any closing quote.
   #   This is set to 0 by rl_complete_internal and may be changed by an
   #   application-specific completion function.
   @rl_completion_suppress_quote = false

   # Set to any quote character readline thinks it finds before any application
   #   completion function is called.
   @rl_completion_quote_character = 0

   # Set to a non-zero value if readline found quoting anywhere in the word to
   #   be completed set before any application completion function is called.
   @rl_completion_found_quote = false

   # If non-zero, a slash will be appended to completed filenames that are
   #  symbolic links to directory names, subject to the value of the
   #  mark-directories variable (which is user-settable).  This exists so
   #  that application completion functions can override the user's preference
   #  (set via the mark-symlinked-directories variable) if appropriate.
   #  It's set to the value of _rl_complete_mark_symlink_dirs in
   #  rl_complete_internal before any application-specific completion
   #  function is called, so without that function doing anything, the user's
   #  preferences are honored.
   @rl_completion_mark_symlink_dirs = false

   # If non-zero, inhibit completion (temporarily).
   @rl_inhibit_completion = false

   # Variables local to this file.

   # Local variable states what happened during the last completion attempt.
   @completion_changed_buffer = nil

   # Non-zero means treat 0200 bit in terminal input as Meta bit.
   @_rl_meta_flag = false

   # Stack of previous values of parsing_conditionalized_out.
   @if_stack = []
   @if_stack_depth = 0


   # The last key bindings file read.
   @last_readline_init_file = nil

   # The file we're currently reading key bindings from.
   @current_readline_init_file = nil
   @current_readline_init_include_level = 0
   @current_readline_init_lineno = 0

   ENV["HOME"] ||= ENV["HOMEDRIVE"]+ENV["HOMEPATH"]

   @directory = nil
   @filename = nil
   @dirname = nil
   @users_dirname = nil
   @filename_len = 0

   attr_accessor :rl_attempted_completion_function,:rl_deprep_term_function,
   :rl_event_hook,:rl_attempted_completion_over,:rl_basic_quote_characters,
   :rl_basic_word_break_characters,:rl_completer_quote_characters,
   :rl_completer_word_break_characters,:rl_completion_append_character,
   :rl_filename_quote_characters,:rl_instream,:rl_library_version,:rl_outstream,
   :rl_readline_name,:history_length,:history_base

   module_function
   # Okay, now we write the entry_function for filename completion.  In the
   #   general case.  Note that completion in the shell is a little different
   #   because of all the pathnames that must be followed when looking up the
   #   completion for a command.
   def rl_filename_completion_function(text, state)
      # If we don't have any state, then do some initialization.
      if (state == 0)
         # If we were interrupted before closing the directory or reading
         #all of its contents, close it.
         if(@directory)
            @directory.close
            @directory = nil
         end
         text.delete!(0.chr)
         if text.length == 0
            text = "."
         end

         @filename = ''
         @directory = nil
         dir = text.dup
         # We also support "~user" and "~/" syntax.
         if (dir[0,1] == '~')
            @users_dirname = dir.dup
            dir = File.expand_path(dir)
         end

         # Try the whole thing as a directory and if that fails, try dirname
         # and basename.  If that doesn't work either, then it wasn't meant to
         # be; we don't have a directory to open or a filename to complete.
         if File.directory?(dir) and File.readable?(dir)
            @directory = Dir.new(dir)
            @dirname = dir.dup
         elsif File.directory?(File.dirname(dir)) and File.readable?(File.dirname(dir))
            @dirname = File.dirname(dir)
            @directory = Dir.new(@dirname)
            @filename = File.basename(dir)
         end

         # Save the version of the directory that the user typed if we didn't
         # have a reason to do so before
         @users_dirname ||= @dirname.dup

         # The directory completion hook should perform any necessary
         #   dequoting.
         if (@rl_directory_completion_hook)
            send(rl_directory_completion_hook,@dirname)
         elsif (@rl_completion_found_quote && @rl_filename_dequoting_function)
            # delete single and double quotes
            temp = send(@rl_filename_dequoting_function,@users_dirname, @rl_completion_quote_character)
            @users_dirname = temp
         end

         # Now dequote a non-null filename.
         if (@filename && @filename.length>0 && @rl_completion_found_quote && @rl_filename_dequoting_function)
            # delete single and double quotes
            temp = send(@rl_filename_dequoting_function,@filename, @rl_completion_quote_character)
            @filename = temp
         end

         @filename_len = @filename.length
         @rl_filename_completion_desired = true
      end

      # At this point we should entertain the possibility of hacking wildcarded
      #   filenames, like /usr/man/man<WILD>/te<TAB>.  If the directory name
      #   contains globbing characters, then build an array of directories, and
      #   then map over that list while completing.
      # *** UNIMPLEMENTED ***

      # Now that we have some state, we can read the directory.
      entry = nil
      while(@directory && (entry = @directory.read))
         d_name = entry
         # Special case for no filename.  If the user has disabled the
         #   `match-hidden-files' variable, skip filenames beginning with `.'.
         #All other entries except "." and ".." match.
         if (@filename_len == 0)
            next if (!@_rl_match_hidden_files && d_name[0,1] == '.')
            break if (d_name != '.' && d_name != '..')
         else
            # Otherwise, if these match up to the length of filename, then
            #   it is a match.

            if (@_rl_completion_case_fold)
               break if d_name =~ /^#{Regexp.escape(@filename)}/i
            else
               break if d_name =~ /^#{Regexp.escape(@filename)}/
            end
         end
      end

      if entry.nil?
         if @directory
            @directory.close
            @directory = nil
         end
         @dirname = nil
         @filename = nil
         @users_dirname = nil

         return nil
      else
         if (@dirname != '.')
            if (@rl_complete_with_tilde_expansion && @users_dirname[0,1] == "~")
               temp = @dirname
            else
               temp = @users_dirname
            end

            # make sure the directory name has a trailing slash before
            # appending the file name
            temp += '/' if (temp[-1,1] != '/')
            temp += entry
         else
            temp = entry.dup
         end
         return (temp)
      end
   end

   # A completion function for usernames.
   #   TEXT contains a partial username preceded by a random
   #   character (usually `~').
   def rl_username_completion_function(text, state)
      return nil if RUBY_PLATFORM =~ /mswin|mingw/

      if (state == 0)
         first_char = text[0,1]
         first_char_loc = (first_char == '~' ? 1 : 0)

         username = text[first_char_loc..-1]
         namelen = username.length
         Etc.setpwent()
      end

      while (entry = Etc.getpwent())
         # Null usernames should result in all users as possible completions.
         break if (namelen == 0 || entry.name =~ /^#{username}/ )
      end

      if entry.nil?
         Etc.endpwent()
         return nil
      else
         value = text.dup
         value[first_char_loc..-1] = entry.name

         if (first_char == '~')
            @rl_filename_completion_desired = true
         end

         return (value)
      end
   end

   #*************************************************************
   #
   #  Application-callable completion match generator functions
   #
   #*************************************************************

   # Return an array of (char *) which is a list of completions for TEXT.
   #   If there are no completions, return a NULL pointer.
   #   The first entry in the returned array is the substitution for TEXT.
   #   The remaining entries are the possible completions.
   #   The array is terminated with a NULL pointer.
   #
   #   ENTRY_FUNCTION is a function of two args, and returns a (char *).
   #     The first argument is TEXT.
   #     The second is a state argument it should be zero on the first call, and
   #     non-zero on subsequent calls.  It returns a NULL pointer to the caller
   #     when there are no more matches.
   #
   def rl_completion_matches(text, entry_function)
      matches = 0
      match_list_size = 10
      match_list = []
      match_list[1] = nil
      while (string = send(entry_function, text, matches))
         match_list[matches+=1] = string
         match_list[matches+1] = nil
      end

      # If there were any matches, then look through them finding out the
      # lowest common denominator.  That then becomes match_list[0].
      if (matches!=0)
         compute_lcd_of_matches(match_list, matches, text)
      else                # There were no matches.
         match_list = nil
      end
      return (match_list)
   end

   def _rl_to_lower(char)
      char.nil? ? nil : char.chr.downcase
   end

   # Find the common prefix of the list of matches, and put it into
   #   matches[0].
   def compute_lcd_of_matches(match_list, matches, text)
      # If only one match, just use that.  Otherwise, compare each
      #   member of the list with the next, finding out where they
      #   stop matching.
      if (matches == 1)
         match_list[0] = match_list[1]
         match_list[1] = nil
         return 1
      end

      i = 1
      low = 100000
      while(i<matches)
         if (@_rl_completion_case_fold)
            si = 0
            while((c1 = _rl_to_lower(match_list[i][si])) &&
               (c2 = _rl_to_lower(match_list[i + 1][si])))
               if !@rl_byte_oriented
                  if(!_rl_compare_chars(match_list[i],si,match_list[i+1],si))
                     break
                  elsif ((v = _rl_get_char_len(match_list[i][si..-1])) > 1)
                     si += v - 1
                  end
               else
                  break if (c1 != c2)
               end
               si += 1
            end
         else
            si = 0
            while((c1 = match_list[i][si]) &&
               (c2 = match_list[i + 1][si]))
               if !@rl_byte_oriented
                  if(!_rl_compare_chars(match_list[i],si,match_list[i+1],si))
                     break
                  elsif ((v = _rl_get_char_len(match_list[i][si..-1])) > 1)
                     si += v - 1
                  end
               else
                  break if (c1 != c2)
               end
               si += 1
            end
         end

         if (low > si)
            low = si
         end
         i += 1
      end

      # If there were multiple matches, but none matched up to even the
      #   first character, and the user typed something, use that as the
      #   value of matches[0].
      if (low == 0 && text && text.length>0 )
         match_list[0] = text.dup
      else
         # XXX - this might need changes in the presence of multibyte chars

         # If we are ignoring case, try to preserve the case of the string
         # the user typed in the face of multiple matches differing in case.
         if (@_rl_completion_case_fold)

            # We're making an assumption here:
            #  IF we're completing filenames AND
            #     the application has defined a filename dequoting function AND
            #     we found a quote character AND
            #     the application has requested filename quoting
            #  THEN
            #     we assume that TEXT was dequoted before checking against
            #     the file system and needs to be dequoted here before we
            #     check against the list of matches
            #  FI
            if (@rl_filename_completion_desired &&
               @rl_filename_dequoting_function &&
               @rl_completion_found_quote &&
               @rl_filename_quoting_desired)

               dtext = send(@rl_filename_dequoting_function,text, @rl_completion_quote_character)
               text = dtext
            end

            # sort the list to get consistent answers.
            match_list = [match_list[0]] + match_list[1..-1].sort

            si = text.length
            if (si <= low)
               for i in 1 .. matches
                  if match_list[i][0,si] == text
                     match_list[0] = match_list[i][0,low]
                     break
                  end
                  # no casematch, use first entry
                  if (i > matches)
                     match_list[0] = match_list[1][0,low]
                  end
               end
            else
               # otherwise, just use the text the user typed.
               match_list[0] = text[0,low]
            end
         else
            match_list[0] = match_list[1][0,low]
         end
      end

      return matches
   end


   def rl_vi_editing_mode(count, key)
      _rl_set_insert_mode(RL_IM_INSERT, 1)    # vi mode ignores insert mode
      @rl_editing_mode = @vi_mode
      rl_vi_insertion_mode(1, key)
      0
   end

   # Switching from one mode to the other really just involves
   #   switching keymaps.
   def rl_vi_insertion_mode(count, key)
      @_rl_keymap = @vi_insertion_keymap
      @_rl_vi_last_key_before_insert = key
      0
   end

   def rl_emacs_editing_mode(count, key)
      @rl_editing_mode = @emacs_mode
      _rl_set_insert_mode(RL_IM_INSERT, 1) # emacs mode default is insert mode
      @_rl_keymap = @emacs_standard_keymap
      0
   end

   # Function for the rest of the library to use to set insert/overwrite mode.
   def _rl_set_insert_mode(im, force)
      @rl_insert_mode = im
   end

   # Toggle overwrite mode.  A positive explicit argument selects overwrite
   #   mode.  A negative or zero explicit argument selects insert mode.
   def rl_overwrite_mode(count, key)
      if (!@rl_explicit_arg)
         _rl_set_insert_mode(@rl_insert_mode ^ 1, 0)
      elsif (count > 0)
         _rl_set_insert_mode(RL_IM_OVERWRITE, 0)
      else
         _rl_set_insert_mode(RL_IM_INSERT, 0)
      end
      0
   end


   # A function for simple tilde expansion.
   def rl_tilde_expand(ignore, key)
      _end = @rl_point
      start = _end - 1

      if (@rl_point == @rl_end && @rl_line_buffer[@rl_point,1] == '~' )
         homedir = File.expand_path("~")
         _rl_replace_text(homedir, start, _end)
         return (0)
      elsif (@rl_line_buffer[start,1] != '~')
         while(!whitespace(@rl_line_buffer[start,1]) && start >= 0)
            start -= 1
         end
         start+=1
      end

      _end = start
      begin
         _end+=1
      end while(!whitespace(@rl_line_buffer[_end,1]) && _end < @rl_end)

      if (whitespace(@rl_line_buffer[_end,1]) || _end >= @rl_end)
         _end-=1
      end

      # If the first character of the current word is a tilde, perform
      #tilde expansion and insert the result.  If not a tilde, do
      #   nothing.
      if (@rl_line_buffer[start,1] == '~')

         len = _end - start + 1
         temp = @rl_line_buffer[start,len]
         homedir = File.expand_path(temp)
         temp = nil

         _rl_replace_text(homedir, start, _end)
      end
      0
   end

   # Clean up the terminal and readline state after catching a signal, before
   #   resending it to the calling application.
   def rl_cleanup_after_signal()
      _rl_clean_up_for_exit()
      if (@rl_deprep_term_function)
         send(@rl_deprep_term_function)
      end
      rl_clear_pending_input()
      rl_clear_signals()
   end

   def _rl_clean_up_for_exit()
      if @readline_echoing_p
         _rl_move_vert(@_rl_vis_botlin)
         @_rl_vis_botlin = 0
         @rl_outstream.flush
         rl_restart_output(1, 0)
      end
   end

   # Move the cursor from _rl_last_c_pos to NEW, which are buffer indices.
   #   (Well, when we don't have multibyte characters, _rl_last_c_pos is a
   #   buffer index.)
   #   DATA is the contents of the screen line of interest; i.e., where
   #   the movement is being done.
   def _rl_move_cursor_relative(new, data, start=0)

      woff = w_offset(@_rl_last_v_pos, @wrap_offset)
      cpos = @_rl_last_c_pos

      if !@rl_byte_oriented
         dpos = _rl_col_width(data, start, start+new)

         if (dpos > @prompt_last_invisible)     # XXX - don't use woff here
            dpos -= woff
            # Since this will be assigned to _rl_last_c_pos at the end (more
            #   precisely, _rl_last_c_pos == dpos when this function returns),
            #   let the caller know.
            @cpos_adjusted = true
         end
      else
         dpos = new
      end
      # If we don't have to do anything, then return.
      if (cpos == dpos)
         return
      end

      if @hConsoleHandle
         csbi = 0.chr * 24
         @GetConsoleScreenBufferInfo.Call(@hConsoleHandle,csbi)
         x,y = csbi[4,4].unpack('SS')
         x = dpos
         @SetConsoleCursorPosition.Call(@hConsoleHandle,y*65536+x)
         @_rl_last_c_pos = dpos
         return
      end

      # It may be faster to output a CR, and then move forwards instead
      #   of moving backwards.
      # i == current physical cursor position.
      if !@rl_byte_oriented
         i = @_rl_last_c_pos
      else
         i = @_rl_last_c_pos - woff
      end

      if (dpos == 0 || cr_faster(dpos, @_rl_last_c_pos) ||
         (@_rl_term_autowrap && i == @_rl_screenwidth))
         @rl_outstream.write(@_rl_term_cr)
         cpos = @_rl_last_c_pos = 0
      end

      if (cpos < dpos)
         # Move the cursor forward.  We do it by printing the command
         # to move the cursor forward if there is one, else print that
         # portion of the output buffer again.  Which is cheaper?

         # The above comment is left here for posterity.  It is faster
         # to print one character (non-control) than to print a control
         # sequence telling the terminal to move forward one character.
         # That kind of control is for people who don't know what the
         # data is underneath the cursor.

         # However, we need a handle on where the current display position is
         # in the buffer for the immediately preceding comment to be true.
         # In multibyte locales, we don't currently have that info available.
         # Without it, we don't know where the data we have to display begins
         # in the buffer and we have to go back to the beginning of the screen
         # line.  In this case, we can use the terminal sequence to move forward
         # if it's available.
         if !@rl_byte_oriented
            if (@_rl_term_forward_char)
               @rl_outstream.write(@_rl_term_forward_char * (dpos-cpos))
            else
               @rl_outstream.write(@_rl_term_cr)
               @rl_outstream.write(data[start,new])
            end
         else
            @rl_outstream.write(data[start+cpos,new-cpos])
         end
      elsif (cpos > dpos)
         _rl_backspace(cpos - dpos)
      end
      @_rl_last_c_pos = dpos
   end


   # PWP: move the cursor up or down.
   def _rl_move_vert(to)
      if (@_rl_last_v_pos == to || to > @_rl_screenheight)
         return
      end

      if ((delta = to - @_rl_last_v_pos) > 0)
         @rl_outstream.write("\n"*delta)
         @rl_outstream.write("\r")
         @_rl_last_c_pos = 0
      else
         if(@_rl_term_up)
            @rl_outstream.write(@_rl_term_up*(-delta))
         end
      end
      @_rl_last_v_pos = to        # Now TO is here
   end

   def rl_setstate(x)
      (@rl_readline_state |= (x))
   end

   def rl_unsetstate(x)
      (@rl_readline_state &= ~(x))
   end

   def rl_isstate(x)
      (@rl_readline_state & (x))!=0
   end

   # Clear any pending input pushed with rl_execute_next()
   def rl_clear_pending_input()
      @rl_pending_input = 0
      rl_unsetstate(RL_STATE_INPUTPENDING)
      0
   end

   def rl_restart_output(count, key)
      0
   end

   def rl_clear_signals()
      if Signal.list['WINCH']
         trap "WINCH",@def_proc
      end
   end

   def rl_set_signals()
      if Signal.list['WINCH']
         @def_proc = trap "WINCH",Proc.new{rl_sigwinch_handler(0)}
      end
   end

   # Current implementation:
   #    \001 (^A) start non-visible characters
   #    \002 (^B) end non-visible characters
   #   all characters except \001 and \002 (following a \001) are copied to
   #   the returned string all characters except those between \001 and
   #   \002 are assumed to be `visible'.
   def expand_prompt(pmt)
      # Short-circuit if we can.
      if (@rl_byte_oriented && pmt[RL_PROMPT_START_IGNORE].nil?)
         r = pmt.dup
         lp = r.length
         lip = 0
         niflp = 0
         vlp = lp
         return [r,lp,lip,niflp,vlp]
      end

      l = pmt.length
      ret = ''
      invfl = 0    # invisible chars in first line of prompt
      invflset = 0    # we only want to set invfl once

      igstart = 0
      rl = 0
      ignoring = false
      last = ninvis = physchars = 0
      for pi in 0 ... pmt.length
         # This code strips the invisible character string markers
         #RL_PROMPT_START_IGNORE and RL_PROMPT_END_IGNORE
         if (!ignoring && pmt[pi,1] == RL_PROMPT_START_IGNORE)        # XXX - check ignoring?
            ignoring = true
            igstart = pi
            next
         elsif (ignoring && pmt[pi,1] == RL_PROMPT_END_IGNORE)
            ignoring = false
            if (pi != (igstart + 1))
               last = ret.length - 1
            end
            next
         else
            if !@rl_byte_oriented
               pind = pi
               ind = _rl_find_next_mbchar(pmt, pind, 1, MB_FIND_NONZERO)
               l = ind - pind
               while (l>0)
                  l-=1
                  ret << pmt[pi]
                  pi += 1
               end
               if (!ignoring)
                  rl += ind - pind
                  physchars += _rl_col_width(pmt, pind, ind)
               else
                  ninvis += ind - pind
               end
               pi-=1       # compensate for later increment
            else
               ret << pmt[pi]
               if (!ignoring)
                  rl+=1            # visible length byte counter
                  physchars+=1
               else
                  ninvis+=1        # invisible chars byte counter
               end

               if (invflset == 0 && rl >= @_rl_screenwidth)
                  invfl = ninvis
                  invflset = 1
               end
            end
         end
      end

      if (rl < @_rl_screenwidth)
         invfl = ninvis
      end
      lp = rl
      lip = last
      niflp = invfl
      vlp = physchars
      return [ret,lp,lip,niflp,vlp]
   end


   #*
   #* Expand the prompt string into the various display components, if
   #* necessary.
   #*
   #* local_prompt = expanded last line of string in rl_display_prompt
   #*          (portion after the final newline)
   #* local_prompt_prefix = portion before last newline of rl_display_prompt,
   #*             expanded via expand_prompt
   #* prompt_visible_length = number of visible characters in local_prompt
   #* prompt_prefix_length = number of visible characters in local_prompt_prefix
   #*
   #* This function is called once per call to readline().  It may also be
   #* called arbitrarily to expand the primary prompt.
   #*
   #* The return value is the number of visible characters on the last line
   #* of the (possibly multi-line) prompt.
   #*
   def rl_expand_prompt(prompt)
      @local_prompt = @local_prompt_prefix = nil
      @local_prompt_len = 0
      @prompt_last_invisible = @prompt_invis_chars_first_line = 0
      @prompt_visible_length = @prompt_physical_chars = 0

      if (prompt.nil? || prompt == '')
         return (0)
      end

      pi = prompt.rindex("\n")
      if pi.nil?
         # The prompt is only one logical line, though it might wrap.
         @local_prompt,@prompt_visible_length,@prompt_last_invisible,@prompt_invis_chars_first_line,@prompt_physical_chars =
         expand_prompt(prompt)
         @local_prompt_prefix = nil
         @local_prompt_len = @local_prompt ? @local_prompt.length : 0
         return (@prompt_visible_length)
      else
         # The prompt spans multiple lines.
         pi += 1 if prompt.length!=pi+1
         t = pi
         @local_prompt,@prompt_visible_length,@prompt_last_invisible,_,@prompt_physical_chars = expand_prompt(prompt[pi..-1])
         c = prompt[t]
         prompt[t] = 0.chr
         # The portion of the prompt string up to and including the
         #final newline is now null-terminated.
         @local_prompt_prefix,@prompt_prefix_length,_,@prompt_invis_chars_first_line, = expand_prompt(prompt)
         prompt[t] = c
         @local_prompt_len = @local_prompt ? @local_prompt.length : 0
         return (@prompt_prefix_length)
      end
   end

   # Set up the prompt and expand it.  Called from readline() and
   #   rl_callback_handler_install ().
   def rl_set_prompt(prompt)
      @rl_prompt = prompt ? prompt.dup : nil
      @rl_display_prompt = @rl_prompt ? @rl_prompt : ""
      @rl_visible_prompt_length = rl_expand_prompt(@rl_prompt)
      0
   end

   def get_term_capabilities(buffer)
      hash = {}
      `infocmp -C`.split(':').select{|x| x =~ /(.*)=(.*)/ and hash[$1]=$2.gsub('\\E',"\e").gsub(/\^(.)/){($1[0].ord ^ ((?a..?z).include?($1[0]) ? 0x60 : 0x40)).chr}}
      @_rl_term_at7          =     hash["@7"]
      @_rl_term_DC           =     hash["DC"]
      @_rl_term_IC           =     hash["IC"]
      @_rl_term_clreol       =     hash["ce"]
      @_rl_term_clrpag       =     hash["cl"]
      @_rl_term_cr           =     hash["cr"]
      @_rl_term_dc           =     hash["dc"]
      @_rl_term_ei           =     hash["ei"]
      @_rl_term_ic           =     hash["ic"]
      @_rl_term_im           =     hash["im"]
      @_rl_term_kD           =     hash["kD"]
      @_rl_term_kH           =     hash["kH"]
      @_rl_term_kI           =     hash["kI"]
      @_rl_term_kd           =     hash["kd"]
      @_rl_term_ke           =     hash["ke"]
      @_rl_term_kh           =     hash["kh"]
      @_rl_term_kl           =     hash["kl"]
      @_rl_term_kr           =     hash["kr"]
      @_rl_term_ks           =     hash["ks"]
      @_rl_term_ku           =     hash["ku"]
      @_rl_term_backspace    =     hash["le"]
      @_rl_term_mm           =     hash["mm"]
      @_rl_term_mo           =     hash["mo"]
      @_rl_term_forward_char =     hash["nd"]
      @_rl_term_pc           =     hash["pc"]
      @_rl_term_up           =     hash["up"]
      @_rl_visible_bell      =     hash["vb"]
      @_rl_term_vs           =     hash["vs"]
      @_rl_term_ve           =     hash["ve"]
      @tcap_initialized = true
   end

   # Set the environment variables LINES and COLUMNS to lines and cols,
   #   respectively.
   def sh_set_lines_and_columns(lines, cols)
      ENV["LINES"] = lines.to_s
      ENV["COLUMNS"] = cols.to_s
   end

   # Get readline's idea of the screen size.  TTY is a file descriptor open
   #   to the terminal.  If IGNORE_ENV is true, we do not pay attention to the
   #   values of $LINES and $COLUMNS.  The tests for TERM_STRING_BUFFER being
   #   non-null serve to check whether or not we have initialized termcap.
   def _rl_get_screen_size(tty, ignore_env)

      if @hConsoleHandle
         csbi = 0.chr * 24
         @GetConsoleScreenBufferInfo.Call(@hConsoleHandle,csbi)
         wc,wr = csbi[0,4].unpack('SS')
         # wr,wc, = `mode con`.scan(/\d+\n/).map{|x| x.to_i}
         @_rl_screenwidth = wc
         @_rl_screenheight = wr
      else
         wr,wc = `stty size`.split(' ').map{|x| x.to_i}
         @_rl_screenwidth = wc
         @_rl_screenheight = wr
         if ignore_env==0 && ENV['LINES']
            @_rl_screenheight = ENV['LINES'].to_i
         end
         if ignore_env==0 && ENV['COLUMNS']
            @_rl_screenwidth = ENV['COLUMNS'].to_i
         end
      end

      # If all else fails, default to 80x24 terminal.
      if @_rl_screenwidth.nil? || @_rl_screenwidth <= 1
         @_rl_screenwidth = 80
      end
      if @_rl_screenheight.nil? || @_rl_screenheight <= 0
         @_rl_screenheight = 24
      end
      # If we're being compiled as part of bash, set the environment
      #   variables $LINES and $COLUMNS to new values.  Otherwise, just
      #   do a pair of putenv () or setenv () calls.
      sh_set_lines_and_columns(@_rl_screenheight, @_rl_screenwidth)

      if !@_rl_term_autowrap
         @_rl_screenwidth-=1
      end
      @_rl_screenchars = @_rl_screenwidth * @_rl_screenheight
   end

   def tgetflag(name)
      `infocmp -C -r`.scan(/\w{2}/).include?(name)
   end

   # Return the function (or macro) definition which would be invoked via
   #   KEYSEQ if executed in MAP.  If MAP is NULL, then the current keymap is
   #   used.  TYPE, if non-NULL, is a pointer to an int which will receive the
   #   type of the object pointed to.  One of ISFUNC (function), ISKMAP (keymap),
   #   or ISMACR (macro).
   def rl_function_of_keyseq(keyseq, map, type)
      map ||= @_rl_keymap
      map[keyseq]
   end

   # Bind the key sequence represented by the string KEYSEQ to
   #   the arbitrary pointer DATA.  TYPE says what kind of data is
   #   pointed to by DATA, right now this can be a function (ISFUNC),
   #   a macro (ISMACR), or a keymap (ISKMAP).  This makes new keymaps
   #   as necessary.  The initial place to do bindings is in MAP.
   def rl_generic_bind(type, keyseq, data, map)
      map[keyseq] = data
      0
   end

   # Bind the key sequence represented by the string KEYSEQ to
   #   FUNCTION.  This makes new keymaps as necessary.  The initial
   #   place to do bindings is in MAP.
   def rl_bind_keyseq_in_map(keyseq, function, map)
      rl_generic_bind(ISFUNC, keyseq, function, map)
   end


   # Bind key sequence KEYSEQ to DEFAULT_FUNC if KEYSEQ is unbound.  Right
   #   now, this is always used to attempt to bind the arrow keys, hence the
   #   check for rl_vi_movement_mode.
   def rl_bind_keyseq_if_unbound_in_map(keyseq, default_func, kmap)
      if (keyseq)
         func = rl_function_of_keyseq(keyseq, kmap, nil)
         if (func.nil? || func == :rl_vi_movement_mode)
            return (rl_bind_keyseq_in_map(keyseq, default_func, kmap))
         else
            return 1
         end
      end
      0
   end

   def rl_bind_keyseq_if_unbound(keyseq, default_func)
      rl_bind_keyseq_if_unbound_in_map(keyseq, default_func, @_rl_keymap)
   end

   # Bind the arrow key sequences from the termcap description in MAP.
   def bind_termcap_arrow_keys(map)
      xkeymap = @_rl_keymap
      @_rl_keymap = map

      rl_bind_keyseq_if_unbound(@_rl_term_ku, :rl_get_previous_history)
      rl_bind_keyseq_if_unbound(@_rl_term_kd, :rl_get_next_history)
      rl_bind_keyseq_if_unbound(@_rl_term_kr, :rl_forward_char)
      rl_bind_keyseq_if_unbound(@_rl_term_kl, :rl_backward_char)

      rl_bind_keyseq_if_unbound(@_rl_term_kh, :rl_beg_of_line) # Home
      rl_bind_keyseq_if_unbound(@_rl_term_at7, :rl_end_of_line)   # End

      rl_bind_keyseq_if_unbound(@_rl_term_kD, :rl_delete)
      rl_bind_keyseq_if_unbound(@_rl_term_kI, :rl_overwrite_mode)

      @_rl_keymap = xkeymap
   end

   def _rl_init_terminal_io(terminal_name)
      term = terminal_name ? terminal_name : ENV["TERM"]
      @_rl_term_clrpag = @_rl_term_cr = @_rl_term_clreol = nil
      tty = @rl_instream ? @rl_instream.fileno : 0

      if no_terminal?
         term = "dumb"
         @_rl_bind_stty_chars = false
      end

      @term_string_buffer ||= 0.chr * 2032

      @term_buffer ||= 0.chr * 4080

      buffer = @term_string_buffer

      tgetent_ret = (term != "dumb") ? 1 : -1

      if (tgetent_ret <= 0)
         buffer = @term_buffer = @term_string_buffer = nil

         @_rl_term_autowrap = false    # used by _rl_get_screen_size

         # Allow calling application to set default height and width, using
         #rl_set_screen_size
         if (@_rl_screenwidth <= 0 || @_rl_screenheight <= 0)
            _rl_get_screen_size(tty, 0)
         end

         # Defaults.
         if (@_rl_screenwidth <= 0 || @_rl_screenheight <= 0)
            @_rl_screenwidth = 79
            @_rl_screenheight = 24
         end

         # Everything below here is used by the redisplay code (tputs).
         @_rl_screenchars = @_rl_screenwidth * @_rl_screenheight
         @_rl_term_cr = "\r"
         @_rl_term_im = @_rl_term_ei = @_rl_term_ic = @_rl_term_IC = nil
         @_rl_term_up = @_rl_term_dc = @_rl_term_DC = @_rl_visible_bell = nil
         @_rl_term_ku = @_rl_term_kd = @_rl_term_kl = @_rl_term_kr = nil
         @_rl_term_kh = @_rl_term_kH = @_rl_term_kI = @_rl_term_kD = nil
         @_rl_term_ks = @_rl_term_ke = @_rl_term_at7 = nil
         @_rl_term_mm = @_rl_term_mo = nil
         @_rl_term_ve = @_rl_term_vs = nil
         @_rl_term_forward_char = nil
         @_rl_terminal_can_insert = @term_has_meta = false

         # Reasonable defaults for tgoto().  Readline currently only uses
         #   tgoto if _rl_term_IC or _rl_term_DC is defined, but just in case we
         #   change that later...
         @_rl_term_backspace = "\b"

         return 0
      end

      get_term_capabilities(buffer)

      @_rl_term_cr ||= "\r"
      @_rl_term_autowrap = !!(tgetflag("am") && tgetflag("xn"))

      # Allow calling application to set default height and width, using
      #   rl_set_screen_size
      if (@_rl_screenwidth <= 0 || @_rl_screenheight <= 0)
         _rl_get_screen_size(tty, 0)
      end

      # "An application program can assume that the terminal can do
      #    character insertion if *any one of* the capabilities `IC',
      #    `im', `ic' or `ip' is provided."  But we can't do anything if
      #    only `ip' is provided, so...
      @_rl_terminal_can_insert = !!(@_rl_term_IC || @_rl_term_im || @_rl_term_ic)

      # Check to see if this terminal has a meta key and clear the capability
      #   variables if there is none.
      @term_has_meta = !!(tgetflag("km") || tgetflag("MT"))
      if !@term_has_meta
         @_rl_term_mm = @_rl_term_mo = nil
      end

      # Attempt to find and bind the arrow keys.  Do not override already
      #   bound keys in an overzealous attempt, however.

      bind_termcap_arrow_keys(@emacs_standard_keymap)

      bind_termcap_arrow_keys(@vi_movement_keymap)
      bind_termcap_arrow_keys(@vi_insertion_keymap)

      return 0
   end

   # New public way to set the system default editing chars to their readline
   #   equivalents.
   def rl_tty_set_default_bindings(kmap)
      h = Hash[*`stty -a`.scan(/(\w+) = ([^;]+);/).flatten]
      h.each {|k,v| v.gsub!(/\^(.)/){($1[0].ord ^ ((?a..?z).include?($1[0]) ? 0x60 : 0x40)).chr}}
      kmap[h['erase']] = :rl_rubout
      kmap[h['kill']] = :rl_unix_line_discard
      kmap[h['werase']] = :rl_unix_word_rubout
      kmap[h['lnext']] = :rl_quoted_insert
   end

   # If this system allows us to look at the values of the regular
   #   input editing characters, then bind them to their readline
   #   equivalents, iff the characters are not bound to keymaps.
   def readline_default_bindings()
      if @_rl_bind_stty_chars
         rl_tty_set_default_bindings(@_rl_keymap)
      end
   end

   def _rl_init_eightbit()

   end


   # Do key bindings from a file.  If FILENAME is NULL it defaults
   #   to the first non-null filename from this list:
   #     1. the filename used for the previous call
   #     2. the value of the shell variable `INPUTRC'
   #     3. ~/.inputrc
   #     4. /etc/inputrc
   #   If the file existed and could be opened and read, 0 is returned,
   #   otherwise errno is returned.
   def rl_read_init_file(filename)


=begin
      # Default the filename.
      filename ||= @last_readline_init_file
      filename ||= ENV["INPUTRC"]
      if (filename.nil? || filename == '')
         filename = DEFAULT_INPUTRC
         # Try to read DEFAULT_INPUTRC; fall back to SYS_INPUTRC on failure
         if (_rl_read_init_file(filename, 0) == 0)
            return 0
         end
         filename = SYS_INPUTRC
      end

      if RUBY_PLATFORM =~ /mswin|mingw/
         return 0 if (_rl_read_init_file(filename, 0) == 0)
         filename = "~/_inputrc"
      end
      return (_rl_read_init_file(filename, 0))
=end
      #
      # This code is too problematic at the moment
      # Just hardcode things and move on
      #
      return 0
   end

   def _rl_read_init_file(filename, include_level)
      @current_readline_init_file = filename
      @current_readline_init_include_level = include_level

      openname = File.expand_path(filename)
      begin
         buffer = File.open(openname).read
      rescue
         return -1
      end

      if (include_level == 0 && filename != @last_readline_init_file)
         @last_readline_init_file = filename.dup
      end

      @currently_reading_init_file = true

      # Loop over the lines in the file.  Lines that start with `#' are
      #   comments; all other lines are commands for readline initialization.
      @current_readline_init_lineno = 1

      buffer.each_line do |line|
         line.strip!
         next if line =~ /^#/
         next if line == ''
         rl_parse_and_bind(line)
      end

      return 0
   end

   # Push _rl_parsing_conditionalized_out, and set parser state based
   #   on ARGS.
   def parser_if(args)
      # Push parser state.
      @if_stack << @_rl_parsing_conditionalized_out

      # If parsing is turned off, then nothing can turn it back on except
      #   for finding the matching endif.  In that case, return right now.
      if @_rl_parsing_conditionalized_out
         return 0
      end

      args.downcase!
      # Handle "$if term=foo" and "$if mode=emacs" constructs.  If this
      #   isn't term=foo, or mode=emacs, then check to see if the first
      #   word in ARGS is the same as the value stored in rl_readline_name.
      if (@rl_terminal_name && args =~ /^term=/)
         # Terminals like "aaa-60" are equivalent to "aaa".
         tname = @rl_terminal_name.downcase.gsub(/-.*$/,'')

         # Test the `long' and `short' forms of the terminal name so that
         #if someone has a `sun-cmd' and does not want to have bindings
         #that will be executed if the terminal is a `sun', they can put
         #`$if term=sun-cmd' into their .inputrc.
         @_rl_parsing_conditionalized_out = (args[5..-1] != tname && args[5..-1] != @rl_terminal_name.downcase)
      elsif args =~ /^mode=/
         if args[5..-1] == "emacs"
            mode = @emacs_mode
         elsif args[5..-1] == "vi"
            $stderr.puts "*** Warning: vi-mode not supported, switching back to emacs mode"
            mode = @emacs_mode
         else
            mode = @no_mode
         end
         @_rl_parsing_conditionalized_out = (mode != @rl_editing_mode)
         # Check to see if the first word in ARGS is the same as the
         #   value stored in rl_readline_name.
      elsif (args == @rl_readline_name)
         @_rl_parsing_conditionalized_out = false
      else
         @_rl_parsing_conditionalized_out = true
      end
      return 0
   end

   # Invert the current parser state if there is anything on the stack.
   def parser_else(args)
      if @if_stack.empty?
         #_rl_init_file_error ("$else found without matching $if")
         return 0
      end

      # Check the previous (n) levels of the stack to make sure that
      #   we haven't previously turned off parsing.
      return 0 if @if_stack.detect {|x| x }

      # Invert the state of parsing if at top level.
      @_rl_parsing_conditionalized_out = !@_rl_parsing_conditionalized_out
      return 0
   end

   # Terminate a conditional, popping the value of
   #   _rl_parsing_conditionalized_out from the stack.
   def parser_endif(args)
      if (@if_stack.length>0)
         @_rl_parsing_conditionalized_out = @if_stack.pop
      else
         #_rl_init_file_error ("$endif without matching $if")
      end
      0
   end

   def parser_include(args)
      return 0 if (@_rl_parsing_conditionalized_out)

      old_init_file = @current_readline_init_file
      old_line_number = @current_readline_init_lineno
      old_include_level = @current_readline_init_include_level

      r = _rl_read_init_file(args, old_include_level + 1)

      @current_readline_init_file = old_init_file
      @current_readline_init_lineno = old_line_number
      @current_readline_init_include_level = old_include_level

      return r
   end

   # Handle a parser directive.  STATEMENT is the line of the directive
   #   without any leading `$'.
   def handle_parser_directive(statement)

      directive,args = statement.split(' ')

      case directive.downcase
      when "if"
         parser_if(args)
         return 0
      when "endif"
         parser_endif(args)
         return 0
      when "else"
         parser_else(args)
         return 0
      when "include"
         parser_include(args)
         return 0
      end

      #_rl_init_file_error("unknown parser directive")
      return 1
   end


   def rl_variable_bind(name,value)
      case name
      when "bind-tty-special-chars"
         @_rl_bind_stty_chars = value.nil? || value=='1' || value == 'on'
      when "blink-matching-paren"
         @rl_blink_matching_paren = value.nil? || value=='1' || value == 'on'
      when "byte-oriented"
         @rl_byte_oriented = value.nil? || value=='1' || value == 'on'
      when "completion-ignore-case"
         @_rl_completion_case_fold = value.nil? || value=='1' || value == 'on'
      when "convert-meta"
         @_rl_convert_meta_chars_to_ascii = value.nil? || value=='1' || value == 'on'
      when "disable-completion"
         @rl_inhibit_completion = value.nil? || value=='1' || value == 'on'
      when "enable-keypad"
         @_rl_enable_keypad = value.nil? || value=='1' || value == 'on'
      when "expand-tilde"
         @rl_complete_with_tilde_expansion = value.nil? || value=='1' || value == 'on'
      when "history-preserve-point"
         @_rl_history_preserve_point = value.nil? || value=='1' || value == 'on'
      when "horizontal-scroll-mode"
         @_rl_horizontal_scroll_mode = value.nil? || value=='1' || value == 'on'
      when "input-meta"
         @_rl_meta_flag = value.nil? || value=='1' || value == 'on'
      when "mark-directories"
         @_rl_complete_mark_directories = value.nil? || value=='1' || value == 'on'
      when "mark-modified-lines"
         @_rl_mark_modified_lines = value.nil? || value=='1' || value == 'on'
      when "mark-symlinked-directories"
         @_rl_complete_mark_symlink_dirs = value.nil? || value=='1' || value == 'on'
      when "match-hidden-files"
         @_rl_match_hidden_files = value.nil? || value=='1' || value == 'on'
      when "meta-flag"
         @_rl_meta_flag = value.nil? || value=='1' || value == 'on'
      when "output-meta"
         @_rl_output_meta_chars = value.nil? || value=='1' || value == 'on'
      when "page-completions"
         @_rl_page_completions = value.nil? || value=='1' || value == 'on'
      when "prefer-visible-bell"
         @_rl_prefer_visible_bell = value.nil? || value=='1' || value == 'on'
      when "print-completions-horizontally"
         @_rl_print_completions_horizontally = value.nil? || value=='1' || value == 'on'
      when "show-all-if-ambiguous"
         @_rl_complete_show_all = value.nil? || value=='1' || value == 'on'
      when "show-all-if-unmodified"
         @_rl_complete_show_unmodified = value.nil? || value=='1' || value == 'on'
      when "visible-stats"
         @rl_visible_stats = value.nil? || value=='1' || value == 'on'
      when "bell-style"
         case value
         when "none","off"
            @_rl_bell_preference = NO_BELL
         when "audible", "on"
            @_rl_bell_preference = AUDIBLE_BELL
         when "visible"
            @_rl_bell_preference = VISIBLE_BELL
         else
            @_rl_bell_preference = AUDIBLE_BELL
         end
      when "comment-begin"
         @_rl_comment_begin = value.dup
      when "completion-query-items"
         @rl_completion_query_items = value.to_i
      when "editing-mode"
         case value
         when "vi"
            $stderr.puts "*** Warning: vi editing-mode not supported, switching back to emacs"
            #@_rl_keymap = @vi_insertion_keymap
            #@rl_editing_mode = @vi_mode
            @_rl_keymap = @emacs_standard_keymap
            @rl_editing_mode = @emacs_mode
         when "emacs"
            @_rl_keymap = @emacs_standard_keymap
            @rl_editing_mode = @emacs_mode
         end
      when "isearch-terminators"
         @_rl_isearch_terminators = instance_eval(value)
      when "keymap"
         case value
         when "emacs","emacs-standard","emacs-meta","emacs-ctlx"
            @_rl_keymap = @emacs_standard_keymap
         when "vi","vi-move","vi-command"
            @_rl_keymap = @vi_movement_keymap
         when "vi-insert"
            @_rl_keymap = @vi_insertion_keymap
         end
      end
   end

   def rl_named_function(name)
      case name
      when "accept-line"
         return :rl_newline
      when "arrow-key-prefix"
         return :rl_arrow_keys
      when "backward-delete-char"
         return :rl_rubout
      when "character-search"
         return :rl_char_search
      when  "character-search-backward"
         return :rl_backward_char_search
      when "copy-region-as-kill"
         return :rl_copy_region_to_kill
      when "delete-char"
         return :rl_delete
      when "delete-char-or-list"
         return :rl_delete_or_show_completions
      when "forward-backward-delete-char"
         return :rl_rubout_or_delete
      when "kill-whole-line"
         return :rl_kill_full_line
      when "non-incremental-forward-search-history"
         return :rl_noninc_forward_search
      when "non-incremental-reverse-search-history"
         return :rl_noninc_reverse_search
      when "non-incremental-forward-search-history-again"
         return :rl_noninc_forward_search_again
      when "non-incremental-reverse-search-history-again"
         return :rl_noninc_reverse_search_again
      when "redraw-current-line"
         return :rl_refresh_line
      when "self-insert"
         return :rl_insert
      when "undo"
         return :rl_undo_command
      when "beginning-of-line"
         return :rl_beg_of_line
      else
         if name =~ /^[-a-z]+$/
            return ('rl_'+name.gsub('-','_')).to_sym
         end
      end
      nil
   end

   # Bind KEY to FUNCTION.  Returns non-zero if KEY is out of range.
   def rl_bind_key(key, function)
      @_rl_keymap[key] = function
      @rl_binding_keymap = @_rl_keymap
      0
   end

   # Read the binding command from STRING and perform it.
   #   A key binding command looks like: Keyname: function-name\0,
   #   a variable binding command looks like: set variable value.
   #   A new-style keybinding looks like "\C-x\C-x": exchange-point-and-mark.
   def rl_parse_and_bind(string)

      # If this is a parser directive, act on it.
      if (string[0,1] == "$")
         handle_parser_directive(string[1..-1])
         return 0
      end

      # If we aren't supposed to be parsing right now, then we're done.
      return 0 if @_rl_parsing_conditionalized_out

      if string =~ /^set/i
         _,var,value = string.downcase.split(' ')
         rl_variable_bind(var, value)
         return 0
      end

      if string =~ /"(.*)"\s*:\s*(.*)$/
       key, funname = $1, $2

         rl_bind_key(key, rl_named_function(funname))
      end

      0
   end


   def _rl_enable_meta_key()
      if(@term_has_meta && @_rl_term_mm)
         @_rl_out_stream.write(@_rl_term_mm)
      end
   end

   def rl_set_keymap_from_edit_mode()
      if (@rl_editing_mode == @emacs_mode)
         @_rl_keymap = @emacs_standard_keymap
      elsif (@rl_editing_mode == @vi_mode)
         @_rl_keymap = @vi_insertion_keymap
      end
   end

   def rl_get_keymap_name_from_edit_mode()
      if (@rl_editing_mode == @emacs_mode)
         "emacs"
      elsif (@rl_editing_mode == @vi_mode)
         "vi"
      else
         "none"
      end
   end

   # Bind some common arrow key sequences in MAP.
   def bind_arrow_keys_internal(map)
      xkeymap = @_rl_keymap
      @_rl_keymap = map

      if RUBY_PLATFORM =~ /mswin|mingw/
         rl_bind_keyseq_if_unbound("\340H", :rl_get_previous_history) # Up
         rl_bind_keyseq_if_unbound("\340P", :rl_get_next_history) # Down
         rl_bind_keyseq_if_unbound("\340M", :rl_forward_char)  # Right
         rl_bind_keyseq_if_unbound("\340K", :rl_backward_char) # Left
         rl_bind_keyseq_if_unbound("\340G", :rl_beg_of_line)   # Home
         rl_bind_keyseq_if_unbound("\340O", :rl_end_of_line)   # End
         rl_bind_keyseq_if_unbound("\340s", :rl_backward_word) # Ctrl-Left
         rl_bind_keyseq_if_unbound("\340t", :rl_forward_word) # Ctrl-Right
         rl_bind_keyseq_if_unbound("\340S", :rl_delete) # Delete
         rl_bind_keyseq_if_unbound("\340R", :rl_overwrite_mode) # Insert
      else
         rl_bind_keyseq_if_unbound("\033[A", :rl_get_previous_history)
         rl_bind_keyseq_if_unbound("\033[B", :rl_get_next_history)
         rl_bind_keyseq_if_unbound("\033[C", :rl_forward_char)
         rl_bind_keyseq_if_unbound("\033[D", :rl_backward_char)
         rl_bind_keyseq_if_unbound("\033[H", :rl_beg_of_line)
         rl_bind_keyseq_if_unbound("\033[F", :rl_end_of_line)

         rl_bind_keyseq_if_unbound("\033OA", :rl_get_previous_history)
         rl_bind_keyseq_if_unbound("\033OB", :rl_get_next_history)
         rl_bind_keyseq_if_unbound("\033OC", :rl_forward_char)
         rl_bind_keyseq_if_unbound("\033OD", :rl_backward_char)
         rl_bind_keyseq_if_unbound("\033OH", :rl_beg_of_line)
         rl_bind_keyseq_if_unbound("\033OF", :rl_end_of_line)
      end

      @_rl_keymap = xkeymap
   end

   # Try and bind the common arrow key prefixes after giving termcap and
   #   the inputrc file a chance to bind them and create `real' keymaps
   #   for the arrow key prefix.
   def bind_arrow_keys()
      bind_arrow_keys_internal(@emacs_standard_keymap)
      bind_arrow_keys_internal(@vi_movement_keymap)
      bind_arrow_keys_internal(@vi_insertion_keymap)
   end

   # Initialize the entire state of the world.
   def readline_initialize_everything()
      # Set up input and output if they are not already set up.
      @rl_instream ||= $stdin

      @rl_outstream ||= $stdout

      # Bind _rl_in_stream and _rl_out_stream immediately.  These values
      #   may change, but they may also be used before readline_internal ()
      #   is called.
      @_rl_in_stream = @rl_instream
      @_rl_out_stream = @rl_outstream

      # Allocate data structures.
      @rl_line_buffer = ""

      # Initialize the terminal interface.
      @rl_terminal_name ||= ENV["TERM"]
      _rl_init_terminal_io(@rl_terminal_name)

      # Bind tty characters to readline functions.
      readline_default_bindings()

      # Decide whether we should automatically go into eight-bit mode.
      _rl_init_eightbit()

      # Read in the init file.
      rl_read_init_file(nil)

      # XXX
      if (@_rl_horizontal_scroll_mode && @_rl_term_autowrap)
         @_rl_screenwidth -= 1
         @_rl_screenchars -= @_rl_screenheight
      end

      # Override the effect of any `set keymap' assignments in the
      #   inputrc file.
      rl_set_keymap_from_edit_mode()

      # Try to bind a common arrow key prefix, if not already bound.
      bind_arrow_keys()

      # Enable the meta key, if this terminal has one.
      if @_rl_enable_meta
         _rl_enable_meta_key()
      end

      # If the completion parser's default word break characters haven't
      #   been set yet, then do so now.
      @rl_completer_word_break_characters ||= @rl_basic_word_break_characters
   end

   def _rl_init_line_state()
      @rl_point = @rl_end = @rl_mark = 0
      @rl_line_buffer = ""
   end

   # Set the history pointer back to the last entry in the history.
   def _rl_start_using_history()
      using_history()
      @_rl_saved_line_for_history = nil
   end


   def cr_faster(new, cur)
      (new + 1) < (cur - new)
   end

   #* _rl_last_c_pos is an absolute cursor position in multibyte locales and a
   #   buffer index in others.  This macro is used when deciding whether the
   #   current cursor position is in the middle of a prompt string containing
   #   invisible characters.
   def prompt_ending_index()
      if !@rl_byte_oriented
         @prompt_physical_chars
      else
         (@prompt_last_invisible+1)
      end
   end

   # Initialize the VISIBLE_LINE and INVISIBLE_LINE arrays, and their associated
   #   arrays of line break markers.  MINSIZE is the minimum size of VISIBLE_LINE
   #   and INVISIBLE_LINE; if it is greater than LINE_SIZE, LINE_SIZE is
   #   increased.  If the lines have already been allocated, this ensures that
   #   they can hold at least MINSIZE characters.
   def init_line_structures(minsize)
      if @invisible_line.nil? # initialize it
         if (@line_size < minsize)
            @line_size = minsize
         end
         @visible_line = 0.chr * @line_size
         @invisible_line = 0.chr * @line_size # 1.chr
      elsif (@line_size < minsize)  # ensure it can hold MINSIZE chars
         @line_size *= 2
         if (@line_size < minsize)
            @line_size = minsize
         end
         @visible_line << 0.chr * (@line_size - @visible_line.length)
         @invisible_line << 1.chr * (@line_size - @invisible_line.length)
      end
      @visible_line[minsize,@line_size-minsize] = 0.chr * (@line_size-minsize)
      @invisible_line[minsize,@line_size-minsize] = 1.chr * (@line_size-minsize)

      if @vis_lbreaks.nil?
         @inv_lbreaks = []
         @vis_lbreaks = []
         @_rl_wrapped_line = []
         @inv_lbreaks[0] = @vis_lbreaks[0] = 0
      end
   end

   # Return the history entry at the current position, as determined by
   #   history_offset.  If there is no entry there, return a NULL pointer.
   def current_history()
      return ((@history_offset == @history_length) || @the_history.nil?) ?
      nil : @the_history[@history_offset]
   end

   def meta_char(c)
      c > "\x7f" && c <= "\xff"
   end

   def ctrl_char(c)
      c < "\x20"
   end

   def isprint(c)
      c >= "\x20" && c < "\x7f"
   end

   def whitespace(c)
      (c == ' ' || c == "\t")
   end

   def w_offset(line, offset)
      ((line) == 0 ? offset : 0)
   end

   def vis_llen(l)
      ((l) > @_rl_vis_botlin ? 0 : (@vis_lbreaks[l+1] - @vis_lbreaks[l]))
   end

   def inv_llen(l)
      (@inv_lbreaks[l+1] - @inv_lbreaks[l])
   end

   def vis_chars(line)
      @visible_line[@vis_lbreaks[line] .. -1]
   end

   def vis_pos(line)
      @vis_lbreaks[line]
   end

   def vis_line(line)
      ((line) > @_rl_vis_botlin) ? "" : vis_chars(line)
   end

   def inv_line(line)
      @invisible_line[@inv_lbreaks[line] .. -1]
   end

   def m_offset(margin, offset)
      ((margin) == 0 ? offset : 0)
   end


   # PWP: update_line() is based on finding the middle difference of each
   #   line on the screen; vis:
   #
   #             /old first difference
   #  /beginning of line   |        /old last same       /old EOL
   #  v          v         v         v
   # old:   eddie> Oh, my little gruntle-buggy is to me, as lurgid as
   # new:   eddie> Oh, my little buggy says to me, as lurgid as
   #  ^          ^   ^           ^
   #  \beginning of line   |  \new last same    \new end of line
   #             \new first difference
   #
   #   All are character pointers for the sake of speed.  Special cases for
   #   no differences, as well as for end of line additions must be handled.
   #
   #   Could be made even smarter, but this works well enough
   def update_line(old, ostart, new, current_line, omax, nmax, inv_botlin)
      # If we're at the right edge of a terminal that supports xn, we're
      #   ready to wrap around, so do so.  This fixes problems with knowing
      #   the exact cursor position and cut-and-paste with certain terminal
      #   emulators.  In this calculation, TEMP is the physical screen
      #   position of the cursor.
      if @encoding == 'X'
         old.force_encoding('ASCII-8BIT')
         new.force_encoding('ASCII-8BIT')
      end

      if !@rl_byte_oriented
         temp = @_rl_last_c_pos
      else
         temp = @_rl_last_c_pos - w_offset(@_rl_last_v_pos, @visible_wrap_offset)
      end
      if (temp == @_rl_screenwidth && @_rl_term_autowrap && !@_rl_horizontal_scroll_mode &&
         @_rl_last_v_pos == current_line - 1)

         if (!@rl_byte_oriented)
            # This fixes only double-column characters, but if the wrapped
            #   character comsumes more than three columns, spaces will be
            #   inserted in the string buffer.
            if (@_rl_wrapped_line[current_line] > 0)
               _rl_clear_to_eol(@_rl_wrapped_line[current_line])
            end

            if new[0,1] != 0.chr
               case @encoding
               when 'E'
                  wc = new.scan(/./me)[0]
                  ret = wc.length
                  tempwidth = wc.length
               when 'S'
                  wc = new.scan(/./ms)[0]
                  ret = wc.length
                  tempwidth = wc.length
               when 'U'
                  wc = new.scan(/./mu)[0]
                  ret = wc.length
                  tempwidth = wc.unpack('U').first >= 0x1000 ? 2 : 1
               when 'X'
                  wc = new[0..-1].force_encoding(@encoding_name)[0]
                  ret = wc.bytesize
                  tempwidth = wc.ord >= 0x1000 ? 2 : 1
               else
                  ret = 1
                  tempwidth = 1
               end
            else
               tempwidth = 0
            end

            if (tempwidth > 0)
               bytes = ret
               @rl_outstream.write(new[0,bytes])
               @_rl_last_c_pos = tempwidth
               @_rl_last_v_pos+=1

               if old[ostart,1] != 0.chr
                  case @encoding
                  when 'E'
                     wc = old[ostart..-1].scan(/./me)[0]
                     ret = wc.length
                  when 'S'
                     wc = old[ostart..-1].scan(/./ms)[0]
                     ret = wc.length
                  when 'U'
                     wc = old[ostart..-1].scan(/./mu)[0]
                     ret = wc.length
                  when 'X'
                     wc = old[ostart..-1].force_encoding(@encoding_name)[0]
                     ret = wc.bytesize
                  end
               else
                  ret = 0
               end
               if (ret != 0 && bytes != 0)
                  if ret != bytes
                     len = old[ostart..-1].index(0.chr,ret)
                     old[ostart+bytes,len-ret] = old[ostart+ret,len-ret]
                  end
                  old[ostart,bytes] = new[0,bytes]
               end
            else
               @rl_outstream.write(' ')
               @_rl_last_c_pos = 1
               @_rl_last_v_pos+=1
               if (old[ostart,1] != 0.chr && new[0,1] != 0.chr)
                  old[ostart,1] = new[0,1]
               end
            end

         else
            if (new[0,1] != 0.chr)
               @rl_outstream.write(new[0,1])
            else
               @rl_outstream.write(' ')
            end
            @_rl_last_c_pos = 1
            @_rl_last_v_pos+=1
            if (old[ostart,1] != 0.chr && new[0,1] != 0.chr)
               old[ostart,1] = new[0,1]
            end
         end
      end

      # Find first difference.
      if (!@rl_byte_oriented)
         # See if the old line is a subset of the new line, so that the
         # only change is adding characters.
         if (index = old.index(0.chr)) && omax+ostart>index
            omax = index - ostart
         end
         if (index = new.index(0.chr)) && nmax>index
            nmax = index
         end

         temp = (omax < nmax) ? omax : nmax
         if old[ostart,temp]==new[0,temp]
            ofd = temp
            nfd = temp
         else
            if (omax == nmax && new[0,omax]==old[ostart,omax])
               ofd = omax
               nfd = nmax
            else
               new_offset = 0
               old_offset = ostart
               ofd = 0
               nfd = 0
               while(ofd < omax && old[ostart+ofd,1] != 0.chr &&
                  _rl_compare_chars(old, old_offset, new, new_offset))

                  old_offset = _rl_find_next_mbchar(old, old_offset, 1, MB_FIND_ANY)
                  new_offset = _rl_find_next_mbchar(new, new_offset, 1, MB_FIND_ANY)
                  ofd = old_offset - ostart
                  nfd = new_offset
               end
            end
         end
      else
         ofd = 0
         nfd = 0
         while(ofd < omax && old[ostart+ofd,1] != 0.chr && old[ostart+ofd,1] == new[nfd,1])
            ofd += 1
            nfd += 1
         end
      end


      # Move to the end of the screen line.  ND and OD are used to keep track
      #   of the distance between ne and new and oe and old, respectively, to
      #   move a subtraction out of each loop.
      oe = old.index(0.chr,ostart+ofd) - ostart
      if oe.nil? || oe>omax
         oe = omax
      end

      ne = new.index(0.chr,nfd)
      if ne.nil? || ne>omax
         ne = nmax
      end

      # If no difference, continue to next line.
      if (ofd == oe && nfd == ne)
         return
      end


      wsatend = true       # flag for trailing whitespace

      if (!@rl_byte_oriented)

         ols = _rl_find_prev_mbchar(old, ostart+oe, MB_FIND_ANY) - ostart
         nls = _rl_find_prev_mbchar(new, ne, MB_FIND_ANY)
         while ((ols > ofd) && (nls > nfd))

            if (!_rl_compare_chars(old, ostart+ols, new, nls))
               break
            end
            if (old[ostart+ols,1] == " ")
               wsatend = false
            end

            ols = _rl_find_prev_mbchar(old, ols+ostart, MB_FIND_ANY) - ostart
            nls = _rl_find_prev_mbchar(new, nls, MB_FIND_ANY)
         end
      else
         ols = oe - 1         # find last same
         nls = ne - 1
         while ((ols > ofd) && (nls > nfd) && old[ostart+ols,1] == new[nls,1])
            if (old[ostart+ols,1] != " ")
               wsatend = false
            end
            ols-=1
            nls-=1
         end
      end

      if (wsatend)
         ols = oe
         nls = ne
      elsif (!_rl_compare_chars(old, ostart+ols, new, nls))
         if (old[ostart+ols,1] != 0.chr)         # don't step past the NUL
            if !@rl_byte_oriented
               ols = _rl_find_next_mbchar(old, ostart+ols, 1, MB_FIND_ANY) - ostart
            else
               ols+=1
            end
         end
         if (new[nls,1] != 0.chr )
            if !@rl_byte_oriented
               nls = _rl_find_next_mbchar(new, nls, 1, MB_FIND_ANY)
            else
               nls+=1
            end
         end
      end

      # count of invisible characters in the current invisible line.
      current_invis_chars = w_offset(current_line, @wrap_offset)
      if (@_rl_last_v_pos != current_line)
         _rl_move_vert(current_line)
         if (@rl_byte_oriented && current_line == 0 && @visible_wrap_offset!=0)
            @_rl_last_c_pos += @visible_wrap_offset
         end
      end

      # If this is the first line and there are invisible characters in the
      #   prompt string, and the prompt string has not changed, and the current
      #   cursor position is before the last invisible character in the prompt,
      #   and the index of the character to move to is past the end of the prompt
      #   string, then redraw the entire prompt string.  We can only do this
      #   reliably if the terminal supports a `cr' capability.

      #  This is not an efficiency hack -- there is a problem with redrawing
      #  portions of the prompt string if they contain terminal escape
      #  sequences (like drawing the `unbold' sequence without a corresponding
      #  `bold') that manifests itself on certain terminals.

      lendiff = @local_prompt_len

      if (current_line == 0 && !@_rl_horizontal_scroll_mode &&
         @_rl_term_cr && lendiff > @prompt_visible_length && @_rl_last_c_pos > 0 &&
         ofd >= lendiff && @_rl_last_c_pos < prompt_ending_index())
         @rl_outstream.write(@_rl_term_cr)
         _rl_output_some_chars(@local_prompt,0,lendiff)
         if !@rl_byte_oriented
            # We take wrap_offset into account here so we can pass correct
            #   information to _rl_move_cursor_relative.
            @_rl_last_c_pos = _rl_col_width(@local_prompt, 0, lendiff) - @wrap_offset
            @cpos_adjusted = true
         else
            @_rl_last_c_pos = lendiff
         end
      end

      # When this function returns, _rl_last_c_pos is correct, and an absolute
      #   cursor postion in multibyte mode, but a buffer index when not in a
      #   multibyte locale.
      _rl_move_cursor_relative(ofd, old, ostart)

      if (current_line == 0 && !@rl_byte_oriented && @_rl_last_c_pos == @prompt_physical_chars)
         @cpos_adjusted = true
      end

      # if (len (new) > len (old))
      #   lendiff == difference in buffer
      #   col_lendiff == difference on screen
      #   When not using multibyte characters, these are equal
      lendiff = (nls - nfd) - (ols - ofd)
      if !@rl_byte_oriented
         col_lendiff = _rl_col_width(new, nfd, nls) - _rl_col_width(old, ostart+ofd, ostart+ols)
      else
         col_lendiff = lendiff
      end

      # If we are changing the number of invisible characters in a line, and
      #   the spot of first difference is before the end of the invisible chars,
      #   lendiff needs to be adjusted.
      if (current_line == 0 && !@_rl_horizontal_scroll_mode &&
         current_invis_chars != @visible_wrap_offset)
         if !@rl_byte_oriented
            lendiff += @visible_wrap_offset - current_invis_chars
            col_lendiff += @visible_wrap_offset - current_invis_chars
         else
            lendiff += @visible_wrap_offset - current_invis_chars
            col_lendiff = lendiff
         end
      end

      # Insert (diff (len (old), len (new)) ch.
      temp = ne - nfd
      if !@rl_byte_oriented
         col_temp = _rl_col_width(new,nfd,ne)
      else
         col_temp = temp
      end
      if (col_lendiff > 0) # XXX - was lendiff

         # Non-zero if we're increasing the number of lines.
         gl = current_line >= @_rl_vis_botlin && inv_botlin > @_rl_vis_botlin
         # Sometimes it is cheaper to print the characters rather than
         # use the terminal's capabilities.  If we're growing the number
         # of lines, make sure we actually cause the new line to wrap
         # around on auto-wrapping terminals.
         if (@_rl_terminal_can_insert && ((2 * col_temp) >= col_lendiff || @_rl_term_IC) && (!@_rl_term_autowrap || !gl))

            # If lendiff > prompt_visible_length and _rl_last_c_pos == 0 and
            #   _rl_horizontal_scroll_mode == 1, inserting the characters with
            #   _rl_term_IC or _rl_term_ic will screw up the screen because of the
            #   invisible characters.  We need to just draw them.
            if (old[ostart+ols,1] != 0.chr && (!@_rl_horizontal_scroll_mode || @_rl_last_c_pos > 0 ||
               lendiff <= @prompt_visible_length || current_invis_chars==0))

               insert_some_chars(new[nfd..-1], lendiff, col_lendiff)
               @_rl_last_c_pos += col_lendiff
            elsif ((@rl_byte_oriented) && old[ostart+ols,1] == 0.chr && lendiff > 0)
               # At the end of a line the characters do not have to
               # be "inserted".  They can just be placed on the screen.
               # However, this screws up the rest of this block, which
               # assumes you've done the insert because you can.
               _rl_output_some_chars(new,nfd, lendiff)
               @_rl_last_c_pos += col_lendiff
            else
               # We have horizontal scrolling and we are not inserting at
               # the end.  We have invisible characters in this line.  This
               # is a dumb update.
               _rl_output_some_chars(new,nfd, temp)
               @_rl_last_c_pos += col_temp
               return
            end
            # Copy (new) chars to screen from first diff to last match.
            temp = nls - nfd
            if ((temp - lendiff) > 0)
               _rl_output_some_chars(new,(nfd + lendiff),temp - lendiff)
               # XXX -- this bears closer inspection.  Fixes a redisplay bug
               # reported against bash-3.0-alpha by Andreas Schwab involving
               # multibyte characters and prompt strings with invisible
               # characters, but was previously disabled.
               @_rl_last_c_pos += _rl_col_width(new,nfd+lendiff, nfd+lendiff+temp-col_lendiff)
            end
         else
            # cannot insert chars, write to EOL
            _rl_output_some_chars(new,nfd, temp)
            @_rl_last_c_pos += col_temp
            # If we're in a multibyte locale and were before the last invisible
            #   char in the current line (which implies we just output some invisible
            #   characters) we need to adjust _rl_last_c_pos, since it represents
            #   a physical character position.
         end
      else           # Delete characters from line.
         # If possible and inexpensive to use terminal deletion, then do so.
         if (@_rl_term_dc && (2 * col_temp) >= -col_lendiff)

            # If all we're doing is erasing the invisible characters in the
            #   prompt string, don't bother.  It screws up the assumptions
            #   about what's on the screen.
            if (@_rl_horizontal_scroll_mode && @_rl_last_c_pos == 0 &&
               -lendiff == @visible_wrap_offset)
               col_lendiff = 0
            end

            if (col_lendiff!=0)
               delete_chars(-col_lendiff) # delete (diff) characters
            end

            # Copy (new) chars to screen from first diff to last match
            temp = nls - nfd
            if (temp > 0)
               _rl_output_some_chars(new,nfd, temp)
               @_rl_last_c_pos += _rl_col_width(new,nfd,nfd+temp)
            end

            # Otherwise, print over the existing material.
         else
            if (temp > 0)
               _rl_output_some_chars(new,nfd, temp)
               @_rl_last_c_pos += col_temp      # XXX
            end

            lendiff = (oe) - (ne)
            if !@rl_byte_oriented
               col_lendiff = _rl_col_width(old, ostart, ostart+oe) - _rl_col_width(new, 0, ne)
            else
               col_lendiff = lendiff
            end

            if (col_lendiff!=0)
               if (@_rl_term_autowrap && current_line < inv_botlin)
                  space_to_eol(col_lendiff)
               else
                  _rl_clear_to_eol(col_lendiff)
               end
            end
         end
      end
   end

   # Basic redisplay algorithm.
   def rl_redisplay()
      return if !@readline_echoing_p

      _rl_wrapped_multicolumn = 0

      @rl_display_prompt ||= ""

      if (@invisible_line.nil? || @vis_lbreaks.nil?)
         init_line_structures(0)
         rl_on_new_line()
      end

      # Draw the line into the buffer.
      @cpos_buffer_position = -1

      line = @invisible_line
      out = inv_botlin = 0

      # Mark the line as modified or not.  We only do this for history
      #   lines.
      modmark = 0
      if (@_rl_mark_modified_lines && current_history() && @rl_undo_list)
         line[out,1] = '*'
         out += 1
         line[out,1] = 0.chr
         modmark = 1
      end

      # If someone thought that the redisplay was handled, but the currently
      #   visible line has a different modification state than the one about
      #   to become visible, then correct the caller's misconception.
      if (@visible_line[0,1] != @invisible_line[0,1])
         @rl_display_fixed = false
      end

      # If the prompt to be displayed is the `primary' readline prompt (the
      #   one passed to readline()), use the values we have already expanded.
      #   If not, use what's already in rl_display_prompt.  WRAP_OFFSET is the
      #   number of non-visible characters in the prompt string.
      if (@rl_display_prompt == @rl_prompt || @local_prompt)

         if (@local_prompt_prefix && @forced_display)
            _rl_output_some_chars(@local_prompt_prefix,0,@local_prompt_prefix.length)
         end
         if (@local_prompt_len > 0)

            temp = @local_prompt_len + out + 2
            if (temp >= @line_size)
               @line_size = (temp + 1024) - (temp % 1024)
               if @visible_line.length >= @line_size
                  @visible_line = @visible_line[0,@line_size]
               else
                  @visible_line += 0.chr * (@line_size-@visible_line.length)
               end

               if @invisible_line.length >= @line_size
                  @invisible_line = @invisible_line[0,@line_size]
               else
                  @invisible_line += 0.chr * (@line_size-@invisible_line.length)
               end
               if @encoding=='X'
                  @visible_line.force_encoding('ASCII-8BIT')
                  @invisible_line.force_encoding('ASCII-8BIT')
               end
               line = @invisible_line
            end
            line[out,@local_prompt_len] = @local_prompt
            out += @local_prompt_len
         end
         line[out,1] = 0.chr
         @wrap_offset = @local_prompt_len - @prompt_visible_length
      else
         prompt_this_line = @rl_display_prompt.rindex("\n")
         if prompt_this_line.nil?
            prompt_this_line = 0
         else
            prompt_this_line+=1

            pmtlen = prompt_this_line # temp var
            if (@forced_display)
               _rl_output_some_chars(@rl_display_prompt,0,pmtlen)
               # Make sure we are at column zero even after a newline,
               #regardless of the state of terminal output processing.
               if (pmtlen < 2 || @rl_display_prompt[prompt_this_line-2,1] != "\r")
                  cr()
               end
            end
         end

         @prompt_physical_chars = pmtlen = @rl_display_prompt.length - prompt_this_line
         temp = pmtlen + out + 2
         if (temp >= @line_size)
            @line_size = (temp + 1024) - (temp % 1024)
            if @visible_line.length >= @line_size
               @visible_line = @visible_line[0,@line_size]
            else
               @visible_line += 0.chr * (@line_size-@visible_line.length)
            end

            if @invisible_line.length >= @line_size
               @invisible_line = @invisible_line[0,@line_size]
            else
               @invisible_line += 0.chr * (@line_size-@invisible_line.length)
            end
            if @encoding=='X'
               @visible_line.force_encoding('ASCII-8BIT')
               @invisible_line.force_encoding('ASCII-8BIT')
            end

            line = @invisible_line
         end
         line[out,pmtlen] = @rl_display_prompt[prompt_this_line,pmtlen]
         out += pmtlen
         line[out,1] = 0.chr
         @wrap_offset = @prompt_invis_chars_first_line = 0
      end
      # inv_lbreaks[i] is where line i starts in the buffer.
      @inv_lbreaks[newlines = 0] = 0
      lpos = @prompt_physical_chars + modmark

      @_rl_wrapped_line = Array.new(@visible_line.length,0)
      num = 0

      # prompt_invis_chars_first_line is the number of invisible characters in
      #   the first physical line of the prompt.
      #  wrap_offset - prompt_invis_chars_first_line is the number of invis
      #   chars on the second line.

      # what if lpos is already >= _rl_screenwidth before we start drawing the
      #   contents of the command line?
      while (lpos >= @_rl_screenwidth)
         # fix from Darin Johnson <darin@acuson.com> for prompt string with
         #   invisible characters that is longer than the screen width.  The
         #   prompt_invis_chars_first_line variable could be made into an array
         #   saying how many invisible characters there are per line, but that's
         #   probably too much work for the benefit gained.  How many people have
         #   prompts that exceed two physical lines?
         #   Additional logic fix from Edward Catmur <ed@catmur.co.uk>
         if (!@rl_byte_oriented)
            n0 = num
            temp = @local_prompt_len
            while (num < temp)
               z = _rl_col_width(@local_prompt, n0, num)
               if (z > @_rl_screenwidth)
                  num = _rl_find_prev_mbchar(@local_prompt, num, MB_FIND_ANY)
                  break
               elsif (z == @_rl_screenwidth)
                  break
               end
               num+=1
            end
            temp = num
         else
            temp = ((newlines + 1) * @_rl_screenwidth)
         end

         # Now account for invisible characters in the current line.
         temp += (@local_prompt_prefix.nil? ? ((newlines == 0) ? @prompt_invis_chars_first_line :
         ((newlines == 1) ? @wrap_offset : 0)) :
         ((newlines == 0) ? @wrap_offset : 0))

         @inv_lbreaks[newlines+=1] = temp
         if !@rl_byte_oriented
            lpos -= _rl_col_width(@local_prompt, n0, num)
         else
            lpos -= @_rl_screenwidth
         end
      end
      @prompt_last_screen_line = newlines

      # Draw the rest of the line (after the prompt) into invisible_line, keeping
      #   track of where the cursor is (cpos_buffer_position), the number of the line containing
      #   the cursor (lb_linenum), the last line number (lb_botlin and inv_botlin).
      #   It maintains an array of line breaks for display (inv_lbreaks).
      #   This handles expanding tabs for display and displaying meta characters.
      lb_linenum = 0
      _in = 0
      if !@rl_byte_oriented && @rl_end>0
         case @encoding
         when 'E'
            wc = @rl_line_buffer[0,@rl_end].scan(/./me)[0]
            wc_bytes = wc ? wc.length : 1
         when 'S'
            wc = @rl_line_buffer[0,@rl_end].scan(/./ms)[0]
            wc_bytes = wc ? wc.length : 1
         when 'U'
            wc = @rl_line_buffer[0,@rl_end].scan(/./mu)[0]
            wc_bytes = wc ? wc.length : 1
         when 'X'
            wc = @rl_line_buffer[0,@rl_end].force_encoding(@encoding_name)[0]
            wc_bytes = wc ? wc.bytesize : 1
         end
      else
         wc_bytes = 1
      end

      while(_in < @rl_end)

         c = @rl_line_buffer[_in,1]
         if(c == 0.chr)
            @rl_end = _in
            break
         end
         if (!@rl_byte_oriented)
            case @encoding
            when 'U'
               wc_width = wc && wc.unpack('U').first >= 0x1000 ? 2 : 1
            when 'X'
               wc_width = wc && wc.ord > 0x1000 ? 2 : 1
            else
               wc_width = wc ? wc.length : 1
            end
         end
         if (out + 8 >= @line_size)    # XXX - 8 for \t
            @line_size *= 2
            if @visible_line.length>=@line_size
               @visible_line = @visible_line[0,@line_size]
            else
               @visible_line += 0.chr * (@line_size-@visible_line.length)
            end
            if @invisible_line.length>=@line_size
               @invisible_line = @invisible_line[0,@line_size]
            else
               @invisible_line += 0.chr * (@line_size-@invisible_line.length)
            end
            line = @invisible_line
         end

         if (_in == @rl_point)
            @cpos_buffer_position = out
            lb_linenum = newlines
         end
         if (false && meta_char(c))
            if (!@_rl_output_meta_chars && false)
               line[out,4] = "\\%03o" % c.ord

               if (lpos + 4 >= @_rl_screenwidth)
                  temp = @_rl_screenwidth - lpos
                  @inv_lbreaks[newlines+=1] = out + temp
                  lpos = 4 - temp
               else
                  lpos += 4
               end
               out += 4
            else
               line[out,1] = c
               out += 1
               lpos+=1
               if (lpos >= @_rl_screenwidth)
                  @inv_lbreaks[newlines+=1] = out
                  @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
                  lpos = 0
               end
            end

         elsif (c == "\t")

            newout = out + 8 - lpos % 8
            temp = newout - out
            if (lpos + temp >= @_rl_screenwidth)
               temp2 = @_rl_screenwidth - lpos
               @inv_lbreaks[newlines+=1] = out + temp2
               lpos = temp - temp2
               while (out < newout)
                  line[out,1] = ' '
                  out += 1
               end

            else

               while (out < newout)
                  line[out,1] = ' '
                  out += 1
               end
               lpos += temp
            end

         elsif (c == "\n" && !@_rl_horizontal_scroll_mode && @_rl_term_up)
            line[out,1] = 0.chr # XXX - sentinel
            out += 1
            @inv_lbreaks[newlines+=1] = out
            lpos = 0
         elsif (ctrl_char(c) || c == RUBOUT)
            line[out,1] = '^'
            out += 1
            lpos+=1
            if (lpos >= @_rl_screenwidth)
               @inv_lbreaks[newlines+=1] = out
               @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
               lpos = 0
            end
            # NOTE: c[0].ord works identically on both 1.8 and 1.9
            line[out,1] = ctrl_char(c) ? (c[0].ord|0x40).chr.upcase : '?'
            out += 1
            lpos+=1
            if (lpos >= @_rl_screenwidth)
               @inv_lbreaks[newlines+=1] = out
               @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
               lpos = 0
            end
         else

            if (!@rl_byte_oriented)
               _rl_wrapped_multicolumn = 0
               if (@_rl_screenwidth < lpos + wc_width)
                  for i in lpos ... @_rl_screenwidth
                     # The space will be removed in update_line()
                     line[out,1] = ' '
                     out += 1
                     _rl_wrapped_multicolumn+=1
                     lpos+=1
                     if (lpos >= @_rl_screenwidth)
                        @inv_lbreaks[newlines+=1] = out
                        @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
                        lpos = 0
                     end
                  end
               end
               if (_in == @rl_point)
                  @cpos_buffer_position = out
                  lb_linenum = newlines
               end
               line[out,wc_bytes] = @rl_line_buffer[_in,wc_bytes]
               out += wc_bytes
               for i in 0 ... wc_width
                  lpos+=1
                  if (lpos >= @_rl_screenwidth)
                     @inv_lbreaks[newlines+=1] = out
                     @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
                     lpos = 0
                  end
               end
            else
               line[out,1] = c
               out += 1
               lpos+=1
               if (lpos >= @_rl_screenwidth)
                  @inv_lbreaks[newlines+=1] = out
                  @_rl_wrapped_line[newlines] = _rl_wrapped_multicolumn
                  lpos = 0
               end
            end

         end

         if (!@rl_byte_oriented)
            _in += wc_bytes
            case @encoding
            when 'E'
               wc = @rl_line_buffer[_in,@rl_end - _in].scan(/./me)[0]
               wc_bytes = wc ? wc.length : 1
            when 'S'
               wc = @rl_line_buffer[_in,@rl_end - _in].scan(/./ms)[0]
               wc_bytes = wc ? wc.length : 1
            when 'U'
               wc = @rl_line_buffer[_in,@rl_end - _in].scan(/./mu)[0]
               wc_bytes = wc ? wc.length : 1
            when 'X'
               wc = @rl_line_buffer[_in,@rl_end - _in].force_encoding(@encoding_name)[0]
               wc_bytes = wc ? wc.bytesize : 1
            end

         else
            _in+=1
         end
      end

      line[out,1] = 0.chr

      if (@cpos_buffer_position < 0)
         @cpos_buffer_position = out
         lb_linenum = newlines
      end

      inv_botlin = lb_botlin = newlines
      @inv_lbreaks[newlines+1] = out
      cursor_linenum = lb_linenum

      # CPOS_BUFFER_POSITION == position in buffer where cursor should be placed.
      #   CURSOR_LINENUM == line number where the cursor should be placed.

      # PWP: now is when things get a bit hairy.  The visible and invisible
      #   line buffers are really multiple lines, which would wrap every
      #   (screenwidth - 1) characters.  Go through each in turn, finding
      #   the changed region and updating it.  The line order is top to bottom.

      # If we can move the cursor up and down, then use multiple lines,
      #   otherwise, let long lines display in a single terminal line, and
      #   horizontally scroll it.

      if (!@_rl_horizontal_scroll_mode && @_rl_term_up)
         if (!@rl_display_fixed || @forced_display)
            @forced_display = false
            # If we have more than a screenful of material to display, then
            #   only display a screenful.  We should display the last screen,
            #   not the first.
            if (out >= @_rl_screenchars)
               if (!@rl_byte_oriented)
                  out = _rl_find_prev_mbchar(line, @_rl_screenchars, MB_FIND_ANY)
               else
                  out = @_rl_screenchars - 1
               end
            end

            # The first line is at character position 0 in the buffer.  The
            #   second and subsequent lines start at inv_lbreaks[N], offset by
            #   OFFSET (which has already been calculated above).

            # For each line in the buffer, do the updating display.
            for linenum in  0 .. inv_botlin
               # This can lead us astray if we execute a program that changes
               #the locale from a non-multibyte to a multibyte one.
               o_cpos = @_rl_last_c_pos
               @cpos_adjusted = false
               update_line(@visible_line,vis_pos(linenum), inv_line(linenum), linenum,
               vis_llen(linenum), inv_llen(linenum), inv_botlin)

               if (linenum == 0 && !@rl_byte_oriented &&
                  !@cpos_adjusted &&
                  @_rl_last_c_pos != o_cpos &&
                  @_rl_last_c_pos > @wrap_offset &&
                  o_cpos < @prompt_last_invisible)
                  @_rl_last_c_pos -= @wrap_offset
               end

               # If this is the line with the prompt, we might need to
               # compensate for invisible characters in the new line. Do
               # this only if there is not more than one new line (which
               # implies that we completely overwrite the old visible line)
               # and the new line is shorter than the old.  Make sure we are
               # at the end of the new line before clearing.
               if (linenum == 0 &&
                  inv_botlin == 0 && @_rl_last_c_pos == out &&
                  (@wrap_offset > @visible_wrap_offset) &&
                  (@_rl_last_c_pos < @visible_first_line_len))
                  if !@rl_byte_oriented
                     nleft = @_rl_screenwidth - @_rl_last_c_pos
                  else
                     nleft = @_rl_screenwidth + @wrap_offset - @_rl_last_c_pos
                  end
                  if (nleft!=0)
                     _rl_clear_to_eol(nleft)
                  end
               end

               # Since the new first line is now visible, save its length.
               if (linenum == 0)
                  @visible_first_line_len = (inv_botlin > 0) ? @inv_lbreaks[1] : out - @wrap_offset
               end
            end

            # We may have deleted some lines.  If so, clear the left over
            #   blank ones at the bottom out.
            if (@_rl_vis_botlin > inv_botlin)
               while(linenum <= @_rl_vis_botlin)
                  tt = vis_chars(linenum)
                  _rl_move_vert(linenum)
                  _rl_move_cursor_relative(0, tt)
                  _rl_clear_to_eol((linenum == @_rl_vis_botlin) ? tt.length : @_rl_screenwidth)
                  linenum += 1
               end
            end
            @_rl_vis_botlin = inv_botlin

            # CHANGED_SCREEN_LINE is set to 1 if we have moved to a
            #   different screen line during this redisplay.
            changed_screen_line = @_rl_last_v_pos != cursor_linenum
            if (changed_screen_line)
               _rl_move_vert(cursor_linenum)
               # If we moved up to the line with the prompt using _rl_term_up,
               # the physical cursor position on the screen stays the same,
               # but the buffer position needs to be adjusted to account
               # for invisible characters.
               if (@rl_byte_oriented && cursor_linenum == 0 && @wrap_offset!=0)
                  @_rl_last_c_pos += @wrap_offset
               end
            end
            # We have to reprint the prompt if it contains invisible
            #   characters, since it's not generally OK to just reprint
            #   the characters from the current cursor position.  But we
            #   only need to reprint it if the cursor is before the last
            #   invisible character in the prompt string.
            nleft = @prompt_visible_length + @wrap_offset
            if (cursor_linenum == 0 && @wrap_offset > 0 && @_rl_last_c_pos > 0 &&
               @_rl_last_c_pos < prompt_ending_index() && @local_prompt)
               if (@_rl_term_cr)
                  @rl_outstream.write(@_rl_term_cr)
               end
               _rl_output_some_chars(@local_prompt,0,nleft)
               if !@rl_byte_oriented
                  @_rl_last_c_pos = _rl_col_width(@local_prompt, 0, nleft) - @wrap_offset
               else
                  @_rl_last_c_pos = nleft
               end
            end

            # Where on that line?  And where does that line start
            #   in the buffer?
            pos = @inv_lbreaks[cursor_linenum]
            # nleft == number of characters in the line buffer between the
            #   start of the line and the desired cursor position.
            nleft = @cpos_buffer_position - pos

            # NLEFT is now a number of characters in a buffer.  When in a
            #   multibyte locale, however, _rl_last_c_pos is an absolute cursor
            #   position that doesn't take invisible characters in the prompt
            #   into account.  We use a fudge factor to compensate.

            # Since _rl_backspace() doesn't know about invisible characters in the
            #   prompt, and there's no good way to tell it, we compensate for
            #   those characters here and call _rl_backspace() directly.

            if (@wrap_offset!=0 && cursor_linenum == 0 && nleft < @_rl_last_c_pos)
               # TX == new physical cursor position in multibyte locale.
               if !@rl_byte_oriented
                  tx = _rl_col_width(@visible_line, pos, pos+nleft) - @visible_wrap_offset
               else
                  tx = nleft
               end
               if (@_rl_last_c_pos > tx)
                  _rl_backspace(@_rl_last_c_pos - tx) # XXX
                  @_rl_last_c_pos = tx
               end
            end
            # We need to note that in a multibyte locale we are dealing with
            #   _rl_last_c_pos as an absolute cursor position, but moving to a
            #   point specified by a buffer position (NLEFT) that doesn't take
            #   invisible characters into account.
            if !@rl_byte_oriented
               _rl_move_cursor_relative(nleft, @invisible_line,pos)
            elsif (nleft != @_rl_last_c_pos)
               _rl_move_cursor_relative(nleft, @invisible_line,pos)
            end
         end

      else           # Do horizontal scrolling.

         # Always at top line.
         @_rl_last_v_pos = 0

         # Compute where in the buffer the displayed line should start.  This
         # will be LMARGIN.

         # The number of characters that will be displayed before the cursor.
         ndisp = @cpos_buffer_position - @wrap_offset
         nleft  = @prompt_visible_length + @wrap_offset
         # Where the new cursor position will be on the screen.  This can be
         # longer than SCREENWIDTH; if it is, lmargin will be adjusted.
         phys_c_pos = @cpos_buffer_position - (@last_lmargin!=0 ? @last_lmargin : @wrap_offset)
         t = @_rl_screenwidth / 3

         # If the number of characters had already exceeded the screenwidth,
         #last_lmargin will be > 0.

         # If the number of characters to be displayed is more than the screen
         # width, compute the starting offset so that the cursor is about
         # two-thirds of the way across the screen.
         if (phys_c_pos > @_rl_screenwidth - 2)
            lmargin = @cpos_buffer_position - (2 * t)
            if (lmargin < 0)
               lmargin = 0
            end
            # If the left margin would be in the middle of a prompt with
            #   invisible characters, don't display the prompt at all.
            if (@wrap_offset!=0 && lmargin > 0 && lmargin < nleft)
               lmargin = nleft
            end
         elsif (ndisp < @_rl_screenwidth - 2)      # XXX - was -1
            lmargin = 0
         elsif (phys_c_pos < 1)
            # If we are moving back towards the beginning of the line and
            #   the last margin is no longer correct, compute a new one.
            lmargin = ((@cpos_buffer_position - 1) / t) * t # XXX
            if (@wrap_offset!=0 && lmargin > 0 && lmargin < nleft)
               lmargin = nleft
            end
         else
            lmargin = @last_lmargin
         end

         # If the first character on the screen isn't the first character
         #in the display line, indicate this with a special character.
         if (lmargin > 0)
            line[lmargin,1] = '<'
         end

         # If SCREENWIDTH characters starting at LMARGIN do not encompass
         # the whole line, indicate that with a special character at the
         # right edge of the screen.  If LMARGIN is 0, we need to take the
         # wrap offset into account.
         t = lmargin + m_offset(lmargin, @wrap_offset) + @_rl_screenwidth
         if (t < out)
            line[t - 1,1] = '>'
         end
         if (!@rl_display_fixed || @forced_display || lmargin != @last_lmargin)

            @forced_display = false
      # in case we scrolled to the right, the prompt is not visible,
      # so temporarily set wrap_offset and visible_wrap_offset to zero.
      old_vwo=@visible_wrap_offset
      old_wo=@wrap_offset
      if (lmargin != 0)
        @visible_wrap_offset=0
        @wrap_offset=0
      end
            update_line(@visible_line,@last_lmargin,@invisible_line[lmargin..-1],
            0,
            @_rl_screenwidth + @visible_wrap_offset,
            @_rl_screenwidth + (lmargin != 0 ? 0 : @wrap_offset),
            0)
            # If the visible new line is shorter than the old, but the number
            #   of invisible characters is greater, and we are at the end of
            #   the new line, we need to clear to eol.
            t = @_rl_last_c_pos - m_offset(lmargin, @wrap_offset)
            if ((m_offset(lmargin, @wrap_offset) > @visible_wrap_offset) &&
               (@_rl_last_c_pos == out) &&
               t < @visible_first_line_len)

               nleft = @_rl_screenwidth - t
               _rl_clear_to_eol(nleft)
            end
            @visible_first_line_len = out - lmargin - m_offset(lmargin, @wrap_offset)
            if (@visible_first_line_len > @_rl_screenwidth)
               @visible_first_line_len = @_rl_screenwidth
            end
            _rl_move_cursor_relative(@cpos_buffer_position - lmargin, @invisible_line ,lmargin)
            @last_lmargin = lmargin
      @visible_wrap_offset=old_vwo
      @wrap_offset=old_wo
         end
      end
      @rl_outstream.flush

      # Swap visible and non-visible lines.
      @visible_line,@invisible_line = @invisible_line,@visible_line
      @vis_lbreaks,@inv_lbreaks = @inv_lbreaks,@vis_lbreaks

      @rl_display_fixed = false
      # If we are displaying on a single line, and last_lmargin is > 0, we
      #   are not displaying any invisible characters, so set visible_wrap_offset
      #   to 0.
      if (@_rl_horizontal_scroll_mode && @last_lmargin!=0)
         @visible_wrap_offset = 0
      else
         @visible_wrap_offset = @wrap_offset
      end
   end

   # Tell the update routines that we have moved onto a new (empty) line.
   def rl_on_new_line()
      if (@visible_line)
         @visible_line[0,1] = 0.chr
      end
      @_rl_last_c_pos = @_rl_last_v_pos = 0
      @_rl_vis_botlin = @last_lmargin = 0
      if (@vis_lbreaks)
         @vis_lbreaks[0] = @vis_lbreaks[1] = 0
      end
      @visible_wrap_offset = 0
      0
   end

   def rl_reset_line_state()
      rl_on_new_line()

      @rl_display_prompt = @rl_prompt ? @rl_prompt : ""
      @forced_display = true
      0
   end

   def _rl_vi_initialize_line
      rl_unsetstate(RL_STATE_VICMDONCE)
   end

   # Initialize readline (and terminal if not already).
   def rl_initialize()
      # If we have never been called before, initialize the
      #   terminal and data structures.
      if (!@rl_initialized)
         rl_setstate(RL_STATE_INITIALIZING)
         readline_initialize_everything()
         rl_unsetstate(RL_STATE_INITIALIZING)
         @rl_initialized = true
         rl_setstate(RL_STATE_INITIALIZED)
      end

      # Initalize the current line information.
      _rl_init_line_state()

      # We aren't done yet.  We haven't even gotten started yet!
      @rl_done = false
      rl_unsetstate(RL_STATE_DONE)

      # Tell the history routines what is going on.
      _rl_start_using_history()

      # Make the display buffer match the state of the line.
      rl_reset_line_state()

      # No such function typed yet.
      @rl_last_func = nil

      # Parsing of key-bindings begins in an enabled state.
      @_rl_parsing_conditionalized_out = 0

      if (@rl_editing_mode == @vi_mode)
         _rl_vi_initialize_line()
      end
      # Each line starts in insert mode (the default).
      _rl_set_insert_mode(RL_IM_DEFAULT, 1)

      return 0
   end

   def _rl_strip_prompt(pmt)
      return expand_prompt(pmt).first
   end

   def _rl_col_width(string,start,_end)
      return 0 if _end <= start

      index = string.index(0.chr)
      str = index ? string[0,index] : string
      width = 0

      case @encoding
      when 'N'
         return (_end - start)
      when 'U'
         str[start ... _end].scan(/./mu).each {|s| width += s.unpack('U').first >= 0x1000 ? 2 : 1 }
      when 'S'
         str[start ... _end].scan(/./ms).each {|s| width += s.length }
      when 'E'
         str[start ... _end].scan(/./me).each {|s| width += s.length }
      when 'X'
         tmp = str[start ... _end]
         return 0 if not tmp
         tmp.force_encoding(@encoding_name).codepoints.each {|s| width += s > 0x1000 ? 2 : 1 }
      end
      width
   end

   # Write COUNT characters from STRING to the output stream.
   def _rl_output_some_chars(string,start,count)
      @_rl_out_stream.write(string[start,count])
   end

   # Tell the update routines that we have moved onto a new line with the
   #   prompt already displayed.  Code originally from the version of readline
   #   distributed with CLISP.  rl_expand_prompt must have already been called
   #   (explicitly or implicitly).  This still doesn't work exactly right.
   def rl_on_new_line_with_prompt()
      # Initialize visible_line and invisible_line to ensure that they can hold
      #   the already-displayed prompt.
      prompt_size = @rl_prompt.length + 1
      init_line_structures(prompt_size)

      # Make sure the line structures hold the already-displayed prompt for
      #   redisplay.
      lprompt = @local_prompt ? @local_prompt : @rl_prompt
      @visible_line[0,lprompt.length] = lprompt
      @invisible_line[0,lprompt.length] = lprompt

      # If the prompt contains newlines, take the last tail.
      prompt_last_line = rl_prompt.rindex("\n")
      if prompt_last_line.nil?
         prompt_last_line = @rl_prompt
      else
         prompt_last_line = @rl_prompt[prompt_last_line..-1]
      end
      l = prompt_last_line.length
      if !@rl_byte_oriented
         @_rl_last_c_pos = _rl_col_width(prompt_last_line, 0, l)
      else
         @_rl_last_c_pos = l
      end

      # Dissect prompt_last_line into screen lines. Note that here we have
      #   to use the real screenwidth. Readline's notion of screenwidth might be
      #   one less, see terminal.c.
      real_screenwidth = @_rl_screenwidth + (@_rl_term_autowrap ? 0 : 1)
      @_rl_last_v_pos = l / real_screenwidth
      # If the prompt length is a multiple of real_screenwidth, we don't know
      #   whether the cursor is at the end of the last line, or already at the
      #   beginning of the next line. Output a newline just to be safe.
      if (l > 0 && (l % real_screenwidth) == 0)
         _rl_output_some_chars("\n",0,1)
      end
      @last_lmargin = 0

      newlines = 0
      i = 0
      while (i <= l)
         @_rl_vis_botlin = newlines
         @vis_lbreaks[newlines] = i
         newlines += 1
         i += real_screenwidth
      end
      @vis_lbreaks[newlines] = l
      @visible_wrap_offset = 0

      @rl_display_prompt = @rl_prompt  # XXX - make sure it's set

      return 0
   end

   def readline_internal_setup()
      @_rl_in_stream = @rl_instream
      @_rl_out_stream = @rl_outstream

      if (@rl_startup_hook)
         send(@rl_startup_hook)
      end

      # If we're not echoing, we still want to at least print a prompt, because
      #   rl_redisplay will not do it for us.  If the calling application has a
      #   custom redisplay function, though, let that function handle it.
      if (!@readline_echoing_p && @rl_redisplay_function == :rl_redisplay)
         if (@rl_prompt && !@rl_already_prompted)
            nprompt = _rl_strip_prompt(@rl_prompt)
            @_rl_out_stream.write(nprompt)
            @_rl_out_stream.flush
         end
      else
         if (@rl_prompt && @rl_already_prompted)
            rl_on_new_line_with_prompt()
         else
            rl_on_new_line()
         end
         send(@rl_redisplay_function)
      end

      if (@rl_editing_mode == @vi_mode)
         rl_vi_insertion_mode(1, 'i')
      end
      if (@rl_pre_input_hook)
         send(@rl_pre_input_hook)
      end
   end

   # Create a default argument.
   def _rl_reset_argument()
      @rl_numeric_arg = @rl_arg_sign = 1
      @rl_explicit_arg = false
      @_rl_argcxt = 0
   end

   # Ring the terminal bell.
   def rl_ding()
      if @MessageBeep
         @MessageBeep.Call(0)
      elsif @readline_echoing_p
         if @_rl_bell_preference == VISIBLE_BELL
            if (@_rl_visible_bell)
               @_rl_out_stream.write(@_rl_visible_bell.chr)
            else
               $stderr.write("\007")
               $stderr.flush
            end
         elsif @_rl_bell_preference == AUDIBLE_BELL
            $stderr.write("\007")
            $stderr.flush
         end
         return 0
      end
      return -1
   end

   def _rl_search_getchar(cxt)
      # Read a key and decide how to proceed.
      rl_setstate(RL_STATE_MOREINPUT)
      c = cxt.lastc = rl_read_key()
      rl_unsetstate(RL_STATE_MOREINPUT)
      if !@rl_byte_oriented
         cxt.mb = ""
         c = cxt.lastc = _rl_read_mbstring(cxt.lastc, cxt.mb, MB_LEN_MAX)
      end
      c
   end

   def endsrch_char(c)
      ((ctrl_char(c) || meta_char(c) || (c) == RUBOUT) && ((c) != "\C-G"))
   end

   def _rl_input_available
      IO.select([ $stdin ], nil, [ $stdin ], @_keyboard_input_timeout)
   end

   # Process just-read character C according to isearch context CXT.  Return
   #   -1 if the caller should just free the context and return, 0 if we should
   #   break out of the loop, and 1 if we should continue to read characters.
   def _rl_isearch_dispatch(cxt, c)
      f = nil

      # Translate the keys we do something with to opcodes.
      if (c && @_rl_keymap[c])
         f = @_rl_keymap[c]
         if (f == :rl_reverse_search_history)
            cxt.lastc = (cxt.sflags & SF_REVERSE)!=0 ? -1 : -2
         elsif (f == :rl_forward_search_history)
            cxt.lastc = (cxt.sflags & SF_REVERSE)!=0 ? -2 : -1
         elsif (f == :rl_rubout)
            cxt.lastc = -3
         elsif (c == "\C-G")
            cxt.lastc = -4
         elsif (c == "\C-W")  # XXX
            cxt.lastc = -5
         elsif (c == "\C-Y")  # XXX
            cxt.lastc = -6
         end
      end

      # The characters in isearch_terminators (set from the user-settable
      #   variable isearch-terminators) are used to terminate the search but
      #   not subsequently execute the character as a command.  The default
      #   value is "\033\012" (ESC and C-J).
      if (cxt.lastc.class == ::String and cxt.search_terminators.include?(cxt.lastc))
         # ESC still terminates the search, but if there is pending
         #input or if input arrives within 0.1 seconds (on systems
         #with select(2)) it is used as a prefix character
         #with rl_execute_next.  WATCH OUT FOR THIS!  This is intended
         #to allow the arrow keys to be used like ^F and ^B are used
         #to terminate the search and execute the movement command.
         #XXX - since _rl_input_available depends on the application-
         #settable keyboard timeout value, this could alternatively
         #use _rl_input_queued(100000)
         if (cxt.lastc == ESC && _rl_input_available())
            rl_execute_next(ESC)
         end
         return (0)
      end

      if !@rl_byte_oriented
         if (cxt.lastc.class == String && (cxt.mb.length == 1) && endsrch_char(cxt.lastc))
            # This sets rl_pending_input to c; it will be picked up the next
            #   time rl_read_key is called.
            rl_execute_next(cxt.lastc)
            return (0)
         end
      elsif (cxt.lastc.class == String && endsrch_char(cxt.lastc))
         # This sets rl_pending_input to LASTC; it will be picked up the next
         #   time rl_read_key is called.
         rl_execute_next(cxt.lastc)
         return (0)
      end

      # Now dispatch on the character.  `Opcodes' affect the search string or
      #   state.  Other characters are added to the string.
      case (cxt.lastc)

         # search again
      when -1
         if (cxt.search_string_index == 0)
            if (@last_isearch_string)
               cxt.search_string_size = 64 + @last_isearch_string_len
               cxt.search_string = @last_isearch_string.dup
               cxt.search_string_index = @last_isearch_string_len
               rl_display_search(cxt.search_string, (cxt.sflags & SF_REVERSE)!=0, -1)
            else
               return (1)
            end
         elsif (cxt.sflags & SF_REVERSE)!=0
            cxt.sline_index-=1
         elsif (cxt.sline_index != cxt.sline_len)
            cxt.sline_index+=1
         else
            rl_ding()
         end

         # switch directions
      when -2
         cxt.direction = -cxt.direction
         if (cxt.direction < 0)
            cxt.sflags |= SF_REVERSE
         else
            cxt.sflags &= ~SF_REVERSE
         end
         # delete character from search string.
      when -3  # C-H, DEL
         # This is tricky.  To do this right, we need to keep a
         # stack of search positions for the current search, with
         # sentinels marking the beginning and end.  But this will
         # do until we have a real isearch-undo.
         if (cxt.search_string_index == 0)
            rl_ding()
         else
            cxt.search_string_index -= 1
            cxt.search_string.chop!
         end
      when -4  # C-G, abort
         rl_replace_line(cxt.lines[cxt.save_line], false)
         @rl_point = cxt.save_point
         @rl_mark = cxt.save_mark
         rl_restore_prompt()
         rl_clear_message()
         return -1
      when -5  # C-W
         # skip over portion of line we already matched and yank word
         wstart = @rl_point + cxt.search_string_index
         if (wstart >= @rl_end)
            rl_ding()
         else
            # if not in a word, move to one.
            cval = _rl_char_value(@rl_line_buffer, wstart)
            if (!_rl_walphabetic(cval))
               rl_ding()
            else
               if !@rl_byte_oriented
                  n = _rl_find_next_mbchar(@rl_line_buffer, wstart, 1, MB_FIND_NONZERO)
               else
                  n = wstart+1
               end
               while (n < @rl_end)
                  cval = _rl_char_value(@rl_line_buffer, n)
                  break if !_rl_walphabetic(cval)
                  if !@rl_byte_oriented
                     n = _rl_find_next_mbchar(@rl_line_buffer, n, 1, MB_FIND_NONZERO)
                  else
                     n = n+1
                  end
               end
               wlen = n - wstart + 1
               if (cxt.search_string_index + wlen + 1 >= cxt.search_string_size)
                  cxt.search_string_size += wlen + 1
               end
               cxt.search_string[cxt.search_string_index..-1] = @rl_line_buffer[wstart,wlen]
               cxt.search_string_index += wlen
            end
         end

      when -6  # C-Y
         # skip over portion of line we already matched and yank rest
         wstart = @rl_point + cxt.search_string_index
         if (wstart >= @rl_end)
            rl_ding()
         else
            n = @rl_end - wstart + 1
            if (cxt.search_string_index + n + 1 >= cxt.search_string_size)
               cxt.search_string_size += n + 1
            end
            cxt.search_string[cxt.search_string_index..-1] = @rl_line_buffer[wstart,n]
         end

         # Add character to search string and continue search.
      else
         if (cxt.search_string_index + 2 >= cxt.search_string_size)
            cxt.search_string_size += 128
         end
         if !@rl_byte_oriented
            for j in 0 ... cxt.mb.length
               cxt.search_string << cxt.mb[j,1]
               cxt.search_string_index += 1
            end
         else
            cxt.search_string << c
            cxt.search_string_index += 1
         end
      end

      while (cxt.sflags &= ~(SF_FOUND|SF_FAILED))!=0
         limit = cxt.sline_len - cxt.search_string_index + 1
         # Search the current line.
         while ((cxt.sflags & SF_REVERSE)!=0 ? (cxt.sline_index >= 0) : (cxt.sline_index < limit))

            if (cxt.search_string[0,cxt.search_string_index] == cxt.sline[cxt.sline_index,cxt.search_string_index])
               cxt.sflags |= SF_FOUND
               break
            else
               cxt.sline_index += cxt.direction
            end
         end
         break if (cxt.sflags & SF_FOUND)!=0

         # Move to the next line, but skip new copies of the line
         # we just found and lines shorter than the string we're
         # searching for.
         begin
            # Move to the next line.
            cxt.history_pos += cxt.direction

            # At limit for direction?
            if ((cxt.sflags & SF_REVERSE)!=0 ? (cxt.history_pos < 0) : (cxt.history_pos == cxt.hlen))
               cxt.sflags |= SF_FAILED
               break
            end

            # We will need these later.
            cxt.sline = cxt.lines[cxt.history_pos]
            cxt.sline_len = cxt.sline.length
         end while ((cxt.prev_line_found && cxt.prev_line_found == cxt.lines[cxt.history_pos]) ||
         (cxt.search_string_index > cxt.sline_len))

         break if (cxt.sflags & SF_FAILED)!=0

         # Now set up the line for searching...
         cxt.sline_index = (cxt.sflags & SF_REVERSE)!=0 ? cxt.sline_len - cxt.search_string_index : 0
      end

      if (cxt.sflags & SF_FAILED)!=0
         # We cannot find the search string.  Ding the bell.
         rl_ding()
         cxt.history_pos = cxt.last_found_line
         return 1
      end

      # We have found the search string.  Just display it.  But don't
      #   actually move there in the history list until the user accepts
      #   the location.
      if (cxt.sflags & SF_FOUND)!=0
         cxt.prev_line_found = cxt.lines[cxt.history_pos]
         if (cxt.prev_line_found)
           rl_replace_line(cxt.lines[cxt.history_pos], false)
         end
         @rl_point = cxt.sline_index
         cxt.last_found_line = cxt.history_pos
         rl_display_search(cxt.search_string, (cxt.sflags & SF_REVERSE)!=0, (cxt.history_pos == cxt.save_line) ? -1 : cxt.history_pos)
      end
      1
   end

   # How to clear things from the "echo-area".
   def rl_clear_message()
      @rl_display_prompt = @rl_prompt
      if (@msg_saved_prompt)
         rl_restore_prompt()
         @msg_saved_prompt = nil
      end
      send(@rl_redisplay_function)
      0
   end

   def _rl_isearch_fini(cxt)
      # First put back the original state.
      @rl_line_buffer = cxt.lines[cxt.save_line].dup
      rl_restore_prompt()

      # Save the search string for possible later use.
      @last_isearch_string = cxt.search_string
      @last_isearch_string_len = cxt.search_string_index
      cxt.search_string = nil

      if (cxt.last_found_line < cxt.save_line)
         rl_get_previous_history(cxt.save_line - cxt.last_found_line, 0)
      else
         rl_get_next_history(cxt.last_found_line - cxt.save_line, 0)
      end

      # If the string was not found, put point at the end of the last matching
      #   line.  If last_found_line == orig_line, we didn't find any matching
      #   history lines at all, so put point back in its original position.
      if (cxt.sline_index < 0)

         if (cxt.last_found_line == cxt.save_line)
            cxt.sline_index = cxt.save_point
         else
            cxt.sline_index = @rl_line_buffer.delete(0.chr).length
         end
         @rl_mark = cxt.save_mark
      end

      @rl_point = cxt.sline_index
      # Don't worry about where to put the mark here; rl_get_previous_history
      #   and rl_get_next_history take care of it.
      rl_clear_message()
   end


   def _rl_isearch_cleanup(cxt, r)
      if (r >= 0)
         _rl_isearch_fini(cxt)
      end
      ctx = nil
      @_rl_iscxt = nil

      rl_unsetstate(RL_STATE_ISEARCH)

      r != 0
   end

   # Do the command associated with KEY in MAP.
   #   If the associated command is really a keymap, then read
   #   another key, and dispatch into that map.
   def _rl_dispatch(key, map)
      @_rl_dispatching_keymap = map
      return _rl_dispatch_subseq(key, map, false)
   end


   def _rl_dispatch_subseq(key, map, got_subseq)
      func = map[key]
      if (func)
         @rl_executing_keymap = map

         @rl_dispatching = true
         rl_setstate(RL_STATE_DISPATCHING)
         send(map[key],@rl_numeric_arg * @rl_arg_sign, key)
         rl_unsetstate(RL_STATE_DISPATCHING)
         @rl_dispatching = false
         if (@rl_pending_input == 0 && map[key] != :rl_digit_argument)
            @rl_last_func = map[key]
         end
      else
         if(map.keys.detect{|x| x =~ /^#{Regexp.escape(key)}/})
            key += _rl_subseq_getchar(key)
            return _rl_dispatch_subseq(key,map,got_subseq)
         elsif(key.length>1 && key[1].ord < 0x7f)
            _rl_abort_internal()
            return -1
         else
            @rl_dispatching = true
            rl_setstate(RL_STATE_DISPATCHING)
            send(:rl_insert,@rl_numeric_arg * @rl_arg_sign, key)
            rl_unsetstate(RL_STATE_DISPATCHING)
            @rl_dispatching = false
         end
      end
      0
   end

   # Add KEY to the buffer of characters to be read.  Returns 1 if the
   #   character was stuffed correctly; 0 otherwise.
   def rl_stuff_char(key)
      return 0 if (ibuffer_space() == 0)

      if (key == EOF)
         key = NEWLINE
         @rl_pending_input = EOF
         rl_setstate(RL_STATE_INPUTPENDING)
      end
      @ibuffer[@push_index] = key
      @push_index += 1
      if (@push_index >= @ibuffer_len)
         @push_index = 0
      end

      return 1
   end

   begin
      # Cygwin will look like Windows, but we want to treat it like a Posix OS:
      raise LoadError, "Cygwin is a Posix OS." if RUBY_PLATFORM =~ /\bcygwin\b/i

    # Try to use win32api regardless of version.  This allows us to correctly
    # fall back to unixy stuff when not on Windows.  Requires some testing on
    # 1.8 for Windows, but msf ships 1.9, so don't worry about it for now.
      #if RUBY_VERSION < '1.9.1'
         require 'Win32API'
      #else
      #   require 'dl'
      #   class Win32API
      #      DLL = {}
      #      TYPEMAP = {"0" => DL::TYPE_VOID, "S" => DL::TYPE_VOIDP, "I" => DL::TYPE_LONG}
      #
      #      def initialize(dllname, func, import, export = "0", calltype = :stdcall)
      #         @proto = [import].join.tr("VPpNnLlIi", "0SSI").sub(/^(.)0*$/, '\1')
      #         handle = DLL[dllname] ||= DL.dlopen(dllname)
      #         @func = DL::CFunc.new(handle[func], TYPEMAP[export.tr("VPpNnLlIi", "0SSI")], func, calltype)
      #      end
      #
      #      def call(*args)
      #         import = @proto.split("")
      #         args.each_with_index do |x, i|
      #            args[i], = [x == 0 ? nil : x].pack("p").unpack("l!*") if import[i] == "S"
      #            args[i], = [x].pack("I").unpack("i") if import[i] == "I"
      #         end
      #         ret, = @func.call(args)
      #         return ret || 0
      #      end
      #
      #      alias Call call
      #   end
      #end

      STD_OUTPUT_HANDLE = -11
      STD_INPUT_HANDLE  = -10
      KEY_EVENT = 1
      VK_SHIFT = 0x10
      VK_MENU = 0x12
      VK_LMENU = 0xA4
      VK_RMENU = 0xA5

      LEFT_CTRL_PRESSED         = 0x0008
      RIGHT_CTRL_PRESSED        = 0x0004
      LEFT_ALT_PRESSED          = 0x0002
      RIGHT_ALT_PRESSED         = 0x0001

      @getch = Win32API.new("msvcrt", "_getch", [], 'I')
      @kbhit = Win32API.new("msvcrt", "_kbhit", [], 'I')
      @GetStdHandle = Win32API.new("kernel32","GetStdHandle",['L'],'L')
      @SetConsoleCursorPosition = Win32API.new("kernel32","SetConsoleCursorPosition",['L','L'],'L')
      @GetConsoleScreenBufferInfo = Win32API.new("kernel32","GetConsoleScreenBufferInfo",['L','P'],'L')
      @FillConsoleOutputCharacter = Win32API.new("kernel32","FillConsoleOutputCharacter",['L','L','L','L','P'],'L')
      @ReadConsoleInput = Win32API.new( "kernel32", "ReadConsoleInput", ['L', 'P', 'L', 'P'], 'L' )
      @MessageBeep = Win32API.new("user32","MessageBeep",['L'],'L')
      @GetKeyboardState = Win32API.new("user32","GetKeyboardState",['P'],'L')
      @GetKeyState = Win32API.new("user32","GetKeyState",['L'],'L')
      @hConsoleHandle = @GetStdHandle.Call(STD_OUTPUT_HANDLE)
      @hConsoleInput =  @GetStdHandle.Call(STD_INPUT_HANDLE)
      @pending_count = 0
      @pending_key = nil

      begin
        case `chcp`.scan(/\d+$/).first.to_i
        when 936,949,950,51932,51936,50225
          @encoding = "E"
        when 932,50220,50221,20222
          @encoding = "S"
        when 65001
          @encoding = "U"
        else
          @encoding = "N"
        end
      rescue
        @encoding = "N"
      end

      def rl_getc(stream)
         while (@kbhit.Call == 0)
            # If there is no input, yield the processor for other threads
            sleep(@_keyboard_input_timeout)
         end
         c = @getch.Call
         alt = (@GetKeyState.call(VK_LMENU) & 0x80) != 0
         if c==0 || c==0xE0
            while (@kbhit.Call == 0)
               # If there is no input, yield the processor for other threads
               sleep(@_keyboard_input_timeout)
            end
            r = c.chr + @getch.Call.chr
         else
            r = c.chr
         end
         r = "\e"+r if alt
         r
      end

      def rl_gather_tyi()
         chars_avail = @kbhit.Call
         return 0 if(chars_avail<=0)
         k = send(@rl_getc_function,@rl_instream)
         rl_stuff_char(k)
         return 1
      end

   rescue LoadError                  # If we're not on Windows try...

      if ENV["LANG"] =~ /\.UTF-8/
         @encoding = "U"
      elsif ENV["LANG"] =~ /\.EUC/
         @encoding = "E"
      elsif ENV["LANG"] =~ /\.SHIFT/
         @encoding = "S"
      else
         @encoding = "N"
      end

      def rl_getc(stream)
         begin
            c = stream.read(1)
         rescue Errno::EINTR
            c = rl_getc(stream)
         end
         return c ? c : EOF
      end

      def rl_gather_tyi()
         chars_avail = 0
         result = select([@rl_instream],nil,nil,0.1)
         return 0 if result.nil?
         k = send(@rl_getc_function,@rl_instream)
         rl_stuff_char(k)
         return 1
      end
   end

   if (Object.const_defined?('Encoding') and Encoding.respond_to?('default_external'))
      @encoding = "X"      # ruby 1.9.x or greater
      @encoding_name = Encoding.default_external.to_s
   end

   @rl_byte_oriented = @encoding == "N"

   # Read a key, including pending input.
   def rl_read_key()
      @rl_key_sequence_length+=1

      if (@rl_pending_input!=0)
         c = @rl_pending_input
         rl_clear_pending_input()
      else
         # If the user has an event function, then call it periodically.
         if (@rl_event_hook)
            while (@rl_event_hook && (c=rl_get_char()).nil?)

               send(@rl_event_hook)
               if (@rl_done)     # XXX - experimental
                  return ("\n")
               end
               if (rl_gather_tyi() < 0)   # XXX - EIO
                  @rl_done = true
                  return ("\n")
               end
            end

         else

            if (c=rl_get_char()).nil?
               c = send(@rl_getc_function,@rl_instream)
            end
         end
      end

      return (c)
   end


   # Return the amount of space available in the buffer for stuffing
   #   characters.
   def ibuffer_space()
      if (@pop_index > @push_index)
         return (@pop_index - @push_index - 1)
      else
         return (@ibuffer_len - (@push_index - @pop_index))
      end
   end

   # Get a key from the buffer of characters to be read.
   #   Return the key in KEY.
   #   Result is KEY if there was a key, or 0 if there wasn't.
   def rl_get_char()
      if (@push_index == @pop_index)
         return nil
      end
      key = @ibuffer[@pop_index]
      @pop_index += 1

      if (@pop_index >= @ibuffer_len)
         @pop_index = 0
      end

      return key
   end

   # Stuff KEY into the *front* of the input buffer.
   #   Returns non-zero if successful, zero if there is
   #   no space left in the buffer.
   def _rl_unget_char(key)
      if (ibuffer_space()!=0)
         @pop_index-=1
         if (@pop_index < 0)
            @pop_index = @ibuffer_len - 1
         end
         @ibuffer[@pop_index] = key
         return (1)
      end
      return (0)
   end

   def _rl_subseq_getchar(key)
      if (key == ESC)
         rl_setstate(RL_STATE_METANEXT)
      end
      rl_setstate(RL_STATE_MOREINPUT)
      k = rl_read_key()
      rl_unsetstate(RL_STATE_MOREINPUT)
      if (key == ESC)
         rl_unsetstate(RL_STATE_METANEXT)
      end

      return k
   end

   # Clear to the end of the line.  COUNT is the minimum
   #   number of character spaces to clear,
   def _rl_clear_to_eol(count)
      if (@_rl_term_clreol)
         @rl_outstream.write(@_rl_term_clreol)
      elsif (count!=0)
         space_to_eol(count)
      end
   end

   # Clear to the end of the line using spaces.  COUNT is the minimum
   #   number of character spaces to clear,
   def space_to_eol(count)
      if @hConsoleHandle
         csbi = 0.chr * 24
         @GetConsoleScreenBufferInfo.Call(@hConsoleHandle,csbi)
         cursor_pos = csbi[4,4].unpack('L').first
         written = 0.chr * 4
         @FillConsoleOutputCharacter.Call(@hConsoleHandle,0x20,count,cursor_pos,written)
      else
         @rl_outstream.write(' ' * count)
      end
      @_rl_last_c_pos += count
   end

   def _rl_clear_screen()
      if (@_rl_term_clrpag)
         @rl_outstream.write(@_rl_term_clrpag)
      else
         rl_crlf()
      end
   end

   # Move the cursor back.
   def _rl_backspace(count)
      if (@_rl_term_backspace)
         @_rl_out_stream.write(@_rl_term_backspace * count)
      else
         @_rl_out_stream.write("\b"*count)
      end
      0
   end

   # Move to the start of the next line.
   def rl_crlf()
      if (@_rl_term_cr)
         @_rl_out_stream.write(@_rl_term_cr)
      end
      @_rl_out_stream.write("\n")
      return 0
   end

   # Move to the start of the current line.
   def cr()
      if (@_rl_term_cr)
         @_rl_out_stream.write(@_rl_term_cr)
         @_rl_last_c_pos = 0
      end
   end

   def _rl_erase_entire_line()
      cr()
      _rl_clear_to_eol(0)
      cr()
      @rl_outstream.flush
   end

   def _rl_internal_char_cleanup()
      # In vi mode, when you exit insert mode, the cursor moves back
      #   over the previous character.  We explicitly check for that here.
      if (@rl_editing_mode == @vi_mode && @_rl_keymap == @vi_movement_keymap)
         rl_vi_check()
      end

      if (@rl_num_chars_to_read!=0 && @rl_end >= @rl_num_chars_to_read)
         send(@rl_redisplay_function)
         @_rl_want_redisplay = false
         rl_newline(1, "\n")
      end

      if (!@rl_done)
         send(@rl_redisplay_function)
         @_rl_want_redisplay = false
      end

      # If the application writer has told us to erase the entire line if
      #   the only character typed was something bound to rl_newline, do so.
      if (@rl_erase_empty_line && @rl_done && @rl_last_func == :rl_newline &&
         @rl_point == 0 && @rl_end == 0)
         _rl_erase_entire_line()
      end
   end

   def readline_internal_charloop()
      lastc = -1
      eof_found = false

      while (!@rl_done)
         lk = @_rl_last_command_was_kill

         #  send(rl_redisplay_function)
         #  @_rl_want_redisplay = false

         if (@rl_pending_input == 0)
            # Then initialize the argument and number of keys read.
            _rl_reset_argument()
            @rl_key_sequence_length = 0
         end

         rl_setstate(RL_STATE_READCMD)
         c = rl_read_key()
         rl_unsetstate(RL_STATE_READCMD)
         # look at input.c:rl_getc() for the circumstances under which this will
         #be returned; punt immediately on read error without converting it to
         #a newline.
         if (c == READERR)
            eof_found = true
            break
         end

         # EOF typed to a non-blank line is a <NL>.
         if (c == EOF && @rl_end!=0)
            c = NEWLINE
         end

         # The character _rl_eof_char typed to blank line, and not as the
         #previous character is interpreted as EOF.
         if (((c == @_rl_eof_char && lastc != c) || c == EOF) && @rl_end==0)
            eof_found = true
            break
         end
         lastc = c
         if _rl_dispatch(c, @_rl_keymap)== -1
            next
         end

         # If there was no change in _rl_last_command_was_kill, then no kill
         #has taken place.  Note that if input is pending we are reading
         #a prefix command, so nothing has changed yet.
         if (@rl_pending_input == 0 && lk == @_rl_last_command_was_kill)
            @_rl_last_command_was_kill = false
         end
         _rl_internal_char_cleanup()
      end

      eof_found
   end

   # How to abort things.
   def _rl_abort_internal()
      rl_ding()
      rl_clear_message()
      _rl_reset_argument()
      rl_clear_pending_input()

      rl_unsetstate(RL_STATE_MACRODEF)

      @rl_last_func = nil
      #throw :readline_top_level
      send(@rl_redisplay_function)
      @_rl_want_redisplay = false
      0
   end

   def rl_abort(count, key)
      _rl_abort_internal()
   end

   def rl_vi_check()
      if (@rl_point!=0 && @rl_point == @rl_end)
         @rl_point-=1
      end
      0
   end

   def readline_internal_teardown(eof)
      # Restore the original of this history line, iff the line that we
      #   are editing was originally in the history, AND the line has changed.
      entry = current_history()

      if (entry && @rl_undo_list)
         temp = @rl_line_buffer.delete(0.chr).dup
         rl_revert_line(1, 0)
         entry = replace_history_entry(where_history(), @rl_line_buffer, nil)
         entry = nil

         @rl_line_buffer = temp+0.chr
         temp = nil
      end

      # At any rate, it is highly likely that this line has an undo list.  Get
      #   rid of it now.
      if (@rl_undo_list)
         rl_free_undo_list()
      end
      # Restore normal cursor, if available.
      _rl_set_insert_mode(RL_IM_INSERT, 0)

      (eof ? nil : @rl_line_buffer.delete(0.chr))
   end

   # Read a line of input from the global rl_instream, doing output on
   #   the global rl_outstream.
   #   If rl_prompt is non-null, then that is our prompt.
   def readline_internal()
      readline_internal_setup()
      eof = readline_internal_charloop()
      readline_internal_teardown(eof)
   end

   # Read a line of input.  Prompt with PROMPT.  An empty PROMPT means
   #   none.  A return value of NULL means that EOF was encountered.
   def readline(prompt)
      # If we are at EOF return a NULL string.
      if (@rl_pending_input == EOF)
         rl_clear_pending_input()
         return nil
      end

      rl_set_prompt(prompt)

      rl_initialize()
      @readline_echoing_p = true
      if (@rl_prep_term_function)
         send(@rl_prep_term_function,@_rl_meta_flag)
      end
      rl_set_signals()

      value = readline_internal()
      if(@rl_deprep_term_function)
         send(@rl_deprep_term_function)
      end

      rl_clear_signals()

      value
   end

   # Increase the size of RL_LINE_BUFFER until it has enough space to hold
   #   LEN characters.
   def rl_extend_line_buffer(len)
      while (len >= @rl_line_buffer.length)
         @rl_line_buffer << 0.chr * DEFAULT_BUFFER_SIZE
      end
      @the_line = @rl_line_buffer
   end

   # Insert a string of text into the line at point.  This is the only
   #   way that you should do insertion.  _rl_insert_char () calls this
   #   function.  Returns the number of characters inserted.
   def rl_insert_text(string)
      string.delete!(0.chr)
      l = string.length
      return 0 if (l == 0)

      if (@rl_end + l >= @rl_line_buffer.length)
         rl_extend_line_buffer(@rl_end + l)
      end
      @rl_line_buffer[@rl_point,0] = string

      # Remember how to undo this if we aren't undoing something.
      if (!@_rl_doing_an_undo)
         # If possible and desirable, concatenate the undos.
         if ((l == 1) &&
            @rl_undo_list &&
            (@rl_undo_list.what == UNDO_INSERT) &&
            (@rl_undo_list.end == @rl_point) &&
            (@rl_undo_list.end - @rl_undo_list.start < 20))
            @rl_undo_list.end+=1
         else
            rl_add_undo(UNDO_INSERT, @rl_point, @rl_point + l, nil)
         end
      end
      @rl_point += l
      @rl_end += l
      if @rl_line_buffer.length <= @rl_end
         @rl_line_buffer << 0.chr * (@rl_end - @rl_line_buffer.length + 1)
      else
         @rl_line_buffer[@rl_end] = "\0"
      end
      l
   end

   def alloc_undo_entry(what, start, _end, text)
      temp = Struct.new(:what,:start,:end,:text,:next).new
      temp.what = what
      temp.start = start
      temp.end = _end
      temp.text = text
      temp.next = nil
      temp
   end

   #* Remember how to undo something.  Concatenate some undos if that
   #   seems right.
   def rl_add_undo(what, start, _end, text)
      temp = alloc_undo_entry(what, start, _end, text)
      temp.next = @rl_undo_list
      @rl_undo_list = temp
   end


   # Delete the string between FROM and TO.  FROM is inclusive, TO is not.
   #   Returns the number of characters deleted.
   def rl_delete_text(from, to)

      # Fix it if the caller is confused.
      if (from > to)
         from,to = to,from
      end

      # fix boundaries
      if (to > @rl_end)
         to = @rl_end
         if (from > to)
            from = to
         end
      end
      if (from < 0)
         from = 0
      end
      text = rl_copy_text(from, to)
      diff = to - from
      @rl_line_buffer[from...to] = ''
      @rl_line_buffer << 0.chr * diff
      # Remember how to undo this delete.
      if (!@_rl_doing_an_undo)
         rl_add_undo(UNDO_DELETE, from, to, text)
      else
         text = nil
      end
      @rl_end -= diff
      @rl_line_buffer[@rl_end] = 0.chr
      return (diff)
   end

   def rl_copy_text(from, to)
      return @rl_line_buffer[from...to]
   end

   # Fix up point so that it is within the line boundaries after killing
   #   text.  If FIX_MARK_TOO is non-zero, the mark is forced within line
   #   boundaries also.

   def __rl_fix_point(x)
      if (x > @rl_end)
         @rl_end
      elsif (x < 0)
         0
      else
         x
      end
   end

   def _rl_fix_point(fix_mark_too)
      @rl_point = __rl_fix_point(@rl_point)
      if (fix_mark_too)
         @rl_mark = __rl_fix_point(@rl_mark)
      end
   end

   # Begin a group.  Subsequent undos are undone as an atomic operation.
   def rl_begin_undo_group()
      rl_add_undo(UNDO_BEGIN, 0, 0, nil)
      @_rl_undo_group_level+=1
      0
   end

   # End an undo group started with rl_begin_undo_group ().
   def rl_end_undo_group()
      rl_add_undo(UNDO_END, 0, 0, nil)
      @_rl_undo_group_level-=1
      0
   end

   def rl_free_undo_list()
      replace_history_data(-1, @rl_undo_list, nil)
      @rl_undo_list = nil
   end

   # Replace the contents of the line buffer between START and END with
   #   TEXT.  The operation is undoable.  To replace the entire line in an
   #   undoable mode, use _rl_replace_text(text, 0, rl_end)
   def _rl_replace_text(text, start, _end)
      rl_begin_undo_group()
      rl_delete_text(start, _end + 1)
      @rl_point = start
      n = rl_insert_text(text)
      rl_end_undo_group()
      n
   end

   # Replace the current line buffer contents with TEXT.  If CLEAR_UNDO is
   #   non-zero, we free the current undo list.
   def rl_replace_line(text, clear_undo)
      len = text.delete(0.chr).length
      @rl_line_buffer = text.dup + 0.chr
      @rl_end = len
      if (clear_undo)
         rl_free_undo_list()
      end
      _rl_fix_point(true)
   end


   # Replace the DATA in the specified history entries, replacing OLD with
   #   NEW.  WHICH says which one(s) to replace:  WHICH == -1 means to replace
   #   all of the history entries where entry->data == OLD; WHICH == -2 means
   #   to replace the `newest' history entry where entry->data == OLD; and
   #   WHICH >= 0 means to replace that particular history entry's data, as
   #   long as it matches OLD.
   def replace_history_data(which,old, new)
      new = new.dup if new
      if (which < -2 || which >= @history_length || @history_length == 0 || @the_history.nil?)
         return
      end
      if (which >= 0)
         entry = @the_history[which]
         if (entry && entry.data == old)
            entry.data = new
         end
         return
      end

      last = -1
      for i in 0 ... @history_length
         entry = @the_history[i]
         if entry.nil?
            next
         end
         if (entry.data == old)
            last = i
            if (which == -1)
               entry.data = new
            end
         end
      end
      if (which == -2 && last >= 0)
         entry = @the_history[last]
         entry.data = new  # XXX - we don't check entry->old
      end
   end

   # Move forward COUNT bytes.
   def rl_forward_byte(count, key)
      if (count < 0)
         return (rl_backward_byte(-count, key))
      end
      if (count > 0)
         _end = @rl_point + count
         lend = @rl_end > 0 ? @rl_end - ((@rl_editing_mode == @vi_mode)?1:0) : @rl_end
         if (_end > lend)
            @rl_point = lend
            rl_ding()
         else
            @rl_point = _end
         end
      end

      if (@rl_end < 0)
         @rl_end = 0
      end
      return 0
   end

   # Move forward COUNT characters.
   def rl_forward_char(count, key)
      if @rl_byte_oriented
         return (rl_forward_byte(count, key))
      end
      if (count < 0)
         return (rl_backward_char(-count, key))
      end
      if (count > 0)
         point = _rl_find_next_mbchar(@rl_line_buffer, @rl_point, count, MB_FIND_NONZERO)
         if (@rl_end <= point && @rl_editing_mode == @vi_mode)
            point = _rl_find_prev_mbchar(@rl_line_buffer, @rl_end, MB_FIND_NONZERO)
         end
         if (@rl_point == point)
            rl_ding()
         end
         @rl_point = point
         if (@rl_end < 0)
            @rl_end = 0
         end
      end
      0
   end

   # Backwards compatibility.
   def rl_forward(count, key)
      rl_forward_char(count, key)
   end

   # Move backward COUNT bytes.
   def rl_backward_byte(count, key)
      if (count < 0)
         return (rl_forward_byte(-count, key))
      end
      if (count > 0)
         if (@rl_point < count)
            @rl_point = 0
            rl_ding()
         else
            @rl_point -= count
         end
      end

      if (@rl_point < 0)
         @rl_point = 0
      end
      0
   end

   # Move backward COUNT characters.
   def rl_backward_char(count, key)
      if @rl_byte_oriented
         return (rl_backward_byte(count, key))
      end
      if (count < 0)
         return (rl_forward_char(-count, key))
      end

      if (count > 0)
         point = @rl_point
         while (count > 0 && point > 0)
            point = _rl_find_prev_mbchar(@rl_line_buffer, point, MB_FIND_NONZERO)
            count-=1
         end
         if (count > 0)
            @rl_point = 0
            rl_ding()
         else
            @rl_point = point
         end
      end
      0
   end

   # Backwards compatibility.
   def rl_backward(count, key)
      rl_backward_char(count, key)
   end

   # Move to the beginning of the line.
   def rl_beg_of_line(count, key)
      @rl_point = 0
      0
   end

   # Move to the end of the line.
   def rl_end_of_line(count, key)
      @rl_point = @rl_end
      0
   end

   def _rl_char_value(buf,ind)
      buf[ind,1]
   end

   @_rl_allow_pathname_alphabetic_chars = false
   @pathname_alphabetic_chars = '/-_=~.#$'

   def rl_alphabetic(c)
      if c =~ /\w/
         return true
      end

      return !!(@_rl_allow_pathname_alphabetic_chars &&
      @pathname_alphabetic_chars[c])
   end

   def _rl_walphabetic(c)
      rl_alphabetic(c)
   end

   # Move forward a word.  We do what Emacs does.  Handles multibyte chars.
   def rl_forward_word(count, key)
      if (count < 0)
         return (rl_backward_word(-count, key))
      end

      while (count>0)
         return 0 if (@rl_point == @rl_end)

         # If we are not in a word, move forward until we are in one.
         # Then, move forward until we hit a non-alphabetic character.
         c = _rl_char_value(@rl_line_buffer, @rl_point)

         if (!_rl_walphabetic(c))
            if !@rl_byte_oriented
               @rl_point = _rl_find_next_mbchar(@rl_line_buffer, @rl_point, 1, MB_FIND_NONZERO)
            else
               @rl_point += 1
            end
            while (@rl_point < @rl_end)
               c = _rl_char_value(@rl_line_buffer, @rl_point)
               if (_rl_walphabetic(c))
                  break
               end
               if !@rl_byte_oriented
                  @rl_point = _rl_find_next_mbchar(@rl_line_buffer, @rl_point, 1, MB_FIND_NONZERO)
               else
                  @rl_point += 1
               end
            end
         end

         return 0 if (@rl_point == @rl_end)

         if !@rl_byte_oriented
            @rl_point = _rl_find_next_mbchar(@rl_line_buffer, @rl_point, 1, MB_FIND_NONZERO)
         else
            @rl_point += 1
         end
         while (@rl_point < @rl_end)
            c = _rl_char_value(@rl_line_buffer, @rl_point)
            if (!_rl_walphabetic(c))
               break
            end
            if !@rl_byte_oriented
               @rl_point = _rl_find_next_mbchar(@rl_line_buffer, @rl_point, 1, MB_FIND_NONZERO)
            else
               @rl_point += 1
            end
         end
         count -= 1
      end
      0
   end

   # Move backward a word.  We do what Emacs does.  Handles multibyte chars.
   def rl_backward_word(count, key)
      if (count < 0)
         return (rl_forward_word(-count, key))
      end
      while (count>0)
         return 0 if (@rl_point == 0)

         # Like rl_forward_word (), except that we look at the characters
         # just before point.
         _p =  !@rl_byte_oriented ? _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO):(@rl_point-1)
         c = _rl_char_value(@rl_line_buffer, _p)
         if (!_rl_walphabetic(c))
            @rl_point = _p
            while (@rl_point > 0)
               _p = !@rl_byte_oriented ? _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO):(@rl_point-1)
               c = _rl_char_value(@rl_line_buffer, _p)
               if (_rl_walphabetic(c))
                  break
               end
               @rl_point = _p
            end
         end
         while (@rl_point>0)
            _p = !@rl_byte_oriented ? _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO):(@rl_point-1)
            c = _rl_char_value(@rl_line_buffer, _p)
            if (!_rl_walphabetic(c))
               break
            else
               @rl_point = _p
            end
         end
         count -= 1
      end
      0
   end

   # return the `current display line' of the cursor -- the number of lines to
   #   move up to get to the first screen line of the current readline line.
   def _rl_current_display_line()
      # Find out whether or not there might be invisible characters in the
      #   editing buffer.
      if (@rl_display_prompt == @rl_prompt)
         nleft = @_rl_last_c_pos - @_rl_screenwidth - @rl_visible_prompt_length
      else
         nleft = @_rl_last_c_pos - @_rl_screenwidth
      end

      if (nleft > 0)
         ret = 1 + nleft / @_rl_screenwidth
      else
         ret = 0
      end

      ret
   end

   # Actually update the display, period.
   def rl_forced_update_display()
      if (@visible_line)
         @visible_line.gsub!(/[^\x00]/n,0.chr)
      end
      rl_on_new_line()
      @forced_display=true if !@forced_display
      send(@rl_redisplay_function)
      0
   end


   # Clear the current line.  Numeric argument to C-l does this.
   def rl_refresh_line(ignore1, ignore2)
      curr_line = _rl_current_display_line()

      _rl_move_vert(curr_line)
      _rl_move_cursor_relative(0, @rl_line_buffer)   # XXX is this right

      _rl_clear_to_eol(0)     # arg of 0 means to not use spaces

      rl_forced_update_display()
      @rl_display_fixed = true

      0
   end

   # C-l typed to a line without quoting clears the screen, and then reprints
   #   the prompt and the current input line.  Given a numeric arg, redraw only
   #   the current line.
   def rl_clear_screen(count, key)
      if (@rl_explicit_arg)
         rl_refresh_line(count, key)
         return 0
      end

      _rl_clear_screen()      # calls termcap function to clear screen
      rl_forced_update_display()
      @rl_display_fixed = true
      0
   end

   # Restore the _rl_saved_line_for_history if there is one.
   def rl_maybe_unsave_line()
      if (@_rl_saved_line_for_history)
         # Can't call with `1' because rl_undo_list might point to an undo
         # list from a history entry, as in rl_replace_from_history() below.
         rl_replace_line(@_rl_saved_line_for_history.line, false)
         @rl_undo_list = @_rl_saved_line_for_history.data
         @_rl_saved_line_for_history = nil
         @rl_point = @rl_end  # rl_replace_line sets rl_end
      else
         rl_ding()
      end
      0
   end

   # Save the current line in _rl_saved_line_for_history.
   def rl_maybe_save_line()
      if @_rl_saved_line_for_history.nil?
         @_rl_saved_line_for_history = Struct.new(:line,:timestamp,:data).new
         @_rl_saved_line_for_history.line = @rl_line_buffer.dup
         @_rl_saved_line_for_history.timestamp = nil
         @_rl_saved_line_for_history.data = @rl_undo_list
      end
      0
   end

   # Returns the magic number which says what history element we are
   #   looking at now.  In this implementation, it returns history_offset.
   def where_history()
      @history_offset
   end

   # Make the history entry at WHICH have LINE and DATA.  This returns
   #   the old entry so you can dispose of the data.  In the case of an
   #   invalid WHICH, a NULL pointer is returned.
   def replace_history_entry (which, line, data)
      if (which < 0 || which >= @history_length)
         return nil
      end
      temp = Struct.new(:line,:timestamp,:data).new
      old_value = @the_history[which]
      temp.line = line.delete(0.chr)
      temp.data = data
      temp.timestamp = old_value.timestamp.dup
      @the_history[which] = temp
      old_value
   end

   # Perhaps put back the current line if it has changed.
   def rl_maybe_replace_line()
      temp = current_history()
      # If the current line has changed, save the changes.
      if (temp && temp.data != @rl_undo_list)
         temp = replace_history_entry(where_history(), @rl_line_buffer, @rl_undo_list)
      end
      0
   end

   # Back up history_offset to the previous history entry, and return
   #   a pointer to that entry.  If there is no previous entry then return
   #   a NULL pointer.
   def previous_history()
      @history_offset!=0 ? @the_history[@history_offset-=1] : nil
   end

   # Move history_offset forward to the next history entry, and return
   #   a pointer to that entry.  If there is no next entry then return a
   #   NULL pointer.
   def next_history()
      (@history_offset == @history_length) ? nil : @the_history[@history_offset+=1]
   end

   # Get the previous item out of our interactive history, making it the current
   #   line.  If there is no previous history, just ding.
   def rl_get_previous_history(count, key)
      if (count < 0)
         return (rl_get_next_history(-count, key))
      end
      if (count == 0)
         return 0
      end
      # either not saved by rl_newline or at end of line, so set appropriately.
      if (@_rl_history_saved_point == -1 && (@rl_point!=0 || @rl_end!=0))
         @_rl_history_saved_point = (@rl_point == @rl_end) ? -1 : @rl_point
      end

      # If we don't have a line saved, then save this one.
      rl_maybe_save_line()

      # If the current line has changed, save the changes.
      rl_maybe_replace_line()

      temp = old_temp = nil
      while (count>0)
         temp = previous_history()
         if temp.nil?
            break
         end
         old_temp = temp
         count -= 1
      end

      # If there was a large argument, and we moved back to the start of the
      #   history, that is not an error.  So use the last value found.
      if (temp.nil? && old_temp)
         temp = old_temp
      end

      if temp.nil?
         rl_ding()
      else
         rl_replace_from_history(temp, 0)
         _rl_history_set_point()
      end

      0
   end

   def _rl_history_set_point ()
      @rl_point = (@_rl_history_preserve_point && @_rl_history_saved_point != -1) ?
      @_rl_history_saved_point : @rl_end
      if (@rl_point > @rl_end)
         @rl_point = @rl_end
      end
      if (@rl_editing_mode == @vi_mode && @_rl_keymap != @vi_insertion_keymap)
         @rl_point = 0
      end
      if (@rl_editing_mode == @emacs_mode)
         @rl_mark = (@rl_point == @rl_end ? 0 : @rl_end)
      end
   end

   # Move down to the next history line.
   def rl_get_next_history(count, key)
      if (count < 0)
         return (rl_get_previous_history(-count, key))
      end
      if (count == 0)
         return 0
      end
      rl_maybe_replace_line()

      # either not saved by rl_newline or at end of line, so set appropriately.
      if (@_rl_history_saved_point == -1 && (@rl_point!=0 || @rl_end!=0))
         @_rl_history_saved_point = (@rl_point == @rl_end) ? -1 : @rl_point
      end
      temp = nil
      while (count>0)
         temp = next_history()
         if temp.nil?
            break
         end
         count -= 1
      end

      if temp.nil?
         rl_maybe_unsave_line()
      else
         rl_replace_from_history(temp, 0)
         _rl_history_set_point()
      end
      0
   end

   def rl_arrow_keys(count, c)
      rl_setstate(RL_STATE_MOREINPUT)
      ch = rl_read_key()
      rl_unsetstate(RL_STATE_MOREINPUT)

      case (ch.upcase)
      when 'A'
         rl_get_previous_history(count, ch)
      when 'B'
         rl_get_next_history(count, ch)
      when 'C'
         rl_forward_byte(count, ch)
      when 'D'
         rl_backward_byte(count, ch)
      else
         rl_ding()
      end
      0
   end

   def _rl_any_typein()
      return (@push_index != @pop_index)
   end

   def _rl_insert_typein(c)
      string = c

      while ((key = rl_get_char()) &&
         @_rl_keymap[key] == :rl_insert)
         string << key
      end
      if (key)
         _rl_unget_char(key)
      end
      rl_insert_text(string)
   end

   # Insert the character C at the current location, moving point forward.
   #   If C introduces a multibyte sequence, we read the whole sequence and
   #   then insert the multibyte char into the line buffer.
   def _rl_insert_char(count, c)
      return 0 if (count <= 0)

      incoming = ''

      if @rl_byte_oriented
         incoming << c
         incoming_length = 1
      else
         @pending_bytes << c
         if _rl_get_char_len(@pending_bytes) == -2
            return 1
         else
            incoming = @pending_bytes
            @pending_bytes = ''
            incoming_length = incoming.length
         end
      end

      if(count>1)
         string = incoming * count
         rl_insert_text(string)
         string = nil
         return 0
      end

      if @rl_byte_oriented
         # We are inserting a single character.
         #If there is pending input, then make a string of all of the
         #pending characters that are bound to rl_insert, and insert
         #them all.
         if (_rl_any_typein())
            _rl_insert_typein(c)
         else
            rl_insert_text(c)
         end
      else
         rl_insert_text(incoming)
      end

      return 0
   end

   # Overwrite the character at point (or next COUNT characters) with C.
   #   If C introduces a multibyte character sequence, read the entire sequence
   #   before starting the overwrite loop.
   def _rl_overwrite_char(count, c)

      # Read an entire multibyte character sequence to insert COUNT times.
      if (count > 0 && !@rl_byte_oriented)
         mbkey = ''
         k = _rl_read_mbstring(c, mbkey, MB_LEN_MAX)
      end
      rl_begin_undo_group()

      count.times do
         if !@rl_byte_oriented
            rl_insert_text(mbkey)
         else
            _rl_insert_char(1, c)
         end
         if (@rl_point < @rl_end)
            rl_delete(1, c)
         end
      end

      rl_end_undo_group()

      return 0
   end

   def rl_insert(count, c)
      ((@rl_insert_mode == RL_IM_INSERT) ? _rl_insert_char(count, c) :
      _rl_overwrite_char(count, c))
   end


   # Insert the next typed character verbatim.
   def _rl_insert_next(count)
      rl_setstate(RL_STATE_MOREINPUT)
      c = rl_read_key()
      rl_unsetstate(RL_STATE_MOREINPUT)

      _rl_insert_char(count, c)
   end

   def rl_quoted_insert(count, key)
      _rl_insert_next(count)
   end

   # Insert a tab character.
   def rl_tab_insert(count, key)
      _rl_insert_char(count, "\t")
   end

   def _rl_vi_save_insert(up)
      if (up.nil? || up.what != UNDO_INSERT)
         if (@vi_insert_buffer_size >= 1)
            @vi_insert_buffer[0] = 0.chr
         end
         return
      end
      start = up.start
      _end = up.end
      len = _end - start + 1
      @vi_insert_buffer = @rl_line_buffer[start,len-1]
   end

   def _rl_vi_done_inserting()
      if (@_rl_vi_doing_insert)

         # The `C', `s', and `S' commands set this.
         rl_end_undo_group()
         # Now, the text between rl_undo_list->next->start and
         # rl_undo_list->next->end is what was inserted while in insert
         # mode.  It gets copied to VI_INSERT_BUFFER because it depends
         # on absolute indices into the line which may change (though they
         # probably will not).
         @_rl_vi_doing_insert = 0
         _rl_vi_save_insert(@rl_undo_list.next)
         @vi_continued_command = 1
      else
         if ((@_rl_vi_last_key_before_insert == 'i' || @_rl_vi_last_key_before_insert == 'a') && @rl_undo_list)
            _rl_vi_save_insert(@rl_undo_list)

            # XXX - Other keys probably need to be checked.
         elsif (@_rl_vi_last_key_before_insert == 'C')
            rl_end_undo_group()
         end
         while (@_rl_undo_group_level > 0)
            rl_end_undo_group()
         end
         @vi_continued_command = 0
      end
   end

   # Is the command C a VI mode text modification command?
   def _rl_vi_textmod_command(c)
      return @vi_textmod[c]
   end

   def _rl_vi_reset_last()
      @_rl_vi_last_command = 'i'
      @_rl_vi_last_repeat = 1
      @_rl_vi_last_arg_sign = 1
      @_rl_vi_last_motion = 0
   end

   def _rl_update_final()
      full_lines = false
      # If the cursor is the only thing on an otherwise-blank last line,
      #   compensate so we don't print an extra CRLF.
      if (@_rl_vis_botlin && @_rl_last_c_pos == 0 &&
         @visible_line[@vis_lbreaks[@_rl_vis_botlin],1] == 0.chr )
         @_rl_vis_botlin-=1
         full_lines = true
      end
      _rl_move_vert(@_rl_vis_botlin)
      # If we've wrapped lines, remove the final xterm line-wrap flag.
      if (full_lines && @_rl_term_autowrap && (vis_llen(@_rl_vis_botlin) == @_rl_screenwidth))
         last_line = @visible_line[@vis_lbreaks[@_rl_vis_botlin]..-1]
         @cpos_buffer_position = -1 # don't know where we are in buffer
         _rl_move_cursor_relative(@_rl_screenwidth - 1, last_line)   # XXX
         _rl_clear_to_eol(0)
         @rl_outstream.write(last_line[@_rl_screenwidth - 1,1])
      end
      @_rl_vis_botlin = 0
      rl_crlf()
      @rl_outstream.flush
      @rl_display_fixed = true if !@rl_display_fixed
   end


   # What to do when a NEWLINE is pressed.  We accept the whole line.
   #   KEY is the key that invoked this command.  I guess it could have
   #   meaning in the future.
   def rl_newline(count, key)
      @rl_done = true

      if (@_rl_history_preserve_point)
         @_rl_history_saved_point = (@rl_point == @rl_end) ? 1 : @rl_point
      end
      rl_setstate(RL_STATE_DONE)

      if (@rl_editing_mode == @vi_mode)
         _rl_vi_done_inserting()
         if (_rl_vi_textmod_command(@_rl_vi_last_command).nil?)   # XXX
            _rl_vi_reset_last()
         end
      end
      # If we've been asked to erase empty lines, suppress the final update,
      #   since _rl_update_final calls rl_crlf().
      if (@rl_erase_empty_line && @rl_point == 0 && @rl_end == 0)
         return 0
      end
      if @readline_echoing_p
         _rl_update_final()
      end
      0
   end

   # What to do for some uppercase characters, like meta characters,
   #   and some characters appearing in emacs_ctlx_keymap.  This function
   #   is just a stub, you bind keys to it and the code in _rl_dispatch ()
   #   is special cased.
   def rl_do_lowercase_version(ignore1, ignore2)
      0
   end

   def rl_character_len(c, pos)
      if (meta_char(c))
         return ((!@_rl_output_meta_chars) ? 4 : 1)
      end
      if (c == "\t")
         return (((pos | 7) + 1) - pos)
      end
      if (ctrl_char(c) || c == RUBOUT)
         return (2)
      end

      return ((isprint(c)) ? 1 : 2)
   end

   # This is different from what vi does, so the code's not shared.  Emacs
   #   rubout in overwrite mode has one oddity:  it replaces a control
   #   character that's displayed as two characters (^X) with two spaces.
   def _rl_overwrite_rubout(count, key)
      if (@rl_point == 0)
         rl_ding()
         return 1
      end

      opoint = @rl_point

      # L == number of spaces to insert
      l = 0
      count.times do
         rl_backward_char(1, key)
         l += rl_character_len(@rl_line_buffer[@rl_point,1], @rl_point) # not exactly right
      end

      rl_begin_undo_group()

      if (count > 1 || @rl_explicit_arg)
         rl_kill_text(opoint, @rl_point)
      else
         rl_delete_text(opoint, @rl_point)
      end
      # Emacs puts point at the beginning of the sequence of spaces.
      if (@rl_point < @rl_end)
         opoint = @rl_point
         _rl_insert_char(l, ' ')
         @rl_point = opoint
      end

      rl_end_undo_group()

      0
   end

   # Rubout the character behind point.
   def rl_rubout(count, key)
      if (count < 0)
         return (rl_delete(-count, key))
      end
      if (@rl_point==0)
         rl_ding()
         return -1
      end

      if (@rl_insert_mode == RL_IM_OVERWRITE)
         return (_rl_overwrite_rubout(count, key))
      end
      _rl_rubout_char(count, key)
   end


   # Quick redisplay hack when erasing characters at the end of the line.
   def _rl_erase_at_end_of_line(l)
      _rl_backspace(l)
      @rl_outstream.write(' '*l)
      _rl_backspace(l)
      @_rl_last_c_pos -= l
      @visible_line[@_rl_last_c_pos,l] = 0.chr * l
      @rl_display_fixed = true if !@rl_display_fixed
   end

   def _rl_rubout_char(count, key)
      # Duplicated code because this is called from other parts of the library.
      if (count < 0)
         return (rl_delete(-count, key))
      end
      if (@rl_point == 0)
         rl_ding()
         return -1
      end

      orig_point = @rl_point
      if (count > 1 || @rl_explicit_arg)
         rl_backward_char(count, key)
         rl_kill_text(orig_point, @rl_point)
      elsif (@rl_byte_oriented)
         c = @rl_line_buffer[@rl_point-=1,1]
         rl_delete_text(@rl_point, orig_point)
         # The erase-at-end-of-line hack is of questionable merit now.
         if (@rl_point == @rl_end && isprint(c) && @_rl_last_c_pos!=0)
            l = rl_character_len(c, @rl_point)
            _rl_erase_at_end_of_line(l)
         end
      else
         @rl_point = _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO)
         rl_delete_text(@rl_point, orig_point)
      end

      0
   end

   # Delete the character under the cursor.  Given a numeric argument,
   #   kill that many characters instead.
   def rl_delete(count, key)
      if (count < 0)
         return (_rl_rubout_char(-count, key))
      end
      if (@rl_point == @rl_end)
         rl_ding()
         return -1
      end

      if (count > 1 || @rl_explicit_arg)
         xpoint = @rl_point
         rl_forward_byte(count, key)

         rl_kill_text(xpoint, @rl_point)
         @rl_point = xpoint
      else
         if !@rl_byte_oriented
            xpoint =_rl_find_next_mbchar(@rl_line_buffer, @rl_point, 1, MB_FIND_NONZERO)
         else
            xpoint = @rl_point + 1
         end

         rl_delete_text(@rl_point, xpoint)
      end
      0
   end

   # Add TEXT to the kill ring, allocating a new kill ring slot as necessary.
   #   This uses TEXT directly, so the caller must not free it.  If APPEND is
   #   non-zero, and the last command was a kill, the text is appended to the
   #   current kill ring slot, otherwise prepended.
   def _rl_copy_to_kill_ring(text, append)
      # First, find the slot to work with.
      if (!@_rl_last_command_was_kill)
         # Get a new slot.
         if @rl_kill_ring.nil?
            # If we don't have any defined, then make one.
            @rl_kill_ring_length = 1
            @rl_kill_ring = Array.new(@rl_kill_ring_length+1)
            @rl_kill_ring[slot = 0] = nil
         else
            # We have to add a new slot on the end, unless we have
            #   exceeded the max limit for remembering kills.
            slot = @rl_kill_ring_length
            if (slot == @rl_max_kills)
               @rl_kill_ring[0,slot] = @rl_kill_ring[1,slot]
            else
               slot = @rl_kill_ring_length += 1
            end
            @rl_kill_ring[slot-=1] = nil
         end
      else
         slot = @rl_kill_ring_length - 1
      end

      # If the last command was a kill, prepend or append.
      if (@_rl_last_command_was_kill && @rl_editing_mode != @vi_mode)
         old = @rl_kill_ring[slot]

         if (append)
            new = old + text
         else
            new = text + old
         end
         old = nil
         text = nil
         @rl_kill_ring[slot] = new
      else
         @rl_kill_ring[slot] = text
      end

      @rl_kill_index = slot
      0
   end

   # The way to kill something.  This appends or prepends to the last
   #   kill, if the last command was a kill command.  if FROM is less
   #   than TO, then the text is appended, otherwise prepended.  If the
   #   last command was not a kill command, then a new slot is made for
   #   this kill.
   def rl_kill_text(from, to)
      # Is there anything to kill?
      if (from == to)
         @_rl_last_command_was_kill = true if !@_rl_last_command_was_kill
         return 0
      end
      text = rl_copy_text(from, to)

      # Delete the copied text from the line.
      rl_delete_text(from, to)
      _rl_copy_to_kill_ring(text, from < to)
      @_rl_last_command_was_kill = true if !@_rl_last_command_was_kill
      0
   end

   # This does what C-w does in Unix.  We can't prevent people from
   #   using behaviour that they expect.
   def rl_unix_word_rubout(count, key)
      if (@rl_point == 0)
         rl_ding()
      else
         orig_point = @rl_point
         if (count <= 0)
            count = 1
         end

         while (count>0)
            while (@rl_point>0 && whitespace(@rl_line_buffer[@rl_point - 1,1]))
               @rl_point-=1
            end

            while (@rl_point>0 && !whitespace(@rl_line_buffer[@rl_point - 1,1]))
               @rl_point-=1
            end
            count -= 1
         end

         rl_kill_text(orig_point, @rl_point)
         if (@rl_editing_mode == @emacs_mode)
            @rl_mark = @rl_point
         end
      end
      0
   end

   # This deletes one filename component in a Unix pathname.  That is, it
   #   deletes backward to directory separator (`/') or whitespace.
   def rl_unix_filename_rubout(count, key)
      if (@rl_point == 0)
         rl_ding()
      else
         orig_point = @rl_point
         if (count <= 0)
            count = 1
         end

         while (count>0)

            c = @rl_line_buffer[@rl_point - 1,1]
            while (@rl_point>0 && (whitespace(c) || c == '/'))
               @rl_point-=1
               c = @rl_line_buffer[@rl_point - 1,1]
            end

            while (@rl_point>0 && !whitespace(c) && c != '/')
               @rl_point-=1
               c = @rl_line_buffer[@rl_point - 1,1]
            end
            count -= 1
         end

         rl_kill_text(orig_point, @rl_point)
         if (@rl_editing_mode == @emacs_mode)
            @rl_mark = @rl_point
         end
      end
      0
   end

   # Delete the character under the cursor, unless the insertion
   #   point is at the end of the line, in which case the character
   #   behind the cursor is deleted.  COUNT is obeyed and may be used
   #   to delete forward or backward that many characters.
   def rl_rubout_or_delete(count, key)
      if (@rl_end != 0 && @rl_point == @rl_end)
         return (_rl_rubout_char(count, key))
      else
         return (rl_delete(count, key))
      end
   end

   # Delete all spaces and tabs around point.
   def rl_delete_horizontal_space(count, ignore)
      start = @rl_point

      while (@rl_point!=0 && whitespace(@rl_line_buffer[@rl_point - 1]))
         @rl_point-=1
      end
      start = @rl_point
      while (@rl_point < @rl_end && whitespace(@rl_line_buffer[@rl_point]))
         @rl_point+=1
      end
      if (start != @rl_point)
         rl_delete_text(start, @rl_point)
         @rl_point = start
      end
      if (@rl_point < 0)
         @rl_point = 0
      end
      0
   end

   # List the possible completions.  See description of rl_complete ().
   def rl_possible_completions(ignore, invoking_key)
      rl_complete_internal('?')
   end

   # Like the tcsh editing function delete-char-or-list.  The eof character
   #   is caught before this is invoked, so this really does the same thing as
   #   delete-char-or-list-or-eof, as long as it's bound to the eof character.
   def rl_delete_or_show_completions(count, key)
      if (@rl_end != 0 && @rl_point == @rl_end)
         return (rl_possible_completions(count, key))
      else
         return (rl_delete(count, key))
      end
   end

   # Turn the current line into a comment in shell history.
   #   A K*rn shell style function.
   def rl_insert_comment(count, key)
      rl_beg_of_line(1, key)
      @rl_comment_text = @_rl_comment_begin ? @_rl_comment_begin : '#'

      if (!@rl_explicit_arg)
         rl_insert_text(@rl_comment_text)
      else
         @rl_comment_len = @rl_comment_text.length
         if @rl_comment_text[0,@rl_comment_len] == @rl_line_buffer[0,@rl_comment_len]
            rl_delete_text(@rl_point, @rl_point + @rl_comment_len)
         else
            rl_insert_text(@rl_comment_text)
         end
      end

      send(@rl_redisplay_function)
      rl_newline(1, "\n")
      0
   end

   def alloc_history_entry(string, ts)
      temp = Struct.new(:line,:data,:timestamp).new
      temp.line = string ? string.delete(0.chr) : string
      temp.data = nil
      temp.timestamp = ts

      return temp
   end

   def hist_inittime()
      t = Time.now.to_i
      ts = "X%u" % t
      ret = ts.dup
      ret[0,1] = @history_comment_char

      ret
   end

   # Place STRING at the end of the history list.  The data field
   #   is  set to NULL.
   def add_history(string)
      if (@history_stifled && (@history_length == @history_max_entries))
         # If the history is stifled, and history_length is zero,
         # and it equals history_max_entries, we don't save items.
         return if (@history_length == 0)
         @the_history.shift
      else
         if @the_history.nil?
            @the_history = []
            @history_length = 1
         else
            @history_length+=1
         end
      end

      temp = alloc_history_entry(string, hist_inittime())
      @the_history[@history_length] = nil
      @the_history[@history_length - 1] = temp
   end

   def using_history()
      @history_offset = @history_length
   end

   # Set default values for readline word completion.  These are the variables
   #   that application completion functions can change or inspect.
   def set_completion_defaults(what_to_do)
      # Only the completion entry function can change these.
      @rl_filename_completion_desired = false
      @rl_filename_quoting_desired = true
      @rl_completion_type = what_to_do
      @rl_completion_suppress_append = @rl_completion_suppress_quote = false

      # The completion entry function may optionally change this.
      @rl_completion_mark_symlink_dirs = @_rl_complete_mark_symlink_dirs
   end

   def _rl_find_completion_word()
      _end = @rl_point
      found_quote = 0
      delimiter = 0.chr
      quote_char = 0.chr

      brkchars = nil
      if @rl_completion_word_break_hook
         brkchars = send(@rl_completion_word_break_hook)
      end
      if brkchars.nil?
         brkchars = @rl_completer_word_break_characters
      end
      if (@rl_completer_quote_characters)
         # We have a list of characters which can be used in pairs to
         # quote substrings for the completer.  Try to find the start
         # of an unclosed quoted substring.
         # FOUND_QUOTE is set so we know what kind of quotes we found.
         scan = 0
         pass_next = false
         while scan < _end
            if (pass_next)
               pass_next = false
               next
            end

            # Shell-like semantics for single quotes -- don't allow backslash
            #   to quote anything in single quotes, especially not the closing
            #   quote.  If you don't like this, take out the check on the value
            #   of quote_char.
            if (quote_char != "'" && @rl_line_buffer[scan,1] == "\\")
               pass_next = true
               found_quote |= RL_QF_BACKSLASH
               next
            end

            if (quote_char != 0.chr)
               # Ignore everything until the matching close quote char.
               if (@rl_line_buffer[scan,1] == quote_char)
                  # Found matching close.  Abandon this substring.
                  quote_char = 0.chr
                  @rl_point = _end
               end

            elsif (@rl_completer_quote_characters.include?(@rl_line_buffer[scan,1]))

               # Found start of a quoted substring.
               quote_char = @rl_line_buffer[scan,1]
               @rl_point = scan + 1
               # Shell-like quoting conventions.
               if (quote_char == "'")
                  found_quote |= RL_QF_SINGLE_QUOTE
               elsif (quote_char == '"')
                  found_quote |= RL_QF_DOUBLE_QUOTE
               else
                  found_quote |= RL_QF_OTHER_QUOTE
               end
            end
            if !@rl_byte_oriented
               scan = _rl_find_next_mbchar(@rl_line_buffer, scan, 1, MB_FIND_ANY)
            else
               scan += 1
            end
         end
      end

      if (@rl_point == _end && quote_char == 0.chr)

         # We didn't find an unclosed quoted substring upon which to do
         #   completion, so use the word break characters to find the
         #   substring on which to complete.


         while (@rl_point =  !@rl_byte_oriented ?
            _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_ANY):(@rl_point-1))>0

            scan = @rl_line_buffer[@rl_point,1]
            if !brkchars.include?(scan)
               next
            end
            # Call the application-specific function to tell us whether
            #   this word break character is quoted and should be skipped.
            if (@rl_char_is_quoted_p && found_quote!=0 &&
               send(@rl_char_is_quoted_p,@rl_line_buffer, @rl_point))
               next
            end

            # Convoluted code, but it avoids an n^2 algorithm with calls
            #   to char_is_quoted.
            break
         end
      end

      # If we are at an unquoted word break, then advance past it.
      scan = @rl_line_buffer[@rl_point,1]

      # If there is an application-specific function to say whether or not
      #   a character is quoted and we found a quote character, let that
      #   function decide whether or not a character is a word break, even
      #   if it is found in rl_completer_word_break_characters.  Don't bother
      #   if we're at the end of the line, though.
      if (scan != 0.chr)
         if (@rl_char_is_quoted_p)
            isbrk = (found_quote == 0 ||
            !send(@rl_char_is_quoted_p,@rl_line_buffer, @rl_point)) &&
            brkchars.include?(scan)
         else
            isbrk = brkchars.include?(scan)
         end

         if (isbrk)
            # If the character that caused the word break was a quoting
            #   character, then remember it as the delimiter.
            if (@rl_basic_quote_characters &&
               @rl_basic_quote_characters.include?(scan) &&
               (_end - @rl_point) > 1)
               delimiter = scan
            end

            # If the character isn't needed to determine something special
            #   about what kind of completion to perform, then advance past it.
            if (@rl_special_prefixes.nil? || !@rl_special_prefixes.include?(scan) )
               @rl_point+=1
            end
         end
      end

      return [quote_char,found_quote!=0,delimiter]
   end

   def gen_completion_matches(text, start, _end, our_func, found_quote, quote_char)
      @rl_completion_found_quote = found_quote
      @rl_completion_quote_character = quote_char

      # If the user wants to TRY to complete, but then wants to give
      #   up and use the default completion function, they set the
      #   variable rl_attempted_completion_function.
      if (@rl_attempted_completion_function)
         matches = Readline.send(@rl_attempted_completion_function,text, start, _end)
         if (matches || @rl_attempted_completion_over)
            @rl_attempted_completion_over = false
            return (matches)
         end
      end
      # XXX -- filename dequoting moved into rl_filename_completion_function

      matches = rl_completion_matches(text, our_func)
      matches
   end

   # Filter out duplicates in MATCHES.  This frees up the strings in
   #   MATCHES.
   def remove_duplicate_matches(matches)
      # Sort the items.
      # Sort the array without matches[0], since we need it to
      #   stay in place no matter what.
      if matches.length>0
         matches[1..-2] = matches[1..-2].sort.uniq
      end
      matches
   end

   def postprocess_matches(matchesp, matching_filenames)
      matches = matchesp

      return 0 if matches.nil?

      # It seems to me that in all the cases we handle we would like
      #   to ignore duplicate possiblilities.  Scan for the text to
      #   insert being identical to the other completions.
      if (@rl_ignore_completion_duplicates)
         remove_duplicate_matches(matches)
      end

      # If we are matching filenames, then here is our chance to
      #   do clever processing by re-examining the list.  Call the
      #   ignore function with the array as a parameter.  It can
      #   munge the array, deleting matches as it desires.
      if (@rl_ignore_some_completions_function && matching_filenames)
         nmatch = matches.length
         send(@rl_ignore_some_completions_function,matches)
         if (matches.nil? || matches[0].nil?)
            matches = nil
            return 0
         else
            # If we removed some matches, recompute the common prefix.
            i = matches.length
            if (i > 1 && i < nmatch)
               t = matches[0]
               compute_lcd_of_matches(matches, i - 1, t)
            end
         end
      end

      matchesp = matches
      1
   end

   def insert_all_matches(matches, point, qc)
      rl_begin_undo_group()
      # remove any opening quote character; make_quoted_replacement will add
      #   it back.
      if (qc && qc.length>0 && point>0 && @rl_line_buffer[point - 1,1] == qc)
         point-=1
      end
      rl_delete_text(point, @rl_point)
      @rl_point = point
      if (matches[1])
         i = 1
         while(matches[i])
            rp = make_quoted_replacement(matches[i], SINGLE_MATCH, qc)
            rl_insert_text(rp)
            rl_insert_text(" ")
            if (rp != matches[i])
               rp = nil
            end
            i += 1
         end
      else
         rp = make_quoted_replacement(matches[0], SINGLE_MATCH, qc)
         rl_insert_text(rp)
         rl_insert_text(" ")
         if (rp != matches[0])
            rp = nil
         end
      end
      rl_end_undo_group()
   end

   def make_quoted_replacement(match, mtype, qc)
      # If we are doing completion on quoted substrings, and any matches
      #   contain any of the completer_word_break_characters, then auto-
      #   matically prepend the substring with a quote character (just pick
      #   the first one from the list of such) if it does not already begin
      #   with a quote string.  FIXME: Need to remove any such automatically
      #   inserted quote character when it no longer is necessary, such as
      #   if we change the string we are completing on and the new set of
      #   matches don't require a quoted substring.
      replacement = match

      should_quote = match && @rl_completer_quote_characters &&
      @rl_filename_completion_desired &&
      @rl_filename_quoting_desired

      if (should_quote)
         should_quote = should_quote && (qc.nil? || qc == 0.chr ||
         (@rl_completer_quote_characters && @rl_completer_quote_characters.include?(qc)))
      end

      if (should_quote)

         # If there is a single match, see if we need to quote it.
         #   This also checks whether the common prefix of several
         # matches needs to be quoted.
         should_quote = @rl_filename_quote_characters ?
         !!match[@rl_filename_quote_characters] :
         false

         do_replace = should_quote ? mtype : NO_MATCH
         # Quote the replacement, since we found an embedded
         # word break character in a potential match.
         if (do_replace != NO_MATCH && @rl_filename_quoting_function)
            replacement = send(@rl_filename_quoting_function,match, do_replace, qc)
         end
      end
      replacement
   end


   def insert_match(match, start, mtype, qc)
      oqc = qc
      replacement = make_quoted_replacement(match, mtype, qc)

      # Now insert the match.
      if (replacement)
         # Don't double an opening quote character.
         if (qc && qc.length>0 && start!=0 && @rl_line_buffer[start - 1,1] == qc &&
            replacement[0,1] == qc)
            start-=1
            # If make_quoted_replacement changed the quoting character, remove
            # the opening quote and insert the (fully-quoted) replacement.
         elsif (qc && (qc != oqc) && start!=0 && @rl_line_buffer[start - 1,1] == oqc &&
            replacement[0,1] != oqc)
            start-=1
         end
         _rl_replace_text(replacement, start, @rl_point - 1)
         if (replacement != match)
            replacement = nil
         end
      end
   end

   # Return the portion of PATHNAME that should be output when listing
   #   possible completions.  If we are hacking filename completion, we
   #   are only interested in the basename, the portion following the
   #   final slash.  Otherwise, we return what we were passed.  Since
   #   printing empty strings is not very informative, if we're doing
   #   filename completion, and the basename is the empty string, we look
   #   for the previous slash and return the portion following that.  If
   #   there's no previous slash, we just return what we were passed.
   def printable_part(pathname)
      if (!@rl_filename_completion_desired)  # don't need to do anything
         return (pathname)
      end

      temp = pathname.rindex('/')
      return pathname if temp.nil?
      File.basename(pathname)
   end

   def fnprint(to_print)
      printed_len = 0

      case @encoding
      when 'E'
         arr = to_print.scan(/./me)
      when 'S'
         arr = to_print.scan(/./ms)
      when 'U'
         arr = to_print.scan(/./mu)
      when 'X'
         arr = to_print.dup.force_encoding(@encoding_name).chars
      else
         arr = to_print.scan(/./m)
      end

      arr.each do |s|
         if(ctrl_char(s))
            @rl_outstream.write('^'+(s[0].ord|0x40).chr.upcase)
            printed_len += 2
         elsif s == RUBOUT
            @rl_outstream.write('^?')
            printed_len += 2
         else
            @rl_outstream.write(s)
            if @encoding=='U'
               printed_len += s.unpack('U').first >= 0x1000 ? 2 : 1
            elsif @encoding=='X'
               printed_len += s.ord >= 0x1000 ? 2 : 1
            else
               printed_len += s.length
            end
         end

      end

      printed_len
   end

   def _rl_internal_pager(lines)
      @rl_outstream.puts "--More--"
      @rl_outstream.flush
      i = get_y_or_n(1)
      _rl_erase_entire_line()
      if (i == 0)
         return -1
      elsif (i == 2)
         return (lines - 1)
      else
         return 0
      end
   end

   def path_isdir(filename)
      return File.directory?(filename)
   end

   # Return the character which best describes FILENAME.
   #     `@' for symbolic links
   #     `/' for directories
   #     `*' for executables
   #     `=' for sockets
   #     `|' for FIFOs
   #     `%' for character special devices
   #     `#' for block special devices
   def stat_char(filename)
      return nil if !File.exists?(filename)

      return '/' if File.directory?(filename)
      return '%' if File.chardev?(filename)
      return '#' if File.blockdev?(filename)
      return '@' if File.symlink?(filename)
      return '=' if File.socket?(filename)
      return '|' if File.pipe?(filename)
      return '*' if File.executable?(filename)
      nil
   end


   # Output TO_PRINT to rl_outstream.  If VISIBLE_STATS is defined and we
   #   are using it, check for and output a single character for `special'
   #   filenames.  Return the number of characters we output.
   def print_filename(to_print, full_pathname)
      extension_char = 0.chr
      printed_len = fnprint(to_print)

      if (@rl_filename_completion_desired && (@rl_visible_stats || @_rl_complete_mark_directories))

         # If to_print != full_pathname, to_print is the basename of the
         # path passed.  In this case, we try to expand the directory
         # name before checking for the stat character.
         if (to_print != full_pathname)

            if full_pathname.nil? || full_pathname.length==0
               dn = '/'
            else
               dn = File.dirname(full_pathname)
            end
            s = File.expand_path(dn)
            if (@rl_directory_completion_hook)
               send(@rl_directory_completion_hook,s)
            end

            slen = s.length
            tlen = to_print.length
            new_full_pathname = s.dup
            if (s[-1,1] == '/' )
               slen-=1
            else
               new_full_pathname[slen,1] = '/'
            end
            new_full_pathname[slen .. -1] = '/' + to_print

            if (@rl_visible_stats)
               extension_char = stat_char(new_full_pathname)
            else
               if (path_isdir(new_full_pathname))
                  extension_char = '/'
               end
            end

            new_full_pathname = nil

         else

            s = File.expand_path(full_pathname)
            if (@rl_visible_stats)
               extension_char = stat_char(s)
            else
               if (path_isdir(s))
                  extension_char = '/'
               end
            end
         end
         s = nil
         if (extension_char)
            @rl_outstream.write(extension_char)
            printed_len+=1
         end
      end

      printed_len
   end

   # The user must press "y" or "n". Non-zero return means "y" pressed.
   def get_y_or_n(for_pager)
      while(true)

         rl_setstate(RL_STATE_MOREINPUT)
         c = rl_read_key()
         rl_unsetstate(RL_STATE_MOREINPUT)

         if (c == 'y' || c == 'Y' || c == ' ')
            return (1)
         end
         if (c == 'n' || c == 'N' || c == RUBOUT)
            return (0)
         end
         if (c == ABORT_CHAR)
            _rl_abort_internal()
         end
         if (for_pager && (c == NEWLINE || c == RETURN))
            return (2)
         end
         if (for_pager && (c == 'q' || c == 'Q'))
            return (0)
         end
         rl_ding()
      end
   end

   # Compute width of STRING when displayed on screen by print_filename
   def fnwidth(string)
      left = string.length + 1
      width = pos = 0
      while (string[pos] && string[pos,1] != 0.chr)
         if (ctrl_char(string[0,1]) || string[0,1] == RUBOUT)
            width += 2
            pos+=1
         else
            case @encoding
            when 'E'
               wc = string[pos,left-pos].scan(/./me)[0]
               bytes = wc.length
               tempwidth = wc.length
            when 'S'
               wc = string[pos,left-pos].scan(/./ms)[0]
               bytes = wc.length
               tempwidth = wc.length
            when 'U'
               wc = string[pos,left-pos].scan(/./mu)[0]
               bytes = wc.length
               tempwidth = wc.unpack('U').first >= 0x1000 ? 2 : 1
            when 'X'
               wc = string[pos,left-pos].force_encoding(@encoding_name)[0]
               bytes = wc.bytesize
               tempwidth = wc.ord >= 0x1000 ? 2 : 1
            else
               wc = string[pos,left-pos].scan(/./m)[0]
               bytes = wc.length
               tempwidth = wc.length
            end
            clen = bytes
            pos += clen
            w = tempwidth
            width += (w >= 0) ? w : 1
         end
      end
      width
   end

   # Display MATCHES, a list of matching filenames in argv format.  This
   # handles the simple case -- a single match -- first.  If there is more
   # than one match, we compute the number of strings in the list and the
   # length of the longest string, which will be needed by the display
   # function.  If the application wants to handle displaying the list of
   # matches itself, it sets RL_COMPLETION_DISPLAY_MATCHES_HOOK to the
   # address of a function, and we just call it.  If we're handling the
   # display ourselves, we just call rl_display_match_list.  We also check
   # that the list of matches doesn't exceed the user-settable threshold,
   # and ask the user if he wants to see the list if there are more matches
   # than RL_COMPLETION_QUERY_ITEMS.
   def display_matches(matches)
      # Move to the last visible line of a possibly-multiple-line command.
      _rl_move_vert(@_rl_vis_botlin)

      # Handle simple case first.  What if there is only one answer?
      if matches[1].nil?
         temp = printable_part(matches[0])
         rl_crlf()
         print_filename(temp, matches[0])
         rl_crlf()
         rl_forced_update_display()
         @rl_display_fixed = true
         return
      end

      # There is more than one answer.  Find out how many there are,
      #   and find the maximum printed length of a single entry.
      max = 0
      i = 1
      while(matches[i])
         temp = printable_part(matches[i])
         len = fnwidth(temp)

         if (len > max)
            max = len
         end
         i += 1
      end
      len = i - 1

      # If the caller has defined a display hook, then call that now.
      if (@rl_completion_display_matches_hook)
         send(@rl_completion_display_matches_hook,matches, len, max)
         return
      end

      # If there are many items, then ask the user if she really wants to
      #   see them all.
      if (@rl_completion_query_items > 0 && len >= @rl_completion_query_items)

         rl_crlf()
         @rl_outstream.write("Display all #{len} possibilities? (y or n)")
         @rl_outstream.flush
         if (get_y_or_n(false)==0)
            rl_crlf()

            rl_forced_update_display()
            @rl_display_fixed = true

            return
         end
      end

      rl_display_match_list(matches, len, max)

      rl_forced_update_display()
      @rl_display_fixed = true
   end

   # Complete the word at or before point.
   #   WHAT_TO_DO says what to do with the completion.
   #   `?' means list the possible completions.
   #   TAB means do standard completion.
   #   `*' means insert all of the possible completions.
   #   `!' means to do standard completion, and list all possible completions if
   #   there is more than one.
   #   `@' means to do standard completion, and list all possible completions if
   #   there is more than one and partial completion is not possible.
   def rl_complete_internal(what_to_do)
      rl_setstate(RL_STATE_COMPLETING)
      set_completion_defaults(what_to_do)

      saved_line_buffer = @rl_line_buffer ? @rl_line_buffer.delete(0.chr) : nil
      our_func = @rl_completion_entry_function ?
      @rl_completion_entry_function : :rl_filename_completion_function
      # We now look backwards for the start of a filename/variable word.
      _end = @rl_point
      found_quote = false
      delimiter = 0.chr
      quote_char = 0.chr

      if (@rl_point!=0)
         # This (possibly) changes rl_point.  If it returns a non-zero char,
         #   we know we have an open quote.
         quote_char,found_quote,delimiter = _rl_find_completion_word()
      end

      start = @rl_point
      @rl_point = _end

      text = rl_copy_text(start, _end)
      matches = gen_completion_matches(text, start, _end, our_func, found_quote, quote_char)
      # nontrivial_lcd is set if the common prefix adds something to the word
      #   being completed.
      nontrivial_lcd = !!(matches && text != matches[0])
      text = nil
      if matches.nil?
         rl_ding()
         saved_line_buffer = nil
         @completion_changed_buffer = false
         rl_unsetstate(RL_STATE_COMPLETING)
         return 0
      end

      # If we are matching filenames, the attempted completion function will
      #   have set rl_filename_completion_desired to a non-zero value.  The basic
      #   rl_filename_completion_function does this.
      i = @rl_filename_completion_desired
      if (postprocess_matches(matches, i) == 0)
         rl_ding()
         saved_line_buffer = nil
         @completion_changed_buffer = false
         rl_unsetstate(RL_STATE_COMPLETING)
         return 0
      end

      case (what_to_do)

      when TAB,'!','@'
         # Insert the first match with proper quoting.
         if (matches[0])
            insert_match(matches[0], start, matches[1] ? MULT_MATCH : SINGLE_MATCH, quote_char)
         end
         # If there are more matches, ring the bell to indicate.
         # If we are in vi mode, Posix.2 says to not ring the bell.
         # If the `show-all-if-ambiguous' variable is set, display
         # all the matches immediately.  Otherwise, if this was the
         # only match, and we are hacking files, check the file to
         # see if it was a directory.  If so, and the `mark-directories'
         # variable is set, add a '/' to the name.  If not, and we
         # are at the end of the line, then add a space.
         if (matches[1])
            if (what_to_do == '!')
               display_matches(matches)
            elsif (what_to_do == '@')
               if (!nontrivial_lcd)
                  display_matches(matches)
               end
            elsif (@rl_editing_mode != @vi_mode)
               rl_ding()   # There are other matches remaining.
            end
         else
            append_to_match(matches[0], delimiter, quote_char, nontrivial_lcd)
         end
      when '*'
         insert_all_matches(matches, start, quote_char)
      when '?'
         display_matches(matches)
      else
         $stderr.write("\r\nreadline: bad value #{what_to_do} for what_to_do in rl_complete\n")
         rl_ding()
         saved_line_buffer = nil
         rl_unsetstate(RL_STATE_COMPLETING)
         return 1
      end

      matches = nil

      # Check to see if the line has changed through all of this manipulation.
      if (saved_line_buffer)
         @completion_changed_buffer = @rl_line_buffer.delete(0.chr) != saved_line_buffer
         saved_line_buffer = nil
      end

      rl_unsetstate(RL_STATE_COMPLETING)
      0
   end

   # Complete the word at or before point.  You have supplied the function
   #   that does the initial simple matching selection algorithm (see
   #   rl_completion_matches ()).  The default is to do filename completion.
   def rl_complete(ignore, invoking_key)
      if (@rl_inhibit_completion)
         return (_rl_insert_char(ignore, invoking_key))
      elsif (@rl_last_func == :rl_complete && !@completion_changed_buffer)
         return (rl_complete_internal('?'))
      elsif (@_rl_complete_show_all)
         return (rl_complete_internal('!'))
      elsif (@_rl_complete_show_unmodified)
         return (rl_complete_internal('@'))
      else
         return (rl_complete_internal(TAB))
      end
   end

   # Return the history entry which is logically at OFFSET in the history array.
   #   OFFSET is relative to history_base.
   def history_get(offset)
      local_index = offset - @history_base
      return (local_index >= @history_length || local_index < 0 || @the_history.nil?) ?
      nil : @the_history[local_index]
   end

   def rl_replace_from_history(entry, flags)
      # Can't call with `1' because rl_undo_list might point to an undo list
      #   from a history entry, just like we're setting up here.
      rl_replace_line(entry.line, false)
      @rl_undo_list = entry.data
      @rl_point = @rl_end
      @rl_mark = 0

      if (@rl_editing_mode == @vi_mode)
         @rl_point = 0
         @rl_mark = @rl_end
      end
   end

   # Remove history element WHICH from the history.  The removed
   #   element is returned to you so you can free the line, data,
   #   and containing structure.
   def remove_history(which)
      if (which < 0 || which >= @history_length || @history_length ==  0 || @the_history.nil?)
         return nil
      end
      return_value = @the_history[which]
      @the_history.delete_at(which)
      @history_length-=1
      return_value
   end

   def block_sigint()
      return if @sigint_blocked
      #@sigint_proc = Signal.trap("INT","IGNORE")
      @sigint_blocked = true
   end

   def release_sigint()
      return if !@sigint_blocked
      #Signal.trap("INT",@sigint_proc)
      @sigint_blocked = false
   end

   def save_tty_chars()
      @_rl_last_tty_chars = @_rl_tty_chars
      h = Hash[*`stty -a`.scan(/(\w+) = ([^;]+);/).flatten]
      h.each {|k,v| v.gsub!(/\^(.)/){($1[0].ord ^ ((?a..?z).include?($1[0]) ? 0x60 : 0x40)).chr}}
      @_rl_tty_chars.t_erase = h['erase']
      @_rl_tty_chars.t_kill = h['kill']
      @_rl_tty_chars.t_intr = h['intr']
      @_rl_tty_chars.t_quit = h['quit']
      @_rl_tty_chars.t_start = h['start']
      @_rl_tty_chars.t_stop = h['stop']
      @_rl_tty_chars.t_eof = h['eof']
      @_rl_tty_chars.t_eol = "\n"
      @_rl_tty_chars.t_eol2 = h['eol2']
      @_rl_tty_chars.t_susp = h['susp']
      @_rl_tty_chars.t_dsusp = h['dsusp']
      @_rl_tty_chars.t_reprint = h['rprnt']
      @_rl_tty_chars.t_flush = h['flush']
      @_rl_tty_chars.t_werase = h['werase']
      @_rl_tty_chars.t_lnext = h['lnext']
      @_rl_tty_chars.t_status = -1
      @otio = `stty -g`
   end

   def _rl_bind_tty_special_chars(kmap)
      kmap[@_rl_tty_chars.t_erase] = :rl_rubout
      kmap[@_rl_tty_chars.t_kill] = :rl_unix_line_discard
      kmap[@_rl_tty_chars.t_werase] = :rl_unix_word_rubout
      kmap[@_rl_tty_chars.t_lnext] = :rl_quoted_insert
   end

   def prepare_terminal_settings(meta_flag)
      @readline_echoing_p = (`stty -a`.scan(/-*echo\b/).first == 'echo')

      # First, the basic settings to put us into character-at-a-time, no-echo
      #   input mode.
      setting = " -echo -icrnl cbreak"

      # If this terminal doesn't care how the 8th bit is used, then we can
      #   use it for the meta-key.  If only one of even or odd parity is
      #  specified, then the terminal is using parity, and we cannot.
      if (`stty -a`.scan(/-parenb\b/).first == '-parenb')
         setting << " pass8"
      end

      setting << " -ixoff"

      rl_bind_key(@_rl_tty_chars.t_start, :rl_restart_output)
      @_rl_eof_char = @_rl_tty_chars.t_eof

      #setting << " -isig"

      `stty #{setting}`
   end

   def _rl_control_keypad(on)
      if on && @_rl_term_ks
         @_rl_out_stream.write(@_rl_term_ks)
      elsif !on && @_rl_term_ke
         @_rl_out_stream.write(@_rl_term_ke)
      end
   end

   # Rebind all of the tty special chars that readline worries about back
   #   to self-insert.  Call this before saving the current terminal special
   #   chars with save_tty_chars().  This only works on POSIX termios or termio
   #   systems.
   def rl_tty_unset_default_bindings(kmap)
      # Don't bother before we've saved the tty special chars at least once.
      return if (!rl_isstate(RL_STATE_TTYCSAVED))

      kmap[@_rl_tty_chars.t_erase] = :rl_insert
      kmap[@_rl_tty_chars.t_kill] = :rl_insert
      kmap[@_rl_tty_chars.t_lnext] = :rl_insert
      kmap[@_rl_tty_chars.t_werase] = :rl_insert
   end

   def rl_prep_terminal(meta_flag)
      if no_terminal?
         @readline_echoing_p = true
         return
      end

      return if (@terminal_prepped)

      # Try to keep this function from being INTerrupted.
      block_sigint()

      if (@_rl_bind_stty_chars)
         # If editing in vi mode, make sure we restore the bindings in the
         # insertion keymap no matter what keymap we ended up in.
         if (@rl_editing_mode == @vi_mode)
            rl_tty_unset_default_bindings(@vi_insertion_keymap)
         else
            rl_tty_unset_default_bindings(@_rl_keymap)
         end
      end

      save_tty_chars()

      rl_setstate(RL_STATE_TTYCSAVED)
      if (@_rl_bind_stty_chars)

         # If editing in vi mode, make sure we set the bindings in the
         # insertion keymap no matter what keymap we ended up in.
         if (@rl_editing_mode == @vi_mode)
            _rl_bind_tty_special_chars(@vi_insertion_keymap)
         else
            _rl_bind_tty_special_chars(@_rl_keymap)
         end
      end

      prepare_terminal_settings(meta_flag)

      if (@_rl_enable_keypad)
         _rl_control_keypad(true)
      end
      @rl_outstream.flush
      @terminal_prepped = true
      rl_setstate(RL_STATE_TERMPREPPED)

      release_sigint()
   end

   # Restore the terminal's normal settings and modes.
   def rl_deprep_terminal()
      return if ENV["TERM"].nil?
      return if (!@terminal_prepped)

      # Try to keep this function from being interrupted.
      block_sigint()

      if (@_rl_enable_keypad)
         _rl_control_keypad(false)
      end

      @rl_outstream.flush

      # restore terminal setting
      `stty #{@otio}`

      @terminal_prepped = false
      rl_unsetstate(RL_STATE_TERMPREPPED)

      release_sigint()
   end

   # Set the mark at POSITION.
   def _rl_set_mark_at_pos(position)
      return -1 if (position > @rl_end)
      @rl_mark = position
      0
   end

   # A bindable command to set the mark.
   def rl_set_mark(count, key)
      _rl_set_mark_at_pos(@rl_explicit_arg ? count : @rl_point)
   end

   # Kill from here to the end of the line.  If DIRECTION is negative, kill
   #   back to the line start instead.
   def rl_kill_line (direction, ignore)
      if (direction < 0)
         return (rl_backward_kill_line(1, ignore))
      else
         orig_point = @rl_point
         rl_end_of_line(1, ignore)
         if (orig_point != @rl_point)
            rl_kill_text(orig_point, @rl_point)
         end
         @rl_point = orig_point
         if (@rl_editing_mode == @emacs_mode)
            @rl_mark = @rl_point
         end
      end
      0
   end

   # Kill backwards to the start of the line.  If DIRECTION is negative, kill
   #   forwards to the line end instead.
   def rl_backward_kill_line(direction, ignore)
      if (direction < 0)
         return (rl_kill_line(1, ignore))
      else
         if (@rl_point==0)
            rl_ding()
         else
            orig_point = @rl_point
            rl_beg_of_line(1, ignore)
            if (@rl_point != orig_point)
               rl_kill_text(orig_point, @rl_point)
            end
            if (@rl_editing_mode == @emacs_mode)
               @rl_mark = @rl_point
            end
         end
      end
      0
   end

   # Kill the whole line, no matter where point is.
   def rl_kill_full_line(count, ignore)
      rl_begin_undo_group()
      @rl_point = 0
      rl_kill_text(@rl_point, @rl_end)
      @rl_mark = 0
      rl_end_undo_group()
      0
   end

   # Search backwards through the history looking for a string which is typed
   #   interactively.  Start with the current line.
   def rl_reverse_search_history(sign, key)
      rl_search_history(-sign, key)
   end

   # Search forwards through the history looking for a string which is typed
   #   interactively.  Start with the current line.
   def rl_forward_search_history(sign, key)
      rl_search_history(sign, key)
   end

   # Search through the history looking for an interactively typed string.
   #   This is analogous to i-search.  We start the search in the current line.
   #   DIRECTION is which direction to search; >= 0 means forward, < 0 means
   #   backwards.
   def rl_search_history(direction, invoking_key)
      rl_setstate(RL_STATE_ISEARCH)
      cxt = _rl_isearch_init(direction)

      rl_display_search(cxt.search_string, (cxt.sflags & SF_REVERSE)!=0, -1)

      # If we are using the callback interface, all we do is set up here and
      #    return.  The key is that we leave RL_STATE_ISEARCH set.
      if (rl_isstate(RL_STATE_CALLBACK))
         return (0)
      end

      r = -1
      while(true)
         c = _rl_search_getchar(cxt)
         # We might want to handle EOF here (c == 0)
         r = _rl_isearch_dispatch(cxt, cxt.lastc)
         break if (r <= 0)
      end

      # The searching is over.  The user may have found the string that she
      #   was looking for, or else she may have exited a failing search.  If
      #   LINE_INDEX is -1, then that shows that the string searched for was
      #   not found.  We use this to determine where to place rl_point.
      _rl_isearch_cleanup(cxt, r)
   end

   def _rl_scxt_alloc(type, flags)
      cxt = Struct.new(:type,:sflags,:search_string,:search_string_index,:search_string_size,:lines,:allocated_line,
      :hlen,:hindex,:save_point,:save_mark,:save_line,:last_found_line,:prev_line_found,:save_undo_list,:history_pos,
      :direction,:lastc,:sline,:sline_len,:sline_index,:search_terminators,:mb).new

      cxt.type = type
      cxt.sflags = flags

      cxt.search_string = nil
      cxt.search_string_size = cxt.search_string_index = 0

      cxt.lines = nil
      cxt.allocated_line = nil
      cxt.hlen = cxt.hindex = 0

      cxt.save_point = @rl_point
      cxt.save_mark = @rl_mark
      cxt.save_line = where_history()
      cxt.last_found_line = cxt.save_line
      cxt.prev_line_found = nil

      cxt.save_undo_list = nil

      cxt.history_pos = 0
      cxt.direction = 0

      cxt.lastc = 0

      cxt.sline = nil
      cxt.sline_len = cxt.sline_index = 0

      cxt.search_terminators = nil

      cxt
   end

   def history_list()
      @the_history
   end

   def _rl_isearch_init(direction)
      cxt = _rl_scxt_alloc(RL_SEARCH_ISEARCH, 0)
      if (direction < 0)
         cxt.sflags |= SF_REVERSE
      end

      cxt.search_terminators = @_rl_isearch_terminators ? @_rl_isearch_terminators :
      @default_isearch_terminators

      # Create an arrary of pointers to the lines that we want to search.
      hlist = history_list()
      rl_maybe_replace_line()
      i = 0
      if (hlist)
         i += 1 while(hlist[i])
      end

      # Allocate space for this many lines, +1 for the current input line,
      #   and remember those lines.
      cxt.hlen = i
      cxt.lines = []
      for i in 0 ... cxt.hlen
         cxt.lines[i] = hlist[i].line
      end

      if (@_rl_saved_line_for_history)
         cxt.lines[i] = @_rl_saved_line_for_history.line.dup
      else
         # Keep track of this so we can free it.
         cxt.allocated_line = @rl_line_buffer.dup
         cxt.lines << cxt.allocated_line
      end

      cxt.hlen+=1

      # The line where we start the search.
      cxt.history_pos = cxt.save_line

      rl_save_prompt()

      # Initialize search parameters.
      cxt.search_string_size = 128
      cxt.search_string_index = 0
      cxt.search_string = ""

      # Normalize DIRECTION into 1 or -1.
      cxt.direction = (direction >= 0) ? 1 : -1

      cxt.sline = @rl_line_buffer
      cxt.sline_len = cxt.sline.delete(0.chr).length
      cxt.sline_index = @rl_point

      @_rl_iscxt = cxt     # save globally
      cxt
   end

   def rl_save_prompt()
      @saved_local_prompt = @local_prompt
      @saved_local_prefix = @local_prompt_prefix
      @saved_prefix_length = @prompt_prefix_length
      @saved_local_length = @local_prompt_len
      @saved_last_invisible = @prompt_last_invisible
      @saved_visible_length = @prompt_visible_length
      @saved_invis_chars_first_line = @prompt_invis_chars_first_line
      @saved_physical_chars = @prompt_physical_chars

      @local_prompt = @local_prompt_prefix = nil
      @local_prompt_len = 0
      @prompt_last_invisible = @prompt_visible_length = @prompt_prefix_length = 0
      @prompt_invis_chars_first_line = @prompt_physical_chars = 0
   end

   def rl_restore_prompt()
      @local_prompt = nil
      @local_prompt_prefix = nil

      @local_prompt = @saved_local_prompt
      @local_prompt_prefix = @saved_local_prefix
      @local_prompt_len = @saved_local_length
      @prompt_prefix_length = @saved_prefix_length
      @prompt_last_invisible = @saved_last_invisible
      @prompt_visible_length = @saved_visible_length
      @prompt_invis_chars_first_line = @saved_invis_chars_first_line
      @prompt_physical_chars = @saved_physical_chars

      # can test saved_local_prompt to see if prompt info has been saved.
      @saved_local_prompt = @saved_local_prefix = nil
      @saved_local_length = 0
      @saved_last_invisible = @saved_visible_length = @saved_prefix_length = 0
      @saved_invis_chars_first_line = @saved_physical_chars = 0
   end

   def rl_message(msg_buf)
      @rl_display_prompt = msg_buf
      if @saved_local_prompt.nil?
         rl_save_prompt()
         @msg_saved_prompt = true
      end
      @local_prompt,@prompt_visible_length,@prompt_last_invisible,@prompt_invis_chars_first_line,@prompt_physical_chars =
      expand_prompt(msg_buf)
      @local_prompt_prefix = nil
      @local_prompt_len = @local_prompt ? @local_prompt.length : 0
      send(@rl_redisplay_function)
      0
   end

   # Display the current state of the search in the echo-area.
   #   SEARCH_STRING contains the string that is being searched for,
   #   DIRECTION is zero for forward, or non-zero for reverse,
   #   WHERE is the history list number of the current line.  If it is
   #   -1, then this line is the starting one.
   def rl_display_search(search_string, reverse_p, where)
      message = '('
      if (reverse_p)
         message << "reverse-"
      end
      message << "i-search)`"

      if (search_string)
         message << search_string
      end
      message << "': "

      rl_message(message)
      message = nil
      send(@rl_redisplay_function)
   end

   # Transpose the characters at point.  If point is at the end of the line,
   #   then transpose the characters before point.
   def rl_transpose_chars(count, key)
      return 0 if (count == 0)

      if (@rl_point==0 || @rl_end < 2)
         rl_ding()
         return -1
      end

      rl_begin_undo_group()

      if (@rl_point == @rl_end)
         if !@rl_byte_oriented
            @rl_point = _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO)
         else
            @rl_point -= 1
         end
         count = 1
      end

      prev_point = @rl_point
      if !@rl_byte_oriented
         @rl_point = _rl_find_prev_mbchar(@rl_line_buffer, @rl_point, MB_FIND_NONZERO)
      else
         @rl_point -= 1
      end

      char_length = prev_point - @rl_point
      dummy = @rl_line_buffer[@rl_point,char_length]

      rl_delete_text(@rl_point, @rl_point + char_length)

      @rl_point += count
      _rl_fix_point(0)
      rl_insert_text(dummy)
      rl_end_undo_group()
      dummy = nil
      0
   end

   # Here is C-u doing what Unix does.  You don't *have* to use these
   # key-bindings.  We have a choice of killing the entire line, or
   # killing from where we are to the start of the line.  We choose the
   # latter, because if you are a Unix weenie, then you haven't backspaced
   # into the line at all, and if you aren't, then you know what you are
   # doing.
   def rl_unix_line_discard(count, key)
      if (@rl_point == 0)
         rl_ding()
      else
         rl_kill_text(@rl_point, 0)
         @rl_point = 0
         if (@rl_editing_mode == @emacs_mode)
            @rl_mark = @rl_point
         end
      end
      0
   end

   # Yank back the last killed text.  This ignores arguments.
   def rl_yank(count, ignore)
      if @rl_kill_ring.nil?
         _rl_abort_internal()
         return -1
      end
      _rl_set_mark_at_pos(@rl_point)
      rl_insert_text(@rl_kill_ring[@rl_kill_index])
      0
   end

   # If the last command was yank, or yank_pop, and the text just
   #   before point is identical to the current kill item, then
   #   delete that text from the line, rotate the index down, and
   #   yank back some other text.
   def rl_yank_pop(count, key)
      if (((@rl_last_func != :rl_yank_pop) && (@rl_last_func != :rl_yank)) ||
         @rl_kill_ring.nil?)
         _rl_abort_internal()
         return -1
      end

      l = @rl_kill_ring[@rl_kill_index].length
      n = @rl_point - l
      if (n >= 0 && @rl_line_buffer[n,l] == @rl_kill_ring[@rl_kill_index][0,l])
         rl_delete_text(n, @rl_point)
         @rl_point = n
         @rl_kill_index-=1
         if (@rl_kill_index < 0)
            @rl_kill_index = @rl_kill_ring_length - 1
         end
         rl_yank(1, 0)
         return 0
      else
         _rl_abort_internal()
         return -1
      end
   end

   # Yank the COUNTh argument from the previous history line, skipping
   #   HISTORY_SKIP lines before looking for the `previous line'.
   def rl_yank_nth_arg_internal(count, ignore, history_skip)
      pos = where_history()
      if (history_skip>0)
         history_skip.times { entry = previous_history() }
      end
      entry = previous_history()
      history_set_pos(pos)
      if entry.nil?
         rl_ding()
         return -1
      end

      arg = history_arg_extract(count, count, entry.line)
      if (arg.nil? || arg=='')
         rl_ding()
         arg = nil
         return -1
      end

      rl_begin_undo_group()

      _rl_set_mark_at_pos(@rl_point)

      # Vi mode always inserts a space before yanking the argument, and it
      #   inserts it right *after* rl_point.
      if (@rl_editing_mode == @vi_mode)
         rl_vi_append_mode(1, ignore)
         rl_insert_text(" ")
      end

      rl_insert_text(arg)
      arg = nil
      rl_end_undo_group()
      return 0
   end

   # Yank the COUNTth argument from the previous history line.
   def rl_yank_nth_arg(count, ignore)
      rl_yank_nth_arg_internal(count, ignore, 0)
   end

   # Yank the last argument from the previous history line.  This `knows'
   #   how rl_yank_nth_arg treats a count of `$'.  With an argument, this
   #   behaves the same as rl_yank_nth_arg.
   @history_skip = 0
   @explicit_arg_p = false
   @count_passed = 1
   @direction = 1
   @undo_needed = false

   def rl_yank_last_arg(count, key)
      if (@rl_last_func != :rl_yank_last_arg)
         @history_skip = 0
         @explicit_arg_p = @rl_explicit_arg
         @count_passed = count
         @direction = 1
      else
         if (@undo_needed)
            rl_do_undo()
         end
         if (count < 1)
            @direction = -@direction
         end
         @history_skip += @direction
         if (@history_skip < 0)
            @history_skip = 0
         end
      end

      if (@explicit_arg_p)
         retval = rl_yank_nth_arg_internal(@count_passed, key, @history_skip)
      else
         retval = rl_yank_nth_arg_internal('$', key, @history_skip)
      end
      @undo_needed = retval == 0
      retval
   end

   def _rl_char_search_internal(count, dir, smbchar, len)
      pos = @rl_point
      inc = (dir < 0) ? -1 : 1
      while (count!=0)
         if ((dir < 0 && pos <= 0) || (dir > 0 && pos >= @rl_end))
            rl_ding()
            return -1
         end
         pos = (inc > 0) ? _rl_find_next_mbchar(@rl_line_buffer, pos, 1, MB_FIND_ANY) :
         _rl_find_prev_mbchar(@rl_line_buffer, pos, MB_FIND_ANY)
         begin
            if (_rl_is_mbchar_matched(@rl_line_buffer, pos, @rl_end, smbchar, len)!=0)
               count-=1
               if (dir < 0)
                  @rl_point = (dir == BTO) ? pos+1 : pos
               else
                  @rl_point = (dir == FTO) ? pos-1 : pos
               end
               break
            end
            prepos = pos
         end while ((dir < 0) ? (pos = _rl_find_prev_mbchar(@rl_line_buffer, pos, MB_FIND_ANY)) != prepos :
         (pos = _rl_find_next_mbchar(@rl_line_buffer, pos, 1, MB_FIND_ANY)) != prepos)
      end
      0
   end

   def _rl_char_search(count, fdir, bdir)
      mbchar = ''
      mb_len = _rl_read_mbchar(mbchar, MB_LEN_MAX)

      if (count < 0)
         return (_rl_char_search_internal(-count, bdir, mbchar, mb_len))
      else
         return (_rl_char_search_internal(count, fdir, mbchar, mb_len))
      end
   end

   def rl_char_search(count, key)
      _rl_char_search(count, FFIND, BFIND)
   end

   # Undo the next thing in the list.  Return 0 if there
   #   is nothing to undo, or non-zero if there was.
   def trans(i)
      ((i) == -1 ? @rl_point : ((i) == -2 ? @rl_end : (i)))
   end

   def rl_do_undo()
      start = _end = waiting_for_begin = 0
      begin
         return 0 if @rl_undo_list.nil?

         @_rl_doing_an_undo = true
         rl_setstate(RL_STATE_UNDOING)

         # To better support vi-mode, a start or end value of -1 means
         # rl_point, and a value of -2 means rl_end.
         if (@rl_undo_list.what == UNDO_DELETE || @rl_undo_list.what == UNDO_INSERT)
            start = trans(@rl_undo_list.start)
            _end = trans(@rl_undo_list.end)
         end

         case (@rl_undo_list.what)
            # Undoing deletes means inserting some text.
         when UNDO_DELETE
            @rl_point = start
            rl_insert_text(@rl_undo_list.text)
            @rl_undo_list.text = nil

            # Undoing inserts means deleting some text.
         when UNDO_INSERT
            rl_delete_text(start, _end)
            @rl_point = start
            # Undoing an END means undoing everything 'til we get to a BEGIN.
         when UNDO_END
            waiting_for_begin+=1
            # Undoing a BEGIN means that we are done with this group.
         when UNDO_BEGIN
            if (waiting_for_begin!=0)
               waiting_for_begin-=1
            else
               rl_ding()
            end
         end

         @_rl_doing_an_undo = false
         rl_unsetstate(RL_STATE_UNDOING)

         release = @rl_undo_list
         @rl_undo_list = @rl_undo_list.next
         replace_history_data(-1, release, @rl_undo_list)
         release = nil
      end while (waiting_for_begin!=0)

      1
   end



   # Do some undoing of things that were done.
   def rl_undo_command(count, key)
      if (count < 0)
         return 0 # Nothing to do.
      end
      while (count>0)
         if (rl_do_undo())
            count-=1
         else
            rl_ding()
            break
         end
      end
      0
   end

   # Delete the word at point, saving the text in the kill ring.
   def rl_kill_word(count, key)
      if (count < 0)
         return (rl_backward_kill_word(-count, key))
      else
         orig_point = @rl_point
         rl_forward_word(count, key)

         if (@rl_point != orig_point)
            rl_kill_text(orig_point, @rl_point)
         end

         @rl_point = orig_point
         if (@rl_editing_mode == @emacs_mode)
            rl_mark = @rl_point
         end
      end
      0
   end

   # Rubout the word before point, placing it on the kill ring.
   def rl_backward_kill_word(count, ignore)
      if (count < 0)
         return (rl_kill_word(-count, ignore))
      else
         orig_point = @rl_point
         rl_backward_word(count, ignore)
         if (@rl_point != orig_point)
            rl_kill_text(orig_point, @rl_point)
         end
         if (@rl_editing_mode == @emacs_mode)
            @rl_mark = @rl_point
         end
      end
      0
   end

   # Revert the current line to its previous state.
   def rl_revert_line(count, key)
      if @rl_undo_list.nil?
         rl_ding()
      else
         while (@rl_undo_list)
            rl_do_undo()
         end
         if (@rl_editing_mode == @vi_mode)
            @rl_point = @rl_mark = 0      # rl_end should be set correctly
         end
      end
      0
   end

   def rl_backward_char_search (count, key)
      _rl_char_search(count, BFIND, FFIND)
   end

   def rl_insert_completions(ignore, invoking_key)
      rl_complete_internal('*')
   end

   def _rl_arg_init()
      rl_save_prompt()
      @_rl_argcxt = 0
      rl_setstate(RL_STATE_NUMERICARG)
   end

   def _rl_arg_getchar()
      rl_message("(arg: #{@rl_arg_sign * @rl_numeric_arg}) ")
      rl_setstate(RL_STATE_MOREINPUT)
      c = rl_read_key()
      rl_unsetstate(RL_STATE_MOREINPUT)
      c
   end

   # Process C as part of the current numeric argument.  Return -1 if the
   #   argument should be aborted, 0 if we should not read any more chars, and
   #   1 if we should continue to read chars.
   def _rl_arg_dispatch(cxt, c)
      key = c

      # If we see a key bound to `universal-argument' after seeing digits,
      #    it ends the argument but is otherwise ignored.
      if (@_rl_keymap[c] == :rl_universal_argument)
         if ((cxt & NUM_SAWDIGITS) == 0)
            @rl_numeric_arg *= 4
            return 1
         elsif (rl_isstate(RL_STATE_CALLBACK))
            @_rl_argcxt |= NUM_READONE
            return 0 # XXX
         else
            rl_setstate(RL_STATE_MOREINPUT)
            key = rl_read_key()
            rl_unsetstate(RL_STATE_MOREINPUT)
            rl_restore_prompt()
            rl_clear_message()
            rl_unsetstate(RL_STATE_NUMERICARG)
            return (_rl_dispatch(key, @_rl_keymap))
         end
      end

      #c = (c[0].ord & ~0x80).chr
      r = c[1,1]
      if (r>='0' && r<='9')
         r = r.to_i
         @rl_numeric_arg = @rl_explicit_arg ? (@rl_numeric_arg * 10) +  r : r
         @rl_explicit_arg = 1
         @_rl_argcxt |= NUM_SAWDIGITS
      elsif (c == '-' && !@rl_explicit_arg)
         @rl_numeric_arg = 1
         @_rl_argcxt |= NUM_SAWMINUS
         @rl_arg_sign = -1
      else
         # Make M-- command equivalent to M--1 command.
         if ((@_rl_argcxt & NUM_SAWMINUS)!=0 && @rl_numeric_arg == 1 && !@rl_explicit_arg)
            @rl_explicit_arg = 1
         end
         rl_restore_prompt()
         rl_clear_message()
         rl_unsetstate(RL_STATE_NUMERICARG)

         r = _rl_dispatch(key, @_rl_keymap)
         if (rl_isstate(RL_STATE_CALLBACK))
            # At worst, this will cause an extra redisplay.  Otherwise,
            #   we have to wait until the next character comes in.
            if (!@rl_done)
               send(@rl_redisplay_function)
            end
            r = 0
         end
         return r
      end
      1
   end

   def _rl_arg_overflow()
      if (@rl_numeric_arg > 1000000)
         @_rl_argcxt = 0
         @rl_explicit_arg = @rl_numeric_arg = 0
         rl_ding()
         rl_restore_prompt()
         rl_clear_message()
         rl_unsetstate(RL_STATE_NUMERICARG)
         return 1
      end
      0
   end

   # Handle C-u style numeric args, as well as M--, and M-digits.
   def rl_digit_loop()
      while (true)
         return 1 if _rl_arg_overflow()!=0
         c = _rl_arg_getchar()
         if (c >= "\xFE")
            _rl_abort_internal()
            return -1
         end
         r = _rl_arg_dispatch(@_rl_argcxt, c)
         break if (r <= 0 || !rl_isstate(RL_STATE_NUMERICARG))
      end

      return r
   end

   # Start a numeric argument with initial value KEY
   def rl_digit_argument(ignore, key)
      _rl_arg_init()
      if (rl_isstate(RL_STATE_CALLBACK))
         _rl_arg_dispatch(@_rl_argcxt, key)
         rl_message("(arg: #{@rl_arg_sign * @rl_numeric_arg}) ")
         return 0
      else
         rl_execute_next(key)
         return (rl_digit_loop())
      end
   end

   # Make C be the next command to be executed.
   def rl_execute_next(c)
      @rl_pending_input = c
      rl_setstate(RL_STATE_INPUTPENDING)
      0
   end

   # Meta-< goes to the start of the history.
   def rl_beginning_of_history(count, key)
      rl_get_previous_history(1 + where_history(), key)
   end

   # Meta-> goes to the end of the history.  (The current line).
   def rl_end_of_history(count, key)
      rl_maybe_replace_line()
      using_history()
      rl_maybe_unsave_line()
      0
   end

   # Uppercase the word at point.
   def rl_upcase_word(count, key)
      rl_change_case(count, UpCase)
   end

   # Lowercase the word at point.
   def rl_downcase_word(count, key)
      rl_change_case(count, DownCase)
   end

   # Upcase the first letter, downcase the rest.
   def rl_capitalize_word(count, key)
      rl_change_case(count, CapCase)
   end

   # Save an undo entry for the text from START to END.
   def rl_modifying(start, _end)
      if (start > _end)
         start,_end = _end,start
      end

      if (start != _end)
         temp = rl_copy_text(start, _end)
         rl_begin_undo_group()
         rl_add_undo(UNDO_DELETE, start, _end, temp)
         rl_add_undo(UNDO_INSERT, start, _end, nil)
         rl_end_undo_group()
      end
      0
   end

   # The meaty function.
   #   Change the case of COUNT words, performing OP on them.
   #   OP is one of UpCase, DownCase, or CapCase.
   #   If a negative argument is given, leave point where it started,
   #   otherwise, leave it where it moves to.
   def rl_change_case(count, op)
      start = @rl_point
      rl_forward_word(count, 0)
      _end = @rl_point

      if (op != UpCase && op != DownCase && op != CapCase)
         rl_ding()
         return -1
      end

      if (count < 0)
         start,_end = _end,start
      end

      # We are going to modify some text, so let's prepare to undo it.
      rl_modifying(start, _end)

      inword = false
      while (start < _end)
         c = _rl_char_value(@rl_line_buffer, start)
         #  This assumes that the upper and lower case versions are the same width.
         if !@rl_byte_oriented
            _next = _rl_find_next_mbchar(@rl_line_buffer, start, 1, MB_FIND_NONZERO)
         else
            _next = start + 1
         end

         if (!_rl_walphabetic(c))
            inword = false
            start = _next
            next
         end

         if (op == CapCase)
            nop = inword ? DownCase : UpCase
            inword = true
         else
            nop = op
         end
         if (isascii(c))
            nc = (nop == UpCase) ? c.upcase : c.downcase
            @rl_line_buffer[start] = nc
         end

         start = _next
      end

      @rl_point = _end
      0
   end

   def isascii(c)
    int_val = c[0].to_i # 1.8 + 1.9 compat.
    return (int_val < 128 && int_val > 0)
   end

   # Search non-interactively through the history list.  DIR < 0 means to
   #   search backwards through the history of previous commands; otherwise
   #   the search is for commands subsequent to the current position in the
   #   history list.  PCHAR is the character to use for prompting when reading
   #   the search string; if not specified (0), it defaults to `:'.
   def noninc_search(dir, pchar)
      cxt = _rl_nsearch_init(dir, pchar)
      if (rl_isstate(RL_STATE_CALLBACK))
         return (0)
      end
      # Read the search string.
      r = 0
      while (true)
         c = _rl_search_getchar(cxt)
         if (c == 0.chr)
            break
         end
         r = _rl_nsearch_dispatch(cxt, c)
         if (r < 0)
            return 1
         elsif (r == 0)
            break
         end
      end

      r = _rl_nsearch_dosearch(cxt)
      (r >= 0) ? _rl_nsearch_cleanup(cxt, r) : (r != 1)
   end

   # Search forward through the history list for a string.  If the vi-mode
   #   code calls this, KEY will be `?'.
   def rl_noninc_forward_search(count, key)
      noninc_search(1, (key == '?') ? '?' : nil)
   end

   # Reverse search the history list for a string.  If the vi-mode code
   #   calls this, KEY will be `/'.
   def rl_noninc_reverse_search(count, key)
      noninc_search(-1, (key == '/') ? '/' : nil)
   end

   # Make the data from the history entry ENTRY be the contents of the
   #   current line.  This doesn't do anything with rl_point; the caller
   #   must set it.
   def make_history_line_current(entry)
      _rl_replace_text(entry.line, 0, @rl_end)
      _rl_fix_point(1)
      if (@rl_editing_mode == @vi_mode)
         # POSIX.2 says that the `U' command doesn't affect the copy of any
         #   command lines to the edit line.  We're going to implement that by
         #   making the undo list start after the matching line is copied to the
         #   current editing buffer.
         rl_free_undo_list()
      end
      if (@_rl_saved_line_for_history)
         @_rl_saved_line_for_history = nil
      end
   end

   # Make the current history item be the one at POS, an absolute index.
   #   Returns zero if POS is out of range, else non-zero.
   def history_set_pos(pos)
      if (pos > @history_length || pos < 0 || @the_history.nil?)
         return (0)
      end
      @history_offset = pos
      1
   end

   # Do an anchored search for string through the history in DIRECTION.
   def history_search_prefix (string, direction)
      history_search_internal(string, direction, ANCHORED_SEARCH)
   end

   # Search for STRING in the history list.  DIR is < 0 for searching
   #   backwards.  POS is an absolute index into the history list at
   #   which point to begin searching.
   def history_search_pos(string, dir, pos)
      old = where_history()
      history_set_pos(pos)
      if (history_search(string, dir) == -1)
         history_set_pos(old)
         return (-1)
      end
      ret = where_history()
      history_set_pos(old)
      ret
   end

   # Search the history list for STRING starting at absolute history position
   #   POS.  If STRING begins with `^', the search must match STRING at the
   #   beginning of a history line, otherwise a full substring match is performed
   #   for STRING.  DIR < 0 means to search backwards through the history list,
   #   DIR >= 0 means to search forward.
   def noninc_search_from_pos(string, pos, dir)
      return 1 if (pos < 0)

      old = where_history()
      return -1 if (history_set_pos(pos) == 0)

      rl_setstate(RL_STATE_SEARCH)
      if (string[0,1] == '^')
         ret = history_search_prefix(string + 1, dir)
      else
         ret = history_search(string, dir)
      end
      rl_unsetstate(RL_STATE_SEARCH)

      if (ret != -1)
         ret = where_history()
      end
      history_set_pos(old)
      ret
   end

   # Search for a line in the history containing STRING.  If DIR is < 0, the
   #   search is backwards through previous entries, else through subsequent
   #   entries.  Returns 1 if the search was successful, 0 otherwise.
   def noninc_dosearch(string, dir)
      if (string.nil? || string == '' || @noninc_history_pos < 0)
         rl_ding()
         return 0
      end

      pos = noninc_search_from_pos(string, @noninc_history_pos + dir, dir)
      if (pos == -1)
         # Search failed, current history position unchanged.
         rl_maybe_unsave_line()
         rl_clear_message()
         @rl_point = 0
         rl_ding()
         return 0
      end

      @noninc_history_pos = pos

      oldpos = where_history()
      history_set_pos(@noninc_history_pos)
      entry = current_history()
      if (@rl_editing_mode != @vi_mode)
         history_set_pos(oldpos)
      end
      make_history_line_current(entry)
      @rl_point = 0
      @rl_mark = @rl_end
      rl_clear_message()
      1
   end

   def _rl_make_prompt_for_search(pchar)
      rl_save_prompt()

      # We've saved the prompt, and can do anything with the various prompt
      #   strings we need before they're restored.  We want the unexpanded
      #   portion of the prompt string after any final newline.
      _p = @rl_prompt ? @rl_prompt.rindex("\n") : nil
      if _p.nil?
         len = (@rl_prompt && @rl_prompt.length>0 ) ? @rl_prompt.length : 0
         if (len>0)
            pmt = @rl_prompt.dup
         else
            pmt = ''
         end
         pmt << pchar
      else
         _p+=1
         pmt = @rl_prompt[_p..-1]
         pmt << pchar
      end

      # will be overwritten by expand_prompt, called from rl_message
      @prompt_physical_chars = @saved_physical_chars + 1
      pmt
   end

   def _rl_nsearch_init(dir, pchar)
      cxt = _rl_scxt_alloc(RL_SEARCH_NSEARCH, 0)
      if (dir < 0)
         cxt.sflags |= SF_REVERSE      # not strictly needed
      end
      cxt.direction = dir
      cxt.history_pos = cxt.save_line
      rl_maybe_save_line()
      # Clear the undo list, since reading the search string should create its
      #   own undo list, and the whole list will end up being freed when we
      #   finish reading the search string.
      @rl_undo_list = nil

      # Use the line buffer to read the search string.
      @rl_line_buffer[0,1] = 0.chr
      @rl_end = @rl_point = 0

      _p = _rl_make_prompt_for_search(pchar ? pchar : ':')
      rl_message(_p)
      _p = nil

      rl_setstate(RL_STATE_NSEARCH)
      @_rl_nscxt = cxt
      cxt
   end

   def _rl_nsearch_cleanup(cxt, r)
      cxt = nil
      @_rl_nscxt = nil
      rl_unsetstate(RL_STATE_NSEARCH)
      r != 1
   end

   def _rl_nsearch_abort(cxt)
      rl_maybe_unsave_line()
      rl_clear_message()
      @rl_point = cxt.save_point
      @rl_mark = cxt.save_mark
      rl_restore_prompt()
      rl_unsetstate(RL_STATE_NSEARCH)
   end

   # Process just-read character C according to search context CXT.  Return -1
   #   if the caller should abort the search, 0 if we should break out of the
   #   loop, and 1 if we should continue to read characters.
   def _rl_nsearch_dispatch(cxt, c)
      case (c)
      when "\C-W"
         rl_unix_word_rubout(1, c)
      when "\C-W"
         rl_unix_line_discard(1, c)
      when RETURN,NEWLINE
         return 0
      when "\C-H",RUBOUT
         if (@rl_point == 0)
            _rl_nsearch_abort(cxt)
            return -1
         end
         _rl_rubout_char(1, c)
      when "\C-C","\C-G"
         rl_ding()
         _rl_nsearch_abort(cxt)
         return -1
      else
         if !@rl_byte_oriented
            rl_insert_text(cxt.mb)
         else
            _rl_insert_char(1, c)
         end
      end

      send(@rl_redisplay_function)
      1
   end

   # Perform one search according to CXT, using NONINC_SEARCH_STRING.  Return
   #   -1 if the search should be aborted, any other value means to clean up
   #   using _rl_nsearch_cleanup ().  Returns 1 if the search was successful,
   #   0 otherwise.
   def _rl_nsearch_dosearch(cxt)
      @rl_mark = cxt.save_mark

      # If rl_point == 0, we want to re-use the previous search string and
      #   start from the saved history position.  If there's no previous search
      #   string, punt.
      if (@rl_point == 0)
         if @noninc_search_string.nil?
            rl_ding()
            rl_restore_prompt()
            rl_unsetstate(RL_STATE_NSEARCH)
            return -1
         end
      else
         # We want to start the search from the current history position.
         @noninc_history_pos = cxt.save_line
         @noninc_search_string = @rl_line_buffer.dup

         # If we don't want the subsequent undo list generated by the search
         #matching a history line to include the contents of the search string,
         #we need to clear rl_line_buffer here.  For now, we just clear the
         #undo list generated by reading the search string.  (If the search
         #fails, the old undo list will be restored by rl_maybe_unsave_line.)
         rl_free_undo_list()
      end

      rl_restore_prompt()
      noninc_dosearch(@noninc_search_string, cxt.direction)
   end

   # Transpose the words at point.  If point is at the end of the line,
   #   transpose the two words before point.
   def rl_transpose_words(count, key)
      orig_point = @rl_point

      return if (count==0)

      # Find the two words.
      rl_forward_word(count, key)
      w2_end = @rl_point
      rl_backward_word(1, key)
      w2_beg = @rl_point
      rl_backward_word(count, key)
      w1_beg = @rl_point
      rl_forward_word(1, key)
      w1_end = @rl_point

      # Do some check to make sure that there really are two words.
      if ((w1_beg == w2_beg) || (w2_beg < w1_end))
         rl_ding()
         @rl_point = orig_point
         return -1
      end

      # Get the text of the words.
      word1 = rl_copy_text(w1_beg, w1_end)
      word2 = rl_copy_text(w2_beg, w2_end)

      # We are about to do many insertions and deletions.  Remember them
      #   as one operation.
      rl_begin_undo_group()

      # Do the stuff at word2 first, so that we don't have to worry
      #   about word1 moving.
      @rl_point = w2_beg
      rl_delete_text(w2_beg, w2_end)
      rl_insert_text(word1)

      @rl_point = w1_beg
      rl_delete_text(w1_beg, w1_end)
      rl_insert_text(word2)

      # This is exactly correct since the text before this point has not
      #   changed in length.
      @rl_point = w2_end

      # I think that does it.
      rl_end_undo_group()
      word1 = nil
      word2 = nil

      0
   end

   # Re-read the current keybindings file.
   def rl_re_read_init_file(count, ignore)
      r = rl_read_init_file(nil)
      rl_set_keymap_from_edit_mode()
      r
   end

   # Exchange the position of mark and point.
   def rl_exchange_point_and_mark(count, key)
      if (@rl_mark > @rl_end)
         @rl_mark = -1
      end
      if (@rl_mark == -1)
         rl_ding()
         return -1
      else
         @rl_point, @rl_mark = @rl_mark, @rl_point
      end
      0
   end

   # A convenience function for displaying a list of strings in
   #   columnar format on readline's output stream.  MATCHES is the list
   #   of strings, in argv format, LEN is the number of strings in MATCHES,
   #   and MAX is the length of the longest string in MATCHES.
   def rl_display_match_list(matches, len, max)
      # How many items of MAX length can we fit in the screen window?
      max += 2
      limit = @_rl_screenwidth / max
      if (limit != 1 && (limit * max == @_rl_screenwidth))
         limit-=1
      end
      # Avoid a possible floating exception.  If max > _rl_screenwidth,
      #   limit will be 0 and a divide-by-zero fault will result.
      if (limit == 0)
         limit = 1
      end
      # How many iterations of the printing loop?
      count = (len + (limit - 1)) / limit

      # Watch out for special case.  If LEN is less than LIMIT, then
      #   just do the inner printing loop.
      #     0 < len <= limit  implies  count = 1.

      # Sort the items if they are not already sorted.
      if (!@rl_ignore_completion_duplicates)
         matches[1,len] = matches[1,len].sort
      end
      rl_crlf()

      lines = 0
      if (!@_rl_print_completions_horizontally)
         # Print the sorted items, up-and-down alphabetically, like ls.
         for i in 1 .. count
            l = i
            for j in 0 ... limit
               if (l > len || matches[l].nil?)
                  break
               else
                  temp = printable_part(matches[l])
                  printed_len = print_filename(temp, matches[l])

                  if (j + 1 < limit)
                     @rl_outstream.write(' '*(max - printed_len))
                  end
               end
               l += count
            end
            rl_crlf()
            lines+=1
            if (@_rl_page_completions && lines >= (@_rl_screenheight - 1) && i < count)
               lines = _rl_internal_pager(lines)
               return if (lines < 0)
            end
         end
      else
         # Print the sorted items, across alphabetically, like ls -x.
         i = 1
         while(matches[i])
            temp = printable_part(matches[i])
            printed_len = print_filename(temp, matches[i])
            # Have we reached the end of this line?
            if (matches[i+1])
               if ((limit > 1) && (i % limit) == 0)
                  rl_crlf()
                  lines+=1
                  if (@_rl_page_completions && lines >= @_rl_screenheight - 1)
                     lines = _rl_internal_pager(lines)
                     return if (lines < 0)
                  end
               else
                  @rl_outstream.write(' '*(max - printed_len))
               end
            end
            i += 1
         end
         rl_crlf()
      end
   end

   # Append any necessary closing quote and a separator character to the
   # just-inserted match.  If the user has specified that directories
   # should be marked by a trailing `/', append one of those instead.  The
   # default trailing character is a space.  Returns the number of characters
   # appended.  If NONTRIVIAL_MATCH is set, we test for a symlink (if the OS
   # has them) and don't add a suffix for a symlink to a directory.  A
   # nontrivial match is one that actually adds to the word being completed.
   # The variable rl_completion_mark_symlink_dirs controls this behavior
   # (it's initially set to the what the user has chosen, indicated by the
   # value of _rl_complete_mark_symlink_dirs, but may be modified by an
   # application's completion function).
   def append_to_match(text, delimiter, quote_char, nontrivial_match)
      temp_string = 0.chr * 4
      temp_string_index = 0
      if (quote_char && @rl_point>0 && !@rl_completion_suppress_quote &&
         @rl_line_buffer[@rl_point - 1,1] != quote_char)
         temp_string[temp_string_index] = quote_char
         temp_string_index += 1
      end
      if (delimiter != 0.chr)
         temp_string[temp_string_index] = delimiter
         temp_string_index += 1
      elsif (!@rl_completion_suppress_append && @rl_completion_append_character)
         temp_string[temp_string_index] = @rl_completion_append_character
         temp_string_index += 1
      end
      temp_string[temp_string_index] = 0.chr
      temp_string_index += 1

      if (@rl_filename_completion_desired)
         filename = File.expand_path(text)
         s = (nontrivial_match && !@rl_completion_mark_symlink_dirs) ?
         File.lstat(filename) : File.stat(filename)
         if s.directory?
            if @_rl_complete_mark_directories
               # This is clumsy.  Avoid putting in a double slash if point
               # is at the end of the line and the previous character is a
               # slash.
               if (@rl_point>0 && @rl_line_buffer[@rl_point,1] == 0.chr && @rl_line_buffer[@rl_point - 1,1] == '/' )

               elsif (@rl_line_buffer[@rl_point,1] != '/')
                  rl_insert_text('/')
               end
            end
            # Don't add anything if the filename is a symlink and resolves to a
            # directory.
         elsif s.symlink? && File.stat(filename).directory?

         else
            if (@rl_point == @rl_end && temp_string_index>0)
               rl_insert_text(temp_string)
            end
         end
         filename = nil
      else
         if (@rl_point == @rl_end && temp_string_index>0)
            rl_insert_text(temp_string)
         end
      end
      temp_string_index
   end

   # Stifle the history list, remembering only MAX number of lines.
   def stifle_history(max)
      max = 0 if (max < 0)

      if (@history_length > max)
         @the_history.slice!(0,(@history_length - max))
         @history_length = max
      end

      @history_stifled = true
      @max_input_history = @history_max_entries = max
   end

   # Stop stifling the history.  This returns the previous maximum
   #   number of history entries.  The value is positive if the history
   #   was stifled,  negative if it wasn't.
   def unstifle_history()
      if (@history_stifled)
         @history_stifled = false
         return (@history_max_entries)
      else
         return (-@history_max_entries)
      end
   end

   def history_is_stifled()
      return (@history_stifled)
   end

   def clear_history()
      @the_history = nil
      @history_offset = @history_length = 0
   end

   # Insert COUNT characters from STRING to the output stream at column COL.
   def insert_some_chars(string, count, col)
      if @hConsoleHandle
         _rl_output_some_chars(string,0,count)
      else
         # DEBUGGING
         if (@rl_byte_oriented)
            if (count != col)
               $stderr.write("readline: debug: insert_some_chars: count (#{count}) != col (#{col})\n");
            end
         end
         # If IC is defined, then we do not have to "enter" insert mode.
         #if (@_rl_term_IC)
         #   buffer = tgoto(@_rl_term_IC, 0, col)
         #   @_rl_out_stream.write(buffer)
         #   _rl_output_some_chars(string,0,count)
         #else
         # If we have to turn on insert-mode, then do so.
         if (@_rl_term_im)
            @_rl_out_stream.write(@_rl_term_im)
         end
         # If there is a special command for inserting characters, then
         # use that first to open up the space.
         if (@_rl_term_ic)
            @_rl_out_stream.write(@_rl_term_ic * count)
         end

         # Print the text.
         _rl_output_some_chars(string,0, count)

         # If there is a string to turn off insert mode, we had best use
         # it now.
         if (@_rl_term_ei)
            @_rl_out_stream.write(@_rl_term_ei)
         end
         #end
      end
   end

   # Delete COUNT characters from the display line.
   def delete_chars(count)
      return if (count > @_rl_screenwidth)   # XXX

      if @hConsoleHandle.nil?
         #if (@_rl_term_DC)
         #   buffer = tgoto(_rl_term_DC, count, count);
         #   @_rl_out_stream.write(buffer * count)
         #else
         if (@_rl_term_dc)
            @_rl_out_stream.write(@_rl_term_dc * count)
         end
         #end
      end
   end

   # adjust pointed byte and find mbstate of the point of string.
   #   adjusted point will be point <= adjusted_point, and returns
   #   differences of the byte(adjusted_point - point).
   #   if point is invalied (point < 0 || more than string length),
   #   it returns -1
   def _rl_adjust_point(string, point)

      length = string.length
      return -1 if (point < 0)
      return -1 if (length < point)

      pos = 0

      case @encoding
      when 'E'
         pos = string.scan(/./me).inject(0){|r,x| r<point ? r += x.length : r }
      when 'S'
         pos = string.scan(/./ms).inject(0){|r,x| r<point ? r += x.length : r }
      when 'U'
         pos = string.scan(/./mu).inject(0){|r,x| r<point ? r += x.length : r }
      when 'X'
         pos = string.dup.force_encoding(@encoding_name).chars.inject(0){|r,x| r<point ? r += x.bytesize : r }
      else
         pos = point
      end
      pos - point
   end

   # Find next `count' characters started byte point of the specified seed.
   #   If flags is MB_FIND_NONZERO, we look for non-zero-width multibyte
   #   characters.
   def _rl_find_next_mbchar(string, seed, count, flags)
      if @encoding == 'N'
         return (seed + count)
      end
      seed = 0 if seed < 0
      return seed if count <= 0

      point = seed + _rl_adjust_point(string,seed)
      if (seed < point)
         count -= 1
      end

      str = (flags == MB_FIND_NONZERO) ? string.sub(/\x00+$/n,'') : string

      case @encoding
      when 'E'
         point += str[point..-1].scan(/./me)[0,count].to_s.length
      when 'S'
         point += str[point..-1].scan(/./ms)[0,count].to_s.length
      when 'U'
         point += str[point..-1].scan(/./mu)[0,count].to_s.length
      when 'X'
         point += str[point..-1].force_encoding(@encoding_name)[0,count].bytesize
      else
         point += count
         point = str.length if point >= str.length
      end
      point
   end

   # Find previous character started byte point of the specified seed.
   #   Returned point will be point <= seed.  If flags is MB_FIND_NONZERO,
   #   we look for non-zero-width multibyte characters.
   def _rl_find_prev_mbchar(string, seed, flags)
      if @encoding == 'N'
         return ((seed == 0) ? seed : seed - 1)
      end

      length = string.length
      if seed < 0
         return 0
      elsif length < seed
         return length
      end

      case @encoding
      when 'E'
         string[0,seed].scan(/./me)[0..-2].to_s.length
      when 'S'
         string[0,seed].scan(/./ms)[0..-2].to_s.length
      when 'U'
         string[0,seed].scan(/./mu)[0..-2].to_s.length
      when 'X'
         string[0,seed].force_encoding(@encoding_name)[0..-2].bytesize
      end
   end

   # compare the specified two characters. If the characters matched,
   #   return true. Otherwise return false.
   def _rl_compare_chars(buf1, pos1, buf2, pos2)
      return false if buf1[pos1].nil? || buf2[pos2].nil?
      case @encoding
      when 'E'
         buf1[pos1..-1].scan(/./me)[0] == buf2[pos2..-1].scan(/./me)[0]
      when 'S'
         buf1[pos1..-1].scan(/./ms)[0] == buf2[pos2..-1].scan(/./ms)[0]
      when 'U'
         buf1[pos1..-1].scan(/./mu)[0] == buf2[pos2..-1].scan(/./mu)[0]
      when 'X'
         buf1[pos1..-1].force_encoding(@encoding_name)[0] == buf2[pos2..-1].force_encoding(@encoding_name)[0]
      else
         buf1[pos1] == buf2[pos2]
      end
   end

   # return the number of bytes parsed from the multibyte sequence starting
   # at src, if a non-L'\0' wide character was recognized. It returns 0,
   # if a L'\0' wide character was recognized. It  returns (size_t)(-1),
   # if an invalid multibyte sequence was encountered. It returns (size_t)(-2)
   # if it couldn't parse a complete  multibyte character.
   def _rl_get_char_len(src)
      return 0 if src[0,1] == 0.chr || src.length==0
      case @encoding
      when 'E'
         len = src.scan(/./me)[0].to_s.length
      when 'S'
         len = src.scan(/./ms)[0].to_s.length
      when 'U'
         len = src.scan(/./mu)[0].to_s.length
      when 'X'
         src = src.dup.force_encoding(@encoding_name)
         len = src.valid_encoding? ? src[0].bytesize : 0
      else
         len = 1
      end
      len==0 ? -2 : len
   end

   # read multibyte char
   def _rl_read_mbchar(mbchar, size)
      mb_len = 0
      while (mb_len < size)
         rl_setstate(RL_STATE_MOREINPUT)
         mbchar << rl_read_key()
         mb_len += 1
         rl_unsetstate(RL_STATE_MOREINPUT)
         case @encoding
         when 'E'
            break unless mbchar.scan(/./me).empty?
         when 'S'
            break unless mbchar.scan(/./ms).empty?
         when 'U'
            break unless mbchar.scan(/./mu).empty?
         when 'X'
            break if mbchar.dup.force_encoding(@encoding_name).valid_encoding?
         end
      end
      mb_len
   end

   # Read a multibyte-character string whose first character is FIRST into
   #   the buffer MB of length MLEN.  Returns the last character read, which
   #   may be FIRST.  Used by the search functions, among others.  Very similar
   #   to _rl_read_mbchar.
   def _rl_read_mbstring(first, mb, mlen)
      c = first
      for i in 0 ... mlen
         mb << c
         if _rl_get_char_len(mb) == -2
            # Read more for multibyte character
            rl_setstate(RL_STATE_MOREINPUT)
            c = rl_read_key()
            rl_unsetstate(RL_STATE_MOREINPUT)
         else
            break
         end
      end
      c
   end

   def _rl_is_mbchar_matched(string, seed, _end, mbchar, length)
      return 0 if ((_end - seed) < length)

      for i in 0 ... length
         if (string[seed + i] != mbchar[i])
            return 0
         end
      end
      1
   end

   # Redraw the last line of a multi-line prompt that may possibly contain
   # terminal escape sequences.  Called with the cursor at column 0 of the
   # line to draw the prompt on.
   def redraw_prompt(t)
      oldp = @rl_display_prompt
      rl_save_prompt()

      @rl_display_prompt = t
      @local_prompt,@prompt_visible_length,@prompt_last_invisible,@prompt_invis_chars_first_line,@prompt_physical_chars =
      expand_prompt(t)
      @local_prompt_prefix = nil
      @local_prompt_len = @local_prompt ? @local_prompt.length : 0

      rl_forced_update_display()

      @rl_display_prompt = oldp
      rl_restore_prompt()
   end

   # Redisplay the current line after a SIGWINCH is received.
   def _rl_redisplay_after_sigwinch()
      # Clear the current line and put the cursor at column 0.  Make sure
      #   the right thing happens if we have wrapped to a new screen line.
      if @_rl_term_cr
         @rl_outstream.write(@_rl_term_cr)
         @_rl_last_c_pos = 0
         if @_rl_term_clreol
            @rl_outstream.write(@_rl_term_clreol)
         else
            space_to_eol(@_rl_screenwidth)
            @rl_outstream.write(@_rl_term_cr)
         end

         if @_rl_last_v_pos > 0
            _rl_move_vert(0)
         end
      else
         rl_crlf()
      end

      # Redraw only the last line of a multi-line prompt.
      t = @rl_display_prompt.index("\n")
      if t
         redraw_prompt(@rl_display_prompt[(t+1)..-1])
      else
         rl_forced_update_display()
      end
   end

   def rl_resize_terminal()
      if @readline_echoing_p
         _rl_get_screen_size(@rl_instream.fileno, 1)
         if @rl_redisplay_function != :rl_redisplay
            rl_forced_update_display()
         else
            _rl_redisplay_after_sigwinch()
         end
      end
   end

   def rl_sigwinch_handler(sig)
      rl_setstate(RL_STATE_SIGHANDLER)
      rl_resize_terminal()
      rl_unsetstate(RL_STATE_SIGHANDLER)
   end



   module_function :rl_attempted_completion_function,:rl_deprep_term_function,
   :rl_event_hook,:rl_attempted_completion_over,:rl_basic_quote_characters,
   :rl_basic_word_break_characters,:rl_completer_quote_characters,
   :rl_completer_word_break_characters,:rl_completion_append_character,
   :rl_filename_quote_characters,:rl_instream,:rl_library_version,:rl_outstream,
   :rl_readline_name,
   :rl_attempted_completion_function=,:rl_deprep_term_function=,
   :rl_event_hook=,:rl_attempted_completion_over=,:rl_basic_quote_characters=,
   :rl_basic_word_break_characters=,:rl_completer_quote_characters=,
   :rl_completer_word_break_characters=,:rl_completion_append_character=,
   :rl_filename_quote_characters=,:rl_instream=,:rl_library_version=,:rl_outstream=,
   :rl_readline_name=,:history_length,:history_base

  def no_terminal?
    term = ENV["TERM"]
    term.nil? || (term == 'dumb') || (term == 'cygwin' && RUBY_PLATFORM =~ /mswin|mingw/)
  end
  private :no_terminal?

end
