Task

Write a program that solves the odd word problem with the restrictions given below.



Description

You are promised an input stream consisting of English letters and punctuations.

It is guaranteed that:

 the words (sequence of consecutive letters) are delimited by one and only one punctuation,
 the stream will begin with a word,
 the words will be at least one letter long,   and 
 a full stop (a period, [.]) appears after, and only after, the last word.


Example

A stream with six words:

 what,is,the;meaning,of:life. 


The task is to reverse the letters in every other word while leaving punctuations intact, producing:

 what,si,the;gninaem,of:efil. 
while observing the following restrictions:

 Only I/O allowed is reading or writing one character at a time, which means: no reading in a string, no peeking ahead, no pushing characters back into the stream, and no storing characters in a global variable for later use;
 You are not to explicitly save characters in a collection data structure, such as arrays, strings, hash tables, etc, for later reversal;
 You are allowed to use recursions, closures, continuations, threads, co-routines, etc., even if their use implies the storage of multiple characters.


Test cases

Work on both the   "life"   example given above, and also the text:

 we,are;not,in,kansas;any,more.


test: procedure options (main);  /* 2 August 2014 */
   declare (ch, ech) character (1);
   declare odd file;
 
get_word: procedure recursive;
   declare ch character (1);
 
   get file (odd) edit (ch) (a(1));
   if index('abcdefghijklmnopqrstuvwxyz', ch) > 0 then call get_word;
   if index('abcdefghijklmnopqrstuvwxyz', ch) > 0 then
      put edit (ch) (a);
   else ech = ch;
end get_word;
 
   open file (odd) input title ('/ODDWORD.DAT,TYPE(text),recsize(100)');
   do forever;
      do  until (index('abcdefghijklmnopqrstuvwxyz', ch) = 0 );
         get file (odd) edit (ch) (a(1)); put edit (ch) (a);
      end;
      if ch = '.' then leave;
      call get_word;
      put edit (ech) (a);
      if ech = '.' then leave;
   end;
end test;