/* Soot - a J*va Optimization Framework
 * Copyright (C) 2004 John Jorgensen
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Modified by the Sable Research Group and others 1997-2004.  
 * See the 'credits' file distributed with Soot for the complete list of
 * contributors.  (Soot is distributed at http://www.sable.mcgill.ca/soot)
 */


 



package soot.toolkits.graph;

import soot.toolkits.graph.DirectedGraph;
import soot.Body;
import soot.Trap;
import java.util.List;
import java.util.Collection;
import soot.toolkits.exceptions.ThrowableSet;


/**
 *  <p>Defines the interface for navigating a control flow graph which
 *  distinguishes exceptional control flow.</p>
 */
public interface ExceptionalGraph extends DirectedGraph
{
    /**
     * <p>Data structure to represent the fact that
     * a given {@link Trap} will catch some subset of the exceptions
     * which may be thrown by a given graph node.</p>
     *
     * <p>Note that these ``destinations'' are different from the
     * edges in the CFG proper which are returned by
     * <code>getSuccsOf()</code> and <code>getPredsOf()</code>. An
     * edge from <code>a</code> to <code>b</code> in the CFG
     * represents the fact that after node <code>a</code> executes
     * (perhaps only partially, if it throws an exception after
     * producing a side effect), execution may proceed to
     * node <code>b</code>.  An ExceptionDest from <code>a</code> to
     * <code>b</code>, on the other hand, says that when
     * <code>a</code> fails to execute, execution may proceed
     * to <code>b</code> instead.</p>
     */
    public interface ExceptionDest {

	/**
	 * Returns the trap corresponding to this destination.
	 *
	 * @return either a {@link Trap} representing the handler that
	 * catches the exceptions, if there is such a handler within
	 * the method, or <code>null</code> if there is no such
	 * handler and the exceptions cause the method to terminate
	 * abruptly.
	 */
	public Trap trap();

	/**
	 * Returns the exceptions thrown to this destination.
	 *
	 * @return a {@link ThrowableSet} representing
	 * the exceptions which may be caught by this 
	 * <code>ExceptionDest</code>'s trap.
	 */
	public ThrowableSet throwables();

	/**
	 * Returns the CFG node corresponding to the beginning of
	 * the exception handler that catches the exceptions (that is,
	 * the node that includes {@link trap().getBeginUnit()})).
	 *
	 * @return the node in this graph which represents the
	 * beginning of the handler which catches these exceptions, or
	 * <code>null</code> if there is no such handler and the
	 * exceptions cause the method to terminate abruptly.
	 */
	// Maybe we should define an interface for Unit and Block to
	// implement, and return an instance of that, rather than
	// an Object.  We chose Object because that's what DirectedGraph
	// deals in.
	public Object getHandlerNode();
    }


    /**
     * Returns the {@link Body} from which this graph was built.
     *
     * @return the <code>Body</code> from which this graph was built.
     */
    public Body getBody();


    /**
     * Returns a list of nodes which are predecessors of a given
     * node when only unexceptional control flow is considered.
     *
     * @param n The node whose predecessors are to be returned.
     *
     * @return a {@link List} of the nodes in this graph from which
     *         there is an unexceptional edge to <code>n</code>.
     */
    public List getUnexceptionalPredsOf(Object n);


    /**
     * Returns a list of nodes which are successors of a given
     * node when only unexceptional control flow is considered.
     *
     * @param n The node whose successors are to be returned.
     *
     * @return a {@link List} of nodes in this graph to which 
     *         there is an unexceptional edge from <code>n</code>.
     */
    public List getUnexceptionalSuccsOf(Object n);


    /**
     * Returns a list of nodes which are predecessors of a given
     * node when only exceptional control flow is considered.
     *
     * @param n The node whose predecessors are to be returned.
     *
     * @return a {@link List} of nodes in this graph from which 
     *         there is an exceptional edge to <code>n</code>.
     */
    public List getExceptionalPredsOf(Object n);


    /**
     * Returns a list of nodes which are successors of a given
     * node when only exceptional control flow is considered.
     *
     * @param n The node whose successors are to be returned.
     *
     * @return a {@link List} of nodes in this graph to which 
     *         there is an exceptional edge from <code>n</code>.
     */
    public List getExceptionalSuccsOf(Object n);


    /**
     * Returns a collection of 
     * {@link ExceptionalGraph.ExceptionDest ExceptionDest}
     * objects which represent how exceptions thrown by a specified
     * node will be handled.
     *
     * @param n The node for which to provide exception information.
     *
     * @return a collection of <code>ExceptionDest</code> objects describing
     *	       the traps and handlers, if any, which catch the exceptions
     *	       which may be thrown by <code>n</code>.
     */
    public Collection getExceptionDests(Object n);
}

Add new interface, ExceptionalGraph.