/jEdit/tags/jedit-4-0-pre3/bsh/BSHSwitchStatement.java

  1/*****************************************************************************
  2 *                                                                           *
  3 *  This file is part of the BeanShell Java Scripting distribution.          *
  4 *  Documentation and updates may be found at http://www.beanshell.org/      *
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  6 *  Sun Public License Notice:                                               *
  7 *                                                                           *
  8 *  The contents of this file are subject to the Sun Public License Version  *
  9 *  1.0 (the "License"); you may not use this file except in compliance with *
 10 *  the License. A copy of the License is available at http://www.sun.com    * 
 11 *                                                                           *
 12 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 13 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 14 *  (C) 2000.  All Rights Reserved.                                          *
 15 *                                                                           *
 16 *  GNU Public License Notice:                                               *
 17 *                                                                           *
 18 *  Alternatively, the contents of this file may be used under the terms of  *
 19 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 20 *  provisions of LGPL are applicable instead of those above. If you wish to *
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 25 *  do not delete the provisions above, a recipient may use your version of  *
 26 *  this file under either the SPL or the LGPL.                              *
 27 *                                                                           *
 28 *  Patrick Niemeyer (pat@pat.net)                                           *
 29 *  Author of Learning Java, O'Reilly & Associates                           *
 30 *  http://www.pat.net/~pat/                                                 *
 31 *                                                                           *
 32 *****************************************************************************/
 33
 34package bsh;
 35
 36class BSHSwitchStatement 
 37	extends SimpleNode 
 38	implements ParserConstants 
 39{
 40
 41	public BSHSwitchStatement(int id) { super(id); }
 42
 43    public Object eval( CallStack callstack, Interpreter interpreter )
 44		throws EvalError
 45	{
 46		int numchild = jjtGetNumChildren();
 47		int child = 0;
 48		SimpleNode switchExp = ((SimpleNode)jjtGetChild(child++));
 49		Object switchVal = switchExp.eval( callstack, interpreter );
 50
 51		/*
 52			Note: this could be made clearer by adding an inner class for the
 53			cases and an object context for the child traversal.
 54		*/
 55		// first label
 56		BSHSwitchLabel label;
 57		Object node;
 58		ReturnControl returnControl=null;
 59
 60		// get the first label
 61		if ( child >= numchild )
 62			throw new EvalError("Empty switch statement...");
 63		label = ((BSHSwitchLabel)jjtGetChild(child++));
 64
 65		// while more labels or blocks and haven't hit return control
 66		while ( child < numchild && returnControl == null ) 
 67		{
 68			// if label is default or equals switchVal
 69			if ( label.isDefault 
 70				|| label.eval( callstack, interpreter ).equals( switchVal ) )
 71			{
 72				// execute nodes, skipping labels, until a break or return
 73				while ( child < numchild ) 
 74				{
 75					node = jjtGetChild(child++);
 76					if ( node instanceof BSHSwitchLabel )
 77						continue;
 78					// eval it
 79					Object value = 
 80						((SimpleNode)node).eval( callstack, interpreter ); 
 81
 82					// should check to disallow continue here?
 83					if ( value instanceof ReturnControl ) {
 84						returnControl = (ReturnControl)value;
 85						break;
 86					}
 87				}
 88			} else 
 89			{
 90				// skip nodes until next label
 91				while ( child < numchild ) 
 92				{
 93					node = jjtGetChild(child++);
 94					if ( node instanceof BSHSwitchLabel ) {
 95						label = (BSHSwitchLabel)node;
 96						break;
 97					}
 98				}
 99			}
100		}
101
102		if ( returnControl != null && returnControl.kind == RETURN )
103			return returnControl;
104		else
105			return Primitive.VOID;
106	}
107
108}
109