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/jEdit/tags/jedit-4-5-pre1/org/gjt/sp/jedit/bsh/BSHForStatement.java

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Java | 143 lines | 68 code | 21 blank | 54 comment | 12 complexity | ebfa5e09ba2c7885a17f36bfb8d8391a MD5 | raw file
  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/      *
  5 *                                                                           *
  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 *
 21 *  allow use of your version of this file only under the  terms of the LGPL *
 22 *  and not to allow others to use your version of this file under the SPL,  *
 23 *  indicate your decision by deleting the provisions above and replace      *
 24 *  them with the notice and other provisions required by the LGPL.  If you  *
 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
 34
 35package org.gjt.sp.jedit.bsh;
 36
 37/**
 38	Implementation of the for(;;) statement.
 39*/
 40class BSHForStatement extends SimpleNode implements ParserConstants
 41{
 42    public boolean hasForInit;
 43    public boolean hasExpression;
 44    public boolean hasForUpdate;
 45
 46    private SimpleNode forInit;
 47    private SimpleNode expression;
 48    private SimpleNode forUpdate;
 49    private SimpleNode statement;
 50
 51    private boolean parsed;
 52
 53    BSHForStatement(int id) { super(id); }
 54
 55    public Object eval(CallStack callstack , Interpreter interpreter)  
 56		throws EvalError
 57    {
 58        int i = 0;
 59        if(hasForInit)
 60            forInit = ((SimpleNode)jjtGetChild(i++));
 61        if(hasExpression)
 62            expression = ((SimpleNode)jjtGetChild(i++));
 63        if(hasForUpdate)
 64            forUpdate = ((SimpleNode)jjtGetChild(i++));
 65        if(i < jjtGetNumChildren()) // should normally be
 66            statement = ((SimpleNode)jjtGetChild(i));
 67
 68		NameSpace enclosingNameSpace= callstack.top();
 69		BlockNameSpace forNameSpace = new BlockNameSpace( enclosingNameSpace );
 70
 71		/*
 72			Note: some interesting things are going on here.
 73
 74			1) We swap instead of push...  The primary mode of operation 
 75			acts like we are in the enclosing namespace...  (super must be 
 76			preserved, etc.)
 77
 78			2) We do *not* call the body block eval with the namespace 
 79			override.  Instead we allow it to create a second subordinate 
 80			BlockNameSpace child of the forNameSpace.  Variable propogation 
 81			still works through the chain, but the block's child cleans the 
 82			state between iteration.  
 83			(which is correct Java behavior... see forscope4.bsh)
 84		*/
 85
 86		// put forNameSpace it on the top of the stack
 87		// Note: it's important that there is only one exit point from this
 88		// method so that we can swap back the namespace.
 89		callstack.swap( forNameSpace );
 90
 91        // Do the for init
 92        if ( hasForInit ) 
 93            forInit.eval( callstack, interpreter );
 94
 95		Object returnControl = Primitive.VOID;
 96        while(true)
 97        {
 98            if ( hasExpression ) 
 99			{
100				boolean cond = BSHIfStatement.evaluateCondition(
101					expression, callstack, interpreter );
102
103				if ( !cond ) 
104					break;
105			}
106
107            boolean breakout = false; // switch eats a multi-level break here?
108            if ( statement != null ) // not empty statement
109            {
110				// do *not* invoke special override for block... (see above)
111                Object ret = statement.eval( callstack, interpreter );
112
113                if (ret instanceof ReturnControl)
114                {
115                    switch(((ReturnControl)ret).kind)
116                    {
117                        case RETURN:
118							returnControl = ret;
119							breakout = true;
120                            break;
121
122                        case CONTINUE:
123                            break;
124
125                        case BREAK:
126                            breakout = true;
127                            break;
128                    }
129                }
130            }
131
132            if ( breakout )
133                break;
134
135            if ( hasForUpdate )
136                forUpdate.eval( callstack, interpreter );
137        }
138
139		callstack.swap( enclosingNameSpace );  // put it back
140        return returnControl;
141    }
142
143}