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/jEdit/tags/jedit-4-0-pre5/bsh/BSHForStatement.java

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Java | 141 lines | 68 code | 21 blank | 52 comment | 12 complexity | 0020a8adf25969ed42dc514ad3fa67f6 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 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 acts 
 75			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 override
 79			We allow it to create a second subordinate BlockNameSpace child
 80			of the forNameSpace.  Variable propogation still works through
 81			the chain, but the block's child cleans the state between iteration.
 82			(which is correct Java behavior... see forscope4.bsh)
 83		*/
 84		callstack.swap( forNameSpace );
 85
 86		// Note: it's important that there is only one exit point from this
 87		// method so that we can swap back the namespace.
 88
 89        // Do the for init
 90        if ( hasForInit ) 
 91            forInit.eval( callstack, interpreter );
 92
 93		Object returnControl = Primitive.VOID;
 94        while(true)
 95        {
 96            if ( hasExpression ) 
 97			{
 98				boolean cond = BSHIfStatement.evaluateCondition(
 99					expression, callstack, interpreter );
100
101				if ( !cond ) 
102					break;
103			}
104
105            boolean breakout = false; // switch eats a multi-level break here?
106            if ( statement != null ) // not empty statement
107            {
108				// do *not* invoke special override for block... (see above)
109                Object ret = statement.eval( callstack, interpreter );
110
111                if (ret instanceof ReturnControl)
112                {
113                    switch(((ReturnControl)ret).kind)
114                    {
115                        case RETURN:
116							returnControl = ret;
117							breakout = true;
118                            break;
119
120                        case CONTINUE:
121                            break;
122
123                        case BREAK:
124                            breakout = true;
125                            break;
126                    }
127                }
128            }
129
130            if ( breakout )
131                break;
132
133            if ( hasForUpdate )
134                forUpdate.eval( callstack, interpreter );
135        }
136
137		callstack.swap( enclosingNameSpace );  // put it back
138        return returnControl;
139    }
140
141}