/*****************************************************************************
* Licensed to the Apache Software Foundation (ASF) under one *
* or more contributor license agreements. See the NOTICE file *
* distributed with this work for additional information *
* regarding copyright ownership. The ASF licenses this file *
* to you under the Apache License, Version 2.0 (the *
* "License"); you may not use this file except in compliance *
* with the License. You may obtain a copy of the License at *
* *
* http://www.apache.org/licenses/LICENSE-2.0 *
* *
* Unless required by applicable law or agreed to in writing, *
* software distributed under the License is distributed on an *
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY *
* KIND, either express or implied. See the License for the *
* specific language governing permissions and limitations *
* under the License. *
* *
* *
* This file is part of the BeanShell Java Scripting distribution. *
* Documentation and updates may be found at http://www.beanshell.org/ *
* Patrick Niemeyer (pat@pat.net) *
* Author of Learning Java, O'Reilly & Associates *
* *
*****************************************************************************/
package bsh;
/**
Implementation of the for(;;) statement.
*/
class
BSHForStatement extends
SimpleNode implements
ParserConstants
{
public boolean
hasForInit;
public boolean
hasExpression;
public boolean
hasForUpdate;
private
SimpleNode forInit;
private
SimpleNode expression;
private
SimpleNode forUpdate;
private
SimpleNode statement;
private boolean
parsed;
BSHForStatement(int
id) { super(
id); }
public
Object eval(
CallStack callstack ,
Interpreter interpreter)
throws
EvalError
{
int
i = 0;
if(
hasForInit)
forInit = ((
SimpleNode)
jjtGetChild(
i++));
if(
hasExpression)
expression = ((
SimpleNode)
jjtGetChild(
i++));
if(
hasForUpdate)
forUpdate = ((
SimpleNode)
jjtGetChild(
i++));
if(
i <
jjtGetNumChildren()) // should normally be
statement = ((
SimpleNode)
jjtGetChild(
i));
NameSpace enclosingNameSpace=
callstack.
top();
BlockNameSpace forNameSpace = new
BlockNameSpace(
enclosingNameSpace );
/*
Note: some interesting things are going on here.
1) We swap instead of push... The primary mode of operation
acts like we are in the enclosing namespace... (super must be
preserved, etc.)
2) We do *not* call the body block eval with the namespace
override. Instead we allow it to create a second subordinate
BlockNameSpace child of the forNameSpace. Variable propagation
still works through the chain, but the block's child cleans the
state between iteration.
(which is correct Java behavior... see forscope4.bsh)
*/
// put forNameSpace it on the top of the stack
// Note: it's important that there is only one exit point from this
// method so that we can swap back the namespace.
callstack.
swap(
forNameSpace );
// Do the for init
if (
hasForInit )
forInit.
eval(
callstack,
interpreter );
Object returnControl =
Primitive.
VOID;
while(true)
{
if (
hasExpression )
{
boolean
cond =
BSHIfStatement.
evaluateCondition(
expression,
callstack,
interpreter );
if ( !
cond )
break;
}
boolean
breakout = false; // switch eats a multi-level break here?
if (
statement != null ) // not empty statement
{
// do *not* invoke special override for block... (see above)
Object ret =
statement.
eval(
callstack,
interpreter );
if (
ret instanceof
ReturnControl)
{
switch(((
ReturnControl)
ret).
kind)
{
case
RETURN:
returnControl =
ret;
breakout = true;
break;
case
CONTINUE:
break;
case
BREAK:
breakout = true;
break;
}
}
}
if (
breakout )
break;
if (
hasForUpdate )
forUpdate.
eval(
callstack,
interpreter );
}
callstack.
swap(
enclosingNameSpace ); // put it back
return
returnControl;
}
}