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BeanShell is a small, free, embeddable Java source interpreter with object scripting language features,
written in Java. BeanShell dynamically executes standard Java syntax and extends it with common scripting
conveniences such as loose types, commands, and method closures like those in Perl and JavaScript.
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/*****************************************************************************
* *
* This file is part of the BeanShell Java Scripting distribution. *
* Documentation and updates may be found at http://www.beanshell.org/ *
* *
* Sun Public License Notice: *
* *
* The contents of this file are subject to the Sun Public License Version *
* 1.0 (the "License"); you may not use this file except in compliance with *
* the License. A copy of the License is available at http://www.sun.com *
* *
* The Original Code is BeanShell. The Initial Developer of the Original *
* Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
* (C) 2000. All Rights Reserved. *
* *
* GNU Public License Notice: *
* *
* Alternatively, the contents of this file may be used under the terms of *
* the GNU Lesser General Public License (the "LGPL"), in which case the *
* provisions of LGPL are applicable instead of those above. If you wish to *
* allow use of your version of this file only under the terms of the LGPL *
* and not to allow others to use your version of this file under the SPL, *
* indicate your decision by deleting the provisions above and replace *
* them with the notice and other provisions required by the LGPL. If you *
* do not delete the provisions above, a recipient may use your version of *
* this file under either the SPL or the LGPL. *
* *
* Patrick Niemeyer ([email protected]) *
* Author of Learning Java, O'Reilly & Associates *
* http://www.pat.net/~pat/ *
* *
*****************************************************************************/
package bsh;
class BSHSwitchStatement
extends SimpleNode
implements ParserConstants
{
public BSHSwitchStatement(int id) { super(id); }
public Object eval( CallStack callstack, Interpreter interpreter )
throws EvalError
{
int numchild = jjtGetNumChildren();
int child = 0;
SimpleNode switchExp = ((SimpleNode)jjtGetChild(child++));
Object switchVal = switchExp.eval( callstack, interpreter );
/*
Note: this could be made clearer by adding an inner class for the
cases and an object context for the child traversal.
*/
// first label
BSHSwitchLabel label;
Object node;
ReturnControl returnControl=null;
// get the first label
if ( child >= numchild )
throw new EvalError("Empty switch statement.", this, callstack );
label = ((BSHSwitchLabel)jjtGetChild(child++));
// while more labels or blocks and haven't hit return control
while ( child < numchild && returnControl == null )
{
// if label is default or equals switchVal
if ( label.isDefault
|| primitiveEquals(
switchVal, label.eval( callstack, interpreter ),
callstack, switchExp )
)
{
// execute nodes, skipping labels, until a break or return
while ( child < numchild )
{
node = jjtGetChild(child++);
if ( node instanceof BSHSwitchLabel )
continue;
// eval it
Object value =
((SimpleNode)node).eval( callstack, interpreter );
// should check to disallow continue here?
if ( value instanceof ReturnControl ) {
returnControl = (ReturnControl)value;
break;
}
}
} else
{
// skip nodes until next label
while ( child < numchild )
{
node = jjtGetChild(child++);
if ( node instanceof BSHSwitchLabel ) {
label = (BSHSwitchLabel)node;
break;
}
}
}
}
if ( returnControl != null && returnControl.kind == RETURN )
return returnControl;
else
return Primitive.VOID;
}
/**
Helper method for testing equals on two primitive or boxable objects.
yuck: factor this out into Primitive.java
*/
private boolean primitiveEquals(
Object switchVal, Object targetVal,
CallStack callstack, SimpleNode switchExp )
throws EvalError
{
if ( switchVal instanceof Primitive || targetVal instanceof Primitive )
try {
// binaryOperation can return Primitive or wrapper type
Object result = Primitive.binaryOperation(
switchVal, targetVal, ParserConstants.EQ );
result = Primitive.unwrap( result );
return result.equals( Boolean.TRUE );
} catch ( UtilEvalError e ) {
throw e.toEvalError(
"Switch value: "+switchExp.getText()+": ",
this, callstack );
}
else
return switchVal.equals( targetVal );
}
}