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* This file is part of the BeanShell Java Scripting distribution. *
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* Patrick Niemeyer ([email protected]) *
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* http://www.pat.net/~pat/ *
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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);
}
}
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