/*
* Copyright 1999,2004 The Apache Software Foundation.
*
* Licensed 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.
*/
package joran.calculator;
import org.apache.joran.ExecutionContext;
import org.apache.joran.action.Action;
import org.apache.log4j.spi.ErrorItem;
import org.xml.sax.Attributes;
import java.util.EmptyStackException;
/**
*
* This action multiplies the two integers at the top of the stack (they are removed)
* and pushes the result on top the stack.
*
* @author Ceki Gülcü
*/
public class MultiplyAction extends Action {
public void begin(ExecutionContext ec, String name, Attributes attributes) {
int first = fetchInteger(ec);
int second = fetchInteger(ec);
ec.pushObject(new Integer(first * second));
}
/**
* Pop the Integer object at the top of the stack.
* This code illustrates usage of Joran's error handling paradigm.
*/
int fetchInteger(ExecutionContext ec) {
int result = 0;
try {
Object o1 = ec.popObject();
if (o1 instanceof Integer) {
result = ((Integer) o1).intValue();
} else {
String errMsg =
"Object [" + o1
+ "] currently at the top of the stack is not an integer.";
ec.addError(new ErrorItem(errMsg));
throw new IllegalArgumentException(errMsg);
}
} catch (EmptyStackException ese) {
ec.addError(
new ErrorItem("Expecting an integer on the execution stack."));
throw ese;
}
return result;
}
public void end(ExecutionContext ec, String name) {
// Nothing to do here.
// In general, the end() method of actions associated with elements
// having no children do not need to perform any processing in their
// end() method.
}
}