| /* |
| * 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. |
| * |
| */ |
| package org.apache.ant.props; |
| |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.Stack; |
| |
| import org.apache.tools.ant.PropertyHelper; |
| import org.apache.tools.ant.PropertyHelper.PropertyEvaluator; |
| |
| /** |
| * Abstract delegating {@link PropertyEvaluator}. |
| */ |
| public abstract class DelegatingPropertyEvaluator implements PropertyHelper.PropertyEvaluator { |
| private final ThreadLocal stack = new ThreadLocal(); |
| |
| private ArrayList delegates = new ArrayList(); |
| |
| /** |
| * Add a {@link PropertyEvaluator} delegate. |
| * @param propertyEvaluator to add |
| */ |
| protected void addDelegate(PropertyEvaluator propertyEvaluator) { |
| delegates.add(propertyEvaluator); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public Object evaluate(String propertyName, PropertyHelper propertyHelper) { |
| if (getRequiredStack().contains(propertyName)) { |
| return null; |
| } |
| push(propertyName); |
| try { |
| for (Iterator iter = delegates.iterator(); iter.hasNext();) { |
| Object value = ((PropertyEvaluator) iter.next()).evaluate(propertyName, |
| propertyHelper); |
| if (value != null) { |
| return value; |
| } |
| } |
| } finally { |
| pop(); |
| } |
| return null; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (obj instanceof DelegatingPropertyEvaluator == false) { |
| return false; |
| } |
| return delegates.equals(((DelegatingPropertyEvaluator) obj).delegates); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int hashCode() { |
| return 17 * delegates.hashCode(); |
| } |
| |
| private synchronized Stack getRequiredStack() { |
| Stack result = (Stack) stack.get(); |
| if (result == null) { |
| result = new Stack(); |
| stack.set(result); |
| } |
| return result; |
| } |
| |
| private synchronized void push(String propertyName) { |
| getRequiredStack().push(propertyName); |
| } |
| |
| private synchronized void pop() { |
| Stack stk = (Stack) stack.get(); |
| if (stk != null) { |
| stk.pop(); |
| if (stk.isEmpty()) { |
| stack.set(null); |
| } |
| } |
| } |
| } |