| /* |
| * 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.tools.ant.types.resources; |
| |
| import java.util.Set; |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.WeakHashMap; |
| import java.util.NoSuchElementException; |
| import java.util.ConcurrentModificationException; |
| |
| /** |
| * Helper class for ResourceCollections to return Iterators |
| * that fail on changes to the object. |
| * @since Ant 1.7 |
| */ |
| /*package-private*/ class FailFast implements Iterator { |
| private static final WeakHashMap MAP = new WeakHashMap(); |
| |
| /** |
| * Invalidate any in-use Iterators from the specified Object. |
| * @param o the parent Object. |
| */ |
| static synchronized void invalidate(Object o) { |
| Set s = (Set) (MAP.get(o)); |
| if (s != null) { |
| s.clear(); |
| } |
| } |
| |
| private static synchronized void add(FailFast f) { |
| Set s = (Set) (MAP.get(f.parent)); |
| if (s == null) { |
| s = new HashSet(); |
| MAP.put(f.parent, s); |
| } |
| s.add(f); |
| } |
| |
| private static synchronized void remove(FailFast f) { |
| Set s = (Set) (MAP.get(f.parent)); |
| if (s != null) { |
| s.remove(f); |
| } |
| } |
| |
| private static synchronized void failFast(FailFast f) { |
| Set s = (Set) (MAP.get(f.parent)); |
| if (!s.contains(f)) { |
| throw new ConcurrentModificationException(); |
| } |
| } |
| |
| private Object parent; |
| private Iterator wrapped; |
| |
| /** |
| * Construct a new FailFast Iterator wrapping the specified Iterator |
| * and dependent upon the specified parent Object. |
| * @param o the parent Object. |
| * @param i the wrapped Iterator. |
| */ |
| FailFast(Object o, Iterator i) { |
| if (o == null) { |
| throw new IllegalArgumentException("parent object is null"); |
| } |
| if (i == null) { |
| throw new IllegalArgumentException("cannot wrap null iterator"); |
| } |
| parent = o; |
| if (i.hasNext()) { |
| wrapped = i; |
| add(this); |
| } |
| } |
| |
| /** |
| * Fulfill the Iterator contract. |
| * @return true if there are more elements. |
| */ |
| public boolean hasNext() { |
| if (wrapped == null) { |
| return false; |
| } |
| failFast(this); |
| return wrapped.hasNext(); |
| } |
| |
| /** |
| * Fulfill the Iterator contract. |
| * @return the next element. |
| * @throws NoSuchElementException if no more elements. |
| */ |
| public Object next() { |
| if (wrapped == null || !wrapped.hasNext()) { |
| throw new NoSuchElementException(); |
| } |
| failFast(this); |
| try { |
| return wrapped.next(); |
| } finally { |
| if (!wrapped.hasNext()) { |
| wrapped = null; |
| remove(this); |
| } |
| } |
| } |
| |
| /** |
| * Fulfill the Iterator contract. |
| * @throws UnsupportedOperationException always. |
| */ |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| } |
| |