| /* |
| * 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.pig.impl.util; |
| |
| import java.util.*; |
| import java.util.Map.Entry; |
| |
| public class IdentityHashSet<E> implements Set<E> { |
| |
| IdentityHashMap<E, Object> map = new IdentityHashMap<E, Object>(); |
| |
| public boolean add(E element) { |
| if (map.containsKey(element)) { |
| return false; |
| } else { |
| map.put(element, null); |
| return true; |
| } |
| } |
| |
| public boolean addAll(Collection<? extends E> elements) { |
| boolean anyChanges = false; |
| for (E element : elements) { |
| if (!map.containsKey(element)) { |
| anyChanges = true; |
| map.put(element, null); |
| } |
| } |
| return anyChanges; |
| } |
| |
| public void clear() { |
| map.clear(); |
| } |
| |
| public boolean contains(Object element) { |
| return map.containsKey(element); |
| } |
| |
| public boolean containsAll(Collection<?> elements) { |
| for (Object element : elements) { |
| if (!map.containsKey(element)) return false; |
| } |
| return true; |
| } |
| |
| public boolean isEmpty() { |
| return map.isEmpty(); |
| } |
| |
| public Iterator<E> iterator() { |
| |
| return new Iterator<E>() { |
| Iterator<Map.Entry<E, Object>> it = map.entrySet().iterator(); |
| |
| public boolean hasNext() { |
| return it.hasNext(); |
| } |
| |
| public E next() { |
| return it.next().getKey(); |
| } |
| |
| public void remove() { |
| it.remove(); |
| } |
| }; |
| } |
| |
| public boolean remove(Object element) { |
| if (map.containsKey(element)) { |
| map.remove(element); |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| public boolean removeAll(Collection<?> elements) { |
| for (Object element : elements) map.remove(element); |
| return true; |
| } |
| |
| @SuppressWarnings("unchecked") |
| public boolean retainAll(Collection<?> elements) { |
| IdentityHashMap<E, Object> newMap = new IdentityHashMap<E, Object>(); |
| |
| for (Object element : elements) { |
| if (map.containsKey(element)) newMap.put((E) element, null); |
| } |
| |
| boolean anyChanges = newMap.size() != map.size(); |
| |
| map = newMap; |
| return anyChanges; |
| } |
| |
| public int size() { |
| return map.size(); |
| } |
| |
| public Object[] toArray() { |
| throw new UnsupportedOperationException("Unsupported operation on IdentityHashSet."); |
| } |
| |
| public <T> T[] toArray(T[] dummy) { |
| throw new UnsupportedOperationException("Unsupported operation on IdentityHashSet."); |
| } |
| |
| public String toString() { |
| StringBuffer buf = new StringBuffer(); |
| buf.append("{"); |
| |
| Iterator<Entry<E, Object>> i = map.entrySet().iterator(); |
| boolean hasNext = i.hasNext(); |
| while (hasNext) { |
| Entry<E, Object> e = i.next(); |
| E key = e.getKey(); |
| buf.append(key); |
| hasNext = i.hasNext(); |
| if (hasNext) |
| buf.append(", "); |
| } |
| |
| buf.append("}"); |
| return buf.toString(); |
| } |
| |
| } |