package org.apache.lucene.util;
/**
* 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.
*/
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;
/**
* A Set implementation that wraps an actual Map based
* implementation.
*
* @lucene.internal
*/
public final class MapBackedSet<E> extends AbstractSet<E> implements Serializable {
private static final long serialVersionUID = -6761513279741915432L;
private final Map<E, Boolean> map;
/**
* Creates a new instance which wraps the specified {@code map}.
*/
public MapBackedSet(Map<E, Boolean> map) {
this.map = map;
}
@Override
public int size() {
return map.size();
}
@Override
public boolean contains(Object o) {
return map.containsKey(o);
}
@Override
public boolean add(E o) {
return map.put(o, Boolean.TRUE) == null;
}
@Override
public boolean remove(Object o) {
return map.remove(o) != null;
}
@Override
public void clear() {
map.clear();
}
@Override
public Iterator<E> iterator() {
return map.keySet().iterator();
}
}