| package org.apache.solr.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 com.google.common.collect.ForwardingMap; |
| |
| import java.util.HashSet; |
| import java.util.Map; |
| import java.util.Set; |
| |
| /** |
| * Wraps another map, keeping track of each key that was seen via {@link #get(Object)} or {@link #remove(Object)}. |
| */ |
| @SuppressWarnings("unchecked") |
| public class MapListener<K, V> extends ForwardingMap<K, V> { |
| private final Map<K, V> target; |
| private final Set<K> seenKeys; |
| |
| public MapListener(Map<K, V> target) { |
| this.target = target; |
| seenKeys = new HashSet<>(target.size()); |
| } |
| |
| public Set<K> getSeenKeys() { |
| return seenKeys; |
| } |
| |
| @Override |
| public V get(Object key) { |
| seenKeys.add((K) key); |
| return super.get(key); |
| } |
| |
| @Override |
| public V remove(Object key) { |
| seenKeys.add((K) key); |
| return super.remove(key); |
| } |
| |
| @Override |
| protected Map<K, V> delegate() { |
| return target; |
| } |
| } |