| /* |
| * 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.lucene.search; |
| |
| |
| import java.util.AbstractCollection; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.Map; |
| |
| /** |
| * A {@link Multiset} is a set that allows for duplicate elements. Two |
| * {@link Multiset}s are equal if they contain the same unique elements and if |
| * each unique element has as many occurrences in both multisets. |
| * Iteration order is not specified. |
| * @lucene.internal |
| */ |
| final class Multiset<T> extends AbstractCollection<T> { |
| |
| private final Map<T, Integer> map = new HashMap<>(); |
| private int size; |
| |
| /** Create an empty {@link Multiset}. */ |
| Multiset() { |
| super(); |
| } |
| |
| @Override |
| public Iterator<T> iterator() { |
| final Iterator<Map.Entry<T, Integer>> mapIterator = map.entrySet().iterator(); |
| return new Iterator<T>() { |
| |
| T current; |
| int remaining; |
| |
| @Override |
| public boolean hasNext() { |
| return remaining > 0 || mapIterator.hasNext(); |
| } |
| |
| @Override |
| public T next() { |
| if (remaining == 0) { |
| Map.Entry<T, Integer> next = mapIterator.next(); |
| current = next.getKey(); |
| remaining = next.getValue(); |
| } |
| assert remaining > 0; |
| remaining -= 1; |
| return current; |
| } |
| }; |
| } |
| |
| @Override |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public void clear() { |
| map.clear(); |
| size = 0; |
| } |
| |
| @Override |
| public boolean add(T e) { |
| map.put(e, map.getOrDefault(e, 0) + 1); |
| size += 1; |
| return true; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public boolean remove(Object o) { |
| final Integer count = map.get(o); |
| if (count == null) { |
| return false; |
| } else if (1 == count.intValue()) { |
| map.remove(o); |
| } else { |
| map.put((T) o, count - 1); |
| } |
| size -= 1; |
| return true; |
| } |
| |
| @Override |
| public boolean contains(Object o) { |
| return map.containsKey(o); |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == null || obj.getClass() != getClass()) { |
| return false; |
| } |
| Multiset<?> that = (Multiset<?>) obj; |
| return size == that.size // not necessary but helps escaping early |
| && map.equals(that.map); |
| } |
| |
| @Override |
| public int hashCode() { |
| return 31 * getClass().hashCode() + map.hashCode(); |
| } |
| |
| } |