99 lines
3.2 KiB
Java
99 lines
3.2 KiB
Java
/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.collect;
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import java.io.IOException;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import java.util.HashMap;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.GwtIncompatible;
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/**
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* Multiset implementation backed by a {@link HashMap}.
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*
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* @author Kevin Bourrillion
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* @author Jared Levy
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* @since 2.0 (imported from Google Collections Library)
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*/
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@GwtCompatible(serializable = true, emulated = true)
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public final class HashMultiset<E> extends AbstractMapBasedMultiset<E> {
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/**
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* Creates a new, empty {@code HashMultiset} using the default initial capacity.
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*/
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public static <E> HashMultiset<E> create() {
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return new HashMultiset<E>();
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}
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/**
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* Creates a new, empty {@code HashMultiset} with the specified expected number
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* of distinct elements.
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*
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* @param distinctElements the expected number of distinct elements
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* @throws IllegalArgumentException if {@code distinctElements} is negative
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*/
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public static <E> HashMultiset<E> create(int distinctElements) {
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return new HashMultiset<E>(distinctElements);
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}
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/**
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* Creates a new {@code HashMultiset} containing the specified elements.
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*
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* <p>
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* This implementation is highly efficient when {@code elements} is itself a
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* {@link Multiset}.
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*
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* @param elements the elements that the multiset should contain
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*/
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public static <E> HashMultiset<E> create(Iterable<? extends E> elements) {
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HashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
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Iterables.addAll(multiset, elements);
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return multiset;
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}
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private HashMultiset() {
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super(new HashMap<E, Count>());
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}
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private HashMultiset(int distinctElements) {
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super(Maps.<E, Count>newHashMapWithExpectedSize(distinctElements));
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}
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/**
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* @serialData the number of distinct elements, the first element, its count,
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* the second element, its count, and so on
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*/
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@GwtIncompatible("java.io.ObjectOutputStream")
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private void writeObject(ObjectOutputStream stream) throws IOException {
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stream.defaultWriteObject();
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Serialization.writeMultiset(this, stream);
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}
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@GwtIncompatible("java.io.ObjectInputStream")
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private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
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stream.defaultReadObject();
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int distinctElements = Serialization.readCount(stream);
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setBackingMap(Maps.<E, Count>newHashMapWithExpectedSize(distinctElements));
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Serialization.populateMultiset(this, stream, distinctElements);
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}
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@GwtIncompatible("Not needed in emulated source.")
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private static final long serialVersionUID = 0;
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}
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