112 lines
3.9 KiB
Java
112 lines
3.9 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.LinkedHashMap;
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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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* A {@code Multiset} implementation with predictable iteration order. Its
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* iterator orders elements according to when the first occurrence of the
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* element was added. When the multiset contains multiple instances of an
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* element, those instances are consecutive in the iteration order. If all
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* occurrences of an element are removed, after which that element is added to
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* the multiset, the element will appear at the end of the iteration.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multiset">
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* {@code Multiset}</a>.
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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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@SuppressWarnings("serial") // we're overriding default serialization
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public final class LinkedHashMultiset<E> extends AbstractMapBasedMultiset<E> {
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/**
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* Creates a new, empty {@code LinkedHashMultiset} using the default initial
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* capacity.
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*/
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public static <E> LinkedHashMultiset<E> create() {
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return new LinkedHashMultiset<E>();
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}
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/**
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* Creates a new, empty {@code LinkedHashMultiset} with the specified expected
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* number 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> LinkedHashMultiset<E> create(int distinctElements) {
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return new LinkedHashMultiset<E>(distinctElements);
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}
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/**
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* Creates a new {@code LinkedHashMultiset} 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> LinkedHashMultiset<E> create(Iterable<? extends E> elements) {
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LinkedHashMultiset<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 LinkedHashMultiset() {
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super(new LinkedHashMap<E, Count>());
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}
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private LinkedHashMultiset(int distinctElements) {
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// Could use newLinkedHashMapWithExpectedSize() if it existed
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super(new LinkedHashMap<E, Count>(Maps.capacity(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(new LinkedHashMap<E, Count>(Maps.capacity(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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