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/*
* Copyright (C) 2007 The Guava Authors
*
* Licensed 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 com.google.common.collect;
import static com.google.common.base.Preconditions.checkArgument;
import com.google.common.annotations.GwtCompatible;
import java.util.EnumMap;
import java.util.Iterator;
/**
* Multiset implementation backed by an {@link EnumMap}.
*
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multiset">
* {@code Multiset}</a>.
*
* @author Jared Levy
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(emulated = true)
public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E> {
/** Creates an empty {@code EnumMultiset}. */
public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
return new EnumMultiset<E>(type);
}
/**
* Creates a new {@code EnumMultiset} containing the specified elements.
*
* <p>This implementation is highly efficient when {@code elements} is itself a {@link
* Multiset}.
*
* @param elements the elements that the multiset should contain
* @throws IllegalArgumentException if {@code elements} is empty
*/
public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
Iterator<E> iterator = elements.iterator();
checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
EnumMultiset<E> multiset = new EnumMultiset<E>(iterator.next().getDeclaringClass());
Iterables.addAll(multiset, elements);
return multiset;
}
/**
* Returns a new {@code EnumMultiset} instance containing the given elements. Unlike
* {@link EnumMultiset#create(Iterable)}, this method does not produce an exception on an empty
* iterable.
*
* @since 14.0
*/
public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements, Class<E> type) {
EnumMultiset<E> result = create(type);
Iterables.addAll(result, elements);
return result;
}
private transient Class<E> type;
/** Creates an empty {@code EnumMultiset}. */
private EnumMultiset(Class<E> type) {
super(WellBehavedMap.wrap(new EnumMap<E, Count>(type)));
this.type = type;
}
}
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