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/*
* Copyright (C) 2011 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 com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multiset.Entry;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedSet;
/**
* Provides static utility methods for creating and working with
* {@link SortedMultiset} instances.
*
* @author Louis Wasserman
*/
@GwtCompatible
final class SortedMultisets {
private SortedMultisets() {
}
/**
* A skeleton implementation for {@link SortedMultiset#elementSet}.
*/
static abstract class ElementSet<E> extends Multisets.ElementSet<E> implements
SortedSet<E> {
@Override abstract SortedMultiset<E> multiset();
@Override public Comparator<? super E> comparator() {
return multiset().comparator();
}
@Override public SortedSet<E> subSet(E fromElement, E toElement) {
return multiset().subMultiset(fromElement, BoundType.CLOSED, toElement,
BoundType.OPEN).elementSet();
}
@Override public SortedSet<E> headSet(E toElement) {
return multiset().headMultiset(toElement, BoundType.OPEN).elementSet();
}
@Override public SortedSet<E> tailSet(E fromElement) {
return multiset().tailMultiset(fromElement, BoundType.CLOSED)
.elementSet();
}
@Override public E first() {
return getElementOrThrow(multiset().firstEntry());
}
@Override public E last() {
return getElementOrThrow(multiset().lastEntry());
}
}
private static <E> E getElementOrThrow(Entry<E> entry) {
if (entry == null) {
throw new NoSuchElementException();
}
return entry.getElement();
}
/**
* A skeleton implementation of a descending multiset. Only needs
* {@code forwardMultiset()} and {@code entryIterator()}.
*/
static abstract class DescendingMultiset<E> extends ForwardingMultiset<E>
implements SortedMultiset<E> {
abstract SortedMultiset<E> forwardMultiset();
private transient Comparator<? super E> comparator;
@Override public Comparator<? super E> comparator() {
Comparator<? super E> result = comparator;
if (result == null) {
return comparator =
Ordering.from(forwardMultiset().comparator()).<E>reverse();
}
return result;
}
private transient SortedSet<E> elementSet;
@Override public SortedSet<E> elementSet() {
SortedSet<E> result = elementSet;
if (result == null) {
return elementSet = new SortedMultisets.ElementSet<E>() {
@Override SortedMultiset<E> multiset() {
return DescendingMultiset.this;
}
};
}
return result;
}
@Override public Entry<E> pollFirstEntry() {
return forwardMultiset().pollLastEntry();
}
@Override public Entry<E> pollLastEntry() {
return forwardMultiset().pollFirstEntry();
}
@Override public SortedMultiset<E> headMultiset(E toElement,
BoundType boundType) {
return forwardMultiset().tailMultiset(toElement, boundType)
.descendingMultiset();
}
@Override public SortedMultiset<E> subMultiset(E fromElement,
BoundType fromBoundType, E toElement, BoundType toBoundType) {
return forwardMultiset().subMultiset(toElement, toBoundType, fromElement,
fromBoundType).descendingMultiset();
}
@Override public SortedMultiset<E> tailMultiset(E fromElement,
BoundType boundType) {
return forwardMultiset().headMultiset(fromElement, boundType)
.descendingMultiset();
}
@Override protected Multiset<E> delegate() {
return forwardMultiset();
}
@Override public SortedMultiset<E> descendingMultiset() {
return forwardMultiset();
}
@Override public Entry<E> firstEntry() {
return forwardMultiset().lastEntry();
}
@Override public Entry<E> lastEntry() {
return forwardMultiset().firstEntry();
}
abstract Iterator<Entry<E>> entryIterator();
private transient Set<Entry<E>> entrySet;
@Override public Set<Entry<E>> entrySet() {
Set<Entry<E>> result = entrySet;
return (result == null) ? entrySet = createEntrySet() : result;
}
Set<Entry<E>> createEntrySet() {
return new Multisets.EntrySet<E>() {
@Override Multiset<E> multiset() {
return DescendingMultiset.this;
}
@Override public Iterator<Entry<E>> iterator() {
return entryIterator();
}
@Override public int size() {
return forwardMultiset().entrySet().size();
}
};
}
@Override public Iterator<E> iterator() {
return Multisets.iteratorImpl(this);
}
@Override public Object[] toArray() {
return standardToArray();
}
@Override public <T> T[] toArray(T[] array) {
return standardToArray(array);
}
@Override public String toString() {
return entrySet().toString();
}
}
}
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