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/*
* Copyright (C) 2012 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.j2objc.annotations.WeakOuter;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
* {@code entryIterator()}.
*
* @author Louis Wasserman
*/
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class DescendingMultiset extends ForwardingMultiset
implements SortedMultiset {
abstract SortedMultiset forwardMultiset();
@CheckForNull private transient Comparator comparator;
@Override
public Comparator comparator() {
Comparator result = comparator;
if (result == null) {
return comparator = Ordering.from(forwardMultiset().comparator()).reverse();
}
return result;
}
@CheckForNull private transient NavigableSet elementSet;
@Override
public NavigableSet elementSet() {
NavigableSet result = elementSet;
if (result == null) {
return elementSet = new SortedMultisets.NavigableElementSet(this);
}
return result;
}
@Override
@CheckForNull
public Entry pollFirstEntry() {
return forwardMultiset().pollLastEntry();
}
@Override
@CheckForNull
public Entry pollLastEntry() {
return forwardMultiset().pollFirstEntry();
}
@Override
public SortedMultiset headMultiset(@ParametricNullness E toElement, BoundType boundType) {
return forwardMultiset().tailMultiset(toElement, boundType).descendingMultiset();
}
@Override
public SortedMultiset subMultiset(
@ParametricNullness E fromElement,
BoundType fromBoundType,
@ParametricNullness E toElement,
BoundType toBoundType) {
return forwardMultiset()
.subMultiset(toElement, toBoundType, fromElement, fromBoundType)
.descendingMultiset();
}
@Override
public SortedMultiset tailMultiset(@ParametricNullness E fromElement, BoundType boundType) {
return forwardMultiset().headMultiset(fromElement, boundType).descendingMultiset();
}
@Override
protected Multiset delegate() {
return forwardMultiset();
}
@Override
public SortedMultiset descendingMultiset() {
return forwardMultiset();
}
@Override
@CheckForNull
public Entry firstEntry() {
return forwardMultiset().lastEntry();
}
@Override
@CheckForNull
public Entry lastEntry() {
return forwardMultiset().firstEntry();
}
abstract Iterator> entryIterator();
@CheckForNull private transient Set> entrySet;
@Override
public Set> entrySet() {
Set> result = entrySet;
return (result == null) ? entrySet = createEntrySet() : result;
}
Set> createEntrySet() {
@WeakOuter
class EntrySetImpl extends Multisets.EntrySet {
@Override
Multiset multiset() {
return DescendingMultiset.this;
}
@Override
public Iterator> iterator() {
return entryIterator();
}
@Override
public int size() {
return forwardMultiset().entrySet().size();
}
}
return new EntrySetImpl();
}
@Override
public Iterator iterator() {
return Multisets.iteratorImpl(this);
}
@Override
public @Nullable Object[] toArray() {
return standardToArray();
}
@Override
@SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
public T[] toArray(T[] array) {
return standardToArray(array);
}
@Override
public String toString() {
return entrySet().toString();
}
}