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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 static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import javax.annotation.Nullable;
/**
* This class provides a skeletal implementation of the {@link SortedMultiset} interface.
*
* <p>The {@link #count} and {@link #size} implementations all iterate across the set returned by
* {@link Multiset#entrySet()}, as do many methods acting on the set returned by
* {@link #elementSet()}. Override those methods for better performance.
*
* @author Louis Wasserman
*/
@GwtCompatible(emulated = true)
abstract class AbstractSortedMultiset<E> extends AbstractMultiset<E> implements SortedMultiset<E> {
@GwtTransient final Comparator<? super E> comparator;
// needed for serialization
@SuppressWarnings("unchecked")
AbstractSortedMultiset() {
this((Comparator) Ordering.natural());
}
AbstractSortedMultiset(Comparator<? super E> comparator) {
this.comparator = checkNotNull(comparator);
}
@Override
public NavigableSet<E> elementSet() {
return (NavigableSet<E>) super.elementSet();
}
@Override
NavigableSet<E> createElementSet() {
return new SortedMultisets.NavigableElementSet<E>(this);
}
@Override
public Comparator<? super E> comparator() {
return comparator;
}
@Override
public Entry<E> firstEntry() {
Iterator<Entry<E>> entryIterator = entryIterator();
return entryIterator.hasNext() ? entryIterator.next() : null;
}
@Override
public Entry<E> lastEntry() {
Iterator<Entry<E>> entryIterator = descendingEntryIterator();
return entryIterator.hasNext() ? entryIterator.next() : null;
}
@Override
public Entry<E> pollFirstEntry() {
Iterator<Entry<E>> entryIterator = entryIterator();
if (entryIterator.hasNext()) {
Entry<E> result = entryIterator.next();
result = Multisets.immutableEntry(result.getElement(), result.getCount());
entryIterator.remove();
return result;
}
return null;
}
@Override
public Entry<E> pollLastEntry() {
Iterator<Entry<E>> entryIterator = descendingEntryIterator();
if (entryIterator.hasNext()) {
Entry<E> result = entryIterator.next();
result = Multisets.immutableEntry(result.getElement(), result.getCount());
entryIterator.remove();
return result;
}
return null;
}
@Override
public SortedMultiset<E> subMultiset(@Nullable E fromElement, BoundType fromBoundType,
@Nullable E toElement, BoundType toBoundType) {
// These are checked elsewhere, but NullPointerTester wants them checked eagerly.
checkNotNull(fromBoundType);
checkNotNull(toBoundType);
return tailMultiset(fromElement, fromBoundType).headMultiset(toElement, toBoundType);
}
abstract Iterator<Entry<E>> descendingEntryIterator();
Iterator<E> descendingIterator() {
return Multisets.iteratorImpl(descendingMultiset());
}
private transient SortedMultiset<E> descendingMultiset;
@Override
public SortedMultiset<E> descendingMultiset() {
SortedMultiset<E> result = descendingMultiset;
return (result == null) ? descendingMultiset = createDescendingMultiset() : result;
}
SortedMultiset<E> createDescendingMultiset() {
return new DescendingMultiset<E>() {
@Override
SortedMultiset<E> forwardMultiset() {
return AbstractSortedMultiset.this;
}
@Override
Iterator<Entry<E>> entryIterator() {
return descendingEntryIterator();
}
@Override
public Iterator<E> iterator() {
return descendingIterator();
}
};
}
}
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