| /* |
| * 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.SortedSet; |
| import org.checkerframework.checker.nullness.qual.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 SortedSet<E> elementSet() { |
| return (SortedSet<E>) super.elementSet(); |
| } |
| |
| @Override |
| SortedSet<E> createElementSet() { |
| return new SortedMultisets.ElementSet<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(); |
| } |
| }; |
| } |
| } |