java.com.google.common.collect.ForwardingMultiset Maven / Gradle / Ivy
Show all versions of guava Show documentation
/*
* 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 com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Objects;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A multiset which forwards all its method calls to another multiset. Subclasses should override
* one or more methods to modify the behavior of the backing multiset as desired per the decorator pattern.
*
* Warning: The methods of {@code ForwardingMultiset} forward indiscriminately to
* the methods of the delegate. For example, overriding {@link #add(Object, int)} alone will
* not change the behavior of {@link #add(Object)}, which can lead to unexpected behavior. In
* this case, you should override {@code add(Object)} as well, either providing your own
* implementation, or delegating to the provided {@code standardAdd} method.
*
*
{@code default} method warning: This class does not forward calls to {@code
* default} methods. Instead, it inherits their default implementations. When those implementations
* invoke methods, they invoke methods on the {@code ForwardingMultiset}.
*
*
The {@code standard} methods and any collection views they return are not guaranteed to be
* thread-safe, even when all of the methods that they depend on are thread-safe.
*
* @author Kevin Bourrillion
* @author Louis Wasserman
* @since 2.0
*/
@GwtCompatible
public abstract class ForwardingMultiset extends ForwardingCollection implements Multiset {
/** Constructor for use by subclasses. */
protected ForwardingMultiset() {}
@Override
protected abstract Multiset delegate();
@Override
public int count(Object element) {
return delegate().count(element);
}
@CanIgnoreReturnValue
@Override
public int add(E element, int occurrences) {
return delegate().add(element, occurrences);
}
@CanIgnoreReturnValue
@Override
public int remove(Object element, int occurrences) {
return delegate().remove(element, occurrences);
}
@Override
public Set elementSet() {
return delegate().elementSet();
}
@Override
public Set> entrySet() {
return delegate().entrySet();
}
@Override
public boolean equals(@Nullable Object object) {
return object == this || delegate().equals(object);
}
@Override
public int hashCode() {
return delegate().hashCode();
}
@CanIgnoreReturnValue
@Override
public int setCount(E element, int count) {
return delegate().setCount(element, count);
}
@CanIgnoreReturnValue
@Override
public boolean setCount(E element, int oldCount, int newCount) {
return delegate().setCount(element, oldCount, newCount);
}
/**
* A sensible definition of {@link #contains} in terms of {@link #count}. If you override {@link
* #count}, you may wish to override {@link #contains} to forward to this implementation.
*
* @since 7.0
*/
@Override
protected boolean standardContains(@Nullable Object object) {
return count(object) > 0;
}
/**
* A sensible definition of {@link #clear} in terms of the {@code iterator} method of {@link
* #entrySet}. If you override {@link #entrySet}, you may wish to override {@link #clear} to
* forward to this implementation.
*
* @since 7.0
*/
@Override
protected void standardClear() {
Iterators.clear(entrySet().iterator());
}
/**
* A sensible, albeit inefficient, definition of {@link #count} in terms of {@link #entrySet}. If
* you override {@link #entrySet}, you may wish to override {@link #count} to forward to this
* implementation.
*
* @since 7.0
*/
@Beta
protected int standardCount(@Nullable Object object) {
for (Entry entry : this.entrySet()) {
if (Objects.equal(entry.getElement(), object)) {
return entry.getCount();
}
}
return 0;
}
/**
* A sensible definition of {@link #add(Object)} in terms of {@link #add(Object, int)}. If you
* override {@link #add(Object, int)}, you may wish to override {@link #add(Object)} to forward to
* this implementation.
*
* @since 7.0
*/
protected boolean standardAdd(E element) {
add(element, 1);
return true;
}
/**
* A sensible definition of {@link #addAll(Collection)} in terms of {@link #add(Object)} and
* {@link #add(Object, int)}. If you override either of these methods, you may wish to override
* {@link #addAll(Collection)} to forward to this implementation.
*
* @since 7.0
*/
@Beta
@Override
protected boolean standardAddAll(Collection elementsToAdd) {
return Multisets.addAllImpl(this, elementsToAdd);
}
/**
* A sensible definition of {@link #remove(Object)} in terms of {@link #remove(Object, int)}. If
* you override {@link #remove(Object, int)}, you may wish to override {@link #remove(Object)} to
* forward to this implementation.
*
* @since 7.0
*/
@Override
protected boolean standardRemove(Object element) {
return remove(element, 1) > 0;
}
/**
* A sensible definition of {@link #removeAll} in terms of the {@code removeAll} method of {@link
* #elementSet}. If you override {@link #elementSet}, you may wish to override {@link #removeAll}
* to forward to this implementation.
*
* @since 7.0
*/
@Override
protected boolean standardRemoveAll(Collection elementsToRemove) {
return Multisets.removeAllImpl(this, elementsToRemove);
}
/**
* A sensible definition of {@link #retainAll} in terms of the {@code retainAll} method of {@link
* #elementSet}. If you override {@link #elementSet}, you may wish to override {@link #retainAll}
* to forward to this implementation.
*
* @since 7.0
*/
@Override
protected boolean standardRetainAll(Collection elementsToRetain) {
return Multisets.retainAllImpl(this, elementsToRetain);
}
/**
* A sensible definition of {@link #setCount(Object, int)} in terms of {@link #count(Object)},
* {@link #add(Object, int)}, and {@link #remove(Object, int)}. {@link #entrySet()}. If you
* override any of these methods, you may wish to override {@link #setCount(Object, int)} to
* forward to this implementation.
*
* @since 7.0
*/
protected int standardSetCount(E element, int count) {
return Multisets.setCountImpl(this, element, count);
}
/**
* A sensible definition of {@link #setCount(Object, int, int)} in terms of {@link #count(Object)}
* and {@link #setCount(Object, int)}. If you override either of these methods, you may wish to
* override {@link #setCount(Object, int, int)} to forward to this implementation.
*
* @since 7.0
*/
protected boolean standardSetCount(E element, int oldCount, int newCount) {
return Multisets.setCountImpl(this, element, oldCount, newCount);
}
/**
* A sensible implementation of {@link Multiset#elementSet} in terms of the following methods:
* {@link ForwardingMultiset#clear}, {@link ForwardingMultiset#contains}, {@link
* ForwardingMultiset#containsAll}, {@link ForwardingMultiset#count}, {@link
* ForwardingMultiset#isEmpty}, the {@link Set#size} and {@link Set#iterator} methods of {@link
* ForwardingMultiset#entrySet}, and {@link ForwardingMultiset#remove(Object, int)}. In many
* situations, you may wish to override {@link ForwardingMultiset#elementSet} to forward to this
* implementation or a subclass thereof.
*
* @since 10.0
*/
@Beta
protected class StandardElementSet extends Multisets.ElementSet {
/** Constructor for use by subclasses. */
public StandardElementSet() {}
@Override
Multiset multiset() {
return ForwardingMultiset.this;
}
@Override
public Iterator iterator() {
return Multisets.elementIterator(multiset().entrySet().iterator());
}
}
/**
* A sensible definition of {@link #iterator} in terms of {@link #entrySet} and {@link
* #remove(Object)}. If you override either of these methods, you may wish to override {@link
* #iterator} to forward to this implementation.
*
* @since 7.0
*/
protected Iterator standardIterator() {
return Multisets.iteratorImpl(this);
}
/**
* A sensible, albeit inefficient, definition of {@link #size} in terms of {@link #entrySet}. If
* you override {@link #entrySet}, you may wish to override {@link #size} to forward to this
* implementation.
*
* @since 7.0
*/
protected int standardSize() {
return Multisets.linearTimeSizeImpl(this);
}
/**
* A sensible, albeit inefficient, definition of {@link #equals} in terms of {@code
* entrySet().size()} and {@link #count}. If you override either of these methods, you may wish to
* override {@link #equals} to forward to this implementation.
*
* @since 7.0
*/
protected boolean standardEquals(@Nullable Object object) {
return Multisets.equalsImpl(this, object);
}
/**
* A sensible definition of {@link #hashCode} as {@code entrySet().hashCode()} . If you override
* {@link #entrySet}, you may wish to override {@link #hashCode} to forward to this
* implementation.
*
* @since 7.0
*/
protected int standardHashCode() {
return entrySet().hashCode();
}
/**
* A sensible definition of {@link #toString} as {@code entrySet().toString()} . If you override
* {@link #entrySet}, you may wish to override {@link #toString} to forward to this
* implementation.
*
* @since 7.0
*/
@Override
protected String standardToString() {
return entrySet().toString();
}
}