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authorYohann Roussel <yroussel@google.com>2014-03-19 16:25:37 +0100
committerYohann Roussel <yroussel@google.com>2014-03-20 15:13:33 +0100
commit4eceb95409e844fdc33c9c706e1dc307bfd40303 (patch)
treeee9f4f3fc79f757c79081c336bce4f1782c6ccd8 /guava/src/com/google/common/collect/ForwardingCollection.java
parent3d2402901b1a6462e2cf47a6fd09711f327961c3 (diff)
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Initial Jack import.
Change-Id: I953cf0a520195a7187d791b2885848ad0d5a9b43
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+/*
+ * 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 java.util.Collection;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+/**
+ * A collection which forwards all its method calls to another collection.
+ * Subclasses should override one or more methods to modify the behavior of the
+ * backing collection as desired per the <a
+ * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
+ *
+ * <p><b>Warning:</b> The methods of {@code ForwardingCollection} forward
+ * <b>indiscriminately</b> to the methods of the delegate. For example,
+ * overriding {@link #add} alone <b>will not</b> change the behavior of {@link
+ * #addAll}, which can lead to unexpected behavior. In this case, you should
+ * override {@code addAll} as well, either providing your own implementation, or
+ * delegating to the provided {@code standardAddAll} method.
+ *
+ * <p>The {@code standard} methods 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 (imported from Google Collections Library)
+ */
+@GwtCompatible
+public abstract class ForwardingCollection<E> extends ForwardingObject
+ implements Collection<E> {
+ // TODO(user): identify places where thread safety is actually lost
+
+ /** Constructor for use by subclasses. */
+ protected ForwardingCollection() {}
+
+ @Override protected abstract Collection<E> delegate();
+
+ @Override
+ public Iterator<E> iterator() {
+ return delegate().iterator();
+ }
+
+ @Override
+ public int size() {
+ return delegate().size();
+ }
+
+ @Override
+ public boolean removeAll(Collection<?> collection) {
+ return delegate().removeAll(collection);
+ }
+
+ @Override
+ public boolean isEmpty() {
+ return delegate().isEmpty();
+ }
+
+ @Override
+ public boolean contains(Object object) {
+ return delegate().contains(object);
+ }
+
+ @Override
+ public boolean add(E element) {
+ return delegate().add(element);
+ }
+
+ @Override
+ public boolean remove(Object object) {
+ return delegate().remove(object);
+ }
+
+ @Override
+ public boolean containsAll(Collection<?> collection) {
+ return delegate().containsAll(collection);
+ }
+
+ @Override
+ public boolean addAll(Collection<? extends E> collection) {
+ return delegate().addAll(collection);
+ }
+
+ @Override
+ public boolean retainAll(Collection<?> collection) {
+ return delegate().retainAll(collection);
+ }
+
+ @Override
+ public void clear() {
+ delegate().clear();
+ }
+
+ @Override
+ public Object[] toArray() {
+ return delegate().toArray();
+ }
+
+ @Override
+ public <T> T[] toArray(T[] array) {
+ return delegate().toArray(array);
+ }
+
+ /**
+ * A sensible definition of {@link #contains} in terms of {@link #iterator}.
+ * If you override {@link #iterator}, you may wish to override {@link
+ * #contains} to forward to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardContains(@Nullable Object object) {
+ return Iterators.contains(iterator(), object);
+ }
+
+ /**
+ * A sensible definition of {@link #containsAll} in terms of {@link #contains}
+ * . If you override {@link #contains}, you may wish to override {@link
+ * #containsAll} to forward to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardContainsAll(Collection<?> collection) {
+ for (Object o : collection) {
+ if (!contains(o)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * A sensible definition of {@link #addAll} in terms of {@link #add}. If you
+ * override {@link #add}, you may wish to override {@link #addAll} to forward
+ * to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardAddAll(Collection<? extends E> collection) {
+ return Iterators.addAll(this, collection.iterator());
+ }
+
+ /**
+ * A sensible definition of {@link #remove} in terms of {@link #iterator},
+ * using the iterator's {@code remove} method. If you override {@link
+ * #iterator}, you may wish to override {@link #remove} to forward to this
+ * implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardRemove(@Nullable Object object) {
+ Iterator<E> iterator = iterator();
+ while (iterator.hasNext()) {
+ if (Objects.equal(iterator.next(), object)) {
+ iterator.remove();
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * A sensible definition of {@link #removeAll} in terms of {@link #iterator},
+ * using the iterator's {@code remove} method. If you override {@link
+ * #iterator}, you may wish to override {@link #removeAll} to forward to this
+ * implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardRemoveAll(Collection<?> collection) {
+ return Iterators.removeAll(iterator(), collection);
+ }
+
+ /**
+ * A sensible definition of {@link #retainAll} in terms of {@link #iterator},
+ * using the iterator's {@code remove} method. If you override {@link
+ * #iterator}, you may wish to override {@link #retainAll} to forward to this
+ * implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardRetainAll(Collection<?> collection) {
+ return Iterators.retainAll(iterator(), collection);
+ }
+
+ /**
+ * A sensible definition of {@link #clear} in terms of {@link #iterator},
+ * using the iterator's {@code remove} method. If you override {@link
+ * #iterator}, you may wish to override {@link #clear} to forward to this
+ * implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected void standardClear() {
+ Iterator<E> iterator = iterator();
+ while (iterator.hasNext()) {
+ iterator.next();
+ iterator.remove();
+ }
+ }
+
+ /**
+ * A sensible definition of {@link #isEmpty} as {@code !iterator().hasNext}.
+ * If you override {@link #isEmpty}, you may wish to override {@link #isEmpty}
+ * to forward to this implementation. Alternately, it may be more efficient to
+ * implement {@code isEmpty} as {@code size() == 0}.
+ *
+ * @since 7.0
+ */
+ @Beta protected boolean standardIsEmpty() {
+ return !iterator().hasNext();
+ }
+
+ /**
+ * A sensible definition of {@link #toString} in terms of {@link #iterator}.
+ * If you override {@link #iterator}, you may wish to override {@link
+ * #toString} to forward to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected String standardToString() {
+ return Collections2.toStringImpl(this);
+ }
+
+ /**
+ * A sensible definition of {@link #toArray()} in terms of {@link
+ * #toArray(Object[])}. If you override {@link #toArray(Object[])}, you may
+ * wish to override {@link #toArray} to forward to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected Object[] standardToArray() {
+ Object[] newArray = new Object[size()];
+ return toArray(newArray);
+ }
+
+ /**
+ * A sensible definition of {@link #toArray(Object[])} in terms of {@link
+ * #size} and {@link #iterator}. If you override either of these methods, you
+ * may wish to override {@link #toArray} to forward to this implementation.
+ *
+ * @since 7.0
+ */
+ @Beta protected <T> T[] standardToArray(T[] array) {
+ return ObjectArrays.toArrayImpl(this, array);
+ }
+}