Lists.java
/*
* 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 org.glassfish.jersey.internal.guava;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import static org.glassfish.jersey.internal.guava.Preconditions.checkElementIndex;
import static org.glassfish.jersey.internal.guava.Preconditions.checkNotNull;
import static org.glassfish.jersey.internal.guava.Preconditions.checkPositionIndex;
import static org.glassfish.jersey.internal.guava.Preconditions.checkPositionIndexes;
import static org.glassfish.jersey.internal.guava.Preconditions.checkState;
/**
* Static utility methods pertaining to {@link List} instances. Also see this
* class's counterparts {@link Sets}, {@link Maps} and {@link Queues}.
* <p>
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/CollectionUtilitiesExplained#Lists">
* {@code Lists}</a>.
*
* @author Kevin Bourrillion
* @author Mike Bostock
* @author Louis Wasserman
* @since 2.0 (imported from Google Collections Library)
*/
public final class Lists {
private Lists() {
}
// ArrayList
/**
* Creates a <i>mutable</i>, empty {@code ArrayList} instance (for Java 6 and
* earlier).
* <p>
* <p><b>Note:</b> if mutability is not required, use {@link
* ImmutableList#of()} instead.
* <p>
* <p><b>Note for Java 7 and later:</b> this method is now unnecessary and
* should be treated as deprecated. Instead, use the {@code ArrayList}
* {@linkplain ArrayList#ArrayList() constructor} directly, taking advantage
* of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
*/
private static <E> ArrayList<E> newArrayList() {
return new ArrayList<E>();
}
/**
* Creates a <i>mutable</i> {@code ArrayList} instance containing the given
* elements; a very thin shortcut for creating an empty list then calling
* {@link Iterables#addAll}.
* <p>
* <p><b>Note:</b> if mutability is not required and the elements are
* non-null, use {@link ImmutableList#copyOf(Iterable)} instead. (Or, change
* {@code elements} to be a {@link FluentIterable} and call
* {@code elements.toList()}.)
* <p>
* <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link
* Collection}, you don't need this method. Use the {@code ArrayList}
* {@linkplain ArrayList#ArrayList(Collection) constructor} directly, taking
* advantage of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
*/
public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
checkNotNull(elements); // for GWT
// Let ArrayList's sizing logic work, if possible
return (elements instanceof Collection)
? new ArrayList<E>(Collections2.cast(elements))
: newArrayList(elements.iterator());
}
/**
* Creates a <i>mutable</i> {@code ArrayList} instance containing the given
* elements; a very thin shortcut for creating an empty list and then calling
* {@link Iterators#addAll}.
* <p>
* <p><b>Note:</b> if mutability is not required and the elements are
* non-null, use {@link ImmutableList#copyOf(Iterator)} instead.
*/
public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements) {
ArrayList<E> list = newArrayList();
Iterators.addAll(list, elements);
return list;
}
/**
* Returns a reversed view of the specified list. For example, {@code
* Lists.reverse(Arrays.asList(1, 2, 3))} returns a list containing {@code 3,
* 2, 1}. The returned list is backed by this list, so changes in the returned
* list are reflected in this list, and vice-versa. The returned list supports
* all of the optional list operations supported by this list.
* <p>
* <p>The returned list is random-access if the specified list is random
* access.
*
* @since 7.0
*/
private static <T> List<T> reverse(List<T> list) {
if (list instanceof ReverseList) {
return ((ReverseList<T>) list).getForwardList();
} else {
return new ReverseList<T>(list);
}
}
/**
* An implementation of {@link List#equals(Object)}.
*/
static boolean equalsImpl(List<?> list, Object object) {
if (object == checkNotNull(list)) {
return true;
}
if (!(object instanceof List)) {
return false;
}
List<?> o = (List<?>) object;
return list.size() == o.size()
&& Iterators.elementsEqual(list.iterator(), o.iterator());
}
/**
* An implementation of {@link List#indexOf(Object)}.
*/
static int indexOfImpl(List<?> list, Object element) {
ListIterator<?> listIterator = list.listIterator();
while (listIterator.hasNext()) {
if (Objects.equals(element, listIterator.next())) {
return listIterator.previousIndex();
}
}
return -1;
}
/**
* An implementation of {@link List#lastIndexOf(Object)}.
*/
static int lastIndexOfImpl(List<?> list, Object element) {
ListIterator<?> listIterator = list.listIterator(list.size());
while (listIterator.hasPrevious()) {
if (Objects.equals(element, listIterator.previous())) {
return listIterator.nextIndex();
}
}
return -1;
}
private static class ReverseList<T> extends AbstractList<T> {
private final List<T> forwardList;
ReverseList(List<T> forwardList) {
this.forwardList = checkNotNull(forwardList);
}
List<T> getForwardList() {
return forwardList;
}
private int reverseIndex(int index) {
int size = size();
checkElementIndex(index, size);
return (size - 1) - index;
}
private int reversePosition(int index) {
int size = size();
checkPositionIndex(index, size);
return size - index;
}
@Override
public void add(int index, T element) {
forwardList.add(reversePosition(index), element);
}
@Override
public void clear() {
forwardList.clear();
}
@Override
public T remove(int index) {
return forwardList.remove(reverseIndex(index));
}
@Override
protected void removeRange(int fromIndex, int toIndex) {
subList(fromIndex, toIndex).clear();
}
@Override
public T set(int index, T element) {
return forwardList.set(reverseIndex(index), element);
}
@Override
public T get(int index) {
return forwardList.get(reverseIndex(index));
}
@Override
public int size() {
return forwardList.size();
}
@Override
public List<T> subList(int fromIndex, int toIndex) {
checkPositionIndexes(fromIndex, toIndex, size());
return reverse(forwardList.subList(
reversePosition(toIndex), reversePosition(fromIndex)));
}
@Override
public Iterator<T> iterator() {
return listIterator();
}
@Override
public ListIterator<T> listIterator(int index) {
int start = reversePosition(index);
final ListIterator<T> forwardIterator = forwardList.listIterator(start);
return new ListIterator<T>() {
boolean canRemoveOrSet;
@Override
public void add(T e) {
forwardIterator.add(e);
forwardIterator.previous();
canRemoveOrSet = false;
}
@Override
public boolean hasNext() {
return forwardIterator.hasPrevious();
}
@Override
public boolean hasPrevious() {
return forwardIterator.hasNext();
}
@Override
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
canRemoveOrSet = true;
return forwardIterator.previous();
}
@Override
public int nextIndex() {
return reversePosition(forwardIterator.nextIndex());
}
@Override
public T previous() {
if (!hasPrevious()) {
throw new NoSuchElementException();
}
canRemoveOrSet = true;
return forwardIterator.next();
}
@Override
public int previousIndex() {
return nextIndex() - 1;
}
@Override
public void remove() {
CollectPreconditions.checkRemove(canRemoveOrSet);
forwardIterator.remove();
canRemoveOrSet = false;
}
@Override
public void set(T e) {
checkState(canRemoveOrSet);
forwardIterator.set(e);
}
};
}
}
}