/*
* 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 static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndex;
import static com.google.common.base.Preconditions.checkPositionIndexes;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.base.Objects;
import com.google.common.primitives.Ints;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.AbstractSequentialList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.RandomAccess;
import java.util.concurrent.CopyOnWriteArrayList;
import javax.annotation.Nullable;
/**
* Static utility methods pertaining to {@link List} instances. Also see this
* class's counterparts {@link Sets} and {@link Maps}.
*
* <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)
*/
@GwtCompatible(emulated = true)
public final class Lists {
private Lists() {}
// ArrayList
/**
* Creates a <i>mutable</i>, empty {@code ArrayList} instance.
*
* <p><b>Note:</b> if mutability is not required, use {@link
* ImmutableList#of()} instead.
*
* @return a new, empty {@code ArrayList}
*/
@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayList() {
return new ArrayList<E>();
}
/**
* Creates a <i>mutable</i> {@code ArrayList} instance containing the given
* elements.
*
* <p><b>Note:</b> if mutability is not required and the elements are
* non-null, use an overload of {@link ImmutableList#of()} (for varargs) or
* {@link ImmutableList#copyOf(Object[])} (for an array) instead.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayList(E... elements) {
checkNotNull(elements); // for GWT
// Avoid integer overflow when a large array is passed in
int capacity = computeArrayListCapacity(elements.length);
ArrayList<E> list = new ArrayList<E>(capacity);
Collections.addAll(list, elements);
return list;
}
@VisibleForTesting static int computeArrayListCapacity(int arraySize) {
checkArgument(arraySize >= 0);
// TODO(kevinb): Figure out the right behavior, and document it
return Ints.saturatedCast(5L + arraySize + (arraySize / 10));
}
/**
* Creates a <i>mutable</i> {@code ArrayList} instance containing the given
* elements.
*
* <p><b>Note:</b> if mutability is not required and the elements are
* non-null, use {@link ImmutableList#copyOf(Iterator)} instead.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
@GwtCompatible(serializable = true)
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.
*
* <p><b>Note:</b> if mutability is not required and the elements are
* non-null, use {@link ImmutableList#copyOf(Iterator)} instead.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements) {
checkNotNull(elements); // for GWT
ArrayList<E> list = newArrayList();
while (elements.hasNext()) {
list.add(elements.next());
}
return list;
}
/**
* Creates an {@code ArrayList} instance backed by an array of the
* <i>exact</i> size specified; equivalent to
* {@link ArrayList#ArrayList(int)}.
*
* <p><b>Note:</b> if you know the exact size your list will be, consider
* using a fixed-size list ({@link Arrays#asList(Object[])}) or an {@link
* ImmutableList} instead of a growable {@link ArrayList}.
*
* <p><b>Note:</b> If you have only an <i>estimate</i> of the eventual size of
* the list, consider padding this estimate by a suitable amount, or simply
* use {@link #newArrayListWithExpectedSize(int)} instead.
*
* @param initialArraySize the exact size of the initial backing array for
* the returned array list ({@code ArrayList} documentation calls this
* value the "capacity")
* @return a new, empty {@code ArrayList} which is guaranteed not to resize
* itself unless its size reaches {@code initialArraySize + 1}
* @throws IllegalArgumentException if {@code initialArraySize} is negative
*/
@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayListWithCapacity(
int initialArraySize) {
checkArgument(initialArraySize >= 0); // for GWT.
return new ArrayList<E>(initialArraySize);
}
/**
* Creates an {@code ArrayList} instance sized appropriately to hold an
* <i>estimated</i> number of elements without resizing. A small amount of
* padding is added in case the estimate is low.
*
* <p><b>Note:</b> If you know the <i>exact</i> number of elements the list
* will hold, or prefer to calculate your own amount of padding, refer to
* {@link #newArrayListWithCapacity(int)}.
*
* @param estimatedSize an estimate of the eventual {@link List#size()} of
* the new list
* @return a new, empty {@code ArrayList}, sized appropriately to hold the
* estimated number of elements
* @throws IllegalArgumentException if {@code estimatedSize} is negative
*/
@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayListWithExpectedSize(
int estimatedSize) {
return new ArrayList<E>(computeArrayListCapacity(estimatedSize));
}
// LinkedList
/**
* Creates an empty {@code LinkedList} instance.
*
* <p><b>Note:</b> if you need an immutable empty {@link List}, use
* {@link ImmutableList#of()} instead.
*
* @return a new, empty {@code LinkedList}
*/
@GwtCompatible(serializable = true)
public static <E> LinkedList<E> newLinkedList() {
return new LinkedList<E>();
}
/**
* Creates a {@code LinkedList} instance containing the given elements.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code LinkedList} containing those elements
*/
@GwtCompatible(serializable = true)
public static <E> LinkedList<E> newLinkedList(
Iterable<? extends E> elements) {
LinkedList<E> list = newLinkedList();
for (E element : elements) {
list.add(element);
}
return list;
}
/**
* Creates an empty {@code CopyOnWriteArrayList} instance.
*
* <p><b>Note:</b> if you need an immutable empty {@link List}, use
* {@link Collections#emptyList} instead.
*
* @return a new, empty {@code CopyOnWriteArrayList}
* @since 12.0
*/
@GwtIncompatible("CopyOnWriteArrayList")
public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
return new CopyOnWriteArrayList<E>();
}
/**
* Creates a {@code CopyOnWriteArrayList} instance containing the given elements.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code CopyOnWriteArrayList} containing those elements
* @since 12.0
*/
@GwtIncompatible("CopyOnWriteArrayList")
public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
Iterable<? extends E> elements) {
// We copy elements to an ArrayList first, rather than incurring the
// quadratic cost of adding them to the COWAL directly.
Collection<? extends E> elementsCollection = (elements instanceof Collection)
? Collections2.cast(elements)
: newArrayList(elements);
return new CopyOnWriteArrayList<E>(elementsCollection);
}
/**
* Returns an unmodifiable list containing the specified first element and
* backed by the specified array of additional elements. Changes to the {@code
* rest} array will be reflected in the returned list. Unlike {@link
* Arrays#asList}, the returned list is unmodifiable.
*
* <p>This is useful when a varargs method needs to use a signature such as
* {@code (Foo firstFoo, Foo... moreFoos)}, in order to avoid overload
* ambiguity or to enforce a minimum argument count.
*
* <p>The returned list is serializable and implements {@link RandomAccess}.
*
* @param first the first element
* @param rest an array of additional elements, possibly empty
* @return an unmodifiable list containing the specified elements
*/
public static <E> List<E> asList(@Nullable E first, E[] rest) {
return new OnePlusArrayList<E>(first, rest);
}
/** @see Lists#asList(Object, Object[]) */
private static class OnePlusArrayList<E> extends AbstractList<E>
implements Serializable, RandomAccess {
final E first;
final E[] rest;
OnePlusArrayList(@Nullable E first, E[] rest) {
this.first = first;
this.rest = checkNotNull(rest);
}
@Override public int size() {
return rest.length + 1;
}
@Override public E get(int index) {
// check explicitly so the IOOBE will have the right message
checkElementIndex(index, size());
return (index == 0) ? first : rest[index - 1];
}
private static final long serialVersionUID = 0;
}
/**
* Returns an unmodifiable list containing the specified first and second
* element, and backed by the specified array of additional elements. Changes
* to the {@code rest} array will be reflected in the returned list. Unlike
* {@link Arrays#asList}, the returned list is unmodifiable.
*
* <p>This is useful when a varargs method needs to use a signature such as
* {@code (Foo firstFoo, Foo secondFoo, Foo... moreFoos)}, in order to avoid
* overload ambiguity or to enforce a minimum argument count.
*
* <p>The returned list is serializable and implements {@link RandomAccess}.
*
* @param first the first element
* @param second the second element
* @param rest an array of additional elements, possibly empty
* @return an unmodifiable list containing the specified elements
*/
public static <E> List<E> asList(
@Nullable E first, @Nullable E second, E[] rest) {
return new TwoPlusArrayList<E>(first, second, rest);
}
/** @see Lists#asList(Object, Object, Object[]) */
private static class TwoPlusArrayList<E> extends AbstractList<E>
implements Serializable, RandomAccess {
final E first;
final E second;
final E[] rest;
TwoPlusArrayList(@Nullable E first, @Nullable E second, E[] rest) {
this.first = first;
this.second = second;
this.rest = checkNotNull(rest);
}
@Override public int size() {
return rest.length + 2;
}
@Override public E get(int index) {
switch (index) {
case 0:
return first;
case 1:
return second;
default:
// check explicitly so the IOOBE will have the right message
checkElementIndex(index, size());
return rest[index - 2];
}
}
private static final long serialVersionUID = 0;
}
/**
* Returns a list that applies {@code function} to each element of {@code
* fromList}. The returned list is a transformed view of {@code fromList};
* changes to {@code fromList} will be reflected in the returned list and vice
* versa.
*
* <p>Since functions are not reversible, the transform is one-way and new
* items cannot be stored in the returned list. The {@code add},
* {@code addAll} and {@code set} methods are unsupported in the returned
* list.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned list to be a view, but it means that the function will be
* applied many times for bulk operations like {@link List#contains} and
* {@link List#hashCode}. For this to perform well, {@code function} should be
* fast. To avoid lazy evaluation when the returned list doesn't need to be a
* view, copy the returned list into a new list of your choosing.
*
* <p>If {@code fromList} implements {@link RandomAccess}, so will the
* returned list. The returned list is threadsafe if the supplied list and
* function are.
*
* <p>If only a {@code Collection} or {@code Iterable} input is available, use
* {@link Collections2#transform} or {@link Iterables#transform}.
*
* <p><b>Note:</b> serializing the returned list is implemented by serializing
* {@code fromList}, its contents, and {@code function} -- <i>not</i> by
* serializing the transformed values. This can lead to surprising behavior,
* so serializing the returned list is <b>not recommended</b>. Instead,
* copy the list using {@link ImmutableList#copyOf(Collection)} (for example),
* then serialize the copy. Other methods similar to this do not implement
* serialization at all for this reason.
*/
public static <F, T> List<T> transform(
List<F> fromList, Function<? super F, ? extends T> function) {
return (fromList instanceof RandomAccess)
? new TransformingRandomAccessList<F, T>(fromList, function)
: new TransformingSequentialList<F, T>(fromList, function);
}
/**
* Implementation of a sequential transforming list.
*
* @see Lists#transform
*/
private static class TransformingSequentialList<F, T>
extends AbstractSequentialList<T> implements Serializable {
final List<F> fromList;
final Function<? super F, ? extends T> function;
TransformingSequentialList(
List<F> fromList, Function<? super F, ? extends T> function) {
this.fromList = checkNotNull(fromList);
this.function = checkNotNull(function);
}
/**
* The default implementation inherited is based on iteration and removal of
* each element which can be overkill. That's why we forward this call
* directly to the backing list.
*/
@Override public void clear() {
fromList.clear();
}
@Override public int size() {
return fromList.size();
}
@Override public ListIterator<T> listIterator(final int index) {
final ListIterator<F> delegate = fromList.listIterator(index);
return new ListIterator<T>() {
@Override
public void add(T e) {
throw new UnsupportedOperationException();
}
@Override
public boolean hasNext() {
return delegate.hasNext();
}
@Override
public boolean hasPrevious() {
return delegate.hasPrevious();
}
@Override
public T next() {
return function.apply(delegate.next());
}
@Override
public int nextIndex() {
return delegate.nextIndex();
}
@Override
public T previous() {
return function.apply(delegate.previous());
}
@Override
public int previousIndex() {
return delegate.previousIndex();
}
@Override
public void remove() {
delegate.remove();
}
@Override
public void set(T e) {
throw new UnsupportedOperationException("not supported");
}
};
}
private static final long serialVersionUID = 0;
}
/**
* Implementation of a transforming random access list. We try to make as many
* of these methods pass-through to the source list as possible so that the
* performance characteristics of the source list and transformed list are
* similar.
*
* @see Lists#transform
*/
private static class TransformingRandomAccessList<F, T>
extends AbstractList<T> implements RandomAccess, Serializable {
final List<F> fromList;
final Function<? super F, ? extends T> function;
TransformingRandomAccessList(
List<F> fromList, Function<? super F, ? extends T> function) {
this.fromList = checkNotNull(fromList);
this.function = checkNotNull(function);
}
@Override public void clear() {
fromList.clear();
}
@Override public T get(int index) {
return function.apply(fromList.get(index));
}
@Override public boolean isEmpty() {
return fromList.isEmpty();
}
@Override public T remove(int index) {
return function.apply(fromList.remove(index));
}
@Override public int size() {
return fromList.size();
}
private static final long serialVersionUID = 0;
}
/**
* Returns consecutive {@linkplain List#subList(int, int) sublists} of a list,
* each of the same size (the final list may be smaller). For example,
* partitioning a list containing {@code [a, b, c, d, e]} with a partition
* size of 3 yields {@code [[a, b, c], [d, e]]} -- an outer list containing
* two inner lists of three and two elements, all in the original order.
*
* <p>The outer list is unmodifiable, but reflects the latest state of the
* source list. The inner lists are sublist views of the original list,
* produced on demand using {@link List#subList(int, int)}, and are subject
* to all the usual caveats about modification as explained in that API.
*
* @param list the list to return consecutive sublists of
* @param size the desired size of each sublist (the last may be
* smaller)
* @return a list of consecutive sublists
* @throws IllegalArgumentException if {@code partitionSize} is nonpositive
*/
public static <T> List<List<T>> partition(List<T> list, int size) {
checkNotNull(list);
checkArgument(size > 0);
return (list instanceof RandomAccess)
? new RandomAccessPartition<T>(list, size)
: new Partition<T>(list, size);
}
private static class Partition<T> extends AbstractList<List<T>> {
final List<T> list;
final int size;
Partition(List<T> list, int size) {
this.list = list;
this.size = size;
}
@Override public List<T> get(int index) {
int listSize = size();
checkElementIndex(index, listSize);
int start = index * size;
int end = Math.min(start + size, list.size());
return list.subList(start, end);
}
@Override public int size() {
// TODO(user): refactor to common.math.IntMath.divide
int result = list.size() / size;
if (result * size != list.size()) {
result++;
}
return result;
}
@Override public boolean isEmpty() {
return list.isEmpty();
}
}
private static class RandomAccessPartition<T> extends Partition<T>
implements RandomAccess {
RandomAccessPartition(List<T> list, int size) {
super(list, size);
}
}
/**
* Returns a view of the specified string as an immutable list of {@code
* Character} values.
*
* @since 7.0
*/
@Beta public static ImmutableList<Character> charactersOf(String string) {
return new StringAsImmutableList(checkNotNull(string));
}
@SuppressWarnings("serial") // serialized using ImmutableList serialization
private static final class StringAsImmutableList
extends ImmutableList<Character> {
private final String string;
StringAsImmutableList(String string) {
this.string = string;
}
@Override public int indexOf(@Nullable Object object) {
return (object instanceof Character)
? string.indexOf((Character) object) : -1;
}
@Override public int lastIndexOf(@Nullable Object object) {
return (object instanceof Character)
? string.lastIndexOf((Character) object) : -1;
}
@Override public ImmutableList<Character> subList(
int fromIndex, int toIndex) {
checkPositionIndexes(fromIndex, toIndex, size()); // for GWT
return charactersOf(string.substring(fromIndex, toIndex));
}
@Override boolean isPartialView() {
return false;
}
@Override public Character get(int index) {
checkElementIndex(index, size()); // for GWT
return string.charAt(index);
}
@Override public int size() {
return string.length();
}
@Override public boolean equals(@Nullable Object obj) {
if (!(obj instanceof List)) {
return false;
}
List<?> list = (List<?>) obj;
int n = string.length();
if (n != list.size()) {
return false;
}
Iterator<?> iterator = list.iterator();
for (int i = 0; i < n; i++) {
Object elem = iterator.next();
if (!(elem instanceof Character)
|| ((Character) elem).charValue() != string.charAt(i)) {
return false;
}
}
return true;
}
int hash = 0;
@Override public int hashCode() {
int h = hash;
if (h == 0) {
h = 1;
for (int i = 0; i < string.length(); i++) {
h = h * 31 + string.charAt(i);
}
hash = h;
}
return h;
}
}
/**
* Returns a view of the specified {@code CharSequence} as a {@code
* List<Character>}, viewing {@code sequence} as a sequence of Unicode code
* units. The view does not support any modification operations, but reflects
* any changes to the underlying character sequence.
*
* @param sequence the character sequence to view as a {@code List} of
* characters
* @return an {@code List<Character>} view of the character sequence
* @since 7.0
*/
@Beta public static List<Character> charactersOf(CharSequence sequence) {
return new CharSequenceAsList(checkNotNull(sequence));
}
private static final class CharSequenceAsList
extends AbstractList<Character> {
private final CharSequence sequence;
CharSequenceAsList(CharSequence sequence) {
this.sequence = sequence;
}
@Override public Character get(int index) {
checkElementIndex(index, size()); // for GWT
return sequence.charAt(index);
}
@Override public boolean contains(@Nullable Object o) {
return indexOf(o) >= 0;
}
@Override public int indexOf(@Nullable Object o) {
if (o instanceof Character) {
char c = (Character) o;
for (int i = 0; i < sequence.length(); i++) {
if (sequence.charAt(i) == c) {
return i;
}
}
}
return -1;
}
@Override public int lastIndexOf(@Nullable Object o) {
if (o instanceof Character) {
char c = ((Character) o).charValue();
for (int i = sequence.length() - 1; i >= 0; i--) {
if (sequence.charAt(i) == c) {
return i;
}
}
}
return -1;
}
@Override public int size() {
return sequence.length();
}
@Override public List<Character> subList(int fromIndex, int toIndex) {
checkPositionIndexes(fromIndex, toIndex, size()); // for GWT
return charactersOf(sequence.subSequence(fromIndex, toIndex));
}
@Override public int hashCode() {
int hash = 1;
for (int i = 0; i < sequence.length(); i++) {
hash = hash * 31 + sequence.charAt(i);
}
return hash;
}
@Override public boolean equals(@Nullable Object o) {
if (!(o instanceof List)) {
return false;
}
List<?> list = (List<?>) o;
int n = sequence.length();
if (n != list.size()) {
return false;
}
Iterator<?> iterator = list.iterator();
for (int i = 0; i < n; i++) {
Object elem = iterator.next();
if (!(elem instanceof Character)
|| ((Character) elem).charValue() != sequence.charAt(i)) {
return false;
}
}
return true;
}
}
/**
* 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>The returned list is random-access if the specified list is random
* access.
*
* @since 7.0
*/
public static <T> List<T> reverse(List<T> list) {
if (list instanceof ReverseList) {
return ((ReverseList<T>) list).getForwardList();
} else if (list instanceof RandomAccess) {
return new RandomAccessReverseList<T>(list);
} else {
return new ReverseList<T>(list);
}
}
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, @Nullable 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, @Nullable T element) {
return forwardList.set(reverseIndex(index), element);
}
@Override public T get(int index) {
return forwardList.get(reverseIndex(index));
}
@Override public boolean isEmpty() {
return forwardList.isEmpty();
}
@Override public int size() {
return forwardList.size();
}
@Override public boolean contains(@Nullable Object o) {
return forwardList.contains(o);
}
@Override public boolean containsAll(Collection<?> c) {
return forwardList.containsAll(c);
}
@Override public List<T> subList(int fromIndex, int toIndex) {
checkPositionIndexes(fromIndex, toIndex, size());
return reverse(forwardList.subList(
reversePosition(toIndex), reversePosition(fromIndex)));
}
@Override public int indexOf(@Nullable Object o) {
int index = forwardList.lastIndexOf(o);
return (index >= 0) ? reverseIndex(index) : -1;
}
@Override public int lastIndexOf(@Nullable Object o) {
int index = forwardList.indexOf(o);
return (index >= 0) ? reverseIndex(index) : -1;
}
@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 canRemove;
boolean canSet;
@Override public void add(T e) {
forwardIterator.add(e);
forwardIterator.previous();
canSet = canRemove = false;
}
@Override public boolean hasNext() {
return forwardIterator.hasPrevious();
}
@Override public boolean hasPrevious() {
return forwardIterator.hasNext();
}
@Override public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
canSet = canRemove = true;
return forwardIterator.previous();
}
@Override public int nextIndex() {
return reversePosition(forwardIterator.nextIndex());
}
@Override public T previous() {
if (!hasPrevious()) {
throw new NoSuchElementException();
}
canSet = canRemove = true;
return forwardIterator.next();
}
@Override public int previousIndex() {
return nextIndex() - 1;
}
@Override public void remove() {
checkState(canRemove);
forwardIterator.remove();
canRemove = canSet = false;
}
@Override public void set(T e) {
checkState(canSet);
forwardIterator.set(e);
}
};
}
}
private static class RandomAccessReverseList<T> extends ReverseList<T>
implements RandomAccess {
RandomAccessReverseList(List<T> forwardList) {
super(forwardList);
}
}
/**
* An implementation of {@link List#hashCode()}.
*/
static int hashCodeImpl(List<?> list){
int hashCode = 1;
for (Object o : list) {
hashCode = 31 * hashCode + (o == null ? 0 : o.hashCode());
}
return hashCode;
}
/**
* An implementation of {@link List#equals(Object)}.
*/
static boolean equalsImpl(List<?> list, @Nullable 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#addAll(int, Collection)}.
*/
static <E> boolean addAllImpl(
List<E> list, int index, Iterable<? extends E> elements) {
boolean changed = false;
ListIterator<E> listIterator = list.listIterator(index);
for (E e : elements) {
listIterator.add(e);
changed = true;
}
return changed;
}
/**
* An implementation of {@link List#indexOf(Object)}.
*/
static int indexOfImpl(List<?> list, @Nullable Object element){
ListIterator<?> listIterator = list.listIterator();
while (listIterator.hasNext()) {
if (Objects.equal(element, listIterator.next())) {
return listIterator.previousIndex();
}
}
return -1;
}
/**
* An implementation of {@link List#lastIndexOf(Object)}.
*/
static int lastIndexOfImpl(List<?> list, @Nullable Object element){
ListIterator<?> listIterator = list.listIterator(list.size());
while (listIterator.hasPrevious()) {
if (Objects.equal(element, listIterator.previous())) {
return listIterator.nextIndex();
}
}
return -1;
}
/**
* Returns an implementation of {@link List#listIterator(int)}.
*/
static <E> ListIterator<E> listIteratorImpl(List<E> list, int index) {
return new AbstractListWrapper<E>(list).listIterator(index);
}
/**
* An implementation of {@link List#subList(int, int)}.
*/
static <E> List<E> subListImpl(
final List<E> list, int fromIndex, int toIndex) {
List<E> wrapper;
if (list instanceof RandomAccess) {
wrapper = new RandomAccessListWrapper<E>(list) {
@Override public ListIterator<E> listIterator(int index) {
return backingList.listIterator(index);
}
private static final long serialVersionUID = 0;
};
} else {
wrapper = new AbstractListWrapper<E>(list) {
@Override public ListIterator<E> listIterator(int index) {
return backingList.listIterator(index);
}
private static final long serialVersionUID = 0;
};
}
return wrapper.subList(fromIndex, toIndex);
}
private static class AbstractListWrapper<E> extends AbstractList<E> {
final List<E> backingList;
AbstractListWrapper(List<E> backingList) {
this.backingList = checkNotNull(backingList);
}
@Override public void add(int index, E element) {
backingList.add(index, element);
}
@Override public boolean addAll(int index, Collection<? extends E> c) {
return backingList.addAll(index, c);
}
@Override public E get(int index) {
return backingList.get(index);
}
@Override public E remove(int index) {
return backingList.remove(index);
}
@Override public E set(int index, E element) {
return backingList.set(index, element);
}
@Override public boolean contains(Object o) {
return backingList.contains(o);
}
@Override public int size() {
return backingList.size();
}
}
private static class RandomAccessListWrapper<E>
extends AbstractListWrapper<E> implements RandomAccess {
RandomAccessListWrapper(List<E> backingList) {
super(backingList);
}
}
/**
* Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557
*/
static <T> List<T> cast(Iterable<T> iterable) {
return (List<T>) iterable;
}
}