Sets.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.io.Serializable;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedSet;
import static org.glassfish.jersey.internal.guava.Preconditions.checkNotNull;
/**
* Static utility methods pertaining to {@link Set} instances. Also see this
* class's counterparts {@link Lists}, {@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#Sets">
* {@code Sets}</a>.
*
* @author Kevin Bourrillion
* @author Jared Levy
* @author Chris Povirk
* @since 2.0 (imported from Google Collections Library)
*/
public final class Sets {
private Sets() {
}
/**
* Creates a <i>mutable</i>, empty {@code HashSet} instance.
* <p>
* <p><b>Note:</b> if mutability is not required, use {@link
* ImmutableSet#of()} instead.
* <p>
* <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link
* EnumSet#noneOf} instead.
*
* @return a new, empty {@code HashSet}
*/
public static <E> HashSet<E> newHashSet() {
return new HashSet<E>();
}
// HashSet
/**
* Creates a {@code HashSet} instance, with a high enough "initial capacity"
* that it <i>should</i> hold {@code expectedSize} elements without growth.
* This behavior cannot be broadly guaranteed, but it is observed to be true
* for OpenJDK 1.6. It also can't be guaranteed that the method isn't
* inadvertently <i>oversizing</i> the returned set.
*
* @param expectedSize the number of elements you expect to add to the
* returned set
* @return a new, empty {@code HashSet} with enough capacity to hold {@code
* expectedSize} elements without resizing
* @throws IllegalArgumentException if {@code expectedSize} is negative
*/
public static <E> HashSet<E> newHashSetWithExpectedSize(int expectedSize) {
return new HashSet<E>(Maps.capacity(expectedSize));
}
// LinkedHashSet
// TreeSet
/**
* An implementation for {@link Set#hashCode()}.
*/
static int hashCodeImpl(Set<?> s) {
int hashCode = 0;
for (Object o : s) {
hashCode += o != null ? o.hashCode() : 0;
hashCode = ~~hashCode;
// Needed to deal with unusual integer overflow in GWT.
}
return hashCode;
}
/**
* An implementation for {@link Set#equals(Object)}.
*/
static boolean equalsImpl(Set<?> s, Object object) {
if (s == object) {
return true;
}
if (object instanceof Set) {
Set<?> o = (Set<?>) object;
try {
return s.size() == o.size() && s.containsAll(o);
} catch (NullPointerException ignored) {
return false;
} catch (ClassCastException ignored) {
return false;
}
}
return false;
}
/**
* Returns an unmodifiable view of the specified navigable set. This method
* allows modules to provide users with "read-only" access to internal
* navigable sets. Query operations on the returned set "read through" to the
* specified set, and attempts to modify the returned set, whether direct or
* via its collection views, result in an
* {@code UnsupportedOperationException}.
* <p>
* <p>The returned navigable set will be serializable if the specified
* navigable set is serializable.
*
* @param set the navigable set for which an unmodifiable view is to be
* returned
* @return an unmodifiable view of the specified navigable set
* @since 12.0
*/
public static <E> NavigableSet<E> unmodifiableNavigableSet(
NavigableSet<E> set) {
return new UnmodifiableNavigableSet<E>(set);
}
/**
* Remove each element in an iterable from a set.
*/
static boolean removeAllImpl(Set<?> set, Iterator<?> iterator) {
boolean changed = false;
while (iterator.hasNext()) {
changed |= set.remove(iterator.next());
}
return changed;
}
static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
checkNotNull(collection); // for GWT
/*
* AbstractSet.removeAll(List) has quadratic behavior if the list size
* is just less than the set's size. We augment the test by
* assuming that sets have fast contains() performance, and other
* collections don't. See
* http://code.google.com/p/guava-libraries/issues/detail?id=1013
*/
if (collection instanceof Set && collection.size() > set.size()) {
return Iterators.removeAll(set.iterator(), collection);
} else {
return removeAllImpl(set, collection.iterator());
}
}
/**
* {@link AbstractSet} substitute without the potentially-quadratic
* {@code removeAll} implementation.
*/
abstract static class ImprovedAbstractSet<E> extends AbstractSet<E> {
@Override
public boolean removeAll(Collection<?> c) {
return removeAllImpl(this, c);
}
@Override
public boolean retainAll(Collection<?> c) {
return super.retainAll(checkNotNull(c)); // GWT compatibility
}
}
static final class UnmodifiableNavigableSet<E>
extends ForwardingSortedSet<E> implements NavigableSet<E>, Serializable {
private static final long serialVersionUID = 0;
private final NavigableSet<E> delegate;
private transient UnmodifiableNavigableSet<E> descendingSet;
UnmodifiableNavigableSet(NavigableSet<E> delegate) {
this.delegate = checkNotNull(delegate);
}
@Override
protected SortedSet<E> delegate() {
return Collections.unmodifiableSortedSet(delegate);
}
@Override
public E lower(E e) {
return delegate.lower(e);
}
@Override
public E floor(E e) {
return delegate.floor(e);
}
@Override
public E ceiling(E e) {
return delegate.ceiling(e);
}
@Override
public E higher(E e) {
return delegate.higher(e);
}
@Override
public E pollFirst() {
throw new UnsupportedOperationException();
}
@Override
public E pollLast() {
throw new UnsupportedOperationException();
}
@Override
public NavigableSet<E> descendingSet() {
UnmodifiableNavigableSet<E> result = descendingSet;
if (result == null) {
result = descendingSet = new UnmodifiableNavigableSet<E>(
delegate.descendingSet());
result.descendingSet = this;
}
return result;
}
@Override
public Iterator<E> descendingIterator() {
return Iterators.unmodifiableIterator(delegate.descendingIterator());
}
@Override
public NavigableSet<E> subSet(
E fromElement,
boolean fromInclusive,
E toElement,
boolean toInclusive) {
return unmodifiableNavigableSet(delegate.subSet(
fromElement,
fromInclusive,
toElement,
toInclusive));
}
@Override
public NavigableSet<E> headSet(E toElement, boolean inclusive) {
return unmodifiableNavigableSet(delegate.headSet(toElement, inclusive));
}
@Override
public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
return unmodifiableNavigableSet(
delegate.tailSet(fromElement, inclusive));
}
}
}