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/*
* Copyright (C) 2008 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.GwtCompatible;
import java.util.Collection;
import java.util.Comparator;
import java.util.NoSuchElementException;
import java.util.Set;
import javax.annotation.Nullable;
/**
* An empty immutable sorted set.
*
* @author Jared Levy
*/
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
class EmptyImmutableSortedSet<E> extends ImmutableSortedSet<E> {
EmptyImmutableSortedSet(Comparator<? super E> comparator) {
super(comparator);
}
@Override
public int size() {
return 0;
}
@Override public boolean isEmpty() {
return true;
}
@Override public boolean contains(Object target) {
return false;
}
@Override public UnmodifiableIterator<E> iterator() {
return Iterators.emptyIterator();
}
@Override boolean isPartialView() {
return false;
}
private static final Object[] EMPTY_ARRAY = new Object[0];
@Override public Object[] toArray() {
return EMPTY_ARRAY;
}
@Override public <T> T[] toArray(T[] a) {
if (a.length > 0) {
a[0] = null;
}
return a;
}
@Override public boolean containsAll(Collection<?> targets) {
return targets.isEmpty();
}
@Override public boolean equals(@Nullable Object object) {
if (object instanceof Set) {
Set<?> that = (Set<?>) object;
return that.isEmpty();
}
return false;
}
@Override public int hashCode() {
return 0;
}
@Override public String toString() {
return "[]";
}
@Override
public E first() {
throw new NoSuchElementException();
}
@Override
public E last() {
throw new NoSuchElementException();
}
@Override
ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive) {
return this;
}
@Override
ImmutableSortedSet<E> subSetImpl(
E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
return this;
}
@Override
ImmutableSortedSet<E> tailSetImpl(E fromElement, boolean inclusive) {
return this;
}
@Override int indexOf(@Nullable Object target) {
return -1;
}
}
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