/*
* 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 com.google.common.annotations.
GwtIncompatible;
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(@
Nullable Object target) {
return false;
}
@
Override public boolean
containsAll(
Collection<?>
targets) {
return
targets.
isEmpty();
}
@
Override public
UnmodifiableIterator<E>
iterator() {
return
Iterators.
emptyIterator();
}
@
GwtIncompatible("NavigableSet")
@
Override public
UnmodifiableIterator<E>
descendingIterator() {
return
Iterators.
emptyIterator();
}
@
Override boolean
isPartialView() {
return false;
}
@
Override public
ImmutableList<E>
asList() {
return
ImmutableList.
of();
}
@
Override
int
copyIntoArray(
Object[]
dst, int
offset) {
return
offset;
}
@
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;
}
@
Override
ImmutableSortedSet<E>
createDescendingSet() {
return new
EmptyImmutableSortedSet<E>(
Ordering.
from(
comparator).
reverse());
}
}