/*
* Copyright (C) 2012 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.checkNotNull;
import com.google.common.annotations.
GwtCompatible;
import java.util.
Comparator;
import javax.annotation.
Nullable;
/**
* An empty immutable sorted map.
*
* @author Louis Wasserman
*/
@
GwtCompatible(emulated = true)
@
SuppressWarnings("serial") // uses writeReplace, not default serialization
final class
EmptyImmutableSortedMap<K, V> extends
ImmutableSortedMap<K, V> {
private final transient
ImmutableSortedSet<K>
keySet;
EmptyImmutableSortedMap(
Comparator<? super K>
comparator) {
this.
keySet =
ImmutableSortedSet.
emptySet(
comparator);
}
EmptyImmutableSortedMap(
Comparator<? super K>
comparator,
ImmutableSortedMap<K, V>
descendingMap) {
super(
descendingMap);
this.
keySet =
ImmutableSortedSet.
emptySet(
comparator);
}
@
Override
public V
get(@
Nullable Object key) {
return null;
}
@
Override
public
ImmutableSortedSet<K>
keySet() {
return
keySet;
}
@
Override
public int
size() {
return 0;
}
@
Override
public boolean
isEmpty() {
return true;
}
@
Override
public
ImmutableCollection<V>
values() {
return
ImmutableList.
of();
}
@
Override
public
String toString() {
return "{}";
}
@
Override
boolean
isPartialView() {
return false;
}
@
Override
public
ImmutableSet<
Entry<K, V>>
entrySet() {
return
ImmutableSet.
of();
}
@
Override
ImmutableSet<
Entry<K, V>>
createEntrySet() {
throw new
AssertionError("should never be called");
}
@
Override
public
ImmutableSetMultimap<K, V>
asMultimap() {
return
ImmutableSetMultimap.
of();
}
@
Override
public
ImmutableSortedMap<K, V>
headMap(K
toKey, boolean
inclusive) {
checkNotNull(
toKey);
return this;
}
@
Override
public
ImmutableSortedMap<K, V>
tailMap(K
fromKey, boolean
inclusive) {
checkNotNull(
fromKey);
return this;
}
@
Override
ImmutableSortedMap<K, V>
createDescendingMap() {
return new
EmptyImmutableSortedMap<K, V>(
Ordering.
from(
comparator()).
reverse(), this);
}
}