/*
* Copyright (C) 2011 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.io.
Serializable;
import java.util.
NoSuchElementException;
import java.util.
Set;
import javax.annotation.
Nullable;
/**
* An empty contiguous set.
*
* @author Gregory Kick
*/
@
GwtCompatible(emulated = true)
@
SuppressWarnings("unchecked") // allow ungenerified Comparable types
final class
EmptyContiguousSet<C extends
Comparable> extends
ContiguousSet<C> {
EmptyContiguousSet(
DiscreteDomain<C>
domain) {
super(
domain);
}
@
Override public C
first() {
throw new
NoSuchElementException();
}
@
Override public C
last() {
throw new
NoSuchElementException();
}
@
Override public int
size() {
return 0;
}
@
Override public
ContiguousSet<C>
intersection(
ContiguousSet<C>
other) {
return this;
}
@
Override public
Range<C>
range() {
throw new
NoSuchElementException();
}
@
Override public
Range<C>
range(
BoundType lowerBoundType,
BoundType upperBoundType) {
throw new
NoSuchElementException();
}
@
Override ContiguousSet<C>
headSetImpl(C
toElement, boolean
inclusive) {
return this;
}
@
Override ContiguousSet<C>
subSetImpl(
C
fromElement, boolean
fromInclusive, C
toElement, boolean
toInclusive) {
return this;
}
@
Override ContiguousSet<C>
tailSetImpl(C
fromElement, boolean
fromInclusive) {
return this;
}
@
GwtIncompatible("not used by GWT emulation")
@
Override int
indexOf(
Object target) {
return -1;
}
@
Override public
UnmodifiableIterator<C>
iterator() {
return
Iterators.
emptyIterator();
}
@
GwtIncompatible("NavigableSet")
@
Override public
UnmodifiableIterator<C>
descendingIterator() {
return
Iterators.
emptyIterator();
}
@
Override boolean
isPartialView() {
return false;
}
@
Override public boolean
isEmpty() {
return true;
}
@
Override public
ImmutableList<C>
asList() {
return
ImmutableList.
of();
}
@
Override public
String toString() {
return "[]";
}
@
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;
}
@
GwtIncompatible("serialization")
private static final class
SerializedForm<C extends
Comparable> implements
Serializable {
private final
DiscreteDomain<C>
domain;
private
SerializedForm(
DiscreteDomain<C>
domain) {
this.
domain =
domain;
}
private
Object readResolve() {
return new
EmptyContiguousSet<C>(
domain);
}
private static final long
serialVersionUID = 0;
}
@
GwtIncompatible("serialization")
@
Override
Object writeReplace() {
return new
SerializedForm<C>(
domain);
}
@
GwtIncompatible("NavigableSet")
ImmutableSortedSet<C>
createDescendingSet() {
return new
EmptyImmutableSortedSet<C>(
Ordering.
natural().
reverse());
}
}