1/*
2 * Copyright (C) 2011 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13*/
14package com.google.common.collect;
15
16import com.google.common.annotations.GwtCompatible;
17
18import java.util.NoSuchElementException;
19import java.util.Set;
20
21import javax.annotation.Nullable;
22
23/**
24 * An empty contiguous set.
25 *
26 * @author Gregory Kick
27 */
28@GwtCompatible(emulated = true)
29@SuppressWarnings("unchecked") // allow ungenerified Comparable types
30final class EmptyContiguousSet<C extends Comparable> extends ContiguousSet<C> {
31  EmptyContiguousSet(DiscreteDomain<C> domain) {
32    super(domain);
33  }
34
35  @Override public C first() {
36    throw new NoSuchElementException();
37  }
38
39  @Override public C last() {
40    throw new NoSuchElementException();
41  }
42
43  @Override public int size() {
44    return 0;
45  }
46
47  @Override public ContiguousSet<C> intersection(ContiguousSet<C> other) {
48    return this;
49  }
50
51  @Override public Range<C> range() {
52    throw new NoSuchElementException();
53  }
54
55  @Override public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
56    throw new NoSuchElementException();
57  }
58
59  @Override ContiguousSet<C> headSetImpl(C toElement, boolean inclusive) {
60    return this;
61  }
62
63  @Override ContiguousSet<C> subSetImpl(
64      C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
65    return this;
66  }
67
68  @Override ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
69    return this;
70  }
71
72  @Override public UnmodifiableIterator<C> iterator() {
73    return Iterators.emptyIterator();
74  }
75
76  @Override boolean isPartialView() {
77    return false;
78  }
79
80  @Override public boolean isEmpty() {
81    return true;
82  }
83
84  @Override public ImmutableList<C> asList() {
85    return ImmutableList.of();
86  }
87
88  @Override public String toString() {
89    return "[]";
90  }
91
92  @Override public boolean equals(@Nullable Object object) {
93    if (object instanceof Set) {
94      Set<?> that = (Set<?>) object;
95      return that.isEmpty();
96    }
97    return false;
98  }
99
100  @Override public int hashCode() {
101    return 0;
102  }
103}
104
105