1/*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef MoveOnly_h
27#define MoveOnly_h
28
29#include <wtf/HashFunctions.h>
30#include <wtf/HashTraits.h>
31
32class MoveOnly {
33public:
34 MoveOnly()
35 : m_value(0)
36 {
37 }
38
39 MoveOnly(unsigned value)
40 : m_value(value)
41 {
42 }
43
44 unsigned value() const
45 {
46 return m_value;
47 }
48
49 unsigned operator()() const
50 {
51 return m_value;
52 }
53
54 MoveOnly(MoveOnly&& other)
55 : m_value(other.m_value)
56 {
57 other.m_value = 0;
58 }
59
60 MoveOnly& operator=(MoveOnly&& other)
61 {
62 if (this == &other)
63 return *this;
64
65 m_value = other.m_value;
66 other.m_value = 0;
67 return *this;
68 }
69
70 friend bool operator==(const MoveOnly& a, const MoveOnly& b)
71 {
72 return a.m_value == b.m_value;
73 }
74
75private:
76 unsigned m_value;
77};
78
79namespace WTF {
80
81template<> struct HashTraits<MoveOnly> : public GenericHashTraits<MoveOnly> {
82 static void constructDeletedValue(MoveOnly& slot) { slot = MoveOnly(std::numeric_limits<unsigned>::max()); }
83 static bool isDeletedValue(const MoveOnly& slot) { return slot.value() == std::numeric_limits<unsigned>::max(); }
84};
85
86template<> struct DefaultHash<MoveOnly> {
87 struct Hash {
88 static unsigned hash(const MoveOnly& key)
89 {
90 return intHash(key.value());
91 }
92
93 static bool equal(const MoveOnly& a, const MoveOnly& b)
94 {
95 return a == b;
96 }
97
98 static const bool safeToCompareToEmptyOrDeleted = true;
99 };
100};
101} // namespace WTF
102
103#endif // MoveOnly_h
104