1/*
2 * Copyright (C) 2015 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. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef GenericOffset_h
27#define GenericOffset_h
28
29#include <limits.h>
30#include <wtf/Assertions.h>
31
32namespace JSC {
33
34// A mixin for creating the various kinds of variable offsets that our engine supports.
35template<typename T>
36class GenericOffset {
37 WTF_MAKE_FAST_ALLOCATED;
38public:
39 static const unsigned invalidOffset = UINT_MAX;
40
41 GenericOffset()
42 : m_offset(invalidOffset)
43 {
44 }
45
46 explicit GenericOffset(unsigned offset)
47 : m_offset(offset)
48 {
49 }
50
51 bool operator!() const { return m_offset == invalidOffset; }
52
53 unsigned offsetUnchecked() const
54 {
55 return m_offset;
56 }
57
58 unsigned offset() const
59 {
60 ASSERT(m_offset != invalidOffset);
61 return m_offset;
62 }
63
64 bool operator==(const T& other) const
65 {
66 return m_offset == other.offsetUnchecked();
67 }
68 bool operator!=(const T& other) const
69 {
70 return m_offset != other.offsetUnchecked();
71 }
72 bool operator<(const T& other) const
73 {
74 return m_offset < other.offsetUnchecked();
75 }
76 bool operator>(const T& other) const
77 {
78 return m_offset > other.offsetUnchecked();
79 }
80 bool operator<=(const T& other) const
81 {
82 return m_offset <= other.offsetUnchecked();
83 }
84 bool operator>=(const T& other) const
85 {
86 return m_offset >= other.offsetUnchecked();
87 }
88
89 T operator+(int value) const
90 {
91 return T(offset() + value);
92 }
93 T operator-(int value) const
94 {
95 return T(offset() - value);
96 }
97 T& operator+=(int value)
98 {
99 return *this = *this + value;
100 }
101 T& operator-=(int value)
102 {
103 return *this = *this - value;
104 }
105
106private:
107 unsigned m_offset;
108};
109
110} // namespace JSC
111
112#endif // GenericOffset_h
113
114