1/*
2 * Copyright (C) 2015-2019 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#pragma once
27
28#include <limits.h>
29#include <wtf/Assertions.h>
30
31namespace JSC {
32
33// A mixin for creating the various kinds of variable offsets that our engine supports.
34template<typename T>
35class GenericOffset {
36 WTF_MAKE_FAST_ALLOCATED;
37public:
38 static constexpr unsigned invalidOffset = UINT_MAX;
39
40 GenericOffset()
41 : m_offset(invalidOffset)
42 {
43 }
44
45 explicit GenericOffset(unsigned offset)
46 : m_offset(offset)
47 {
48 }
49
50 bool operator!() const { return m_offset == invalidOffset; }
51
52 unsigned offsetUnchecked() const
53 {
54 return m_offset;
55 }
56
57 unsigned offset() const
58 {
59 ASSERT(m_offset != invalidOffset);
60 return m_offset;
61 }
62
63 bool operator==(const T& other) const
64 {
65 return m_offset == other.offsetUnchecked();
66 }
67 bool operator!=(const T& other) const
68 {
69 return m_offset != other.offsetUnchecked();
70 }
71 bool operator<(const T& other) const
72 {
73 return m_offset < other.offsetUnchecked();
74 }
75 bool operator>(const T& other) const
76 {
77 return m_offset > other.offsetUnchecked();
78 }
79 bool operator<=(const T& other) const
80 {
81 return m_offset <= other.offsetUnchecked();
82 }
83 bool operator>=(const T& other) const
84 {
85 return m_offset >= other.offsetUnchecked();
86 }
87
88 T operator+(int value) const
89 {
90 return T(offset() + value);
91 }
92 T operator-(int value) const
93 {
94 return T(offset() - value);
95 }
96 T& operator+=(int value)
97 {
98 return *static_cast<T*>(this) = *this + value;
99 }
100 T& operator-=(int value)
101 {
102 return *static_cast<T*>(this) = *this - value;
103 }
104
105private:
106 unsigned m_offset;
107};
108
109} // namespace JSC
110