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. ``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 WTF_EnumClass_h
27#define WTF_EnumClass_h
28
29#include "wtf/Compiler.h"
30
31namespace WTF {
32
33// How to define a type safe enum list using the ENUM_CLASS macros?
34// ===============================================================
35// To get an enum list like this:
36//
37//     enum class MyEnums {
38//         Value1,
39//         Value2,
40//         ...
41//         ValueN
42//     };
43//
44// ... write this:
45//
46//     ENUM_CLASS(MyEnums) {
47//         Value1,
48//         Value2,
49//         ...
50//         ValueN
51//     } ENUM_CLASS_END(MyEnums);
52//
53// The ENUM_CLASS macros will use C++11's enum class if the compiler supports it.
54// Otherwise, it will use the EnumClass template below.
55
56#if COMPILER_SUPPORTS(CXX_STRONG_ENUMS)
57
58#define ENUM_CLASS(__enumName) \
59    enum class __enumName
60
61#define ENUM_CLASS_END(__enumName)
62
63#else // !COMPILER_SUPPORTS(CXX_STRONG_ENUMS)
64
65// How to define a type safe enum list using the EnumClass template?
66// ================================================================
67// Definition should be a struct that encapsulates an enum list.
68// The enum list should be names Enums.
69//
70// Here's an example of how to define a type safe enum named MyEnum using
71// the EnumClass template:
72//
73//     struct MyEnumDefinition {
74//         enum Enums {
75//             ValueDefault,
76//             Value1,
77//             ...
78//             ValueN
79//         };
80//     };
81//     typedef EnumClass<MyEnumDefinition, MyEnumDefinition::ValueDefault> MyEnum;
82//
83// With that, you can now use MyEnum enum values as follow:
84//
85//     MyEnum value1; // value1 is assigned MyEnum::ValueDefault by default.
86//     MyEnum value2 = MyEnum::Value1; // value2 is assigned MyEnum::Value1;
87
88template <typename Definition>
89class EnumClass : public Definition {
90    typedef enum Definition::Enums Value;
91public:
92    ALWAYS_INLINE EnumClass() { }
93    ALWAYS_INLINE EnumClass(Value value) : m_value(value) { }
94
95    ALWAYS_INLINE Value value() const { return m_value; }
96
97    ALWAYS_INLINE bool operator==(const EnumClass other) { return m_value == other.m_value; }
98    ALWAYS_INLINE bool operator!=(const EnumClass other) { return m_value != other.m_value; }
99    ALWAYS_INLINE bool operator<(const EnumClass other) { return m_value < other.m_value; }
100    ALWAYS_INLINE bool operator<=(const EnumClass other) { return m_value <= other.m_value; }
101    ALWAYS_INLINE bool operator>(const EnumClass other) { return m_value > other.m_value; }
102    ALWAYS_INLINE bool operator>=(const EnumClass other) { return m_value >= other.m_value; }
103
104    ALWAYS_INLINE bool operator==(const Value value) { return m_value == value; }
105    ALWAYS_INLINE bool operator!=(const Value value) { return m_value != value; }
106    ALWAYS_INLINE bool operator<(const Value value) { return m_value < value; }
107    ALWAYS_INLINE bool operator<=(const Value value) { return m_value <= value; }
108    ALWAYS_INLINE bool operator>(const Value value) { return m_value > value; }
109    ALWAYS_INLINE bool operator>=(const Value value) { return m_value >= value; }
110
111    ALWAYS_INLINE operator Value() { return m_value; }
112
113private:
114    Value m_value;
115};
116
117#define ENUM_CLASS(__enumName) \
118    struct __enumName ## Definition { \
119        enum Enums
120
121#define ENUM_CLASS_END(__enumName) \
122        ; \
123    }; \
124    typedef EnumClass< __enumName ## Definition > __enumName
125
126#endif // !COMPILER_SUPPORTS(CXX_STRONG_ENUMS)
127
128} // namespace WTF
129
130#if !COMPILER_SUPPORTS(CXX_STRONG_ENUMS)
131using WTF::EnumClass;
132#endif
133
134#endif // WTF_EnumClass_h
135