1// Copyright 2014 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_BASE_FLAGS_H_
6#define V8_BASE_FLAGS_H_
7
8#include "src/base/compiler-specific.h"
9
10namespace v8 {
11namespace base {
12
13// The Flags class provides a type-safe way of storing OR-combinations of enum
14// values. The Flags<T, S> class is a template class, where T is an enum type,
15// and S is the underlying storage type (usually int).
16//
17// The traditional C++ approach for storing OR-combinations of enum values is to
18// use an int or unsigned int variable. The inconvenience with this approach is
19// that there's no type checking at all; any enum value can be OR'd with any
20// other enum value and passed on to a function that takes an int or unsigned
21// int.
22template <typename T, typename S = int>
23class Flags FINAL {
24 public:
25  typedef T flag_type;
26  typedef S mask_type;
27
28  Flags() : mask_(0) {}
29  Flags(flag_type flag) : mask_(flag) {}  // NOLINT(runtime/explicit)
30  explicit Flags(mask_type mask) : mask_(mask) {}
31
32  Flags& operator&=(const Flags& flags) {
33    mask_ &= flags.mask_;
34    return *this;
35  }
36  Flags& operator|=(const Flags& flags) {
37    mask_ |= flags.mask_;
38    return *this;
39  }
40  Flags& operator^=(const Flags& flags) {
41    mask_ ^= flags.mask_;
42    return *this;
43  }
44
45  Flags operator&(const Flags& flags) const { return Flags(*this) &= flags; }
46  Flags operator|(const Flags& flags) const { return Flags(*this) |= flags; }
47  Flags operator^(const Flags& flags) const { return Flags(*this) ^= flags; }
48
49  Flags& operator&=(flag_type flag) { return operator&=(Flags(flag)); }
50  Flags& operator|=(flag_type flag) { return operator|=(Flags(flag)); }
51  Flags& operator^=(flag_type flag) { return operator^=(Flags(flag)); }
52
53  Flags operator&(flag_type flag) const { return operator&(Flags(flag)); }
54  Flags operator|(flag_type flag) const { return operator|(Flags(flag)); }
55  Flags operator^(flag_type flag) const { return operator^(Flags(flag)); }
56
57  Flags operator~() const { return Flags(~mask_); }
58
59  operator mask_type() const { return mask_; }
60  bool operator!() const { return !mask_; }
61
62 private:
63  mask_type mask_;
64};
65
66
67#define DEFINE_OPERATORS_FOR_FLAGS(Type)                                       \
68  inline Type operator&(Type::flag_type lhs,                                   \
69                        Type::flag_type rhs)ALLOW_UNUSED WARN_UNUSED_RESULT;   \
70  inline Type operator&(Type::flag_type lhs, Type::flag_type rhs) {            \
71    return Type(lhs) & rhs;                                                    \
72  }                                                                            \
73  inline Type operator&(Type::flag_type lhs,                                   \
74                        const Type& rhs)ALLOW_UNUSED WARN_UNUSED_RESULT;       \
75  inline Type operator&(Type::flag_type lhs, const Type& rhs) {                \
76    return rhs & lhs;                                                          \
77  }                                                                            \
78  inline void operator&(Type::flag_type lhs, Type::mask_type rhs)ALLOW_UNUSED; \
79  inline void operator&(Type::flag_type lhs, Type::mask_type rhs) {}           \
80  inline Type operator|(Type::flag_type lhs, Type::flag_type rhs)              \
81      ALLOW_UNUSED WARN_UNUSED_RESULT;                                         \
82  inline Type operator|(Type::flag_type lhs, Type::flag_type rhs) {            \
83    return Type(lhs) | rhs;                                                    \
84  }                                                                            \
85  inline Type operator|(Type::flag_type lhs, const Type& rhs)                  \
86      ALLOW_UNUSED WARN_UNUSED_RESULT;                                         \
87  inline Type operator|(Type::flag_type lhs, const Type& rhs) {                \
88    return rhs | lhs;                                                          \
89  }                                                                            \
90  inline void operator|(Type::flag_type lhs, Type::mask_type rhs)              \
91      ALLOW_UNUSED;                                                            \
92  inline void operator|(Type::flag_type lhs, Type::mask_type rhs) {}           \
93  inline Type operator^(Type::flag_type lhs, Type::flag_type rhs)              \
94      ALLOW_UNUSED WARN_UNUSED_RESULT;                                         \
95  inline Type operator^(Type::flag_type lhs, Type::flag_type rhs) {            \
96    return Type(lhs) ^ rhs;                                                    \
97  } inline Type operator^(Type::flag_type lhs, const Type& rhs)                \
98      ALLOW_UNUSED WARN_UNUSED_RESULT;                                         \
99  inline Type operator^(Type::flag_type lhs, const Type& rhs) {                \
100    return rhs ^ lhs;                                                          \
101  } inline void operator^(Type::flag_type lhs, Type::mask_type rhs)            \
102      ALLOW_UNUSED;                                                            \
103  inline void operator^(Type::flag_type lhs, Type::mask_type rhs) {}
104
105}  // namespace base
106}  // namespace v8
107
108#endif  // V8_BASE_FLAGS_H_
109