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 10 namespace v8 { 11 namespace 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. 22 template <typename T, typename S = int> 23 class 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
