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1 // Copyright 2014 the V8 project authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef V8_BASE_FLAGS_H_ | 5 #ifndef V8_BASE_FLAGS_H_ |
6 #define V8_BASE_FLAGS_H_ | 6 #define V8_BASE_FLAGS_H_ |
7 | 7 |
8 #include "src/base/compiler-specific.h" | 8 #include "src/base/compiler-specific.h" |
9 | 9 |
10 namespace v8 { | 10 namespace v8 { |
11 namespace base { | 11 namespace base { |
12 | 12 |
13 // The Flags class provides a type-safe way of storing OR-combinations of enum | 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, | 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). | 15 // and S is the underlying storage type (usually int). |
16 // | 16 // |
17 // The traditional C++ approach for storing OR-combinations of enum values is to | 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 | 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 | 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 | 20 // other enum value and passed on to a function that takes an int or unsigned |
21 // int. | 21 // int. |
22 template <typename T, typename S = int> | 22 template <typename T, typename S = int> |
23 class Flags FINAL { | 23 class Flags final { |
24 public: | 24 public: |
25 typedef T flag_type; | 25 typedef T flag_type; |
26 typedef S mask_type; | 26 typedef S mask_type; |
27 | 27 |
28 Flags() : mask_(0) {} | 28 Flags() : mask_(0) {} |
29 Flags(flag_type flag) // NOLINT(runtime/explicit) | 29 Flags(flag_type flag) // NOLINT(runtime/explicit) |
30 : mask_(static_cast<S>(flag)) {} | 30 : mask_(static_cast<S>(flag)) {} |
31 explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {} | 31 explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {} |
32 | 32 |
33 Flags& operator&=(const Flags& flags) { | 33 Flags& operator&=(const Flags& flags) { |
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102 inline Type operator^(Type::flag_type lhs, const Type& rhs) { \ | 102 inline Type operator^(Type::flag_type lhs, const Type& rhs) { \ |
103 return rhs ^ lhs; \ | 103 return rhs ^ lhs; \ |
104 } inline void operator^(Type::flag_type lhs, Type::mask_type rhs) \ | 104 } inline void operator^(Type::flag_type lhs, Type::mask_type rhs) \ |
105 ALLOW_UNUSED_TYPE; \ | 105 ALLOW_UNUSED_TYPE; \ |
106 inline void operator^(Type::flag_type lhs, Type::mask_type rhs) {} | 106 inline void operator^(Type::flag_type lhs, Type::mask_type rhs) {} |
107 | 107 |
108 } // namespace base | 108 } // namespace base |
109 } // namespace v8 | 109 } // namespace v8 |
110 | 110 |
111 #endif // V8_BASE_FLAGS_H_ | 111 #endif // V8_BASE_FLAGS_H_ |
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