1 | // (C) Copyright John Maddock 2015. |
---|---|

2 | // Use, modification and distribution are subject to the |

3 | // Boost Software License, Version 1.0. (See accompanying file |

4 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |

5 | |

6 | #ifndef BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP |

7 | #define BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP |

8 | |

9 | #include <boost/config.hpp> |

10 | #include <boost/detail/workaround.hpp> |

11 | |

12 | #if (BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \ |

13 | || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x610)) \ |

14 | || BOOST_WORKAROUND(__DMC__, BOOST_TESTED_AT(0x840)) \ |

15 | || BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \ |

16 | || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, BOOST_TESTED_AT(810)) ) |

17 | |

18 | |

19 | namespace boost{ |

20 | namespace mpl |

21 | { |

22 | template <bool B> struct bool_; |

23 | template <class I, I val> struct integral_c; |

24 | struct integral_c_tag; |

25 | } |

26 | } |

27 | |

28 | #else |

29 | |

30 | namespace mpl_{ |

31 | |

32 | template <bool B> struct bool_; |

33 | template <class I, I val> struct integral_c; |

34 | struct integral_c_tag; |

35 | } |

36 | |

37 | namespace boost |

38 | { |

39 | namespace mpl |

40 | { |

41 | using ::mpl_::bool_; |

42 | using ::mpl_::integral_c; |

43 | using ::mpl_::integral_c_tag; |

44 | } |

45 | } |

46 | |

47 | #endif |

48 | |

49 | namespace boost{ |

50 | |

51 | template <class T, T val> |

52 | struct integral_constant |

53 | { |

54 | typedef mpl::integral_c_tag tag; |

55 | typedef T value_type; |

56 | typedef integral_constant<T, val> type; |

57 | static const T value = val; |

58 | // |

59 | // This helper function is just to disable type-punning |

60 | // warnings from GCC: |

61 | // |

62 | template <class U> |

63 | static U& dereference(U* p) { return *p; } |

64 | |

65 | operator const mpl::integral_c<T, val>& ()const |

66 | { |

67 | static const char data[sizeof(long)] = { 0 }; |

68 | return dereference(reinterpret_cast<const mpl::integral_c<T, val>*>(&data)); |

69 | } |

70 | BOOST_CONSTEXPR operator T()const { return val; } |

71 | }; |

72 | |

73 | template <class T, T val> |

74 | T const integral_constant<T, val>::value; |

75 | |

76 | template <bool val> |

77 | struct integral_constant<bool, val> |

78 | { |

79 | typedef mpl::integral_c_tag tag; |

80 | typedef bool value_type; |

81 | typedef integral_constant<bool, val> type; |

82 | static const bool value = val; |

83 | // |

84 | // This helper function is just to disable type-punning |

85 | // warnings from GCC: |

86 | // |

87 | template <class T> |

88 | static T& dereference(T* p) { return *p; } |

89 | |

90 | operator const mpl::bool_<val>& ()const |

91 | { |

92 | static const char data = 0; |

93 | return dereference(reinterpret_cast<const mpl::bool_<val>*>(&data)); |

94 | } |

95 | BOOST_CONSTEXPR operator bool()const { return val; } |

96 | }; |

97 | |

98 | template <bool val> |

99 | bool const integral_constant<bool, val>::value; |

100 | |

101 | typedef integral_constant<bool, true> true_type; |

102 | typedef integral_constant<bool, false> false_type; |

103 | |

104 | } |

105 | |

106 | #endif |

107 |