Jeff Thompson | a28eed8 | 2013-08-22 16:21:10 -0700 | [diff] [blame] | 1 | // common_type.hpp ---------------------------------------------------------// |
| 2 | |
| 3 | // Copyright 2008 Howard Hinnant |
| 4 | // Copyright 2008 Beman Dawes |
| 5 | |
| 6 | // Distributed under the Boost Software License, Version 1.0. |
| 7 | // See http://www.boost.org/LICENSE_1_0.txt |
| 8 | |
| 9 | #ifndef BOOST_TYPE_TRAITS_COMMON_TYPE_HPP |
| 10 | #define BOOST_TYPE_TRAITS_COMMON_TYPE_HPP |
| 11 | |
| 12 | #include <ndnboost/config.hpp> |
| 13 | |
| 14 | #if defined(__SUNPRO_CC) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) |
| 15 | # define BOOST_COMMON_TYPE_DONT_USE_TYPEOF |
| 16 | #endif |
| 17 | #if defined(__IBMCPP__) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) |
| 18 | # define BOOST_COMMON_TYPE_DONT_USE_TYPEOF |
| 19 | #endif |
| 20 | |
| 21 | //----------------------------------------------------------------------------// |
| 22 | #if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_COMMON_TYPE_ARITY) |
| 23 | #define BOOST_COMMON_TYPE_ARITY 3 |
| 24 | #endif |
| 25 | |
| 26 | //----------------------------------------------------------------------------// |
| 27 | #if defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) |
| 28 | #include <ndnboost/typeof/typeof.hpp> // boost wonders never cease! |
| 29 | #endif |
| 30 | |
| 31 | //----------------------------------------------------------------------------// |
| 32 | #ifndef BOOST_NO_CXX11_STATIC_ASSERT |
| 33 | #define BOOST_COMMON_TYPE_STATIC_ASSERT(CND, MSG, TYPES) static_assert(CND,MSG) |
| 34 | #elif defined(BOOST_COMMON_TYPE_USES_MPL_ASSERT) |
| 35 | #include <ndnboost/mpl/assert.hpp> |
| 36 | #include <ndnboost/mpl/bool.hpp> |
| 37 | #define BOOST_COMMON_TYPE_STATIC_ASSERT(CND, MSG, TYPES) \ |
| 38 | BOOST_MPL_ASSERT_MSG(ndnboost::mpl::bool_< (CND) >::type::value, MSG, TYPES) |
| 39 | #else |
| 40 | #include <ndnboost/static_assert.hpp> |
| 41 | #define BOOST_COMMON_TYPE_STATIC_ASSERT(CND, MSG, TYPES) BOOST_STATIC_ASSERT(CND) |
| 42 | #endif |
| 43 | |
| 44 | #if !defined(BOOST_NO_CXX11_STATIC_ASSERT) || !defined(BOOST_COMMON_TYPE_USES_MPL_ASSERT) |
| 45 | #define BOOST_COMMON_TYPE_MUST_BE_A_COMPLE_TYPE "must be complete type" |
| 46 | #endif |
| 47 | |
| 48 | #if defined(BOOST_NO_CXX11_DECLTYPE) && defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) |
| 49 | #include <ndnboost/type_traits/detail/common_type_imp.hpp> |
| 50 | #include <ndnboost/type_traits/remove_cv.hpp> |
| 51 | #endif |
| 52 | #include <ndnboost/mpl/if.hpp> |
| 53 | #include <ndnboost/utility/declval.hpp> |
| 54 | #include <ndnboost/type_traits/add_rvalue_reference.hpp> |
| 55 | |
| 56 | //----------------------------------------------------------------------------// |
| 57 | // // |
| 58 | // C++03 implementation of // |
| 59 | // 20.9.7.6 Other transformations [meta.trans.other] // |
| 60 | // Written by Howard Hinnant // |
| 61 | // Adapted for Boost by Beman Dawes, Vicente Botet and Jeffrey Hellrung // |
| 62 | // // |
| 63 | //----------------------------------------------------------------------------// |
| 64 | |
| 65 | namespace ndnboost { |
| 66 | |
| 67 | // prototype |
| 68 | #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) |
| 69 | template<typename... T> |
| 70 | struct common_type; |
| 71 | #else // or no specialization |
| 72 | template <class T, class U = void, class V = void> |
| 73 | struct common_type |
| 74 | { |
| 75 | public: |
| 76 | typedef typename common_type<typename common_type<T, U>::type, V>::type type; |
| 77 | }; |
| 78 | #endif |
| 79 | |
| 80 | |
| 81 | // 1 arg |
| 82 | template<typename T> |
| 83 | #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) |
| 84 | struct common_type<T> |
| 85 | #else |
| 86 | struct common_type<T, void, void> |
| 87 | |
| 88 | #endif |
| 89 | { |
| 90 | BOOST_COMMON_TYPE_STATIC_ASSERT(sizeof(T) > 0, BOOST_COMMON_TYPE_MUST_BE_A_COMPLE_TYPE, (T)); |
| 91 | public: |
| 92 | typedef T type; |
| 93 | }; |
| 94 | |
| 95 | // 2 args |
| 96 | namespace type_traits_detail { |
| 97 | |
| 98 | template <class T, class U> |
| 99 | struct common_type_2 |
| 100 | { |
| 101 | private: |
| 102 | BOOST_COMMON_TYPE_STATIC_ASSERT(sizeof(T) > 0, BOOST_COMMON_TYPE_MUST_BE_A_COMPLE_TYPE, (T)); |
| 103 | BOOST_COMMON_TYPE_STATIC_ASSERT(sizeof(U) > 0, BOOST_COMMON_TYPE_MUST_BE_A_COMPLE_TYPE, (U)); |
| 104 | static bool declval_bool(); // workaround gcc bug; not required by std |
| 105 | static typename add_rvalue_reference<T>::type declval_T(); // workaround gcc bug; not required by std |
| 106 | static typename add_rvalue_reference<U>::type declval_U(); // workaround gcc bug; not required by std |
| 107 | static typename add_rvalue_reference<bool>::type declval_b(); |
| 108 | |
| 109 | #if !defined(BOOST_NO_CXX11_DECLTYPE) |
| 110 | public: |
| 111 | typedef decltype(declval<bool>() ? declval<T>() : declval<U>()) type; |
| 112 | #elif defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) |
| 113 | public: |
| 114 | typedef typename detail_type_traits_common_type::common_type_impl< |
| 115 | typename remove_cv<T>::type, |
| 116 | typename remove_cv<U>::type |
| 117 | >::type type; |
| 118 | #else |
| 119 | public: |
| 120 | typedef BOOST_TYPEOF_TPL(declval_b() ? declval_T() : declval_U()) type; |
| 121 | #endif |
| 122 | |
| 123 | #if defined(__GNUC__) && __GNUC__ == 3 && (__GNUC_MINOR__ == 2 || __GNUC_MINOR__ == 3) |
| 124 | public: |
| 125 | void public_dummy_function_just_to_silence_warning(); |
| 126 | #endif |
| 127 | }; |
| 128 | |
| 129 | template <class T> |
| 130 | struct common_type_2<T, T> |
| 131 | { |
| 132 | typedef T type; |
| 133 | }; |
| 134 | } |
| 135 | |
| 136 | #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) |
| 137 | template <class T, class U> |
| 138 | struct common_type<T, U> |
| 139 | #else |
| 140 | template <class T, class U> |
| 141 | struct common_type<T, U, void> |
| 142 | #endif |
| 143 | : public type_traits_detail::common_type_2<T,U> |
| 144 | { }; |
| 145 | |
| 146 | |
| 147 | // 3 or more args |
| 148 | #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) |
| 149 | template<typename T, typename U, typename... V> |
| 150 | struct common_type<T, U, V...> { |
| 151 | public: |
| 152 | typedef typename common_type<typename common_type<T, U>::type, V...>::type type; |
| 153 | }; |
| 154 | #endif |
| 155 | } // namespace ndnboost |
| 156 | |
| 157 | #endif // BOOST_TYPE_TRAITS_COMMON_TYPE_HPP |