1 #ifndef PETSC_CPP_FUNCTIONAL_HPP 2 #define PETSC_CPP_FUNCTIONAL_HPP 3 4 #if defined(__cplusplus) 5 #include <petsc/private/cpp/macros.hpp> 6 #include <petsc/private/cpp/utility.hpp> // index_sequence 7 #include <petsc/private/cpp/type_traits.hpp> // decay_t 8 #include <petsc/private/cpp/tuple.hpp> // tuple_element_t 9 10 #include <functional> 11 12 namespace Petsc 13 { 14 15 namespace util 16 { 17 18 namespace detail 19 { 20 21 struct can_call_test { 22 template <typename F, typename... A> 23 static decltype(std::declval<F>()(std::declval<A>()...), std::true_type()) f(int); 24 25 template <typename F, typename... A> 26 static std::false_type f(...); 27 }; 28 29 // generic template 30 template <typename T> 31 struct func_traits_impl : func_traits_impl<decltype(&T::operator())> { }; 32 33 // function pointers 34 template <typename Ret, typename... Args> 35 struct func_traits_impl<Ret (*)(Args...)> { 36 using result_type = Ret; 37 38 template <std::size_t ix> 39 struct arg { 40 using type = util::tuple_element_t<ix, std::tuple<Args...>>; 41 }; 42 }; 43 44 // class-like operator() 45 template <typename C, typename Ret, typename... Args> 46 struct func_traits_impl<Ret (C::*)(Args...) const> { 47 using result_type = Ret; 48 49 template <std::size_t ix> 50 struct arg { 51 using type = util::tuple_element_t<ix, std::tuple<Args...>>; 52 }; 53 }; 54 55 template <typename C, typename Ret, typename... Args> 56 struct func_traits_impl<Ret (C::*)(Args...)> { 57 using result_type = Ret; 58 59 template <std::size_t ix> 60 struct arg { 61 using type = util::tuple_element_t<ix, std::tuple<Args...>>; 62 }; 63 }; 64 65 } // namespace detail 66 67 template <typename F, typename... A> 68 struct can_call : decltype(detail::can_call_test::f<F, A...>(0)) { }; 69 70 template <typename... A, typename F> 71 inline constexpr can_call<F, A...> is_callable_with(F &&) noexcept 72 { 73 return can_call<F, A...>{}; 74 } 75 76 template <typename T> 77 struct func_traits : detail::func_traits_impl<decay_t<T>> { 78 template <std::size_t idx> 79 using arg_t = typename detail::func_traits_impl<decay_t<T>>::template arg<idx>::type; 80 }; 81 82 } // namespace util 83 84 } // namespace Petsc 85 86 #define PETSC_ALIAS_FUNCTION_WITH_PROLOGUE_AND_EPILOGUE_(alias, original, dispatch, prologue, epilogue) \ 87 template <typename... Args> \ 88 static inline auto dispatch(int, Args &&...args) PETSC_DECLTYPE_NOEXCEPT_AUTO_RETURNS(original(std::forward<Args>(args)...)) \ 89 template <typename... Args> \ 90 static inline int dispatch(char, Args...) \ 91 { \ 92 using namespace Petsc::util; \ 93 static_assert(is_callable_with<Args...>(original) && always_false<Args...>::value, "function " PetscStringize(original) "() is not callable with given arguments"); \ 94 return EXIT_FAILURE; \ 95 } \ 96 template <typename... Args> \ 97 PETSC_NODISCARD auto alias(Args &&...args) PETSC_DECLTYPE_NOEXCEPT_AUTO(dispatch(0, std::forward<Args>(args)...)) \ 98 { \ 99 prologue; \ 100 auto ret = dispatch(0, std::forward<Args>(args)...); \ 101 epilogue; \ 102 return ret; \ 103 } 104 105 #define PETSC_ALIAS_FUNCTION_(alias, original, dispatch) PETSC_ALIAS_FUNCTION_WITH_PROLOGUE_AND_EPILOGUE_(alias, original, dispatch, ((void)0), ((void)0)) 106 107 #ifndef PetscConcat5 108 #define PetscConcat5_(a, b, c, d, e) a##b##c##d##e 109 #define PetscConcat5(a, b, c, d, e) PetscConcat5_(a, b, c, d, e) 110 #endif 111 112 // makes prefix_lineno_name 113 #define PETSC_ALIAS_UNIQUE_NAME_INTERNAL(prefix, name) PetscConcat5(prefix, _, __LINE__, _, name) 114 115 // PETSC_ALIAS_FUNCTION() - Alias a function 116 // 117 // input params: 118 // alias - the new name for the function 119 // original - the name of the function you would like to alias 120 // 121 // notes: 122 // Using this macro in effect creates 123 // 124 // template <typename... T> 125 // auto alias(T&&... args) 126 // { 127 // return original(std::forward<T>(args)...); 128 // } 129 // 130 // meaning it will transparently work for any kind of alias (including overloads). 131 // 132 // example usage: 133 // PETSC_ALIAS_FUNCTION(bar,foo); 134 #define PETSC_ALIAS_FUNCTION(alias, original) PETSC_ALIAS_FUNCTION_(alias, original, PETSC_ALIAS_UNIQUE_NAME_INTERNAL(PetscAliasFunctionDispatch, original)) 135 136 // Similar to PETSC_ALIAS_FUNCTION() this macro creates a thin wrapper which passes all 137 // arguments to the target function ~except~ the last N arguments. So 138 // 139 // PETSC_ALIAS_FUNCTION_GOBBLE_NTH_ARGS(bar,foo,3); 140 // 141 // creates a function with the effect of 142 // 143 // returnType bar(argType1 arg1, argType2 arg2, ..., argTypeN argN) 144 // { 145 // IGNORE(argN); 146 // IGNORE(argN-1); 147 // IGNORE(argN-2); 148 // return foo(arg1,arg2,...,argN-3); 149 // } 150 // 151 // for you. 152 #define PETSC_ALIAS_FUNCTION_GOBBLE_NTH_LAST_ARGS_(alias, original, gobblefn, N) \ 153 static_assert(std::is_integral<decltype(N)>::value && ((N) >= 0), ""); \ 154 template <typename TupleT, std::size_t... idx> \ 155 static inline auto gobblefn(TupleT &&tuple, Petsc::util::index_sequence<idx...>) PETSC_DECLTYPE_NOEXCEPT_AUTO_RETURNS(original(std::get<idx>(tuple)...)) \ 156 template <typename... Args> \ 157 PETSC_NODISCARD auto alias(Args &&...args) PETSC_DECLTYPE_NOEXCEPT_AUTO_RETURNS(gobblefn(std::forward_as_tuple(args...), Petsc::util::make_index_sequence<sizeof...(Args) - (N)>{})) 158 159 #define PETSC_ALIAS_FUNCTION_GOBBLE_NTH_LAST_ARGS(alias, original, N) PETSC_ALIAS_FUNCTION_GOBBLE_NTH_LAST_ARGS_(alias, original, PETSC_ALIAS_UNIQUE_NAME_INTERNAL(PetscAliasFunctionGobbleDispatch, original), N) 160 161 #endif // __cplusplus 162 163 #endif // PETSC_CPP_FUNCTIONAL_HPP 164