utility.hpp 7.2 KB

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  1. #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED
  2. #define BOOST_MP11_UTILITY_HPP_INCLUDED
  3. // Copyright 2015-2020 Peter Dimov.
  4. //
  5. // Distributed under the Boost Software License, Version 1.0.
  6. //
  7. // See accompanying file LICENSE_1_0.txt or copy at
  8. // http://www.boost.org/LICENSE_1_0.txt
  9. #include <boost/mp11/integral.hpp>
  10. #include <boost/mp11/detail/mp_list.hpp>
  11. #include <boost/mp11/detail/mp_fold.hpp>
  12. #include <boost/mp11/detail/mp_front.hpp>
  13. #include <boost/mp11/detail/mp_rename.hpp>
  14. #include <boost/mp11/detail/config.hpp>
  15. namespace boost
  16. {
  17. namespace mp11
  18. {
  19. // mp_identity
  20. template<class T> struct mp_identity
  21. {
  22. using type = T;
  23. };
  24. // mp_identity_t
  25. template<class T> using mp_identity_t = typename mp_identity<T>::type;
  26. // mp_inherit
  27. template<class... T> struct mp_inherit: T... {};
  28. // mp_if, mp_if_c
  29. namespace detail
  30. {
  31. template<bool C, class T, class... E> struct mp_if_c_impl
  32. {
  33. };
  34. template<class T, class... E> struct mp_if_c_impl<true, T, E...>
  35. {
  36. using type = T;
  37. };
  38. template<class T, class E> struct mp_if_c_impl<false, T, E>
  39. {
  40. using type = E;
  41. };
  42. } // namespace detail
  43. template<bool C, class T, class... E> using mp_if_c = typename detail::mp_if_c_impl<C, T, E...>::type;
  44. template<class C, class T, class... E> using mp_if = typename detail::mp_if_c_impl<static_cast<bool>(C::value), T, E...>::type;
  45. // mp_valid
  46. #if BOOST_MP11_WORKAROUND( BOOST_MP11_INTEL, != 0 ) // tested at 1800
  47. // contributed by Roland Schulz in https://github.com/boostorg/mp11/issues/17
  48. namespace detail
  49. {
  50. template<class...> using void_t = void;
  51. template<class, template<class...> class F, class... T>
  52. struct mp_valid_impl: mp_false {};
  53. template<template<class...> class F, class... T>
  54. struct mp_valid_impl<void_t<F<T...>>, F, T...>: mp_true {};
  55. } // namespace detail
  56. template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<void, F, T...>;
  57. #else
  58. // implementation by Bruno Dutra (by the name is_evaluable)
  59. namespace detail
  60. {
  61. template<template<class...> class F, class... T> struct mp_valid_impl
  62. {
  63. template<template<class...> class G, class = G<T...>> static mp_true check(int);
  64. template<template<class...> class> static mp_false check(...);
  65. using type = decltype(check<F>(0));
  66. };
  67. } // namespace detail
  68. template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<F, T...>::type;
  69. #endif
  70. template<class Q, class... T> using mp_valid_q = mp_valid<Q::template fn, T...>;
  71. // mp_defer
  72. namespace detail
  73. {
  74. template<template<class...> class F, class... T> struct mp_defer_impl
  75. {
  76. using type = F<T...>;
  77. };
  78. struct mp_no_type
  79. {
  80. };
  81. #if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
  82. template<template<class...> class F, class... T> struct mp_defer_cuda_workaround
  83. {
  84. using type = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
  85. };
  86. #endif
  87. } // namespace detail
  88. #if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
  89. template<template<class...> class F, class... T> using mp_defer = typename detail::mp_defer_cuda_workaround< F, T...>::type;
  90. #else
  91. template<template<class...> class F, class... T> using mp_defer = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
  92. #endif
  93. // mp_eval_if, mp_eval_if_c
  94. namespace detail
  95. {
  96. template<bool C, class T, template<class...> class F, class... U> struct mp_eval_if_c_impl;
  97. template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<true, T, F, U...>
  98. {
  99. using type = T;
  100. };
  101. template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<false, T, F, U...>: mp_defer<F, U...>
  102. {
  103. };
  104. } // namespace detail
  105. template<bool C, class T, template<class...> class F, class... U> using mp_eval_if_c = typename detail::mp_eval_if_c_impl<C, T, F, U...>::type;
  106. template<class C, class T, template<class...> class F, class... U> using mp_eval_if = typename detail::mp_eval_if_c_impl<static_cast<bool>(C::value), T, F, U...>::type;
  107. template<class C, class T, class Q, class... U> using mp_eval_if_q = typename detail::mp_eval_if_c_impl<static_cast<bool>(C::value), T, Q::template fn, U...>::type;
  108. // mp_eval_if_not
  109. template<class C, class T, template<class...> class F, class... U> using mp_eval_if_not = mp_eval_if<mp_not<C>, T, F, U...>;
  110. template<class C, class T, class Q, class... U> using mp_eval_if_not_q = mp_eval_if<mp_not<C>, T, Q::template fn, U...>;
  111. // mp_eval_or
  112. template<class T, template<class...> class F, class... U> using mp_eval_or = mp_eval_if_not<mp_valid<F, U...>, T, F, U...>;
  113. template<class T, class Q, class... U> using mp_eval_or_q = mp_eval_or<T, Q::template fn, U...>;
  114. // mp_valid_and_true
  115. template<template<class...> class F, class... T> using mp_valid_and_true = mp_eval_or<mp_false, F, T...>;
  116. template<class Q, class... T> using mp_valid_and_true_q = mp_valid_and_true<Q::template fn, T...>;
  117. // mp_cond
  118. // so elegant; so doesn't work
  119. // template<class C, class T, class... E> using mp_cond = mp_eval_if<C, T, mp_cond, E...>;
  120. namespace detail
  121. {
  122. template<class C, class T, class... E> struct mp_cond_impl;
  123. } // namespace detail
  124. template<class C, class T, class... E> using mp_cond = typename detail::mp_cond_impl<C, T, E...>::type;
  125. namespace detail
  126. {
  127. template<class C, class T, class... E> using mp_cond_ = mp_eval_if<C, T, mp_cond, E...>;
  128. template<class C, class T, class... E> struct mp_cond_impl: mp_defer<mp_cond_, C, T, E...>
  129. {
  130. };
  131. } // namespace detail
  132. // mp_quote
  133. template<template<class...> class F> struct mp_quote
  134. {
  135. // the indirection through mp_defer works around the language inability
  136. // to expand T... into a fixed parameter list of an alias template
  137. template<class... T> using fn = typename mp_defer<F, T...>::type;
  138. };
  139. // mp_quote_trait
  140. template<template<class...> class F> struct mp_quote_trait
  141. {
  142. template<class... T> using fn = typename F<T...>::type;
  143. };
  144. // mp_invoke_q
  145. #if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
  146. namespace detail
  147. {
  148. template<class Q, class... T> struct mp_invoke_q_impl: mp_defer<Q::template fn, T...> {};
  149. } // namespace detail
  150. template<class Q, class... T> using mp_invoke_q = typename detail::mp_invoke_q_impl<Q, T...>::type;
  151. #elif BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 50000 )
  152. template<class Q, class... T> using mp_invoke_q = typename mp_defer<Q::template fn, T...>::type;
  153. #else
  154. template<class Q, class... T> using mp_invoke_q = typename Q::template fn<T...>;
  155. #endif
  156. // mp_not_fn<P>
  157. template<template<class...> class P> struct mp_not_fn
  158. {
  159. template<class... T> using fn = mp_not< mp_invoke_q<mp_quote<P>, T...> >;
  160. };
  161. template<class Q> using mp_not_fn_q = mp_not_fn<Q::template fn>;
  162. // mp_compose
  163. namespace detail
  164. {
  165. template<class L, class Q> using mp_compose_helper = mp_list< mp_apply_q<Q, L> >;
  166. } // namespace detail
  167. #if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
  168. template<template<class...> class... F> struct mp_compose
  169. {
  170. template<class... T> using fn = mp_front< mp_fold<mp_list<mp_quote<F>...>, mp_list<T...>, detail::mp_compose_helper> >;
  171. };
  172. #endif
  173. template<class... Q> struct mp_compose_q
  174. {
  175. template<class... T> using fn = mp_front< mp_fold<mp_list<Q...>, mp_list<T...>, detail::mp_compose_helper> >;
  176. };
  177. } // namespace mp11
  178. } // namespace boost
  179. #endif // #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED