ceph/src/boost/boost/type_erasure/detail/extract_concept.hpp

   1 // Boost.TypeErasure library
   2 //
   3 // Copyright 2011 Steven Watanabe
   4 //
   5 // Distributed under the Boost Software License Version 1.0. (See
   6 // accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 //
   9 // $Id$
  10
  11 #if !defined(BOOST_PP_IS_ITERATING)
  12
  13 #ifndef BOOST_TYPE_ERASURE_DETAIL_EXTRACT_CONCEPT_HPP_INCLUDED
  14 #define BOOST_TYPE_ERASURE_DETAIL_EXTRACT_CONCEPT_HPP_INCLUDED
  15
  16 #include <boost/mpl/eval_if.hpp>
  17 #include <boost/mpl/identity.hpp>
  18 #include <boost/type_traits/remove_cv.hpp>
  19 #include <boost/type_traits/remove_reference.hpp>
  20 #include <boost/preprocessor/cat.hpp>
  21 #include <boost/preprocessor/inc.hpp>
  22 #include <boost/preprocessor/iteration/iterate.hpp>
  23 #include <boost/preprocessor/repetition/repeat.hpp>
  24 #include <boost/preprocessor/repetition/enum_params.hpp>
  25 #include <boost/type_erasure/is_placeholder.hpp>
  26 #include <boost/type_erasure/concept_of.hpp>
  27 #include <boost/type_erasure/config.hpp>
  28
  29 namespace boost {
  30 namespace type_erasure {
  31 namespace detail {
  32
  33 template<class T, class U>
  34 struct combine_concepts;
  35
  36 template<class T>
  37 struct combine_concepts<T, T> { typedef T type; };
  38 template<class T>
  39 struct combine_concepts<T, void> { typedef T type; };
  40 template<class T>
  41 struct combine_concepts<void, T> { typedef T type; };
  42 template<>
  43 struct combine_concepts<void, void> { typedef void type; };
  44
  45 #ifdef BOOST_TYPE_ERASURE_USE_MP11
  46
  47 template<class T, class U>
  48 using combine_concepts_t = typename ::boost::type_erasure::detail::combine_concepts<T, U>::type;
  49
  50 template<class T, class U>
  51 using extract_concept_or_void =
  52     ::boost::mp11::mp_eval_if_c<
  53         !::boost::type_erasure::is_placeholder<
  54             ::boost::remove_cv_t<
  55                 ::boost::remove_reference_t<T>
  56             >
  57         >::value,
  58         void,
  59         ::boost::type_erasure::concept_of_t, U
  60     >;
  61
  62 template<class L1, class L2>
  63 using extract_concept_t =
  64     ::boost::mp11::mp_fold<
  65         ::boost::mp11::mp_transform< ::boost::type_erasure::detail::extract_concept_or_void, L1, L2>,
  66         void,
  67         ::boost::type_erasure::detail::combine_concepts_t
  68     >;
  69
  70 #else
  71
  72 template<class T, class U>
  73 struct maybe_extract_concept
  74 {
  75     typedef typename ::boost::mpl::eval_if<
  76         ::boost::type_erasure::is_placeholder<
  77             typename ::boost::remove_cv<
  78                 typename ::boost::remove_reference<T>::type
  79             >::type
  80         >,
  81         ::boost::type_erasure::concept_of<typename ::boost::remove_reference<U>::type>,
  82         ::boost::mpl::identity<void>
  83     >::type type;
  84 };
  85
  86 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
  87
  88 template<class Args, class... U>
  89 struct extract_concept;
  90
  91 template<class R, class T0, class... T, class U0, class... U>
  92 struct extract_concept<R(T0, T...), U0, U...>
  93 {
  94     typedef typename ::boost::type_erasure::detail::combine_concepts<
  95         typename ::boost::type_erasure::detail::maybe_extract_concept<
  96             T0, U0
  97         >::type,
  98         typename ::boost::type_erasure::detail::extract_concept<
  99             void(T...),
 100             U...
 101         >::type
 102     >::type type;
 103 };
 104
 105 template<>
 106 struct extract_concept<void()>
 107 {
 108     typedef void type;
 109 };
 110
 111 #else
 112
 113 #define BOOST_PP_FILENAME_1 <boost/type_erasure/detail/extract_concept.hpp>
 114 #define BOOST_PP_ITERATION_LIMITS (1, BOOST_TYPE_ERASURE_MAX_ARITY)
 115 #include BOOST_PP_ITERATE()
 116
 117 #endif
 118
 119 #endif
 120
 121 }
 122 }
 123 }
 124
 125 #endif
 126
 127 #else
 128
 129 #define N BOOST_PP_ITERATION()
 130
 131 #define BOOST_TYPE_ERASURE_EXTRACT_CONCEPT(z, n, data)                  \
 132     typedef typename ::boost::type_erasure::detail::combine_concepts<   \
 133         typename ::boost::type_erasure::detail::maybe_extract_concept<  \
 134             BOOST_PP_CAT(T, n), BOOST_PP_CAT(U, n)                      \
 135         >::type,                                                        \
 136         BOOST_PP_CAT(concept, n)                                        \
 137     >::type BOOST_PP_CAT(concept, BOOST_PP_INC(n));
 138
 139 template<
 140     BOOST_PP_ENUM_PARAMS(N, class T),
 141     BOOST_PP_ENUM_PARAMS(N, class U)>
 142 struct BOOST_PP_CAT(extract_concept, N)
 143 {
 144     typedef void concept0;
 145
 146     BOOST_PP_REPEAT(N, BOOST_TYPE_ERASURE_EXTRACT_CONCEPT, ~)
 147
 148     typedef BOOST_PP_CAT(concept, N) type;
 149 };
 150
 151 #undef BOOST_TYPE_ERASURE_EXTRACT_CONCEPT
 152 #undef N
 153
 154 #endif