ceph/src/boost/libs/type_erasure/include/boost/type_erasure/dynamic_any_cast.hpp

   1 // Boost.TypeErasure library
   2 //
   3 // Copyright 2015 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 #ifndef BOOST_TYPE_ERASURE_DYNAMIC_ANY_CAST_HPP_INCLUDED
  12 #define BOOST_TYPE_ERASURE_DYNAMIC_ANY_CAST_HPP_INCLUDED
  13
  14 #include <boost/type_erasure/detail/normalize.hpp>
  15 #include <boost/type_erasure/binding_of.hpp>
  16 #include <boost/type_erasure/static_binding.hpp>
  17 #include <boost/type_erasure/dynamic_binding.hpp>
  18 #include <boost/type_erasure/concept_of.hpp>
  19 #include <boost/type_erasure/placeholder_of.hpp>
  20 #include <boost/type_erasure/any.hpp>
  21 #include <boost/type_erasure/binding.hpp>
  22 #include <boost/mpl/vector.hpp>
  23 #include <boost/mpl/set.hpp>
  24 #include <boost/mpl/fold.hpp>
  25 #include <boost/type_traits/add_const.hpp>
  26 #include <boost/type_traits/add_reference.hpp>
  27 #include <boost/type_traits/remove_const.hpp>
  28 #include <boost/type_traits/remove_reference.hpp>
  29
  30 namespace boost {
  31 namespace type_erasure {
  32
  33 namespace detail {
  34
  35 template<class P, class P2, class Any>
  36 struct make_ref_placeholder;
  37
  38 template<class P, class P2, class Any>
  39 struct make_ref_placeholder<P, P2, const Any&> { typedef const P& type; };
  40 template<class P, class P2, class Any>
  41 struct make_ref_placeholder<P, P2, Any&> { typedef P& type; };
  42 template<class P, class P2, class Any>
  43 struct make_ref_placeholder<P, P2&, const Any&> { typedef P& type; };
  44 template<class P, class P2, class Any>
  45 struct make_ref_placeholder<P, P2&, Any&> { typedef P& type; };
  46 template<class P, class P2, class Any>
  47 struct make_ref_placeholder<P, const P2&, const Any&> { typedef const P& type; };
  48 template<class P, class P2, class Any>
  49 struct make_ref_placeholder<P, const P2&, Any&> { typedef const P& type; };
  50
  51 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
  52 template<class P, class P2, class Any>
  53 struct make_ref_placeholder { typedef P&& type; };
  54 template<class P, class P2, class Any>
  55 struct make_ref_placeholder<P, P2&, Any> { typedef P& type; };
  56 template<class P, class P2, class Any>
  57 struct make_ref_placeholder<P, const P2&, Any> { typedef const P& type; };
  58 template<class P, class P2, class Any>
  59 struct make_ref_placeholder<P, P2&&, Any> { typedef P&& type; };
  60 template<class P, class P2, class Any>
  61 struct make_ref_placeholder<P, P2&&, const Any&> { typedef const P& type; };
  62 template<class P, class P2, class Any>
  63 struct make_ref_placeholder<P, P2&&, Any&> { typedef P& type; };
  64 #endif
  65
  66 template<class R, class Tag>
  67 struct make_result_placeholder_map
  68 {
  69     typedef ::boost::mpl::map<
  70         ::boost::mpl::pair<
  71             typename ::boost::remove_const<
  72                 typename ::boost::remove_reference<
  73                     typename ::boost::type_erasure::placeholder_of<R>::type
  74                 >::type
  75             >::type,
  76             typename ::boost::remove_const<
  77                 typename ::boost::remove_reference<
  78                     Tag
  79                 >::type
  80             >::type
  81         >
  82     > type;
  83 };
  84
  85 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
  86 template<class R, class Any, class Map>
  87 R dynamic_any_cast_impl(Any&& arg, const static_binding<Map>& map)
  88 #else
  89 template<class R, class Any, class Map>
  90 R dynamic_any_cast_impl(Any& arg, const static_binding<Map>& map)
  91 #endif
  92 {
  93     typedef typename ::boost::remove_const<typename ::boost::remove_reference<Any>::type>::type src_type;
  94     typedef typename ::boost::type_erasure::detail::normalize_concept<
  95         typename ::boost::type_erasure::concept_of<src_type>::type
  96     >::type normalized;
  97     typedef typename ::boost::mpl::fold<
  98         normalized,
  99         ::boost::mpl::set0<>,
 100         ::boost::type_erasure::detail::get_placeholders<
 101             ::boost::mpl::_2,
 102             ::boost::mpl::_1
 103         >
 104     >::type placeholders;
 105     typedef ::boost::type_erasure::detail::substitution_map< ::boost::mpl::map0<> > identity_map;
 106     ::boost::type_erasure::dynamic_binding<placeholders> my_binding(
 107         ::boost::type_erasure::binding_of(arg),
 108         ::boost::type_erasure::make_binding<identity_map>());
 109     typedef typename ::boost::remove_const<
 110         typename ::boost::remove_reference<
 111             typename ::boost::type_erasure::placeholder_of<R>::type
 112         >::type
 113     >::type result_placeholder;
 114     ::boost::type_erasure::binding< typename ::boost::type_erasure::concept_of<R>::type> new_binding(
 115         my_binding,
 116         map);
 117     typedef ::boost::type_erasure::any<
 118         typename ::boost::type_erasure::concept_of<R>::type,
 119         typename ::boost::type_erasure::detail::make_ref_placeholder<
 120             result_placeholder,
 121             typename ::boost::type_erasure::placeholder_of<src_type>::type,
 122 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
 123             Any
 124 #else
 125             Any&
 126 #endif
 127         >::type
 128     > result_ref_type;
 129 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
 130     return result_ref_type(std::forward<Any>(arg), new_binding);
 131 #else
 132     return result_ref_type(arg, new_binding);
 133 #endif
 134 }
 135
 136 }
 137
 138 #ifdef BOOST_TYPE_ERASURE_DOXYGEN
 139
 140 /**
 141  * Downcasts or crosscasts an @ref any.
 142  *
 143  * \pre @c R and @c Any must both be specializations of @ref any.
 144  * \pre PlaceholderMap must be an MPL map with a key
 145  *      for every non-deduced placeholder used by R.
 146  *      The value associated with each key should
 147  *      be the corresponding placeholder in Any.
 148  * \pre The concept of Any must include @ref typeid_, for every
 149  *      @ref placeholder which is used by R.
 150  *
 151  * The single argument form can only be used when @c R uses
 152  * a single non-deduced placeholder.
 153  *
 154  * \throws bad_any_cast if the concepts used by R were
 155  *         not previously registered via a call to
 156  *         @ref register_binding.
 157  *
 158  * Example:
 159  * \code
 160  * // Assume that typeid_<>, copy_constructible<>, and incrementable<>
 161  * // have all been registered for int.
 162  * any<mpl::vector<typeid_<>, copy_constructible<> > > x(1);
 163  * typedef any<
 164  *     mpl::vector<
 165  *         typeid_<>,
 166  *         copy_constructible<>,
 167  *         incrementable<>
 168  *     >
 169  * > incrementable_any;
 170  * auto y = dynamic_any_cast<incrementable_any>(x);
 171  * ++y;
 172  * assert(any_cast<int>(y) == 2);
 173  * \endcode
 174  */
 175 template<class R, class Any>
 176 R dynamic_any_cast(Any&& arg);
 177
 178 /**
 179  * \overload
 180  */
 181 template<class R, class Any, class Map>
 182 R dynamic_any_cast(Any&& arg, const static_binding<Map>&);
 183
 184 #else
 185
 186 template<class R, class Concept, class Tag>
 187 R dynamic_any_cast(const any<Concept, Tag>& arg)
 188 {
 189     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg,
 190         ::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
 191 }
 192
 193 template<class R, class Concept, class Tag>
 194 R dynamic_any_cast(any<Concept, Tag>& arg)
 195 {
 196     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg,
 197         ::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
 198 }
 199
 200 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
 201 template<class R, class Concept, class Tag>
 202 R dynamic_any_cast(any<Concept, Tag>&& arg)
 203 {
 204     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(::std::move(arg),
 205         ::boost::type_erasure::make_binding<typename ::boost::type_erasure::detail::make_result_placeholder_map<R, Tag>::type>());
 206 }
 207 #endif
 208
 209 template<class R, class Concept, class Tag, class Map>
 210 R dynamic_any_cast(const any<Concept, Tag>& arg, const static_binding<Map>& map)
 211 {
 212     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg, map);
 213 }
 214
 215 template<class R, class Concept, class Tag, class Map>
 216 R dynamic_any_cast(any<Concept, Tag>& arg, const static_binding<Map>& map)
 217 {
 218     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(arg, map);
 219 }
 220
 221 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
 222 template<class R, class Concept, class Tag, class Map>
 223 R dynamic_any_cast(any<Concept, Tag>&& arg, const static_binding<Map>& map)
 224 {
 225     return ::boost::type_erasure::detail::dynamic_any_cast_impl<R>(::std::move(arg), map);
 226 }
 227 #endif
 228
 229 #endif
 230
 231 }
 232 }
 233
 234 #endif