ceph/src/boost/libs/ptr_container/include/boost/ptr_container/detail/is_convertible.hpp

   1 // (C) Copyright Thorsten Ottosen 2005
   2 // (C) Copyright Howard Hinnant 2004
   3 // (C) Copyright Jonathan Turkanis 2004
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
   6
   7 //
   8 // Contains type traits machinery for incomplete arrays. MPL compatibility
   9 // is included for completeness, but is not necessary for the current
  10 // application.
  11 //
  12
  13 #ifndef BOOST_MOVE_PTR_ARRAYS_HPP_INCLUDED
  14 #define BOOST_MOVE_PTR_ARRAYS_HPP_INCLUDED
  15
  16 #include <boost/config.hpp> // BOOST_STATIC_CONSTANT.
  17 #include <boost/mpl/aux_/lambda_support.hpp>
  18 #include <boost/mpl/and.hpp>
  19 #include <boost/mpl/bool.hpp>
  20 #include <boost/mpl/identity.hpp>
  21 #include <boost/mpl/if.hpp>
  22 #include <boost/type_traits/is_array.hpp>
  23 #include <boost/type_traits/is_convertible.hpp>
  24 #include <boost/type_traits/is_same.hpp>
  25 #include <boost/type_traits/remove_bounds.hpp>
  26 #include <boost/type_traits/remove_cv.hpp>
  27 #include <boost/utility/enable_if.hpp>
  28
  29 namespace boost { namespace ptr_container_detail { namespace move_ptrs {
  30
  31 // From Howard Hinnant.
  32 template<typename T, typename U>
  33 struct is_array_convertible {
  34     typedef typename remove_bounds<T>::type      t_element;
  35     typedef typename remove_bounds<U>::type      u_element;
  36     typedef typename remove_cv<t_element>::type  t_base;
  37     typedef typename remove_cv<u_element>::type  u_base;
  38     typedef typename
  39             mpl::and_<
  40                 is_array<T>,
  41                 is_array<U>,
  42                 is_same<t_base, u_base>,
  43                 is_convertible<t_element*, u_element*>
  44             >::type                                     type;
  45     BOOST_STATIC_CONSTANT(bool, value = type::value);
  46     BOOST_MPL_AUX_LAMBDA_SUPPORT(2, is_array_convertible, (T, U))
  47 };
  48
  49 template<typename T, typename U>
  50 struct is_smart_ptr_convertible
  51     : mpl::if_<
  52           is_array<T>,
  53           is_array_convertible<T, U>,
  54           is_convertible<T*, U*>
  55       >::type
  56     { };
  57
  58 #ifndef BOOST_NO_SFINAE
  59     template<typename Src, typename Tgt, typename T = void>
  60     struct enable_if_convertible
  61         : enable_if<
  62               is_smart_ptr_convertible<Src, Tgt>,
  63               T
  64           >
  65         { };
  66 #else
  67     template<typename Src, typename Tgt, class T >
  68     struct enable_if_convertible : mpl::identity<T> { };
  69 #endif
  70
  71 } } }         // End namespaces ptr_container_detail, move_ptrs, boost.
  72
  73 #endif      // #ifndef BOOST_MOVE_PTR_ARRAYS_HPP_INCLUDED