ceph/src/boost/libs/python/include/boost/python/cast.hpp

   1 // Copyright David Abrahams 2002.
   2 // Distributed under the Boost Software License, Version 1.0. (See
   3 // accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5 #ifndef CAST_DWA200269_HPP
   6 # define CAST_DWA200269_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9
  10 # include <boost/type_traits/same_traits.hpp>
  11 # include <boost/type_traits/cv_traits.hpp>
  12 # include <boost/type.hpp>
  13 # include <boost/python/base_type_traits.hpp>
  14 # include <boost/python/detail/convertible.hpp>
  15
  16 namespace boost { namespace python {
  17
  18 namespace detail
  19 {
  20   template <class Source, class Target> inline Target* upcast_impl(Source*, Target*);
  21
  22   template <class Source, class Target>
  23   inline Target* upcast(Source* p, yes_convertible, no_convertible, Target*)
  24   {
  25       return p;
  26   }
  27
  28   template <class Source, class Target>
  29   inline Target* upcast(Source* p, no_convertible, no_convertible, Target*)
  30   {
  31       typedef typename base_type_traits<Source>::type base;
  32
  33       return detail::upcast_impl((base*)p, (Target*)0);
  34   }
  35
  36   template <bool is_same = true>
  37   struct upcaster
  38   {
  39       template <class T>
  40       static inline T* execute(T* x, T*) { return x; }
  41   };
  42
  43   template <>
  44   struct upcaster<false>
  45   {
  46       template <class Source, class Target>
  47       static inline Target* execute(Source* x, Target*)
  48       {
  49           return detail::upcast(
  50               x, detail::convertible<Target*>::check(x)
  51               , detail::convertible<Source*>::check((Target*)0)
  52               , (Target*)0);
  53       }
  54   };
  55
  56
  57   template <class Target, class Source>
  58   inline Target* downcast(Source* p, yes_convertible)
  59   {
  60       return static_cast<Target*>(p);
  61   }
  62
  63   template <class Target, class Source>
  64   inline Target* downcast(Source* p, no_convertible, boost::type<Target>* = 0)
  65   {
  66       typedef typename base_type_traits<Source>::type base;
  67       return (Target*)detail::downcast<base>(p, convertible<Source*>::check((base*)0));
  68   }
  69
  70   template <class T>
  71   inline void assert_castable(boost::type<T>* = 0)
  72   {
  73       typedef char must_be_a_complete_type[sizeof(T)] BOOST_ATTRIBUTE_UNUSED;
  74   }
  75
  76   template <class Source, class Target>
  77   inline Target* upcast_impl(Source* x, Target*)
  78   {
  79       typedef typename add_cv<Source>::type src_t;
  80       typedef typename add_cv<Target>::type target_t;
  81       bool const same = is_same<src_t,target_t>::value;
  82
  83       return detail::upcaster<same>::execute(x, (Target*)0);
  84   }
  85 }
  86
  87 template <class Target, class Source>
  88 inline Target* upcast(Source* x, Target* = 0)
  89 {
  90     detail::assert_castable<Source>();
  91     detail::assert_castable<Target>();
  92     return detail::upcast_impl(x, (Target*)0);
  93
  94 }
  95
  96 template <class Target, class Source>
  97 inline Target* downcast(Source* x, Target* = 0)
  98 {
  99     detail::assert_castable<Source>();
 100     detail::assert_castable<Target>();
 101     return detail::downcast<Target>(x, detail::convertible<Source*>::check((Target*)0));
 102 }
 103
 104 }} // namespace boost::python
 105
 106 #endif // CAST_DWA200269_HPP