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