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>
upcast(Source * p,yes_convertible,no_convertible,Target *)22 inline Target* upcast(Source* p, yes_convertible, no_convertible, Target*)
23 {
24 return p;
25 }
26
27 template <class Source, class Target>
upcast(Source * p,no_convertible,no_convertible,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>
executeboost::python::detail::upcaster39 static inline T* execute(T* x, T*) { return x; }
40 };
41
42 template <>
43 struct upcaster<false>
44 {
45 template <class Source, class Target>
executeboost::python::detail::upcaster46 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>
downcast(Source * p,yes_convertible)57 inline Target* downcast(Source* p, yes_convertible)
58 {
59 return static_cast<Target*>(p);
60 }
61
62 template <class Target, class Source>
downcast(Source * p,no_convertible,boost::type<Target> * =0)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>
assert_castable(boost::type<T> * =0)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>
upcast_impl(Source * x,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>
upcast(Source * x,Target * =0)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>
downcast(Source * x,Target * =0)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
106