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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 |