1 | // boost polymorphic_pointer_cast.hpp header file ----------------------------------------------// |
2 | // (C) Copyright Boris Rasin and Antony Polukhin 2014-2015. |
3 | // Distributed under the Boost |
4 | // Software License, Version 1.0. (See accompanying file |
5 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
6 | |
7 | // See http://www.boost.org/libs/conversion for Documentation. |
8 | |
9 | #ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |
10 | #define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |
11 | |
12 | # include <boost/config.hpp> |
13 | # include <boost/assert.hpp> |
14 | # include <boost/pointer_cast.hpp> |
15 | # include <boost/throw_exception.hpp> |
16 | # include <boost/utility/declval.hpp> |
17 | # ifdef BOOST_NO_CXX11_DECLTYPE |
18 | # include <boost/typeof/typeof.hpp> |
19 | # endif |
20 | |
21 | #ifdef BOOST_HAS_PRAGMA_ONCE |
22 | # pragma once |
23 | #endif |
24 | |
25 | namespace boost |
26 | { |
27 | // See the documentation for descriptions of how to choose between |
28 | // static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<> |
29 | |
30 | // polymorphic_pointer_downcast --------------------------------------------// |
31 | |
32 | // BOOST_ASSERT() checked polymorphic downcast. Crosscasts prohibited. |
33 | // Supports any type with static_pointer_cast/dynamic_pointer_cast functions: |
34 | // built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc. |
35 | |
36 | // WARNING: Because this cast uses BOOST_ASSERT(), it violates |
37 | // the One Definition Rule if used in multiple translation units |
38 | // where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER |
39 | // NDEBUG are defined inconsistently. |
40 | |
41 | // Contributed by Boris Rasin |
42 | |
43 | namespace detail |
44 | { |
45 | template <typename Target, typename Source> |
46 | struct dynamic_pointer_cast_result |
47 | { |
48 | #ifdef BOOST_NO_CXX11_DECLTYPE |
49 | BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>())) |
50 | typedef typename nested::type type; |
51 | #else |
52 | typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type; |
53 | #endif |
54 | }; |
55 | } |
56 | |
57 | template <typename Target, typename Source> |
58 | inline typename detail::dynamic_pointer_cast_result<Target, Source>::type |
59 | polymorphic_pointer_downcast (const Source& x) |
60 | { |
61 | BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x); |
62 | return static_pointer_cast<Target> (x); |
63 | } |
64 | |
65 | template <typename Target, typename Source> |
66 | inline typename detail::dynamic_pointer_cast_result<Target, Source>::type |
67 | polymorphic_pointer_cast (const Source& x) |
68 | { |
69 | typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp |
70 | = dynamic_pointer_cast<Target> (x); |
71 | if ( !tmp ) boost::throw_exception( e: std::bad_cast() ); |
72 | |
73 | return tmp; |
74 | } |
75 | |
76 | } // namespace boost |
77 | |
78 | #endif // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |
79 | |