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1 | // |
2 | // Copyright (c) Chris Glover, 2016. | |
3 | // | |
4 | // | |
5 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
6 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
7 | // | |
8 | ||
9 | #ifndef BOOST_TYPE_INDEX_RUNTIME_CAST_REFERENCE_CAST_HPP | |
10 | #define BOOST_TYPE_INDEX_RUNTIME_CAST_REFERENCE_CAST_HPP | |
11 | ||
12 | /// \file reference_cast.hpp | |
13 | /// \brief Contains the overload of boost::typeindex::runtime_cast for | |
14 | /// reference types. | |
15 | ||
16 | #include <boost/core/addressof.hpp> | |
17 | #include <boost/type_index/runtime_cast/detail/runtime_cast_impl.hpp> | |
18 | #include <boost/throw_exception.hpp> | |
19 | #include <boost/type_traits/add_reference.hpp> | |
20 | #include <boost/type_traits/remove_reference.hpp> | |
21 | #include <boost/type_traits/is_base_and_derived.hpp> | |
22 | ||
23 | #ifdef BOOST_HAS_PRAGMA_ONCE | |
24 | # pragma once | |
25 | #endif | |
26 | ||
27 | namespace boost { namespace typeindex { | |
28 | ||
29 | /// \brief Indicates that runtime_cast was unable to perform the desired cast operation | |
30 | /// because the source instance was not also an instance of the target type. | |
31 | struct bad_runtime_cast : std::exception | |
32 | {}; | |
33 | ||
34 | /// \brief Safely converts references to classes up, down, and sideways along the inheritance hierarchy. | |
35 | /// \tparam T The desired target type. Like dynamic_cast, must be a pointer to complete class type. | |
36 | /// \tparam U A complete class type of the source instance, u. | |
37 | /// \return If there exists a valid conversion from U& to T, returns a T that references an address | |
38 | /// suitably offset from u. If no such conversion exists, throws boost::typeindex::bad_runtime_cast. | |
39 | template<typename T, typename U> | |
40 | typename boost::add_reference<T>::type runtime_cast(U& u) { | |
41 | typedef typename boost::remove_reference<T>::type impl_type; | |
42 | impl_type* value = detail::runtime_cast_impl<impl_type>( | |
43 | boost::addressof(u), boost::is_base_and_derived<T, U>()); | |
44 | if(!value) | |
45 | BOOST_THROW_EXCEPTION(bad_runtime_cast()); | |
46 | return *value; | |
47 | } | |
48 | ||
49 | /// \brief Safely converts references to classes up, down, and sideways along the inheritance hierarchy. | |
50 | /// \tparam T The desired target type. Like dynamic_cast, must be a pointer to complete class type. | |
51 | /// \tparam U A complete class type of the source instance, u. | |
52 | /// \return If there exists a valid conversion from U const& to T const, returns a T const that references an address | |
53 | /// suitably offset from u. If no such conversion exists, throws boost::typeindex::bad_runtime_cast. | |
54 | template<typename T, typename U> | |
55 | typename boost::add_reference<const T>::type runtime_cast(U const& u) { | |
56 | typedef typename boost::remove_reference<T>::type impl_type; | |
57 | impl_type* value = detail::runtime_cast_impl<impl_type>( | |
58 | boost::addressof(u), boost::is_base_and_derived<T, U>()); | |
59 | if(!value) | |
60 | BOOST_THROW_EXCEPTION(bad_runtime_cast()); | |
61 | return *value; | |
62 | } | |
63 | ||
64 | }} // namespace boost::typeindex | |
65 | ||
66 | #endif // BOOST_TYPE_INDEX_RUNTIME_CAST_REFERENCE_CAST_HPP |