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_BOOST_SHARED_PTR_CAST_HPP
10#define BOOST_TYPE_INDEX_RUNTIME_CAST_BOOST_SHARED_PTR_CAST_HPP
11
12/// \file boost_shared_ptr_cast.hpp
13/// \brief Contains the overload of boost::typeindex::runtime_pointer_cast for
14/// boost::shared_ptr types.
15
16#include <boost/type_index/runtime_cast/detail/runtime_cast_impl.hpp>
17
18#include <type_traits>
19
20#ifdef BOOST_HAS_PRAGMA_ONCE
21# pragma once
22#endif
23
24namespace boost {
25 template<class T> class shared_ptr;
26}
27
28namespace boost { namespace typeindex {
29
30/// \brief Creates a new instance of std::shared_ptr whose stored pointer is obtained from u's
31/// stored pointer using a runtime_cast.
32///
33/// The new shared_ptr will share ownership with u, except that it is empty if the runtime_cast
34/// performed by runtime_pointer_cast returns a null pointer.
35/// \tparam T The desired target type to return a pointer of.
36/// \tparam U A complete class type of the source instance pointed to from u.
37/// \return If there exists a valid conversion from U* to T*, returns a boost::shared_ptr<T>
38/// that points to an address suitably offset from u.
39/// If no such conversion exists, returns boost::shared_ptr<T>();
40template<typename T, typename U>
41boost::shared_ptr<T> runtime_pointer_cast(boost::shared_ptr<U> const& u) {
42 T* value = detail::runtime_cast_impl<T>(u.get(), std::is_base_of<T, U>());
43 if(value)
44 return boost::shared_ptr<T>(u, value);
45 return boost::shared_ptr<T>();
46}
47
48}} // namespace boost::typeindex
49
50#endif // BOOST_TYPE_INDEX_RUNTIME_CAST_BOOST_SHARED_PTR_CAST_HPP
51

source code of boost/libs/type_index/include/boost/type_index/runtime_cast/boost_shared_ptr_cast.hpp