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Diffstat (limited to 'boost/type_index/runtime_cast/std_shared_ptr_cast.hpp')
-rw-r--r-- | boost/type_index/runtime_cast/std_shared_ptr_cast.hpp | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/boost/type_index/runtime_cast/std_shared_ptr_cast.hpp b/boost/type_index/runtime_cast/std_shared_ptr_cast.hpp new file mode 100644 index 0000000000..277a524260 --- /dev/null +++ b/boost/type_index/runtime_cast/std_shared_ptr_cast.hpp @@ -0,0 +1,46 @@ +// +// Copyright (c) Chris Glover, 2016. +// +// +// Distributed under the Boost Software License, Version 1.0. (See accompanying +// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) +// + +#ifndef BOOST_TYPE_INDEX_RUNTIME_CAST_STD_SHARED_PTR_CAST_HPP +#define BOOST_TYPE_INDEX_RUNTIME_CAST_STD_SHARED_PTR_CAST_HPP + +/// \file std_shared_ptr_cast.hpp +/// \brief Contains the overload of boost::typeindex::runtime_pointer_cast for +/// std::shared_ptr types. + +#include <boost/type_index/runtime_cast/detail/runtime_cast_impl.hpp> +#include <boost/type_traits/is_base_and_derived.hpp> +#include <memory> + +#ifdef BOOST_HAS_PRAGMA_ONCE +# pragma once +#endif + +namespace boost { namespace typeindex { + +/// \brief Creates a new instance of std::shared_ptr whose stored pointer is obtained from u's +/// stored pointer using a runtime_cast. +/// +/// The new shared_ptr will share ownership with u, except that it is empty if the runtime_cast +/// performed by runtime_pointer_cast returns a null pointer. +/// \tparam T The desired target type to return a pointer of. +/// \tparam U A complete class type of the source instance pointed to from u. +/// \return If there exists a valid conversion from U* to T*, returns a std::shared_ptr<T> +/// that points to an address suitably offset from u. +/// If no such conversion exists, returns std::shared_ptr<T>(); +template<typename T, typename U> +std::shared_ptr<T> runtime_pointer_cast(std::shared_ptr<U> const& u) { + T* value = detail::runtime_cast_impl<T>(u.get(), boost::is_base_and_derived<T, U>()); + if(value) + return std::shared_ptr<T>(u, value); + return std::shared_ptr<T>(); +} + +}} // namespace boost::typeindex + +#endif // BOOST_TYPE_INDEX_RUNTIME_CAST_STD_SHARED_PTR_CAST_HPP |