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