| // boost polymorphic_pointer_cast.hpp header file ----------------------------------------------// |
| // (C) Copyright Boris Rasin and Antony Polukhin 2014-2021. |
| // 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) |
| |
| // See http://www.boost.org/libs/conversion for Documentation. |
| |
| #ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |
| #define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |
| |
| # include <boost/config.hpp> |
| # include <boost/assert.hpp> |
| # include <boost/pointer_cast.hpp> |
| # include <boost/throw_exception.hpp> |
| # include <boost/utility/declval.hpp> |
| # ifdef BOOST_NO_CXX11_DECLTYPE |
| # include <boost/typeof/typeof.hpp> |
| # endif |
| |
| #ifdef BOOST_HAS_PRAGMA_ONCE |
| # pragma once |
| #endif |
| |
| namespace boost |
| { |
| // See the documentation for descriptions of how to choose between |
| // static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<> |
| |
| // polymorphic_pointer_downcast --------------------------------------------// |
| |
| // BOOST_ASSERT() checked polymorphic downcast. Crosscasts prohibited. |
| // Supports any type with static_pointer_cast/dynamic_pointer_cast functions: |
| // built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc. |
| |
| // WARNING: Because this cast uses BOOST_ASSERT(), it violates |
| // the One Definition Rule if used in multiple translation units |
| // where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER |
| // NDEBUG are defined inconsistently. |
| |
| // Contributed by Boris Rasin |
| |
| namespace detail |
| { |
| template <typename Target, typename Source> |
| struct dynamic_pointer_cast_result |
| { |
| #ifdef BOOST_NO_CXX11_DECLTYPE |
| BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>())) |
| typedef typename nested::type type; |
| #else |
| typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type; |
| #endif |
| }; |
| } |
| |
| template <typename Target, typename Source> |
| inline typename detail::dynamic_pointer_cast_result<Target, Source>::type |
| polymorphic_pointer_downcast (const Source& x) |
| { |
| BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x); |
| return static_pointer_cast<Target> (x); |
| } |
| |
| template <typename Target, typename Source> |
| inline typename detail::dynamic_pointer_cast_result<Target, Source>::type |
| polymorphic_pointer_cast (const Source& x) |
| { |
| typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp |
| = dynamic_pointer_cast<Target> (x); |
| if ( !tmp ) boost::throw_exception( std::bad_cast() ); |
| |
| return tmp; |
| } |
| |
| } // namespace boost |
| |
| #endif // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP |