79 lines
2.8 KiB
C++
79 lines
2.8 KiB
C++
// boost polymorphic_pointer_cast.hpp header file ----------------------------------------------//
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// (C) Copyright Boris Rasin and Antony Polukhin 2014-2015.
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// Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// See http://www.boost.org/libs/conversion for Documentation.
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#ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
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#define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
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# include <boost/config.hpp>
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# include <boost/assert.hpp>
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# include <boost/pointer_cast.hpp>
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# include <boost/throw_exception.hpp>
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# include <boost/utility/declval.hpp>
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# ifdef BOOST_NO_CXX11_DECLTYPE
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# include <boost/typeof/typeof.hpp>
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# endif
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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
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{
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// See the documentation for descriptions of how to choose between
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// static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<>
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// polymorphic_pointer_downcast --------------------------------------------//
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// BOOST_ASSERT() checked polymorphic downcast. Crosscasts prohibited.
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// Supports any type with static_pointer_cast/dynamic_pointer_cast functions:
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// built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc.
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// WARNING: Because this cast uses BOOST_ASSERT(), it violates
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// the One Definition Rule if used in multiple translation units
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// where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
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// NDEBUG are defined inconsistently.
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// Contributed by Boris Rasin
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namespace detail
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{
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template <typename Target, typename Source>
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struct dynamic_pointer_cast_result
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{
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#ifdef BOOST_NO_CXX11_DECLTYPE
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BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>()))
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typedef typename nested::type type;
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#else
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typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type;
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#endif
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};
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}
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template <typename Target, typename Source>
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inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
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polymorphic_pointer_downcast (const Source& x)
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{
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BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x);
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return static_pointer_cast<Target> (x);
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}
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template <typename Target, typename Source>
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inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
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polymorphic_pointer_cast (const Source& x)
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{
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typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp
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= dynamic_pointer_cast<Target> (x);
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if ( !tmp ) boost::throw_exception( std::bad_cast() );
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return tmp;
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}
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} // namespace boost
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#endif // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
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