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Editing: polymorphic_cast.hpp
// boost polymorphic_cast.hpp header file ----------------------------------------------// // (C) Copyright Kevlin Henney and Dave Abrahams 1999. // (C) Copyright Boris Rasin 2014. // 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. // Revision History // 10 Nov 14 polymorphic_pointer_downcast moved to a separate header, // minor improvements to stisfy latest Boost coding style // 08 Nov 14 Add polymorphic_pointer_downcast (Boris Rasin) // 09 Jun 14 "cast.hpp" was renamed to "polymorphic_cast.hpp" and // inclusion of numeric_cast was removed (Antony Polukhin) // 23 Jun 05 numeric_cast removed and redirected to the new verion (Fernando Cacciola) // 02 Apr 01 Removed BOOST_NO_LIMITS workarounds and included // <boost/limits.hpp> instead (the workaround did not // actually compile when BOOST_NO_LIMITS was defined in // any case, so we loose nothing). (John Maddock) // 21 Jan 01 Undid a bug I introduced yesterday. numeric_cast<> never // worked with stock GCC; trying to get it to do that broke // vc-stlport. // 20 Jan 01 Moved BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS to config.hpp. // Removed unused BOOST_EXPLICIT_TARGET macro. Moved // boost::detail::type to boost/type.hpp. Made it compile with // stock gcc again (Dave Abrahams) // 29 Nov 00 Remove nested namespace cast, cleanup spacing before Formal // Review (Beman Dawes) // 19 Oct 00 Fix numeric_cast for floating-point types (Dave Abrahams) // 15 Jul 00 Suppress numeric_cast warnings for GCC, Borland and MSVC // (Dave Abrahams) // 30 Jun 00 More MSVC6 wordarounds. See comments below. (Dave Abrahams) // 28 Jun 00 Removed implicit_cast<>. See comment below. (Beman Dawes) // 27 Jun 00 More MSVC6 workarounds // 15 Jun 00 Add workarounds for MSVC6 // 2 Feb 00 Remove bad_numeric_cast ";" syntax error (Doncho Angelov) // 26 Jan 00 Add missing throw() to bad_numeric_cast::what(0 (Adam Levar) // 29 Dec 99 Change using declarations so usages in other namespaces work // correctly (Dave Abrahams) // 23 Sep 99 Change polymorphic_downcast assert to also detect M.I. errors // as suggested Darin Adler and improved by Valentin Bonnard. // 2 Sep 99 Remove controversial asserts, simplify, rename. // 30 Aug 99 Move to cast.hpp, replace value_cast with numeric_cast, // place in nested namespace. // 3 Aug 99 Initial version #ifndef BOOST_POLYMORPHIC_CAST_HPP #define BOOST_POLYMORPHIC_CAST_HPP # include <boost/config.hpp> #ifdef BOOST_HAS_PRAGMA_ONCE # pragma once #endif # include <boost/assert.hpp> # include <boost/core/addressof.hpp> # include <boost/core/enable_if.hpp> # include <boost/throw_exception.hpp> # include <boost/type_traits/is_reference.hpp> # include <boost/type_traits/remove_reference.hpp> # include <typeinfo> namespace boost { // See the documentation for descriptions of how to choose between // static_cast<>, dynamic_cast<>, polymorphic_cast<> and polymorphic_downcast<> // polymorphic_cast --------------------------------------------------------// // Runtime checked polymorphic downcasts and crosscasts. // Suggested in The C++ Programming Language, 3rd Ed, Bjarne Stroustrup, // section 15.8 exercise 1, page 425. template <class Target, class Source> inline Target polymorphic_cast(Source* x) { Target tmp = dynamic_cast<Target>(x); if ( tmp == 0 ) boost::throw_exception( std::bad_cast() ); return tmp; } // polymorphic_downcast ----------------------------------------------------// // BOOST_ASSERT() checked raw pointer polymorphic downcast. Crosscasts prohibited. // 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 Dave Abrahams template <class Target, class Source> inline Target polymorphic_downcast(Source* x) { BOOST_ASSERT( dynamic_cast<Target>(x) == x ); // detect logic error return static_cast<Target>(x); } // BOOST_ASSERT() checked reference polymorphic downcast. Crosscasts prohibited. // 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 Julien Delacroix template <class Target, class Source> inline typename boost::enable_if_c< boost::is_reference<Target>::value, Target >::type polymorphic_downcast(Source& x) { typedef typename boost::remove_reference<Target>::type* target_pointer_type; return *boost::polymorphic_downcast<target_pointer_type>( boost::addressof(x) ); } } // namespace boost #endif // BOOST_POLYMORPHIC_CAST_HPP
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