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