| 1 | // boost polymorphic_cast.hpp header file ----------------------------------------------// |
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| 2 | |
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| 3 | // (C) Copyright Kevlin Henney and Dave Abrahams 1999. |
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| 4 | // (C) Copyright Boris Rasin 2014. |
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| 5 | // Distributed under the Boost |
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| 6 | // Software License, Version 1.0. (See accompanying file |
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| 7 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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| 8 | |
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| 9 | // See http://www.boost.org/libs/conversion for Documentation. |
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| 10 | |
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| 11 | // Revision History |
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| 12 | // 10 Nov 14 polymorphic_pointer_downcast moved to a separate header, |
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| 13 | // minor improvements to stisfy latest Boost coding style |
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| 14 | // 08 Nov 14 Add polymorphic_pointer_downcast (Boris Rasin) |
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| 15 | // 09 Jun 14 "cast.hpp" was renamed to "polymorphic_cast.hpp" and |
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| 16 | // inclusion of numeric_cast was removed (Antony Polukhin) |
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| 17 | // 23 Jun 05 numeric_cast removed and redirected to the new verion (Fernando Cacciola) |
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| 18 | // 02 Apr 01 Removed BOOST_NO_LIMITS workarounds and included |
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| 19 | // <boost/limits.hpp> instead (the workaround did not |
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| 20 | // actually compile when BOOST_NO_LIMITS was defined in |
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| 21 | // any case, so we loose nothing). (John Maddock) |
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| 22 | // 21 Jan 01 Undid a bug I introduced yesterday. numeric_cast<> never |
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| 23 | // worked with stock GCC; trying to get it to do that broke |
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| 24 | // vc-stlport. |
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| 25 | // 20 Jan 01 Moved BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS to config.hpp. |
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| 26 | // Removed unused BOOST_EXPLICIT_TARGET macro. Moved |
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| 27 | // boost::detail::type to boost/type.hpp. Made it compile with |
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| 28 | // stock gcc again (Dave Abrahams) |
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| 29 | // 29 Nov 00 Remove nested namespace cast, cleanup spacing before Formal |
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| 30 | // Review (Beman Dawes) |
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| 31 | // 19 Oct 00 Fix numeric_cast for floating-point types (Dave Abrahams) |
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| 32 | // 15 Jul 00 Suppress numeric_cast warnings for GCC, Borland and MSVC |
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| 33 | // (Dave Abrahams) |
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| 34 | // 30 Jun 00 More MSVC6 wordarounds. See comments below. (Dave Abrahams) |
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| 35 | // 28 Jun 00 Removed implicit_cast<>. See comment below. (Beman Dawes) |
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| 36 | // 27 Jun 00 More MSVC6 workarounds |
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| 37 | // 15 Jun 00 Add workarounds for MSVC6 |
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| 38 | // 2 Feb 00 Remove bad_numeric_cast ";" syntax error (Doncho Angelov) |
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| 39 | // 26 Jan 00 Add missing throw() to bad_numeric_cast::what(0 (Adam Levar) |
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| 40 | // 29 Dec 99 Change using declarations so usages in other namespaces work |
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| 41 | // correctly (Dave Abrahams) |
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| 42 | // 23 Sep 99 Change polymorphic_downcast assert to also detect M.I. errors |
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| 43 | // as suggested Darin Adler and improved by Valentin Bonnard. |
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| 44 | // 2 Sep 99 Remove controversial asserts, simplify, rename. |
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| 45 | // 30 Aug 99 Move to cast.hpp, replace value_cast with numeric_cast, |
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| 46 | // place in nested namespace. |
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| 47 | // 3 Aug 99 Initial version |
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| 48 | |
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| 49 | #ifndef BOOST_POLYMORPHIC_CAST_HPP |
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| 50 | #define BOOST_POLYMORPHIC_CAST_HPP |
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| 51 | |
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| 52 | # include <boost/config.hpp> |
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| 53 | # include <boost/assert.hpp> |
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| 54 | # include <boost/throw_exception.hpp> |
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| 55 | # include <typeinfo> |
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| 56 | |
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| 57 | #ifdef BOOST_HAS_PRAGMA_ONCE |
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| 58 | # pragma once |
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| 59 | #endif |
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| 60 | |
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| 61 | namespace boost |
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| 62 | { |
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| 63 | // See the documentation for descriptions of how to choose between |
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| 64 | // static_cast<>, dynamic_cast<>, polymorphic_cast<> and polymorphic_downcast<> |
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| 65 | |
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| 66 | // polymorphic_cast --------------------------------------------------------// |
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| 67 | |
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| 68 | // Runtime checked polymorphic downcasts and crosscasts. |
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| 69 | // Suggested in The C++ Programming Language, 3rd Ed, Bjarne Stroustrup, |
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| 70 | // section 15.8 exercise 1, page 425. |
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| 71 | |
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| 72 | template <class Target, class Source> |
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| 73 | inline Target polymorphic_cast(Source* x) |
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| 74 | { |
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| 75 | Target tmp = dynamic_cast<Target>(x); |
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| 76 | if ( tmp == 0 ) boost::throw_exception( e: std::bad_cast() ); |
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| 77 | return tmp; |
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| 78 | } |
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| 79 | |
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| 80 | // polymorphic_downcast ----------------------------------------------------// |
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| 81 | |
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| 82 | // BOOST_ASSERT() checked polymorphic downcast. Crosscasts prohibited. |
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| 83 | |
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| 84 | // WARNING: Because this cast uses BOOST_ASSERT(), it violates |
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| 85 | // the One Definition Rule if used in multiple translation units |
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| 86 | // where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER |
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| 87 | // NDEBUG are defined inconsistently. |
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| 88 | |
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| 89 | // Contributed by Dave Abrahams |
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| 90 | |
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| 91 | template <class Target, class Source> |
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| 92 | inline Target polymorphic_downcast(Source* x) |
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| 93 | { |
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| 94 | BOOST_ASSERT( dynamic_cast<Target>(x) == x ); // detect logic error |
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| 95 | return static_cast<Target>(x); |
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| 96 | } |
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| 97 | |
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| 98 | } // namespace boost |
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| 99 | |
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| 100 | #endif // BOOST_POLYMORPHIC_CAST_HPP |
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| 101 | |
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