108 lines
4.4 KiB
C++
108 lines
4.4 KiB
C++
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// boost cast.hpp header file ----------------------------------------------//
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// (C) Copyright Kevlin Henney and Dave Abrahams 1999.
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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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// 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_CAST_HPP
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#define BOOST_CAST_HPP
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# include <boost/config.hpp>
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# include <boost/assert.hpp>
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# include <typeinfo>
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# include <boost/type.hpp>
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# include <boost/limits.hpp>
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# include <boost/detail/select_type.hpp>
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// It has been demonstrated numerous times that MSVC 6.0 fails silently at link
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// time if you use a template function which has template parameters that don't
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// appear in the function's argument list.
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//
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// TODO: Add this to config.hpp?
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# if defined(BOOST_MSVC) && BOOST_MSVC < 1300
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# define BOOST_EXPLICIT_DEFAULT_TARGET , ::boost::type<Target>* = 0
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# else
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# define BOOST_EXPLICIT_DEFAULT_TARGET
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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 BOOST_EXPLICIT_DEFAULT_TARGET)
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{
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Target tmp = dynamic_cast<Target>(x);
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if ( tmp == 0 ) throw 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 BOOST_EXPLICIT_DEFAULT_TARGET)
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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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# undef BOOST_EXPLICIT_DEFAULT_TARGET
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} // namespace boost
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# include <boost/numeric/conversion/cast.hpp>
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#endif // BOOST_CAST_HPP
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