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Diffstat (limited to 'boost/cast.hpp')
| -rw-r--r-- | boost/cast.hpp | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/boost/cast.hpp b/boost/cast.hpp new file mode 100644 index 0000000000..2615d183fa --- /dev/null +++ b/boost/cast.hpp @@ -0,0 +1,107 @@ +// boost cast.hpp header file ----------------------------------------------// + +// (C) Copyright Kevlin Henney and Dave Abrahams 1999. +// 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 +// 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_CAST_HPP +#define BOOST_CAST_HPP + +# include <boost/config.hpp> +# include <boost/assert.hpp> +# include <typeinfo> +# include <boost/type.hpp> +# include <boost/limits.hpp> +# include <boost/detail/select_type.hpp> + +// It has been demonstrated numerous times that MSVC 6.0 fails silently at link +// time if you use a template function which has template parameters that don't +// appear in the function's argument list. +// +// TODO: Add this to config.hpp? +# if defined(BOOST_MSVC) && BOOST_MSVC < 1300 +# define BOOST_EXPLICIT_DEFAULT_TARGET , ::boost::type<Target>* = 0 +# else +# define BOOST_EXPLICIT_DEFAULT_TARGET +# endif + +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 BOOST_EXPLICIT_DEFAULT_TARGET) + { + Target tmp = dynamic_cast<Target>(x); + if ( tmp == 0 ) throw std::bad_cast(); + return tmp; + } + +// polymorphic_downcast ----------------------------------------------------// + + // BOOST_ASSERT() checked 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_EXPLICIT_DEFAULT_TARGET) + { + BOOST_ASSERT( dynamic_cast<Target>(x) == x ); // detect logic error + return static_cast<Target>(x); + } + +# undef BOOST_EXPLICIT_DEFAULT_TARGET + +} // namespace boost + +# include <boost/numeric/conversion/cast.hpp> + +#endif // BOOST_CAST_HPP |