// 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 |