williamr@4: //  boost cast.hpp header file  ----------------------------------------------//
williamr@2: 
williamr@4: //  (C) Copyright Kevlin Henney and Dave Abrahams 1999.
williamr@4: //  Distributed under the Boost
williamr@4: //  Software License, Version 1.0. (See accompanying file
williamr@4: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
williamr@4: 
williamr@4: //  See http://www.boost.org/libs/conversion for Documentation.
williamr@4: 
williamr@4: //  Revision History
williamr@4: //  23 JUn 05  numeric_cast removed and redirected to the new verion (Fernando Cacciola)
williamr@4: //  02 Apr 01  Removed BOOST_NO_LIMITS workarounds and included
williamr@4: //             <boost/limits.hpp> instead (the workaround did not
williamr@4: //             actually compile when BOOST_NO_LIMITS was defined in
williamr@4: //             any case, so we loose nothing). (John Maddock)
williamr@4: //  21 Jan 01  Undid a bug I introduced yesterday. numeric_cast<> never
williamr@4: //             worked with stock GCC; trying to get it to do that broke
williamr@4: //             vc-stlport.
williamr@4: //  20 Jan 01  Moved BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS to config.hpp.
williamr@4: //             Removed unused BOOST_EXPLICIT_TARGET macro. Moved
williamr@4: //             boost::detail::type to boost/type.hpp. Made it compile with
williamr@4: //             stock gcc again (Dave Abrahams)
williamr@4: //  29 Nov 00  Remove nested namespace cast, cleanup spacing before Formal
williamr@4: //             Review (Beman Dawes)
williamr@4: //  19 Oct 00  Fix numeric_cast for floating-point types (Dave Abrahams)
williamr@4: //  15 Jul 00  Suppress numeric_cast warnings for GCC, Borland and MSVC
williamr@4: //             (Dave Abrahams)
williamr@4: //  30 Jun 00  More MSVC6 wordarounds.  See comments below.  (Dave Abrahams)
williamr@4: //  28 Jun 00  Removed implicit_cast<>.  See comment below. (Beman Dawes)
williamr@4: //  27 Jun 00  More MSVC6 workarounds
williamr@4: //  15 Jun 00  Add workarounds for MSVC6
williamr@4: //   2 Feb 00  Remove bad_numeric_cast ";" syntax error (Doncho Angelov)
williamr@4: //  26 Jan 00  Add missing throw() to bad_numeric_cast::what(0 (Adam Levar)
williamr@4: //  29 Dec 99  Change using declarations so usages in other namespaces work
williamr@4: //             correctly (Dave Abrahams)
williamr@4: //  23 Sep 99  Change polymorphic_downcast assert to also detect M.I. errors
williamr@4: //             as suggested Darin Adler and improved by Valentin Bonnard.
williamr@4: //   2 Sep 99  Remove controversial asserts, simplify, rename.
williamr@4: //  30 Aug 99  Move to cast.hpp, replace value_cast with numeric_cast,
williamr@4: //             place in nested namespace.
williamr@4: //   3 Aug 99  Initial version
williamr@4: 
williamr@4: #ifndef BOOST_CAST_HPP
williamr@4: #define BOOST_CAST_HPP
williamr@4: 
williamr@4: # include <boost/config.hpp>
williamr@4: # include <boost/assert.hpp>
williamr@4: # include <typeinfo>
williamr@4: # include <boost/type.hpp>
williamr@4: # include <boost/limits.hpp>
williamr@4: # include <boost/detail/select_type.hpp>
williamr@4: 
williamr@4: //  It has been demonstrated numerous times that MSVC 6.0 fails silently at link
williamr@4: //  time if you use a template function which has template parameters that don't
williamr@4: //  appear in the function's argument list.
williamr@2: //
williamr@4: //  TODO: Add this to config.hpp?
williamr@4: # if defined(BOOST_MSVC) && BOOST_MSVC < 1300
williamr@4: #  define BOOST_EXPLICIT_DEFAULT_TARGET , ::boost::type<Target>* = 0
williamr@4: # else
williamr@4: #  define BOOST_EXPLICIT_DEFAULT_TARGET
williamr@4: # endif
williamr@2: 
williamr@2: namespace boost
williamr@2: {
williamr@4: //  See the documentation for descriptions of how to choose between
williamr@4: //  static_cast<>, dynamic_cast<>, polymorphic_cast<> and polymorphic_downcast<>
williamr@2: 
williamr@4: //  polymorphic_cast  --------------------------------------------------------//
williamr@4: 
williamr@4:     //  Runtime checked polymorphic downcasts and crosscasts.
williamr@4:     //  Suggested in The C++ Programming Language, 3rd Ed, Bjarne Stroustrup,
williamr@4:     //  section 15.8 exercise 1, page 425.
williamr@4: 
williamr@4:     template <class Target, class Source>
williamr@4:     inline Target polymorphic_cast(Source* x BOOST_EXPLICIT_DEFAULT_TARGET)
williamr@4:     {
williamr@4:         Target tmp = dynamic_cast<Target>(x);
williamr@4:         if ( tmp == 0 ) throw std::bad_cast();
williamr@4:         return tmp;
williamr@4:     }
williamr@4: 
williamr@4: //  polymorphic_downcast  ----------------------------------------------------//
williamr@4: 
williamr@4:     //  BOOST_ASSERT() checked polymorphic downcast.  Crosscasts prohibited.
williamr@4: 
williamr@4:     //  WARNING: Because this cast uses BOOST_ASSERT(), it violates
williamr@4:     //  the One Definition Rule if used in multiple translation units
williamr@4:     //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
williamr@4:     //  NDEBUG are defined inconsistently.
williamr@4: 
williamr@4:     //  Contributed by Dave Abrahams
williamr@4: 
williamr@4:     template <class Target, class Source>
williamr@4:     inline Target polymorphic_downcast(Source* x BOOST_EXPLICIT_DEFAULT_TARGET)
williamr@4:     {
williamr@4:         BOOST_ASSERT( dynamic_cast<Target>(x) == x );  // detect logic error
williamr@4:         return static_cast<Target>(x);
williamr@4:     }
williamr@4: 
williamr@4: #  undef BOOST_EXPLICIT_DEFAULT_TARGET
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@4: # include <boost/numeric/conversion/cast.hpp>
williamr@2: 
williamr@4: #endif  // BOOST_CAST_HPP