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[SVN r7621]

include/boost/cast.hpp

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+//  boost cast.hpp header file  ----------------------------------------------//
+
+//  (C) Copyright boost.org 1999. Permission to copy, use, modify, sell
+//  and distribute this software is granted provided this copyright
+//  notice appears in all copies. This software is provided "as is" without
+//  express or implied warranty, and with no claim as to its suitability for
+//  any purpose.
+
+//  See http://www.boost.org for most recent version including documentation.
+
+//  Revision History
+//  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 <cassert>
+# include <typeinfo> 
+# include <limits>
+
+//  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 <= 1200 // 1200 = VC6
+#  define BOOST_EXPLICIT_DEFAULT_TARGET , ::boost::detail::type_wrapper<Target>* = 0
+#  define BOOST_EXPLICIT_TARGET ,::boost::detail::type_wrapper<Target>*
+# else
+#  define BOOST_EXPLICIT_DEFAULT_TARGET
+#  define BOOST_EXPLICIT_TARGET
+# endif
+
+namespace boost
+{
+  namespace detail {
+    template <class T> struct type_wrapper {};
+  }
+#if !(defined(BOOST_MSVC) && BOOST_MSVC <= 1200) // 1200 = VC6
+  namespace cast
+  {
+#endif
+
+//  See the documentation for descriptions of how to choose between
+//  static_cast<>, dynamic_cast<>, polymorphic_cast<>. and down_cast<>
+
+//  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  ----------------------------------------------------//
+
+    //  assert() checked polymorphic downcast.  Crosscasts prohibited.
+
+    //  WARNING: Because this cast uses assert(), it violates the One Definition
+    //  Rule if NDEBUG is inconsistently defined across translation units.
+
+    //  Contributed by Dave Abrahams
+
+    template <class Target, class Source>
+    inline Target polymorphic_downcast(Source* x BOOST_EXPLICIT_DEFAULT_TARGET)
+    {
+        assert( dynamic_cast<Target>(x) == x );  // detect logic error
+        return static_cast<Target>(x);
+    }
+
+//  implicit_cast  -----------------------------------------------------------//
+//
+//  Removed due to uncertain purpose.  Use either numeric_cast (see below)
+//  or static_cast according to the need. 
+
+//  numeric_cast and related exception  --------------------------------------//
+
+//  Contributed by Kevlin Henney
+
+//  bad_numeric_cast  --------------------------------------------------------//
+
+    // exception used to indicate runtime numeric_cast failure
+    class bad_numeric_cast : public std::bad_cast
+    {
+    public:
+        // constructors, destructors and assignment operator defaulted
+
+        // function inlined for brevity and consistency with rest of library
+        virtual const char *what() const throw()
+        {
+            return "bad numeric cast: loss of range in numeric_cast";
+        }
+    };
+
+//  numeric_cast  ------------------------------------------------------------//
+
+    template<typename Target, typename Source>
+    inline Target numeric_cast(Source arg BOOST_EXPLICIT_DEFAULT_TARGET)
+    {
+        // typedefs abbreviating respective trait classes
+        typedef std::numeric_limits<Source> arg_traits;
+        typedef std::numeric_limits<Target> result_traits;
+
+        // typedefs that act as compile time assertions
+        // (to be replaced by boost compile time assertions
+        // as and when they become available and are stable)
+        typedef bool argument_must_be_numeric[arg_traits::is_specialized];
+        typedef bool result_must_be_numeric[result_traits::is_specialized];
+
+        if( (arg < 0 && !result_traits::is_signed) ||  // loss of negative range
+              (arg_traits::is_signed &&
+                 arg < result_traits::min()) ||        // underflow
+               arg > result_traits::max() )            // overflow
+            throw bad_numeric_cast();
+        return static_cast<Target>(arg);
+    }
+
+//  Visual C++ workarounds  --------------------------------------------------//
+
+#  if !(defined(BOOST_MSVC) && BOOST_MSVC <= 1200) // 1200 = VC6
+  } // namespace cast
+
+  using ::boost::cast::polymorphic_cast;
+  using ::boost::cast::polymorphic_downcast;
+  using ::boost::cast::bad_numeric_cast;
+  using ::boost::cast::numeric_cast;
+#  else
+  namespace cast {
+    using ::boost::polymorphic_cast;
+    using ::boost::polymorphic_downcast;
+    using ::boost::bad_numeric_cast;
+    using ::boost::numeric_cast;
+  }
+#  endif
+
+#  undef BOOST_EXPLICIT_DEFAULT_TARGET
+#  undef BOOST_EXPLICIT_TARGET
+
+} // namespace boost
+
+#endif  // BOOST_CAST_HPP
+