source: NonGTP/Boost/boost/cast.hpp @ 857

Revision 857, 4.4 KB checked in by igarcia, 19 years ago (diff)
RevLine 
[857]1//  boost cast.hpp header file  ----------------------------------------------//
2
3//  (C) Copyright Kevlin Henney and Dave Abrahams 1999.
4//  Distributed under the Boost
5//  Software License, Version 1.0. (See accompanying file
6//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7
8//  See http://www.boost.org/libs/conversion for Documentation.
9
10//  Revision History
11//  23 JUn 05  numeric_cast removed and redirected to the new verion (Fernando Cacciola)
12//  02 Apr 01  Removed BOOST_NO_LIMITS workarounds and included
13//             <boost/limits.hpp> instead (the workaround did not
14//             actually compile when BOOST_NO_LIMITS was defined in
15//             any case, so we loose nothing). (John Maddock)
16//  21 Jan 01  Undid a bug I introduced yesterday. numeric_cast<> never
17//             worked with stock GCC; trying to get it to do that broke
18//             vc-stlport.
19//  20 Jan 01  Moved BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS to config.hpp.
20//             Removed unused BOOST_EXPLICIT_TARGET macro. Moved
21//             boost::detail::type to boost/type.hpp. Made it compile with
22//             stock gcc again (Dave Abrahams)
23//  29 Nov 00  Remove nested namespace cast, cleanup spacing before Formal
24//             Review (Beman Dawes)
25//  19 Oct 00  Fix numeric_cast for floating-point types (Dave Abrahams)
26//  15 Jul 00  Suppress numeric_cast warnings for GCC, Borland and MSVC
27//             (Dave Abrahams)
28//  30 Jun 00  More MSVC6 wordarounds.  See comments below.  (Dave Abrahams)
29//  28 Jun 00  Removed implicit_cast<>.  See comment below. (Beman Dawes)
30//  27 Jun 00  More MSVC6 workarounds
31//  15 Jun 00  Add workarounds for MSVC6
32//   2 Feb 00  Remove bad_numeric_cast ";" syntax error (Doncho Angelov)
33//  26 Jan 00  Add missing throw() to bad_numeric_cast::what(0 (Adam Levar)
34//  29 Dec 99  Change using declarations so usages in other namespaces work
35//             correctly (Dave Abrahams)
36//  23 Sep 99  Change polymorphic_downcast assert to also detect M.I. errors
37//             as suggested Darin Adler and improved by Valentin Bonnard.
38//   2 Sep 99  Remove controversial asserts, simplify, rename.
39//  30 Aug 99  Move to cast.hpp, replace value_cast with numeric_cast,
40//             place in nested namespace.
41//   3 Aug 99  Initial version
42
43#ifndef BOOST_CAST_HPP
44#define BOOST_CAST_HPP
45
46# include <boost/config.hpp>
47# include <cassert>
48# include <typeinfo>
49# include <boost/type.hpp>
50# include <boost/limits.hpp>
51# include <boost/detail/select_type.hpp>
52
53//  It has been demonstrated numerous times that MSVC 6.0 fails silently at link
54//  time if you use a template function which has template parameters that don't
55//  appear in the function's argument list.
56//
57//  TODO: Add this to config.hpp?
58# if defined(BOOST_MSVC) && BOOST_MSVC <= 1200 // 1200 = VC6
59#  define BOOST_EXPLICIT_DEFAULT_TARGET , ::boost::type<Target>* = 0
60# else
61#  define BOOST_EXPLICIT_DEFAULT_TARGET
62# endif
63
64namespace boost
65{
66//  See the documentation for descriptions of how to choose between
67//  static_cast<>, dynamic_cast<>, polymorphic_cast<> and polymorphic_downcast<>
68
69//  polymorphic_cast  --------------------------------------------------------//
70
71    //  Runtime checked polymorphic downcasts and crosscasts.
72    //  Suggested in The C++ Programming Language, 3rd Ed, Bjarne Stroustrup,
73    //  section 15.8 exercise 1, page 425.
74
75    template <class Target, class Source>
76    inline Target polymorphic_cast(Source* x BOOST_EXPLICIT_DEFAULT_TARGET)
77    {
78        Target tmp = dynamic_cast<Target>(x);
79        if ( tmp == 0 ) throw std::bad_cast();
80        return tmp;
81    }
82
83//  polymorphic_downcast  ----------------------------------------------------//
84
85    //  assert() checked polymorphic downcast.  Crosscasts prohibited.
86
87    //  WARNING: Because this cast uses assert(), it violates the One Definition
88    //  Rule if NDEBUG is inconsistently defined across translation units.
89
90    //  Contributed by Dave Abrahams
91
92    template <class Target, class Source>
93    inline Target polymorphic_downcast(Source* x BOOST_EXPLICIT_DEFAULT_TARGET)
94    {
95        assert( dynamic_cast<Target>(x) == x );  // detect logic error
96        return static_cast<Target>(x);
97    }
98
99#  undef BOOST_EXPLICIT_DEFAULT_TARGET
100
101} // namespace boost
102
103# include <boost/numeric/conversion/cast.hpp>
104
105#endif  // BOOST_CAST_HPP
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