ceph/src/boost/boost/polymorphic_cast.hpp

   1 //  boost polymorphic_cast.hpp header file  ----------------------------------------------//
   2
   3 //  (C) Copyright Kevlin Henney and Dave Abrahams 1999.
   4 //  (C) Copyright Boris Rasin 2014.
   5 //  Distributed under the Boost
   6 //  Software License, Version 1.0. (See accompanying file
   7 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8
   9 //  See http://www.boost.org/libs/conversion for Documentation.
  10
  11 //  Revision History
  12 //  10 Nov 14  polymorphic_pointer_downcast moved to a separate header,
  13 //             minor improvements to stisfy latest Boost coding style
  14 //  08 Nov 14  Add polymorphic_pointer_downcast (Boris Rasin)
  15 //  09 Jun 14  "cast.hpp" was renamed to "polymorphic_cast.hpp" and
  16 //             inclusion of numeric_cast was removed (Antony Polukhin)
  17 //  23 Jun 05  numeric_cast removed and redirected to the new verion (Fernando Cacciola)
  18 //  02 Apr 01  Removed BOOST_NO_LIMITS workarounds and included
  19 //             <boost/limits.hpp> instead (the workaround did not
  20 //             actually compile when BOOST_NO_LIMITS was defined in
  21 //             any case, so we loose nothing). (John Maddock)
  22 //  21 Jan 01  Undid a bug I introduced yesterday. numeric_cast<> never
  23 //             worked with stock GCC; trying to get it to do that broke
  24 //             vc-stlport.
  25 //  20 Jan 01  Moved BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS to config.hpp.
  26 //             Removed unused BOOST_EXPLICIT_TARGET macro. Moved
  27 //             boost::detail::type to boost/type.hpp. Made it compile with
  28 //             stock gcc again (Dave Abrahams)
  29 //  29 Nov 00  Remove nested namespace cast, cleanup spacing before Formal
  30 //             Review (Beman Dawes)
  31 //  19 Oct 00  Fix numeric_cast for floating-point types (Dave Abrahams)
  32 //  15 Jul 00  Suppress numeric_cast warnings for GCC, Borland and MSVC
  33 //             (Dave Abrahams)
  34 //  30 Jun 00  More MSVC6 wordarounds.  See comments below.  (Dave Abrahams)
  35 //  28 Jun 00  Removed implicit_cast<>.  See comment below. (Beman Dawes)
  36 //  27 Jun 00  More MSVC6 workarounds
  37 //  15 Jun 00  Add workarounds for MSVC6
  38 //   2 Feb 00  Remove bad_numeric_cast ";" syntax error (Doncho Angelov)
  39 //  26 Jan 00  Add missing throw() to bad_numeric_cast::what(0 (Adam Levar)
  40 //  29 Dec 99  Change using declarations so usages in other namespaces work
  41 //             correctly (Dave Abrahams)
  42 //  23 Sep 99  Change polymorphic_downcast assert to also detect M.I. errors
  43 //             as suggested Darin Adler and improved by Valentin Bonnard.
  44 //   2 Sep 99  Remove controversial asserts, simplify, rename.
  45 //  30 Aug 99  Move to cast.hpp, replace value_cast with numeric_cast,
  46 //             place in nested namespace.
  47 //   3 Aug 99  Initial version
  48
  49 #ifndef BOOST_POLYMORPHIC_CAST_HPP
  50 #define BOOST_POLYMORPHIC_CAST_HPP
  51
  52 # include <boost/config.hpp>
  53
  54 #ifdef BOOST_HAS_PRAGMA_ONCE
  55 #   pragma once
  56 #endif
  57
  58 # include <boost/assert.hpp>
  59 # include <boost/core/addressof.hpp>
  60 # include <boost/core/enable_if.hpp>
  61 # include <boost/throw_exception.hpp>
  62 # include <boost/type_traits/is_reference.hpp>
  63 # include <boost/type_traits/remove_reference.hpp>
  64
  65 # include <typeinfo>
  66
  67 namespace boost
  68 {
  69 //  See the documentation for descriptions of how to choose between
  70 //  static_cast<>, dynamic_cast<>, polymorphic_cast<> and polymorphic_downcast<>
  71
  72 //  polymorphic_cast  --------------------------------------------------------//
  73
  74     //  Runtime checked polymorphic downcasts and crosscasts.
  75     //  Suggested in The C++ Programming Language, 3rd Ed, Bjarne Stroustrup,
  76     //  section 15.8 exercise 1, page 425.
  77
  78     template <class Target, class Source>
  79     inline Target polymorphic_cast(Source* x)
  80     {
  81         Target tmp = dynamic_cast<Target>(x);
  82         if ( tmp == 0 ) boost::throw_exception( std::bad_cast() );
  83         return tmp;
  84     }
  85
  86 //  polymorphic_downcast  ----------------------------------------------------//
  87
  88     //  BOOST_ASSERT() checked raw pointer polymorphic downcast.  Crosscasts prohibited.
  89
  90     //  WARNING: Because this cast uses BOOST_ASSERT(), it violates
  91     //  the One Definition Rule if used in multiple translation units
  92     //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
  93     //  NDEBUG are defined inconsistently.
  94
  95     //  Contributed by Dave Abrahams
  96
  97     template <class Target, class Source>
  98     inline Target polymorphic_downcast(Source* x)
  99     {
 100         BOOST_ASSERT( dynamic_cast<Target>(x) == x );  // detect logic error
 101         return static_cast<Target>(x);
 102     }
 103
 104     //  BOOST_ASSERT() checked reference polymorphic downcast.  Crosscasts prohibited.
 105
 106     //  WARNING: Because this cast uses BOOST_ASSERT(), it violates
 107     //  the One Definition Rule if used in multiple translation units
 108     //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
 109     //  NDEBUG are defined inconsistently.
 110
 111     //  Contributed by Julien Delacroix
 112
 113     template <class Target, class Source>
 114     inline typename boost::enable_if_c<
 115         boost::is_reference<Target>::value, Target
 116     >::type polymorphic_downcast(Source& x)
 117     {
 118         typedef typename boost::remove_reference<Target>::type* target_pointer_type;
 119         return *boost::polymorphic_downcast<target_pointer_type>(
 120             boost::addressof(x)
 121         );
 122     }
 123
 124 } // namespace boost
 125
 126 #endif  // BOOST_POLYMORPHIC_CAST_HPP