ceph/src/boost/boost/polymorphic_pointer_cast.hpp

   1 //  boost polymorphic_pointer_cast.hpp header file  ----------------------------------------------//
   2 //  (C) Copyright Boris Rasin, 2014-2021.
   3 //  (C) Copyright Antony Polukhin, 2014-2022.
   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 #ifndef BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
  11 #define BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP
  12
  13 # include <boost/config.hpp>
  14 # include <boost/assert.hpp>
  15 # include <boost/pointer_cast.hpp>
  16 # include <boost/throw_exception.hpp>
  17 # include <boost/utility/declval.hpp>
  18 # ifdef BOOST_NO_CXX11_DECLTYPE
  19 #   include <boost/typeof/typeof.hpp>
  20 # endif
  21
  22 #ifdef BOOST_HAS_PRAGMA_ONCE
  23 #   pragma once
  24 #endif
  25
  26 namespace boost
  27 {
  28 //  See the documentation for descriptions of how to choose between
  29 //  static_pointer_cast<>, dynamic_pointer_cast<>, polymorphic_pointer_cast<> and polymorphic_pointer_downcast<>
  30
  31 //  polymorphic_pointer_downcast  --------------------------------------------//
  32
  33     //  BOOST_ASSERT() checked polymorphic downcast.  Crosscasts prohibited.
  34     //  Supports any type with static_pointer_cast/dynamic_pointer_cast functions:
  35     //  built-in pointers, std::shared_ptr, boost::shared_ptr, boost::intrusive_ptr, etc.
  36
  37     //  WARNING: Because this cast uses BOOST_ASSERT(), it violates
  38     //  the One Definition Rule if used in multiple translation units
  39     //  where BOOST_DISABLE_ASSERTS, BOOST_ENABLE_ASSERT_HANDLER
  40     //  NDEBUG are defined inconsistently.
  41
  42     //  Contributed by Boris Rasin
  43
  44     namespace detail
  45     {
  46         template <typename Target, typename Source>
  47         struct dynamic_pointer_cast_result
  48         {
  49 #ifdef BOOST_NO_CXX11_DECLTYPE
  50             BOOST_TYPEOF_NESTED_TYPEDEF_TPL(nested, dynamic_pointer_cast<Target>(boost::declval<Source>()))
  51             typedef typename nested::type type;
  52 #else
  53             typedef decltype(dynamic_pointer_cast<Target>(boost::declval<Source>())) type;
  54 #endif
  55         };
  56     }
  57
  58     template <typename Target, typename Source>
  59     inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
  60     polymorphic_pointer_downcast (const Source& x)
  61     {
  62         BOOST_ASSERT(dynamic_pointer_cast<Target> (x) == x);
  63         return static_pointer_cast<Target> (x);
  64     }
  65
  66     template <typename Target, typename Source>
  67     inline typename detail::dynamic_pointer_cast_result<Target, Source>::type
  68     polymorphic_pointer_cast (const Source& x)
  69     {
  70         typename detail::dynamic_pointer_cast_result<Target, Source>::type tmp
  71             = dynamic_pointer_cast<Target> (x);
  72         if ( !tmp ) boost::throw_exception( std::bad_cast() );
  73
  74         return tmp;
  75     }
  76
  77 } // namespace boost
  78
  79 #endif  // BOOST_CONVERSION_POLYMORPHIC_POINTER_CAST_HPP