ceph/src/boost/boost/type_index/runtime_cast/register_runtime_class.hpp

   1 //
   2 // Copyright (c) Chris Glover, 2016.
   3 //
   4 //
   5 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   6 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 //
   8
   9 #ifndef BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP
  10 #define BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP
  11
  12 /// \file register_runtime_class.hpp
  13 /// \brief Contains the macros BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST and
  14 /// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
  15 #include <boost/type_index.hpp>
  16 #include <boost/preprocessor/seq/for_each.hpp>
  17
  18 #ifdef BOOST_HAS_PRAGMA_ONCE
  19 # pragma once
  20 #endif
  21
  22 namespace boost { namespace typeindex {
  23
  24 namespace detail {
  25
  26 template<typename T>
  27 inline type_index runtime_class_construct_type_id(T const*) {
  28     return type_id<T>();
  29 }
  30
  31 } // namespace detail
  32
  33 }} // namespace boost::typeindex
  34
  35 /// @cond
  36
  37 #define BOOST_TYPE_INDEX_CHECK_BASE_(r, data, Base) \
  38     if(void const* ret_val = this->Base::boost_type_index_find_instance_(idx)) return ret_val;
  39
  40 /// @endcond
  41
  42 /// \def BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
  43 /// \brief Macro used to make a class compatible with boost::typeindex::runtime_cast
  44 ///
  45 /// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS generates a virtual function
  46 /// in the current class that, when combined with the supplied base class information, allows
  47 /// boost::typeindex::runtime_cast to accurately convert between dynamic types of instances of
  48 /// the current class.
  49 ///
  50 /// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS also adds support for boost::typeindex::type_id_runtime
  51 /// by including BOOST_TYPE_INDEX_REGISTER_CLASS. It is typical that these features are used together,
  52 /// but in the event that BOOST_TYPE_INDEX_REGISTER_CLASS is undesirable in the current class,
  53 /// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST is provided.
  54 ///
  55 /// \b Example:
  56 /// \code
  57 /// struct base1 {
  58 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
  59 ///     virtual ~base1();
  60 /// };
  61 ///
  62 /// struct base2 {
  63 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
  64 ///     virtual ~base2();
  65 /// };
  66 ///
  67 /// struct derived1 : base1 {
  68 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1))
  69 /// };
  70 ///
  71 /// struct derived2 : base1, base2 {
  72 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1)(base2))
  73 /// };
  74 ///
  75 /// ...
  76 ///
  77 /// base1* pb1 = get_object();
  78 /// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1)) {
  79 ///     assert(boost::typeindex::type_id_runtime(*pb1)) == boost::typeindex::type_id<derived2>());
  80 /// }
  81 /// \endcode
  82 ///
  83 /// \param base_class_seq A Boost.Preprocessor sequence of the current class' direct bases, or
  84 /// BOOST_TYPE_INDEX_NO_BASE_CLASS if this class has no direct base classes.
  85 #define BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(base_class_seq)                                                          \
  86     BOOST_TYPE_INDEX_REGISTER_CLASS                                                                                                                                                                      \
  87     BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(base_class_seq)
  88
  89 /// \def BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST
  90 /// \brief Macro used to make a class compatible with boost::typeindex::runtime_cast without including
  91 /// support for boost::typeindex::type_id_runtime.
  92 ///
  93 /// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST is provided as an alternative to BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
  94 /// in the event that support for boost::typeindex::type_id_runtime is undesirable.
  95 ///
  96 /// \b Example:
  97 /// \code
  98 /// struct base1 {
  99 ///     BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(BOOST_TYPE_INDEX_NO_BASE_CLASS)
 100 ///     virtual ~base1();
 101 /// };
 102 ///
 103 /// struct base2 {
 104 ///     BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(BOOST_TYPE_INDEX_NO_BASE_CLASS)
 105 ///     virtual ~base2();
 106 /// };
 107 ///
 108 /// struct derived1 : base1 {
 109 ///     BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST((base1))
 110 /// };
 111 ///
 112 /// struct derived2 : base1, base2 {
 113 ///     BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST((base1)(base2))
 114 /// };
 115 ///
 116 /// ...
 117 ///
 118 /// base1* pb1 = get_object();
 119 /// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1))
 120 /// { /* can't call boost::typeindex::type_id_runtime(*pb1) here */ }
 121 /// \endcode
 122 ///
 123 /// \param base_class_seq A Boost.Preprocessor sequence of the current class' direct bases, or
 124 /// BOOST_TYPE_INDEX_NO_BASE_CLASS if this class has no direct base classes.
 125 #define BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(base_class_seq)                                                          \
 126     virtual void const* boost_type_index_find_instance_(boost::typeindex::type_index const& idx) const BOOST_NOEXCEPT {  \
 127         if(idx == boost::typeindex::detail::runtime_class_construct_type_id(this))                                       \
 128             return this;                                                                                                 \
 129          BOOST_PP_SEQ_FOR_EACH(BOOST_TYPE_INDEX_CHECK_BASE_, _, base_class_seq)                                          \
 130          return NULL;                                                                                                    \
 131     }
 132
 133 /// \def BOOST_TYPE_INDEX_NO_BASE_CLASS
 134 /// \brief Instructs BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS and BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST
 135 /// that this class has no base classes.
 136 #define BOOST_TYPE_INDEX_NO_BASE_CLASS BOOST_PP_SEQ_NIL
 137
 138 #endif // BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP