ceph/src/boost/libs/type_index/include/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 macro BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
  14 #include <boost/type_index.hpp>
  15 #include <boost/preprocessor/seq/for_each.hpp>
  16
  17 #ifdef BOOST_HAS_PRAGMA_ONCE
  18 # pragma once
  19 #endif
  20
  21 namespace boost { namespace typeindex {
  22
  23 namespace detail {
  24
  25 template<typename T>
  26 inline type_index runtime_class_construct_type_id(T const*) {
  27     return type_id<T>();
  28 }
  29
  30 } // namespace detail
  31
  32 /// @cond
  33
  34 #define BOOST_TYPE_INDEX_CHECK_BASE_(r, data, Base) \
  35     if(void const* ret_val = this->Base::boost_type_index_find_instance_(idx)) return ret_val;
  36
  37 /// @endcond
  38
  39 /// \def BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
  40 /// \brief Macro used to make a class compatible with boost::typeindex::runtime_cast
  41 ///
  42 /// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS generates a virtual function
  43 /// in the current class that, when combined with the supplied base class information, allows
  44 /// boost::typeindex::runtime_cast to accurately convert between dynamic types of instances of
  45 /// the current class.
  46 ///
  47 /// \b Example:
  48 /// \code
  49 /// struct base1 {
  50 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
  51 ///     virtual ~base1();
  52 /// };
  53 ///
  54 /// struct base2 {
  55 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
  56 ///     virtual ~base2();
  57 /// };
  58 ///
  59 /// struct derived1 : base1 {
  60 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1))
  61 /// };
  62 ///
  63 /// struct derived2 : base1, base2 {
  64 ///     BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1)(base2))
  65 /// };
  66 ///
  67 /// ...
  68 ///
  69 /// base1* pb1 = get_object();
  70 /// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1))
  71 /// { /* ... */ }
  72 /// \endcode
  73 ///
  74 /// \param base_class_seq A Boost.Preprocessor sequence of the current class' direct bases, or
  75 /// BOOST_PP_SEQ_NIL if this class has no direct base classes.
  76 #define BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(base_class_seq)                                                          \
  77     BOOST_TYPE_INDEX_REGISTER_CLASS                                                                                      \
  78     virtual void const* boost_type_index_find_instance_(boost::typeindex::type_index const& idx) const BOOST_NOEXCEPT {  \
  79         if(idx == boost::typeindex::detail::runtime_class_construct_type_id(this))                                       \
  80             return this;                                                                                                 \
  81          BOOST_PP_SEQ_FOR_EACH(BOOST_TYPE_INDEX_CHECK_BASE_, _, base_class_seq)                                          \
  82          return NULL;                                                                                                    \
  83     }
  84 }} // namespace boost::typeindex
  85
  86 #define BOOST_TYPE_INDEX_NO_BASE_CLASS BOOST_PP_SEQ_NIL
  87
  88 #endif // BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP