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Add BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST, which implementes the functionality for runtime_cast to function, but does not include the BOOST_TYPE_INDEX_REGISTER_CLASS macro.

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Reimplement BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS to simply call BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST and BOOST_TYPE_INDEX_REGISTER_CLASS.

This allows users to opt-in to one or the other, instead of forcing them to generate both virtual functions.
This commit is contained in:
Chris Glover
2016-11-05 16:04:13 -04:00
parent c52fdfe30c
commit d8bdbad2ec
1 changed files with 56 additions and 6 deletions
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62
include/boost/type_index/runtime_cast/register_runtime_class.hpp
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@ -10,7 +10,8 @@
#define BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP
/// \file register_runtime_class.hpp
/// \brief Contains the macro BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
/// \brief Contains the macros BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST and
/// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
#include <boost/type_index.hpp>
#include <boost/preprocessor/seq/for_each.hpp>
@ -29,6 +30,8 @@ inline type_index runtime_class_construct_type_id(T const*) {
} // namespace detail
}} // namespace boost::typeindex
/// @cond
#define BOOST_TYPE_INDEX_CHECK_BASE_(r, data, Base) \
@ -44,6 +47,11 @@ inline type_index runtime_class_construct_type_id(T const*) {
/// boost::typeindex::runtime_cast to accurately convert between dynamic types of instances of
/// the current class.
///
/// BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS also adds support for boost::typeindex::type_id_runtime
/// by including BOOST_TYPE_INDEX_REGISTER_CLASS. It is typical that these features are used together,
/// but in the event that BOOST_TYPE_INDEX_REGISTER_CLASS is undesirable in the current class,
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST is provided.
///
/// \b Example:
/// \code
/// struct base1 {
@ -67,22 +75,64 @@ inline type_index runtime_class_construct_type_id(T const*) {
/// ...
///
/// base1* pb1 = get_object();
/// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1))
/// { /* ... */ }
/// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1)) {
/// assert(boost::typeindex::type_id_runtime(*pb1)) == boost::typeindex::type_id<derived2>());
/// }
/// \endcode
///
/// \param base_class_seq A Boost.Preprocessor sequence of the current class' direct bases, or
/// BOOST_PP_SEQ_NIL if this class has no direct base classes.
/// BOOST_TYPE_INDEX_NO_BASE_CLASS if this class has no direct base classes.
#define BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(base_class_seq) \
BOOST_TYPE_INDEX_REGISTER_CLASS \
BOOST_TYPE_INDEX_REGISTER_CLASS \
BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(base_class_seq)
/// \def BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST
/// \brief Macro used to make a class compatible with boost::typeindex::runtime_cast without including
/// support for boost::typeindex::type_id_runtime.
///
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST is provided as an alternative to BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS
/// in the event that support for boost::typeindex::type_id_runtime is undesirable.
///
/// \b Example:
/// \code
/// struct base1 {
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(BOOST_TYPE_INDEX_NO_BASE_CLASS)
/// virtual ~base1();
/// };
///
/// struct base2 {
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(BOOST_TYPE_INDEX_NO_BASE_CLASS)
/// virtual ~base2();
/// };
///
/// struct derived1 : base1 {
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST((base1))
/// };
///
/// struct derived2 : base1, base2 {
/// BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST((base1)(base2))
/// };
///
/// ...
///
/// base1* pb1 = get_object();
/// if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1))
/// { /* can't call boost::typeindex::type_id_runtime(*pb1) here */ }
/// \endcode
///
/// \param base_class_seq A Boost.Preprocessor sequence of the current class' direct bases, or
/// BOOST_TYPE_INDEX_NO_BASE_CLASS if this class has no direct base classes.
#define BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST(base_class_seq) \
virtual void const* boost_type_index_find_instance_(boost::typeindex::type_index const& idx) const BOOST_NOEXCEPT { \
if(idx == boost::typeindex::detail::runtime_class_construct_type_id(this)) \
return this; \
BOOST_PP_SEQ_FOR_EACH(BOOST_TYPE_INDEX_CHECK_BASE_, _, base_class_seq) \
return NULL; \
}
}} // namespace boost::typeindex
/// \def BOOST_TYPE_INDEX_NO_BASE_CLASS
/// \brief Instructs BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS and BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST
/// that this class has no base classes.
#define BOOST_TYPE_INDEX_NO_BASE_CLASS BOOST_PP_SEQ_NIL
#endif // BOOST_TYPE_INDEX_RUNTIME_CAST_REGISTER_RUNTIME_CLASS_HPP