boost/function_types/components.hpp
// (C) Copyright Tobias Schwinger // // Use modification and distribution are subject to the boost Software License, // Version 1.0. (See http://www.boost.org/LICENSE_1_0.txt). //------------------------------------------------------------------------------ #ifndef BOOST_FT_COMPONENTS_HPP_INCLUDED #define BOOST_FT_COMPONENTS_HPP_INCLUDED #include <cstddef> #include <boost/config.hpp> #include <boost/detail/workaround.hpp> #include <boost/mpl/aux_/lambda_support.hpp> #include <boost/type_traits/detail/template_arity_spec.hpp> #include <boost/type_traits/integral_constant.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/integral_c.hpp> #include <boost/mpl/vector/vector0.hpp> #if BOOST_WORKAROUND(__BORLANDC__, <= 0x565) # include <boost/type_traits/remove_cv.hpp> # include <boost/mpl/identity.hpp> # include <boost/mpl/bitand.hpp> # include <boost/mpl/vector/vector10.hpp> # include <boost/mpl/front.hpp> # include <boost/mpl/begin.hpp> # include <boost/mpl/advance.hpp> # include <boost/mpl/iterator_range.hpp> # include <boost/mpl/joint_view.hpp> # include <boost/mpl/equal_to.hpp> # include <boost/mpl/copy.hpp> # include <boost/mpl/front_inserter.hpp> # include <boost/function_types/detail/classifier.hpp> #endif #ifndef BOOST_FT_NO_CV_FUNC_SUPPORT # include <boost/mpl/remove.hpp> #endif #include <boost/function_types/config/config.hpp> #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION # if BOOST_FT_MAX_ARITY < 10 # include <boost/mpl/vector/vector10.hpp> # elif BOOST_FT_MAX_ARITY < 20 # include <boost/mpl/vector/vector20.hpp> # elif BOOST_FT_MAX_ARITY < 30 # include <boost/mpl/vector/vector30.hpp> # elif BOOST_FT_MAX_ARITY < 40 # include <boost/mpl/vector/vector40.hpp> # elif BOOST_FT_MAX_ARITY < 50 # include <boost/mpl/vector/vector50.hpp> # endif #else # include <boost/function_types/detail/classifier.hpp> #endif #include <boost/function_types/detail/class_transform.hpp> #include <boost/function_types/property_tags.hpp> // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - namespace boost { namespace function_types { using mpl::placeholders::_; template< typename T, typename ClassTypeTransform = add_reference<_> > struct components; namespace detail { template<typename T, typename L> struct components_impl; #if BOOST_WORKAROUND(__BORLANDC__, <= 0x565) template<typename T, typename OrigT, typename L> struct components_bcc; #endif } template<typename T, typename ClassTypeTransform> struct components #if !BOOST_WORKAROUND(__BORLANDC__, <= 0x565) : detail::components_impl<T, ClassTypeTransform> #else : detail::components_bcc<typename remove_cv<T>::type,T, ClassTypeTransform> #endif { typedef components<T,ClassTypeTransform> type; BOOST_MPL_AUX_LAMBDA_SUPPORT(2,components,(T,ClassTypeTransform)) }; // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - namespace detail { struct components_mpl_sequence_tag; struct components_non_func_base { typedef mpl::vector0<> types; typedef void function_arity; typedef detail::constant<0> bits; typedef detail::constant<0> mask; typedef components_mpl_sequence_tag tag; }; template < typename Components , typename IfTagged , typename ThenTag , typename DefaultBase = components_non_func_base > struct retagged_if : mpl::if_ < detail::represents_impl<Components, IfTagged> , detail::changed_tag<Components,IfTagged,ThenTag> , DefaultBase >::type { }; // We detect plain function types and function references as function // pointers by recursive instantiation of components_impl. // The third specialization of components_impl makes sure the recursion // terminates (when adding pointers). template<typename T, typename L> struct components_impl : detail::retagged_if < detail::components_impl<T*,L> , pointer_tag, /* --> */ function_tag > { }; template<typename T, typename L> struct components_impl<T&, L> : detail::retagged_if < detail::components_impl<T*,L> , pointer_tag, /* --> */ reference_tag > { }; #if !BOOST_FT_NO_CV_FUNC_SUPPORT // Retry the type with a member pointer attached to detect cv functions class a_class; template<typename Base, typename T, typename L> struct cv_func_base : detail::retagged_if<Base,member_pointer_tag,function_tag> { typedef typename mpl::remove < typename Base::types , typename detail::class_transform<a_class,L>::type>::type types; }; template<typename T, typename L> struct components_impl<T*, L> : mpl::if_ < detail::represents_impl< detail::components_impl<T a_class::*, L> , member_pointer_tag > , detail::cv_func_base< detail::components_impl<T a_class::*, L>, T, L> , components_non_func_base >::type { }; template<typename T, typename L> struct components_impl<T a_class::*, L> : components_non_func_base { }; #else template<typename T, typename L> struct components_impl<T*, L> : components_non_func_base { }; #endif template<typename T, typename L> struct components_impl<T* const, L> : components_impl<T*,L> { }; template<typename T, typename L> struct components_impl<T* volatile, L> : components_impl<T*,L> { }; template<typename T, typename L> struct components_impl<T* const volatile, L> : components_impl<T*,L> { }; template<typename T, typename L> struct components_impl<T const, L> : components_impl<T,L> { }; template<typename T, typename L> struct components_impl<T volatile, L> : components_impl<T,L> { }; template<typename T, typename L> struct components_impl<T const volatile, L> : components_impl<T,L> { }; template<typename T, class C> struct member_obj_ptr_result { typedef T & type; }; template<typename T, class C> struct member_obj_ptr_result<T, C const> { typedef T const & type; }; template<typename T, class C> struct member_obj_ptr_result<T, C volatile> { typedef T volatile & type; }; template<typename T, class C> struct member_obj_ptr_result<T, C const volatile> { typedef T const volatile & type; }; template<typename T, class C> struct member_obj_ptr_result<T &, C> { typedef T & type; }; template<typename T, class C> struct member_obj_ptr_result<T &, C const> { typedef T & type; }; template<typename T, class C> struct member_obj_ptr_result<T &, C volatile> { typedef T & type; }; template<typename T, class C> struct member_obj_ptr_result<T &, C const volatile> { typedef T & type; }; template<typename T, class C, typename L> struct member_obj_ptr_components : member_object_pointer_base { typedef function_types::components<T C::*, L> type; typedef components_mpl_sequence_tag tag; typedef mpl::integral_c<std::size_t,1> function_arity; typedef mpl::vector2< typename detail::member_obj_ptr_result<T,C>::type, typename detail::class_transform<C,L>::type > types; }; #if !BOOST_WORKAROUND(__BORLANDC__, <= 0x565) # define BOOST_FT_variations BOOST_FT_pointer|BOOST_FT_member_pointer template<typename T, class C, typename L> struct components_impl<T C::*, L> : member_obj_ptr_components<T,C,L> { }; #else # define BOOST_FT_variations BOOST_FT_pointer // This workaround removes the member pointer from the type to allow // detection of member function pointers with BCC. template<typename T, typename C, typename L> struct components_impl<T C::*, L> : detail::retagged_if < detail::components_impl<typename boost::remove_cv<T>::type *, L> , pointer_tag, /* --> */ member_function_pointer_tag , member_obj_ptr_components<T,C,L> > { }; // BCC lets us test the cv-qualification of a function type by template // partial specialization - so we use this bug feature to find out the // member function's cv-qualification (unfortunately there are some // invisible modifiers that impose some limitations on these types even if // we remove the qualifiers, So we cannot exploit the same bug to make the // library work for cv-qualified function types). template<typename T> struct encode_cv { typedef char (& type)[1]; BOOST_STATIC_CONSTANT(std::size_t, value = 1); }; template<typename T> struct encode_cv<T const *> { typedef char (& type)[2]; BOOST_STATIC_CONSTANT(std::size_t, value = 2); }; template<typename T> struct encode_cv<T volatile *> { typedef char (& type)[3]; BOOST_STATIC_CONSTANT(std::size_t, value = 3); }; template<typename T> struct encode_cv<T const volatile *> { typedef char (& type)[4]; BOOST_STATIC_CONSTANT(std::size_t, value = 4); }; // For member function pointers we have to use a function template (partial // template specialization for a member pointer drops the cv qualification // of the function type). template<typename T, typename C> typename encode_cv<T *>::type mfp_cv_tester(T C::*); template<typename T> struct encode_mfp_cv { BOOST_STATIC_CONSTANT(std::size_t, value = sizeof(detail::mfp_cv_tester((T)0L))); }; // Associate bits with the CV codes above. template<std::size_t> struct cv_tag_mfp_impl; template<typename T> struct cv_tag_mfp : detail::cv_tag_mfp_impl < ::boost::function_types::detail::encode_mfp_cv<T>::value > { }; template<> struct cv_tag_mfp_impl<1> : non_cv { }; template<> struct cv_tag_mfp_impl<2> : const_non_volatile { }; template<> struct cv_tag_mfp_impl<3> : volatile_non_const { }; template<> struct cv_tag_mfp_impl<4> : cv_qualified { }; // Metafunction to decode the cv code and apply it to a type. // We add a pointer, because otherwise cv-qualifiers won't stick (another bug). template<typename T, std::size_t CV> struct decode_cv; template<typename T> struct decode_cv<T,1> : mpl::identity<T *> {}; template<typename T> struct decode_cv<T,2> : mpl::identity<T const *> {}; template<typename T> struct decode_cv<T,3> : mpl::identity<T volatile *> {}; template<typename T> struct decode_cv<T,4> : mpl::identity<T const volatile *> {}; // The class type transformation comes after adding cv-qualifiers. We have // wrap it to remove the pointer added in decode_cv_impl. template<typename T, typename L> struct bcc_class_transform_impl; template<typename T, typename L> struct bcc_class_transform_impl<T *, L> : class_transform<T,L> { }; template<typename T, typename D, typename L> struct bcc_class_transform : bcc_class_transform_impl < typename decode_cv < T , ::boost::function_types::detail::encode_mfp_cv<D>::value >::type , L > { }; // After extracting the member pointee from the type the class type is still // in the type (somewhere -- you won't see with RTTI, that is) and that type // is flagged unusable and *not* identical to the nonmember function type. // We can, however, decompose this type via components_impl but surprisingly // a pointer to the const qualified class type pops up again as the first // parameter type. // We have to replace this type with the properly cv-qualified and // transformed class type, integrate the cv qualification into the bits. template<typename Base, typename MFP, typename OrigT, typename L> struct mfp_components; template<typename Base, typename T, typename C, typename OrigT, typename L> struct mfp_components<Base,T C::*,OrigT,L> { private: typedef typename mpl::front<typename Base::types>::type result_type; typedef typename detail::bcc_class_transform<C,OrigT,L>::type class_type; typedef mpl::vector2<result_type, class_type> result_and_class_type; typedef typename mpl::advance < typename mpl::begin<typename Base::types>::type , typename mpl::if_ < mpl::equal_to< typename detail::classifier<OrigT>::function_arity , typename Base::function_arity > , mpl::integral_c<int,2> , mpl::integral_c<int,1> >::type >::type from; typedef typename mpl::end<typename Base::types>::type to; typedef mpl::iterator_range<from,to> param_types; typedef mpl::joint_view< result_and_class_type, param_types> types_view; public: typedef typename mpl::reverse_copy<types_view, mpl::front_inserter< mpl::vector0<> > >::type types; typedef typename function_types::tag< Base, detail::cv_tag_mfp<OrigT> >::bits bits; typedef typename Base::mask mask; typedef typename detail::classifier<OrigT>::function_arity function_arity; typedef components_mpl_sequence_tag tag; }; // Now put it all together: detect cv-qualification of function types and do // the weird transformations above for member function pointers. template<typename T, typename OrigT, typename L> struct components_bcc : mpl::if_ < detail::represents_impl< detail::components_impl<T,L> , member_function_pointer_tag> , detail::mfp_components<detail::components_impl<T,L>,T,OrigT,L> , detail::components_impl<T,L> >::type { }; #endif // end of BORLAND WORKAROUND #define BOOST_FT_al_path boost/function_types/detail/components_impl #include <boost/function_types/detail/pp_loop.hpp> } } // namespace function_types::detail BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(2,function_types::components) } // namespace ::boost #include <boost/function_types/detail/components_as_mpl_sequence.hpp> #include <boost/function_types/detail/retag_default_cc.hpp> #endif