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/integral_constant.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/integral_c.hpp>
#include <boost/mpl/vector/vector0.hpp>
#if BOOST_WORKAROUND(BOOST_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>
# 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
#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(BOOST_BORLANDC, <= 0x565)
template<typename T, typename OrigT, typename L> struct components_bcc;
#endif
}
template<typename T, typename ClassTypeTransform>
struct components
#if !BOOST_WORKAROUND(BOOST_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(BOOST_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
} // namespace ::boost
#include <boost/function_types/detail/components_as_mpl_sequence.hpp>
#include <boost/function_types/detail/retag_default_cc.hpp>
#endif