Chris@16: // Copyright David Abrahams 2002.
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: #ifndef DEF_HELPER_DWA200287_HPP
Chris@16: # define DEF_HELPER_DWA200287_HPP
Chris@16: 
Chris@16: # include <boost/python/args.hpp>
Chris@16: # include <boost/type_traits/ice.hpp>
Chris@16: # include <boost/type_traits/same_traits.hpp>
Chris@16: # include <boost/python/detail/indirect_traits.hpp>
Chris@16: # include <boost/mpl/not.hpp>
Chris@16: # include <boost/mpl/and.hpp>
Chris@16: # include <boost/mpl/or.hpp>
Chris@16: # include <boost/type_traits/add_reference.hpp>
Chris@16: # include <boost/mpl/lambda.hpp>
Chris@16: # include <boost/mpl/apply.hpp>
Chris@16: # include <boost/tuple/tuple.hpp>
Chris@16: # include <boost/python/detail/not_specified.hpp>
Chris@16: # include <boost/python/detail/def_helper_fwd.hpp>
Chris@16: 
Chris@16: namespace boost { namespace python {
Chris@16: 
Chris@16: struct default_call_policies;
Chris@16: 
Chris@16: namespace detail
Chris@16: {
Chris@16:   // tuple_extract<Tuple,Predicate>::extract(t) returns the first
Chris@16:   // element of a Tuple whose type E satisfies the given Predicate
Chris@16:   // applied to add_reference<E>. The Predicate must be an MPL
Chris@16:   // metafunction class.
Chris@16:   template <class Tuple, class Predicate>
Chris@16:   struct tuple_extract;
Chris@16: 
Chris@16:   // Implementation class for when the tuple's head type does not
Chris@16:   // satisfy the Predicate
Chris@16:   template <bool matched>
Chris@16:   struct tuple_extract_impl
Chris@16:   {
Chris@16:       template <class Tuple, class Predicate>
Chris@16:       struct apply
Chris@16:       {
Chris@16:           typedef typename Tuple::head_type result_type;
Chris@16:           
Chris@16:           static typename Tuple::head_type extract(Tuple const& x)
Chris@16:           {
Chris@16:               return x.get_head();
Chris@16:           }
Chris@16:       };
Chris@16:   };
Chris@16: 
Chris@16:   // Implementation specialization for when the tuple's head type
Chris@16:   // satisfies the predicate
Chris@16:   template <>
Chris@16:   struct tuple_extract_impl<false>
Chris@16:   {
Chris@16:       template <class Tuple, class Predicate>
Chris@16:       struct apply
Chris@16:       {
Chris@16:           // recursive application of tuple_extract on the tail of the tuple
Chris@16:           typedef tuple_extract<typename Tuple::tail_type, Predicate> next;
Chris@16:           typedef typename next::result_type result_type;
Chris@16:           
Chris@16:           static result_type extract(Tuple const& x)
Chris@16:           {
Chris@16:               return next::extract(x.get_tail());
Chris@16:           }
Chris@16:       };
Chris@16:   };
Chris@16: 
Chris@16:   // A metafunction which selects a version of tuple_extract_impl to
Chris@16:   // use for the implementation of tuple_extract
Chris@16:   template <class Tuple, class Predicate>
Chris@16:   struct tuple_extract_base_select
Chris@16:   {
Chris@16:       typedef typename Tuple::head_type head_type;
Chris@16:       typedef typename mpl::apply1<Predicate, typename add_reference<head_type>::type>::type match_t;
Chris@16:       BOOST_STATIC_CONSTANT(bool, match = match_t::value);
Chris@16:       typedef typename tuple_extract_impl<match>::template apply<Tuple,Predicate> type;
Chris@16:   };
Chris@16:   
Chris@16:   template <class Tuple, class Predicate>
Chris@16:   struct tuple_extract
Chris@16:       : tuple_extract_base_select<
Chris@16:          Tuple
Chris@16:          , typename mpl::lambda<Predicate>::type
Chris@16:       >::type
Chris@16:   {
Chris@16:   };
Chris@16: 
Chris@16: 
Chris@16:   //
Chris@16:   // Specialized extractors for the docstring, keywords, CallPolicies,
Chris@16:   // and default implementation of virtual functions
Chris@16:   //
Chris@16: 
Chris@16:   template <class Tuple>
Chris@16:   struct doc_extract
Chris@16:       : tuple_extract<
Chris@16:         Tuple
Chris@16:         , mpl::not_<
Chris@16:            mpl::or_<
Chris@16:                indirect_traits::is_reference_to_class<mpl::_1>
Chris@16:              , indirect_traits::is_reference_to_member_function_pointer<mpl::_1 >
Chris@16:            >
Chris@16:         >
Chris@16:      >
Chris@16:   {
Chris@16:   };
Chris@16:   
Chris@16:   template <class Tuple>
Chris@16:   struct keyword_extract
Chris@16:       : tuple_extract<Tuple, is_reference_to_keywords<mpl::_1 > >
Chris@16:   {
Chris@16:   };
Chris@16: 
Chris@16:   template <class Tuple>
Chris@16:   struct policy_extract
Chris@16:       : tuple_extract<
Chris@16:           Tuple
Chris@16:           , mpl::and_<
Chris@16:              mpl::not_<is_same<not_specified const&,mpl::_1> >
Chris@16:               , indirect_traits::is_reference_to_class<mpl::_1 >
Chris@16:               , mpl::not_<is_reference_to_keywords<mpl::_1 > >
Chris@16:           >
Chris@16:         >
Chris@16:   {
Chris@16:   };
Chris@16: 
Chris@16:   template <class Tuple>
Chris@16:   struct default_implementation_extract
Chris@16:       : tuple_extract<
Chris@16:           Tuple
Chris@16:           , indirect_traits::is_reference_to_member_function_pointer<mpl::_1 >
Chris@16:           >
Chris@16:   {
Chris@16:   };
Chris@16: 
Chris@16:   //
Chris@16:   // A helper class for decoding the optional arguments to def()
Chris@16:   // invocations, which can be supplied in any order and are
Chris@16:   // discriminated by their type properties. The template parameters
Chris@16:   // are expected to be the types of the actual (optional) arguments
Chris@16:   // passed to def().
Chris@16:   //
Chris@16:   template <class T1, class T2, class T3, class T4>
Chris@16:   struct def_helper
Chris@16:   {
Chris@16:       // A tuple type which begins with references to the supplied
Chris@16:       // arguments and ends with actual representatives of the default
Chris@16:       // types.
Chris@16:       typedef boost::tuples::tuple<
Chris@16:           T1 const&
Chris@16:           , T2 const&
Chris@16:           , T3 const&
Chris@16:           , T4 const&
Chris@16:           , default_call_policies
Chris@16:           , detail::keywords<0>
Chris@16:           , char const*
Chris@16:           , void(not_specified::*)()   // A function pointer type which is never an
Chris@16:                                        // appropriate default implementation
Chris@16:           > all_t;
Chris@16: 
Chris@16:       // Constructors; these initialize an member of the tuple type
Chris@16:       // shown above.
Chris@16:       def_helper(T1 const& a1) : m_all(a1,m_nil,m_nil,m_nil) {}
Chris@16:       def_helper(T1 const& a1, T2 const& a2) : m_all(a1,a2,m_nil,m_nil) {}
Chris@16:       def_helper(T1 const& a1, T2 const& a2, T3 const& a3) : m_all(a1,a2,a3,m_nil) {}
Chris@16:       def_helper(T1 const& a1, T2 const& a2, T3 const& a3, T4 const& a4) : m_all(a1,a2,a3,a4) {}
Chris@16: 
Chris@16:    private: // types
Chris@16:       typedef typename default_implementation_extract<all_t>::result_type default_implementation_t;
Chris@16:       
Chris@16:    public: // Constants which can be used for static assertions.
Chris@16: 
Chris@16:       // Users must not supply a default implementation for non-class
Chris@16:       // methods.
Chris@16:       BOOST_STATIC_CONSTANT(
Chris@16:           bool, has_default_implementation = (
Chris@16:               !is_same<default_implementation_t, void(not_specified::*)()>::value));
Chris@16:       
Chris@16:    public: // Extractor functions which pull the appropriate value out
Chris@16:            // of the tuple
Chris@16:       char const* doc() const
Chris@16:       {
Chris@16:           return doc_extract<all_t>::extract(m_all);
Chris@16:       }
Chris@16:       
Chris@16:       typename keyword_extract<all_t>::result_type keywords() const
Chris@16:       {
Chris@16:           return keyword_extract<all_t>::extract(m_all);
Chris@16:       }
Chris@16:       
Chris@16:       typename policy_extract<all_t>::result_type policies() const
Chris@16:       {
Chris@16:           return policy_extract<all_t>::extract(m_all);
Chris@16:       }
Chris@16: 
Chris@16:       default_implementation_t default_implementation() const
Chris@16:       {
Chris@16:           return default_implementation_extract<all_t>::extract(m_all);
Chris@16:       }
Chris@16:       
Chris@16:    private: // data members
Chris@16:       all_t m_all; 
Chris@16:       not_specified m_nil; // for filling in not_specified slots
Chris@16:   };
Chris@16: }
Chris@16: 
Chris@16: }} // namespace boost::python::detail
Chris@16: 
Chris@16: #endif // DEF_HELPER_DWA200287_HPP