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