sl@0: // Copyright David Abrahams 2003.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: #ifndef PURE_VIRTUAL_DWA2003810_HPP
sl@0: # define PURE_VIRTUAL_DWA2003810_HPP
sl@0: 
sl@0: # include <boost/python/def_visitor.hpp>
sl@0: # include <boost/python/default_call_policies.hpp>
sl@0: # include <boost/mpl/push_front.hpp>
sl@0: # include <boost/mpl/pop_front.hpp>
sl@0: 
sl@0: # include <boost/python/detail/nullary_function_adaptor.hpp>
sl@0: 
sl@0: namespace boost { namespace python { 
sl@0: 
sl@0: namespace detail
sl@0: {
sl@0:   //
sl@0:   // @group Helpers for pure_virtual_visitor. {
sl@0:   //
sl@0:   
sl@0:   // Raises a Python RuntimeError reporting that a pure virtual
sl@0:   // function was called.
sl@0:   void BOOST_PYTHON_DECL pure_virtual_called();
sl@0: 
sl@0:   // Replace the two front elements of S with T1 and T2
sl@0:   template <class S, class T1, class T2>
sl@0:   struct replace_front2
sl@0:   {
sl@0:       // Metafunction forwarding seemed to confound vc6 
sl@0:       typedef typename mpl::push_front<
sl@0:           typename mpl::push_front<
sl@0:               typename mpl::pop_front<
sl@0:                   typename mpl::pop_front<
sl@0:                       S
sl@0:                   >::type
sl@0:               >::type
sl@0:             , T2
sl@0:           >::type
sl@0:         , T1
sl@0:       >::type type;
sl@0:   };
sl@0: 
sl@0:   // Given an MPL sequence representing a member function [object]
sl@0:   // signature, returns a new MPL sequence whose return type is
sl@0:   // replaced by void, and whose first argument is replaced by C&.
sl@0:   template <class C, class S>
sl@0:   typename replace_front2<S,void,C&>::type
sl@0:   error_signature(S BOOST_APPEND_EXPLICIT_TEMPLATE_TYPE(C))
sl@0:   {
sl@0:       typedef typename replace_front2<S,void,C&>::type r;
sl@0:       return r();
sl@0:   }
sl@0: 
sl@0:   //
sl@0:   // } 
sl@0:   //
sl@0: 
sl@0:   //
sl@0:   // A def_visitor which defines a method as usual, then adds a
sl@0:   // corresponding function which raises a "pure virtual called"
sl@0:   // exception unless it's been overridden.
sl@0:   //
sl@0:   template <class PointerToMemberFunction>
sl@0:   struct pure_virtual_visitor
sl@0:     : def_visitor<pure_virtual_visitor<PointerToMemberFunction> >
sl@0:   {
sl@0:       pure_virtual_visitor(PointerToMemberFunction pmf)
sl@0:         : m_pmf(pmf)
sl@0:       {}
sl@0:       
sl@0:    private:
sl@0:       friend class python::def_visitor_access;
sl@0:       
sl@0:       template <class C_, class Options>
sl@0:       void visit(C_& c, char const* name, Options& options) const
sl@0:       {
sl@0:           // This should probably be a nicer error message
sl@0:           BOOST_STATIC_ASSERT(!Options::has_default_implementation);
sl@0: 
sl@0:           // Add the virtual function dispatcher
sl@0:           c.def(
sl@0:               name
sl@0:             , m_pmf
sl@0:             , options.doc()
sl@0:             , options.keywords()
sl@0:             , options.policies()
sl@0:           );
sl@0: 
sl@0:           typedef BOOST_DEDUCED_TYPENAME C_::metadata::held_type held_type;
sl@0:           
sl@0:           // Add the default implementation which raises the exception
sl@0:           c.def(
sl@0:               name
sl@0:             , make_function(
sl@0:                   detail::nullary_function_adaptor<void(*)()>(pure_virtual_called)
sl@0:                 , default_call_policies()
sl@0:                 , detail::error_signature<held_type>(detail::get_signature(m_pmf))
sl@0:               )
sl@0:           );
sl@0:       }
sl@0:       
sl@0:    private: // data members
sl@0:       PointerToMemberFunction m_pmf;
sl@0:   };
sl@0: }
sl@0: 
sl@0: //
sl@0: // Passed a pointer to member function, generates a def_visitor which
sl@0: // creates a method that only dispatches to Python if the function has
sl@0: // been overridden, either in C++ or in Python, raising a "pure
sl@0: // virtual called" exception otherwise.
sl@0: //
sl@0: template <class PointerToMemberFunction>
sl@0: detail::pure_virtual_visitor<PointerToMemberFunction>
sl@0: pure_virtual(PointerToMemberFunction pmf)
sl@0: {
sl@0:     return detail::pure_virtual_visitor<PointerToMemberFunction>(pmf);
sl@0: }
sl@0: 
sl@0: }} // namespace boost::python
sl@0: 
sl@0: #endif // PURE_VIRTUAL_DWA2003810_HPP