Chris@16: // Copyright David Abrahams 2003.
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 PURE_VIRTUAL_DWA2003810_HPP
Chris@16: # define PURE_VIRTUAL_DWA2003810_HPP
Chris@16: 
Chris@16: # include <boost/python/def_visitor.hpp>
Chris@16: # include <boost/python/default_call_policies.hpp>
Chris@16: # include <boost/mpl/push_front.hpp>
Chris@16: # include <boost/mpl/pop_front.hpp>
Chris@16: 
Chris@16: # include <boost/python/detail/nullary_function_adaptor.hpp>
Chris@16: 
Chris@16: namespace boost { namespace python { 
Chris@16: 
Chris@16: namespace detail
Chris@16: {
Chris@16:   //
Chris@16:   // @group Helpers for pure_virtual_visitor. {
Chris@16:   //
Chris@16:   
Chris@16:   // Raises a Python RuntimeError reporting that a pure virtual
Chris@16:   // function was called.
Chris@16:   void BOOST_PYTHON_DECL pure_virtual_called();
Chris@16: 
Chris@16:   // Replace the two front elements of S with T1 and T2
Chris@16:   template <class S, class T1, class T2>
Chris@16:   struct replace_front2
Chris@16:   {
Chris@16:       // Metafunction forwarding seemed to confound vc6 
Chris@16:       typedef typename mpl::push_front<
Chris@16:           typename mpl::push_front<
Chris@16:               typename mpl::pop_front<
Chris@16:                   typename mpl::pop_front<
Chris@16:                       S
Chris@16:                   >::type
Chris@16:               >::type
Chris@16:             , T2
Chris@16:           >::type
Chris@16:         , T1
Chris@16:       >::type type;
Chris@16:   };
Chris@16: 
Chris@16:   // Given an MPL sequence representing a member function [object]
Chris@16:   // signature, returns a new MPL sequence whose return type is
Chris@16:   // replaced by void, and whose first argument is replaced by C&.
Chris@16:   template <class C, class S>
Chris@16:   typename replace_front2<S,void,C&>::type
Chris@16:   error_signature(S BOOST_APPEND_EXPLICIT_TEMPLATE_TYPE(C))
Chris@16:   {
Chris@16:       typedef typename replace_front2<S,void,C&>::type r;
Chris@16:       return r();
Chris@16:   }
Chris@16: 
Chris@16:   //
Chris@16:   // } 
Chris@16:   //
Chris@16: 
Chris@16:   //
Chris@16:   // A def_visitor which defines a method as usual, then adds a
Chris@16:   // corresponding function which raises a "pure virtual called"
Chris@16:   // exception unless it's been overridden.
Chris@16:   //
Chris@16:   template <class PointerToMemberFunction>
Chris@16:   struct pure_virtual_visitor
Chris@16:     : def_visitor<pure_virtual_visitor<PointerToMemberFunction> >
Chris@16:   {
Chris@16:       pure_virtual_visitor(PointerToMemberFunction pmf)
Chris@16:         : m_pmf(pmf)
Chris@16:       {}
Chris@16:       
Chris@16:    private:
Chris@16:       friend class python::def_visitor_access;
Chris@16:       
Chris@16:       template <class C_, class Options>
Chris@16:       void visit(C_& c, char const* name, Options& options) const
Chris@16:       {
Chris@16:           // This should probably be a nicer error message
Chris@16:           BOOST_STATIC_ASSERT(!Options::has_default_implementation);
Chris@16: 
Chris@16:           // Add the virtual function dispatcher
Chris@16:           c.def(
Chris@16:               name
Chris@16:             , m_pmf
Chris@16:             , options.doc()
Chris@16:             , options.keywords()
Chris@16:             , options.policies()
Chris@16:           );
Chris@16: 
Chris@16:           typedef BOOST_DEDUCED_TYPENAME C_::metadata::held_type held_type;
Chris@16:           
Chris@16:           // Add the default implementation which raises the exception
Chris@16:           c.def(
Chris@16:               name
Chris@16:             , make_function(
Chris@16:                   detail::nullary_function_adaptor<void(*)()>(pure_virtual_called)
Chris@16:                 , default_call_policies()
Chris@16:                 , detail::error_signature<held_type>(detail::get_signature(m_pmf))
Chris@16:               )
Chris@16:           );
Chris@16:       }
Chris@16:       
Chris@16:    private: // data members
Chris@16:       PointerToMemberFunction m_pmf;
Chris@16:   };
Chris@16: }
Chris@16: 
Chris@16: //
Chris@16: // Passed a pointer to member function, generates a def_visitor which
Chris@16: // creates a method that only dispatches to Python if the function has
Chris@16: // been overridden, either in C++ or in Python, raising a "pure
Chris@16: // virtual called" exception otherwise.
Chris@16: //
Chris@16: template <class PointerToMemberFunction>
Chris@16: detail::pure_virtual_visitor<PointerToMemberFunction>
Chris@16: pure_virtual(PointerToMemberFunction pmf)
Chris@16: {
Chris@16:     return detail::pure_virtual_visitor<PointerToMemberFunction>(pmf);
Chris@16: }
Chris@16: 
Chris@16: }} // namespace boost::python
Chris@16: 
Chris@16: #endif // PURE_VIRTUAL_DWA2003810_HPP