Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: /// \file poly_function.hpp
Chris@16: /// A wrapper that makes a tr1-style function object that handles const
Chris@16: /// and non-const refs and reference_wrapper arguments, too, and forwards
Chris@16: /// the arguments on to the specified implementation.
Chris@16: //
Chris@16: //  Copyright 2008 Eric Niebler. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_PROTO_DETAIL_POLY_FUNCTION_EAN_2008_05_02
Chris@16: #define BOOST_PROTO_DETAIL_POLY_FUNCTION_EAN_2008_05_02
Chris@16: 
Chris@16: #include <boost/ref.hpp>
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/void.hpp>
Chris@16: #include <boost/mpl/size_t.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/preprocessor/cat.hpp>
Chris@16: #include <boost/preprocessor/facilities/intercept.hpp>
Chris@16: #include <boost/preprocessor/iteration/iterate.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_params.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_trailing_params.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_binary_params.hpp>
Chris@16: #include <boost/proto/proto_fwd.hpp>
Chris@16: #include <boost/proto/detail/is_noncopyable.hpp>
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: # pragma warning(push)
Chris@16: # pragma warning(disable: 4181) // const applied to reference type
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost { namespace proto { namespace detail
Chris@16: {
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg
Chris@16:     {
Chris@16:         typedef typename mpl::if_c<is_noncopyable<T>::value, T &, T>::type type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<T const>
Chris@16:     {
Chris@16:         typedef typename mpl::if_c<is_noncopyable<T>::value, T const &, T>::type type;
Chris@16:         typedef T const &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<T &>
Chris@16:     {
Chris@16:         typedef typename mpl::if_c<is_noncopyable<T>::value, T &, T>::type type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<T const &>
Chris@16:     {
Chris@16:         typedef typename mpl::if_c<is_noncopyable<T>::value, T const &, T>::type type;
Chris@16:         typedef T const &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<boost::reference_wrapper<T> >
Chris@16:     {
Chris@16:         typedef T &type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<boost::reference_wrapper<T> const>
Chris@16:     {
Chris@16:         typedef T &type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<boost::reference_wrapper<T> &>
Chris@16:     {
Chris@16:         typedef T &type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct normalize_arg<boost::reference_wrapper<T> const &>
Chris@16:     {
Chris@16:         typedef T &type;
Chris@16:         typedef T &reference;
Chris@16:     };
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename T>
Chris@16:     struct arg
Chris@16:     {
Chris@16:         typedef T const &type;
Chris@16: 
Chris@16:         arg(type t)
Chris@16:           : value(t)
Chris@16:         {}
Chris@16: 
Chris@16:         operator type() const
Chris@16:         {
Chris@16:             return this->value;
Chris@16:         }
Chris@16: 
Chris@16:         type operator()() const
Chris@16:         {
Chris@16:             return this->value;
Chris@16:         }
Chris@16: 
Chris@16:     private:
Chris@16:         arg &operator =(arg const &);
Chris@16:         type value;
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct arg<T &>
Chris@16:     {
Chris@16:         typedef T &type;
Chris@16: 
Chris@16:         arg(type t)
Chris@16:           : value(t)
Chris@16:         {}
Chris@16: 
Chris@16:         operator type() const
Chris@16:         {
Chris@16:             return this->value;
Chris@16:         }
Chris@16: 
Chris@16:         type operator()() const
Chris@16:         {
Chris@16:             return this->value;
Chris@16:         }
Chris@16: 
Chris@16:     private:
Chris@16:         arg &operator =(arg const &);
Chris@16:         type value;
Chris@16:     };
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename T, typename Void = void>
Chris@16:     struct is_poly_function
Chris@16:       : mpl::false_
Chris@16:     {};
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct is_poly_function<T, typename T::is_poly_function_base_>
Chris@16:       : mpl::true_
Chris@16:     {};
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     #define BOOST_PROTO_POLY_FUNCTION()                                                             \
Chris@16:         typedef void is_poly_function_base_;                                                        \
Chris@16:         /**/
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     struct poly_function_base
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         BOOST_PROTO_POLY_FUNCTION()
Chris@16:     };
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename Derived, typename NullaryResult = void>
Chris@16:     struct poly_function
Chris@16:       : poly_function_base
Chris@16:     {
Chris@16:         template<typename Sig>
Chris@16:         struct result;
Chris@16: 
Chris@16:         template<typename This>
Chris@16:         struct result<This()>
Chris@16:           : Derived::template impl<>
Chris@16:         {
Chris@16:             typedef typename result::result_type type;
Chris@16:         };
Chris@16: 
Chris@16:         NullaryResult operator()() const
Chris@16:         {
Chris@16:             result<Derived const()> impl;
Chris@16:             return impl();
Chris@16:         }
Chris@16: 
Chris@16:         #include <boost/proto/detail/poly_function_funop.hpp>
Chris@16:     };
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     struct wrap_t;
Chris@16: 
Chris@16:     typedef char poly_function_t;
Chris@16:     typedef char (&mono_function_t)[2];
Chris@16:     typedef char (&unknown_function_t)[3];
Chris@16: 
Chris@16:     template<typename T> poly_function_t test_poly_function(T *, wrap_t<typename T::is_poly_function_base_> * = 0);
Chris@16:     template<typename T> mono_function_t test_poly_function(T *, wrap_t<typename T::result_type> * = 0);
Chris@16:     template<typename T> unknown_function_t test_poly_function(T *, ...);
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename Fun, typename Sig, typename Switch = mpl::size_t<sizeof(test_poly_function<Fun>(0,0))> >
Chris@16:     struct poly_function_traits
Chris@16:     {
Chris@16:         typedef typename Fun::template result<Sig>::type result_type;
Chris@16:         typedef Fun function_type;
Chris@16:     };
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename Fun, typename Sig>
Chris@16:     struct poly_function_traits<Fun, Sig, mpl::size_t<sizeof(mono_function_t)> >
Chris@16:     {
Chris@16:         typedef typename Fun::result_type result_type;
Chris@16:         typedef Fun function_type;
Chris@16:     };
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename PolyFunSig, bool IsPolyFunction>
Chris@16:     struct as_mono_function_impl;
Chris@16: 
Chris@16:     ////////////////////////////////////////////////////////////////////////////////////////////////
Chris@16:     template<typename PolyFunSig>
Chris@16:     struct as_mono_function;
Chris@16: 
Chris@16:     #include <boost/proto/detail/poly_function_traits.hpp>
Chris@16: 
Chris@16: }}} // namespace boost::proto::detail
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: # pragma warning(pop)
Chris@16: #endif
Chris@16: 
Chris@16: #endif
Chris@16: