boost/proto/transform/call.hpp
/////////////////////////////////////////////////////////////////////////////// /// \file call.hpp /// Contains definition of the call<> transform. // // Copyright 2008 Eric Niebler. Distributed under the Boost // Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) #ifndef BOOST_PROTO_TRANSFORM_CALL_HPP_EAN_11_02_2007 #define BOOST_PROTO_TRANSFORM_CALL_HPP_EAN_11_02_2007 #if defined(_MSC_VER) # pragma warning(push) # pragma warning(disable: 4714) // function 'xxx' marked as __forceinline not inlined #endif #include <boost/preprocessor/cat.hpp> #include <boost/preprocessor/facilities/intercept.hpp> #include <boost/preprocessor/iteration/iterate.hpp> #include <boost/preprocessor/repetition/enum.hpp> #include <boost/preprocessor/repetition/repeat.hpp> #include <boost/preprocessor/repetition/enum_params.hpp> #include <boost/preprocessor/repetition/enum_binary_params.hpp> #include <boost/preprocessor/repetition/enum_trailing_params.hpp> #include <boost/ref.hpp> #include <boost/utility/result_of.hpp> #include <boost/proto/proto_fwd.hpp> #include <boost/proto/traits.hpp> #include <boost/proto/transform/impl.hpp> #include <boost/proto/detail/as_lvalue.hpp> #include <boost/proto/detail/poly_function.hpp> #include <boost/proto/transform/detail/pack.hpp> namespace boost { namespace proto { /// \brief Wrap \c PrimitiveTransform so that <tt>when\<\></tt> knows /// it is callable. Requires that the parameter is actually a /// PrimitiveTransform. /// /// This form of <tt>call\<\></tt> is useful for annotating an /// arbitrary PrimitiveTransform as callable when using it with /// <tt>when\<\></tt>. Consider the following transform, which /// is parameterized with another transform. /// /// \code /// template<typename Grammar> /// struct Foo /// : when< /// unary_plus<Grammar> /// , Grammar(_child) // May or may not work. /// > /// {}; /// \endcode /// /// The problem with the above is that <tt>when\<\></tt> may or /// may not recognize \c Grammar as callable, depending on how /// \c Grammar is implemented. (See <tt>is_callable\<\></tt> for /// a discussion of this issue.) You can guard against /// the issue by wrapping \c Grammar in <tt>call\<\></tt>, such /// as: /// /// \code /// template<typename Grammar> /// struct Foo /// : when< /// unary_plus<Grammar> /// , call<Grammar>(_child) // OK, this works /// > /// {}; /// \endcode /// /// The above could also have been written as: /// /// \code /// template<typename Grammar> /// struct Foo /// : when< /// unary_plus<Grammar> /// , call<Grammar(_child)> // OK, this works, too /// > /// {}; /// \endcode template<typename PrimitiveTransform> struct call : PrimitiveTransform {}; /// \brief A specialization that treats function pointer Transforms as /// if they were function type Transforms. /// /// This specialization requires that \c Fun is actually a function type. /// /// This specialization is required for nested transforms such as /// <tt>call\<T0(T1(_))\></tt>. In C++, functions that are used as /// parameters to other functions automatically decay to funtion /// pointer types. In other words, the type <tt>T0(T1(_))</tt> is /// indistinguishable from <tt>T0(T1(*)(_))</tt>. This specialization /// is required to handle these nested function pointer type transforms /// properly. template<typename Fun> struct call<Fun *> : call<Fun> {}; /// INTERNAL ONLY template<typename Fun> struct call<detail::msvc_fun_workaround<Fun> > : call<Fun> {}; /// \brief Either call the PolymorphicFunctionObject with 0 /// arguments, or invoke the PrimitiveTransform with 3 /// arguments. template<typename Fun> struct call<Fun()> : transform<call<Fun()> > { /// INTERNAL ONLY template<typename Expr, typename State, typename Data, bool B> struct impl2 : transform_impl<Expr, State, Data> { typedef typename BOOST_PROTO_RESULT_OF<Fun()>::type result_type; BOOST_FORCEINLINE result_type operator()( typename impl2::expr_param , typename impl2::state_param , typename impl2::data_param ) const { return Fun()(); } }; /// INTERNAL ONLY template<typename Expr, typename State, typename Data> struct impl2<Expr, State, Data, true> : Fun::template impl<Expr, State, Data> {}; /// Either call the PolymorphicFunctionObject \c Fun with 0 arguments; or /// invoke the PrimitiveTransform \c Fun with 3 arguments: the current /// expression, state, and data. /// /// If \c Fun is a nullary PolymorphicFunctionObject, return <tt>Fun()()</tt>. /// Otherwise, return <tt>Fun()(e, s, d)</tt>. /// /// \param e The current expression /// \param s The current state /// \param d An arbitrary data /// If \c Fun is a nullary PolymorphicFunctionObject, \c type is a typedef /// for <tt>boost::result_of\<Fun()\>::type</tt>. Otherwise, it is /// a typedef for <tt>boost::result_of\<Fun(Expr, State, Data)\>::type</tt>. template<typename Expr, typename State, typename Data> struct impl : impl2<Expr, State, Data, detail::is_transform_<Fun>::value> {}; }; /// \brief Either call the PolymorphicFunctionObject with 1 /// argument, or invoke the PrimitiveTransform with 3 /// arguments. template<typename Fun, typename A0> struct call<Fun(A0)> : transform<call<Fun(A0)> > { template<typename Expr, typename State, typename Data, bool B> struct impl2 : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename detail::poly_function_traits<Fun, Fun(a0)>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename detail::poly_function_traits<Fun, Fun(a0)>::function_type()( detail::as_lvalue(typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d)) ); } }; template<typename Expr, typename State, typename Data> struct impl2<Expr, State, Data, true> : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename Fun::template impl<a0, State, Data>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename Fun::template impl<a0, State, Data>()( typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d) , s , d ); } }; /// Let \c x be <tt>when\<_, A0\>()(e, s, d)</tt> and \c X /// be the type of \c x. /// If \c Fun is a unary PolymorphicFunctionObject that accepts \c x, /// then \c type is a typedef for <tt>boost::result_of\<Fun(X)\>::type</tt>. /// Otherwise, it is a typedef for <tt>boost::result_of\<Fun(X, State, Data)\>::type</tt>. /// Either call the PolymorphicFunctionObject with 1 argument: /// the result of applying the \c A0 transform; or /// invoke the PrimitiveTransform with 3 arguments: /// result of applying the \c A0 transform, the state, and the /// data. /// /// Let \c x be <tt>when\<_, A0\>()(e, s, d)</tt>. /// If \c Fun is a unary PolymorphicFunctionObject that accepts \c x, /// then return <tt>Fun()(x)</tt>. Otherwise, return /// <tt>Fun()(x, s, d)</tt>. /// /// \param e The current expression /// \param s The current state /// \param d An arbitrary data template<typename Expr, typename State, typename Data> struct impl : impl2<Expr, State, Data, detail::is_transform_<Fun>::value> {}; }; /// \brief Either call the PolymorphicFunctionObject with 2 /// arguments, or invoke the PrimitiveTransform with 3 /// arguments. template<typename Fun, typename A0, typename A1> struct call<Fun(A0, A1)> : transform<call<Fun(A0, A1)> > { template<typename Expr, typename State, typename Data, bool B> struct impl2 : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename when<_, A1>::template impl<Expr, State, Data>::result_type a1; typedef typename detail::poly_function_traits<Fun, Fun(a0, a1)>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename detail::poly_function_traits<Fun, Fun(a0, a1)>::function_type()( detail::as_lvalue(typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d)) , detail::as_lvalue(typename when<_, A1>::template impl<Expr, State, Data>()(e, s, d)) ); } }; template<typename Expr, typename State, typename Data> struct impl2<Expr, State, Data, true> : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename when<_, A1>::template impl<Expr, State, Data>::result_type a1; typedef typename Fun::template impl<a0, a1, Data>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename Fun::template impl<a0, a1, Data>()( typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d) , typename when<_, A1>::template impl<Expr, State, Data>()(e, s, d) , d ); } }; /// Let \c x be <tt>when\<_, A0\>()(e, s, d)</tt> and \c X /// be the type of \c x. /// Let \c y be <tt>when\<_, A1\>()(e, s, d)</tt> and \c Y /// be the type of \c y. /// If \c Fun is a binary PolymorphicFunction object that accepts \c x /// and \c y, then \c type is a typedef for /// <tt>boost::result_of\<Fun(X, Y)\>::type</tt>. Otherwise, it is /// a typedef for <tt>boost::result_of\<Fun(X, Y, Data)\>::type</tt>. /// Either call the PolymorphicFunctionObject with 2 arguments: /// the result of applying the \c A0 transform, and the /// result of applying the \c A1 transform; or invoke the /// PrimitiveTransform with 3 arguments: the result of applying /// the \c A0 transform, the result of applying the \c A1 /// transform, and the data. /// /// Let \c x be <tt>when\<_, A0\>()(e, s, d)</tt>. /// Let \c y be <tt>when\<_, A1\>()(e, s, d)</tt>. /// If \c Fun is a binary PolymorphicFunction object that accepts \c x /// and \c y, return <tt>Fun()(x, y)</tt>. Otherwise, return /// <tt>Fun()(x, y, d)</tt>. /// /// \param e The current expression /// \param s The current state /// \param d An arbitrary data template<typename Expr, typename State, typename Data> struct impl : impl2<Expr, State, Data, detail::is_transform_<Fun>::value> {}; }; /// \brief Call the PolymorphicFunctionObject or the /// PrimitiveTransform with the current expression, state /// and data, transformed according to \c A0, \c A1, and /// \c A2, respectively. template<typename Fun, typename A0, typename A1, typename A2> struct call<Fun(A0, A1, A2)> : transform<call<Fun(A0, A1, A2)> > { template<typename Expr, typename State, typename Data, bool B> struct impl2 : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename when<_, A1>::template impl<Expr, State, Data>::result_type a1; typedef typename when<_, A2>::template impl<Expr, State, Data>::result_type a2; typedef typename detail::poly_function_traits<Fun, Fun(a0, a1, a2)>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename detail::poly_function_traits<Fun, Fun(a0, a1, a2)>::function_type()( detail::as_lvalue(typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d)) , detail::as_lvalue(typename when<_, A1>::template impl<Expr, State, Data>()(e, s, d)) , detail::as_lvalue(typename when<_, A2>::template impl<Expr, State, Data>()(e, s, d)) ); } }; template<typename Expr, typename State, typename Data> struct impl2<Expr, State, Data, true> : transform_impl<Expr, State, Data> { typedef typename when<_, A0>::template impl<Expr, State, Data>::result_type a0; typedef typename when<_, A1>::template impl<Expr, State, Data>::result_type a1; typedef typename when<_, A2>::template impl<Expr, State, Data>::result_type a2; typedef typename Fun::template impl<a0, a1, a2>::result_type result_type; BOOST_FORCEINLINE result_type operator ()( typename impl2::expr_param e , typename impl2::state_param s , typename impl2::data_param d ) const { return typename Fun::template impl<a0, a1, a2>()( typename when<_, A0>::template impl<Expr, State, Data>()(e, s, d) , typename when<_, A1>::template impl<Expr, State, Data>()(e, s, d) , typename when<_, A2>::template impl<Expr, State, Data>()(e, s, d) ); } }; /// Let \c x be <tt>when\<_, A0\>()(e, s, d)</tt>. /// Let \c y be <tt>when\<_, A1\>()(e, s, d)</tt>. /// Let \c z be <tt>when\<_, A2\>()(e, s, d)</tt>. /// Return <tt>Fun()(x, y, z)</tt>. /// /// \param e The current expression /// \param s The current state /// \param d An arbitrary data template<typename Expr, typename State, typename Data> struct impl : impl2<Expr, State, Data, detail::is_transform_<Fun>::value> {}; }; #include <boost/proto/transform/detail/call.hpp> /// INTERNAL ONLY /// template<typename Fun> struct is_callable<call<Fun> > : mpl::true_ {}; }} // namespace boost::proto #if defined(_MSC_VER) # pragma warning(pop) #endif #endif