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