402 lines
16 KiB
Plaintext
402 lines
16 KiB
Plaintext
///////////////////////////////////////////////////////////////////////////////
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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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#if defined(_MSC_VER)
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# pragma warning(push)
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# pragma warning(disable: 4714) // function 'xxx' marked as __forceinline not inlined
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#endif
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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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#include <boost/proto/transform/detail/pack.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 A specialization that treats function pointer Transforms as
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/// if they were function type Transforms.
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///
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/// This specialization requires that \c Fun is actually a function type.
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///
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/// This specialization is required for nested transforms such as
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/// <tt>call\<T0(T1(_))\></tt>. In C++, functions that are used as
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/// parameters to other functions automatically decay to funtion
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/// pointer types. In other words, the type <tt>T0(T1(_))</tt> is
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/// indistinguishable from <tt>T0(T1(*)(_))</tt>. This specialization
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/// is required to handle these nested function pointer type transforms
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/// properly.
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template<typename Fun>
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struct call<Fun *>
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: call<Fun>
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{};
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/// INTERNAL ONLY
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template<typename Fun>
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struct call<detail::msvc_fun_workaround<Fun> >
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: call<Fun>
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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BOOST_FORCEINLINE
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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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#if defined(_MSC_VER)
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# pragma warning(pop)
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#endif
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#endif
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