boost/proto/transform/call.hpp
#ifndef BOOST_PP_IS_ITERATING
///////////////////////////////////////////////////////////////////////////////
/// \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
#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>
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 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::result_of<Fun()>::type result_type;
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, 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;
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;
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, 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;
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;
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, 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;
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;
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, is_transform<Fun>::value>
{};
};
#if BOOST_PROTO_MAX_ARITY > 3
#define BOOST_PP_ITERATION_PARAMS_1 (3, (4, BOOST_PROTO_MAX_ARITY, <boost/proto/transform/call.hpp>))
#include BOOST_PP_ITERATE()
#endif
/// INTERNAL ONLY
///
template<typename Fun>
struct is_callable<call<Fun> >
: mpl::true_
{};
}} // namespace boost::proto
#endif
#else
#define N BOOST_PP_ITERATION()
/// \brief Call the PolymorphicFunctionObject \c Fun with the
/// current expression, state and data, transformed according
/// to \c A0 through \c AN.
template<typename Fun BOOST_PP_ENUM_TRAILING_PARAMS(N, typename A)>
struct call<Fun(BOOST_PP_ENUM_PARAMS(N, A))> : transform<call<Fun(BOOST_PP_ENUM_PARAMS(N, A))> >
{
template<typename Expr, typename State, typename Data>
struct impl : transform_impl<Expr, State, Data>
{
#define M0(Z, M, DATA) \
typedef \
typename when<_, BOOST_PP_CAT(A, M)> \
::template impl<Expr, State, Data> \
::result_type \
BOOST_PP_CAT(a, M); \
/**/
BOOST_PP_REPEAT(N, M0, ~)
#undef M0
typedef
typename detail::poly_function_traits<Fun, Fun(BOOST_PP_ENUM_PARAMS(N, a))>::result_type
result_type;
/// Let \c ax be <tt>when\<_, Ax\>()(e, s, d)</tt>
/// for each \c x in <tt>[0,N]</tt>.
/// Return <tt>Fun()(a0, a1,... aN)</tt>.
///
/// \param e The current expression
/// \param s The current state
/// \param d An arbitrary data
result_type operator ()(
typename impl::expr_param e
, typename impl::state_param s
, typename impl::data_param d
) const
{
#define M0(Z, M, DATA) \
detail::as_lvalue( \
typename when<_, BOOST_PP_CAT(A, M)> \
::template impl<Expr, State, Data>()(e, s, d)) \
/**/
return typename detail::poly_function_traits<Fun, Fun(BOOST_PP_ENUM_PARAMS(N, a))>::function_type()(
BOOST_PP_ENUM(N, M0, ~)
);
#undef M0
}
};
};
#undef N
#endif
