boost/proto/traits.hpp
#ifndef BOOST_PP_IS_ITERATING
///////////////////////////////////////////////////////////////////////////////
/// \file traits.hpp
/// Contains definitions for child\<\>, child_c\<\>, left\<\>,
/// right\<\>, tag_of\<\>, and the helper functions child(), child_c(),
/// value(), left() and right().
//
// 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_ARG_TRAITS_HPP_EAN_04_01_2005
#define BOOST_PROTO_ARG_TRAITS_HPP_EAN_04_01_2005
#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/preprocessor/iteration/iterate.hpp>
#include <boost/preprocessor/repetition/enum.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/repetition/enum_trailing.hpp>
#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/preprocessor/repetition/repeat_from_to.hpp>
#include <boost/preprocessor/facilities/intercept.hpp>
#include <boost/preprocessor/arithmetic/sub.hpp>
#include <boost/ref.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/or.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/aux_/template_arity.hpp>
#include <boost/mpl/aux_/lambda_arity_param.hpp>
#include <boost/static_assert.hpp>
#include <boost/utility/result_of.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/type_traits/is_pod.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_function.hpp>
#include <boost/type_traits/remove_cv.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/proto/proto_fwd.hpp>
#include <boost/proto/args.hpp>
#include <boost/proto/tags.hpp>
#include <boost/proto/transform/pass_through.hpp>
#if BOOST_WORKAROUND( BOOST_MSVC, >= 1400 )
#pragma warning(push)
#pragma warning(disable: 4180) // warning C4180: qualifier applied to function type has no meaning; ignored
#endif
namespace boost { namespace proto
{
namespace detail
{
template<typename T, typename Void = void>
struct if_vararg
{};
template<typename T>
struct if_vararg<T, typename T::proto_is_vararg_>
: T
{};
template<typename T, typename Void = void>
struct is_callable2_
: mpl::false_
{};
template<typename T>
struct is_callable2_<T, typename T::proto_is_callable_>
: mpl::true_
{};
template<typename T BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(long Arity = mpl::aux::template_arity<T>::value)>
struct is_callable_
: is_callable2_<T>
{};
}
/// \brief Boolean metafunction which detects whether a type is
/// a callable function object type or not.
///
/// <tt>is_callable\<\></tt> is used by the <tt>when\<\></tt> transform
/// to determine whether a function type <tt>R(A1,A2,...AN)</tt> is a
/// callable transform or an object transform. (The former are evaluated
/// using <tt>call\<\></tt> and the later with <tt>make\<\></tt>.) If
/// <tt>is_callable\<R\>::::value</tt> is \c true, the function type is
/// a callable transform; otherwise, it is an object transform.
///
/// Unless specialized for a type \c T, <tt>is_callable\<T\>::::value</tt>
/// is computed as follows:
///
/// \li If \c T is a template type <tt>X\<Y0,Y1,...YN\></tt>, where all \c Yx
/// are types for \c x in <tt>[0,N]</tt>, <tt>is_callable\<T\>::::value</tt>
/// is <tt>is_same\<YN, proto::callable\>::::value</tt>.
/// \li If \c T has a nested type \c proto_is_callable_ that is a typedef
/// for \c void, <tt>is_callable\<T\>::::value</tt> is \c true. (Note: this is
/// the case for any type that derives from \c proto::callable.)
/// \li Otherwise, <tt>is_callable\<T\>::::value</tt> is \c false.
template<typename T>
struct is_callable
: proto::detail::is_callable_<T>
{};
/// INTERNAL ONLY
///
template<>
struct is_callable<proto::_>
: mpl::true_
{};
/// INTERNAL ONLY
///
template<>
struct is_callable<proto::callable>
: mpl::false_
{};
#if BOOST_WORKAROUND(__GNUC__, == 3) || (__GNUC__ == 4 && __GNUC_MINOR__ == 0)
// work around GCC bug
template<typename Tag, typename Args, long N>
struct is_callable<proto::expr<Tag, Args, N> >
: mpl::false_
{};
#endif
/// \brief A Boolean metafunction that indicates whether a type requires
/// aggregate initialization.
///
/// <tt>is_aggregate\<\></tt> is used by the <tt>make\<\></tt> transform
/// to determine how to construct an object of some type \c T, given some
/// initialization arguments <tt>a0,a1,...aN</tt>.
/// If <tt>is_aggregate\<T\>::::value</tt> is \c true, then an object of
/// type T will be initialized as <tt>T t = {a0,a1,...aN};</tt>. Otherwise,
/// it will be initialized as <tt>T t(a0,a1,...aN)</tt>.
template<typename T, typename Void>
struct is_aggregate
: is_pod<T>
{};
/// \brief Specialization of <tt>is_aggregate\<\></tt> that indicates
/// that objects of <tt>expr\<\></tt> type require aggregate initialization.
template<typename Tag, typename Args, long N>
struct is_aggregate<proto::expr<Tag, Args, N>, void>
: mpl::true_
{};
/// INTERNAL ONLY
template<typename T>
struct is_aggregate<T, typename T::proto_is_aggregate_>
: mpl::true_
{};
/// TODO document me!
template<typename T, typename Void /* = void*/>
struct is_transform
: mpl::false_
{};
template<typename T>
struct is_transform<T, typename T::proto_is_transform_>
: mpl::true_
{};
namespace result_of
{
/// \brief A Boolean metafunction that indicates whether a given
/// type \c T is a Proto expression type.
///
/// If \c T has a nested type \c proto_is_expr_ that is a typedef
/// for \c void, <tt>is_expr\<T\>::::value</tt> is \c true. (Note, this
/// is the case for <tt>proto::expr\<\></tt>, any type that is derived
/// from <tt>proto::extends\<\></tt> or that uses the
/// <tt>BOOST_PROTO_BASIC_EXTENDS()</tt> macro.) Otherwise,
/// <tt>is_expr\<T\>::::value</tt> is \c false.
template<typename T, typename Void /* = void*/>
struct is_expr
: mpl::false_
{};
/// \brief A Boolean metafunction that indicates whether a given
/// type \c T is a Proto expression type.
///
/// If \c T has a nested type \c proto_is_expr_ that is a typedef
/// for \c void, <tt>is_expr\<T\>::::value</tt> is \c true. (Note, this
/// is the case for <tt>proto::expr\<\></tt>, any type that is derived
/// from <tt>proto::extends\<\></tt> or that uses the
/// <tt>BOOST_PROTO_BASIC_EXTENDS()</tt> macro.) Otherwise,
/// <tt>is_expr\<T\>::::value</tt> is \c false.
template<typename T>
struct is_expr<T, typename T::proto_is_expr_>
: mpl::true_
{};
template<typename T>
struct is_expr<T &, void>
: is_expr<T>
{};
/// \brief A metafunction that returns the tag type of a
/// Proto expression.
template<typename Expr>
struct tag_of
{
typedef typename Expr::proto_tag type;
};
template<typename Expr>
struct tag_of<Expr &>
{
typedef typename Expr::proto_tag type;
};
/// \brief A metafunction that returns the arity of a
/// Proto expression.
template<typename Expr>
struct arity_of
: Expr::proto_arity
{};
template<typename Expr>
struct arity_of<Expr &>
: Expr::proto_arity
{};
/// \brief A metafunction that computes the return type of the \c as_expr()
/// function.
///
/// The <tt>as_expr\<\></tt> metafunction turns types into Proto types, if
/// they are not already, by making them Proto terminals held by value if
/// possible. Types which are already Proto types are left alone.
///
/// This specialization is selected when the type is not yet a Proto type.
/// The resulting terminal type is calculated as follows:
///
/// If \c T is a function type, let \c A be <tt>T &</tt>.
/// Otherwise, let \c A be the type \c T stripped of cv-qualifiers.
/// Then, the result type <tt>as_expr\<T, Domain\>::::type</tt> is
/// <tt>boost::result_of\<Domain(expr\< tag::terminal, term\<A\> \>)\>::::type</tt>.
template<
typename T
, typename Domain // = default_domain
, typename Void // = void
#ifdef BOOST_PROTO_BROKEN_PTS
, typename Void2 // = void
#endif
>
struct as_expr
{
typedef
typename mpl::eval_if_c<
is_function<T>::value
, add_reference<T>
, remove_cv<T>
>::type
arg0_;
typedef proto::expr<proto::tag::terminal, term<arg0_>, 0> expr_;
typedef typename Domain::template result<Domain(expr_)>::type type;
typedef type const reference;
/// INTERNAL ONLY
///
template<typename T2>
static reference call(T2 &t)
{
return Domain()(expr_::make(t));
}
};
/// \brief A metafunction that computes the return type of the \c as_expr()
/// function.
///
/// The <tt>as_expr\<\></tt> metafunction turns types into Proto types, if
/// they are not already, by making them Proto terminals held by value if
/// possible. Types which are already Proto types are left alone.
///
/// This specialization is selected when the type is already a Proto type.
/// The result type <tt>as_expr\<T, Domain\>::::type</tt> is \c T stripped
/// of cv-qualifiers.
template<typename T, typename Domain>
struct as_expr<
T
, Domain
, typename T::proto_is_expr_
#ifdef BOOST_PROTO_BROKEN_PTS
, typename disable_if<is_same<Domain, typename T::proto_domain> >::type
#endif
>
{
typedef typename T::proto_derived_expr expr_; // removes the const
typedef typename Domain::template result<Domain(expr_)>::type type;
typedef type const reference;
/// INTERNAL ONLY
///
template<typename T2>
static reference call(T2 &t)
{
return Domain()(t);
}
};
template<typename T>
struct as_expr<
T
, typename T::proto_domain
, typename T::proto_is_expr_
#ifdef BOOST_PROTO_BROKEN_PTS
, void
#endif
>
{
typedef typename T::proto_derived_expr type; // removes the const
typedef T &reference;
/// INTERNAL ONLY
///
template<typename T2>
static T2 &call(T2 &t)
{
return t;
}
};
/// \brief A metafunction that computes the return type of the \c as_child()
/// function.
///
/// The <tt>as_child\<\></tt> metafunction turns types into Proto types, if
/// they are not already, by making them Proto terminals held by reference.
/// Types which are already Proto types are returned by reference.
///
/// This specialization is selected when the type is not yet a Proto type.
/// The result type <tt>as_child\<T, Domain\>::::type</tt> is
/// <tt>boost::result_of\<Domain(expr\< tag::terminal, term\<T &\> \>)\>::::type</tt>.
template<
typename T
, typename Domain // = default_domain
, typename Void // = void
#ifdef BOOST_PROTO_BROKEN_PTS
, typename Void2 // = void
#endif
>
struct as_child
{
typedef proto::expr<proto::tag::terminal, term<T &>, 0> expr_;
typedef typename Domain::template result<Domain(expr_)>::type type;
/// INTERNAL ONLY
///
template<typename T2>
static type call(T2 &t)
{
return Domain()(expr_::make(t));
}
};
/// \brief A metafunction that computes the return type of the \c as_child()
/// function.
///
/// The <tt>as_child\<\></tt> metafunction turns types into Proto types, if
/// they are not already, by making them Proto terminals held by reference.
/// Types which are already Proto types are returned by reference.
///
/// This specialization is selected when the type is already a Proto type.
/// The result type <tt>as_child\<T, Domain\>::::type</tt> is
/// <tt>T &</tt>.
template<typename T, typename Domain>
struct as_child<
T
, Domain
, typename T::proto_is_expr_
#ifdef BOOST_PROTO_BROKEN_PTS
, typename disable_if<is_same<Domain, typename T::proto_domain> >::type
#endif
>
{
// BUGBUG should be able to hold this guy by reference, no?
#if BOOST_WORKAROUND(BOOST_MSVC, == 1310) || \
BOOST_WORKAROUND(BOOST_INTEL, BOOST_TESTED_AT(1010))
// These compilers don't strip top-level cv qualifiers
// on arguments in function types
typedef typename Domain::template result<Domain(typename T::proto_derived_expr)>::type type;
#else
typedef typename Domain::template result<Domain(T)>::type type;
#endif
/// INTERNAL ONLY
///
template<typename T2>
static type call(T2 &t)
{
return Domain()(t);
}
};
/// \brief A metafunction that computes the return type of the \c as_child()
/// function.
///
/// The <tt>as_child\<\></tt> metafunction turns types into Proto types, if
/// they are not already, by making them Proto terminals held by reference.
/// Types which are already Proto types are returned by reference.
///
/// This specialization is selected when the type is already a Proto type.
/// The result type <tt>as_child\<T, Domain\>::::type</tt> is
/// <tt>T &</tt>.
template<typename T>
struct as_child<
T
, typename T::proto_domain
, typename T::proto_is_expr_
#ifdef BOOST_PROTO_BROKEN_PTS
, void
#endif
>
{
typedef T &type;
/// INTERNAL ONLY
///
template<typename T2>
static T2 &call(T2 &t)
{
return t;
}
};
/// \brief A metafunction that returns the type of the Nth child
/// of a Proto expression, where N is an MPL Integral Constant.
///
/// <tt>result_of::child\<Expr, N\></tt> is equivalent to
/// <tt>result_of::child_c\<Expr, N::value\></tt>.
template<typename Expr, typename N /* = mpl::long_<0>*/>
struct child
: child_c<Expr, N::value>
{};
/// \brief A metafunction that returns the type of the value
/// of a terminal Proto expression.
///
template<typename Expr>
struct value
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::proto_child0 value_type;
/// The "value" type of the child, suitable for storage by value,
/// computed as follows:
/// \li <tt>T const(&)[N]</tt> becomes <tt>T[N]</tt>
/// \li <tt>T[N]</tt> becomes <tt>T[N]</tt>
/// \li <tt>T(&)[N]</tt> becomes <tt>T[N]</tt>
/// \li <tt>R(&)(A0,...)</tt> becomes <tt>R(&)(A0,...)</tt>
/// \li <tt>T const &</tt> becomes <tt>T</tt>
/// \li <tt>T &</tt> becomes <tt>T</tt>
/// \li <tt>T</tt> becomes <tt>T</tt>
typedef typename detail::term_traits<typename Expr::proto_child0>::value_type type;
};
template<typename Expr>
struct value<Expr &>
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::proto_child0 value_type;
/// The "reference" type of the child, suitable for storage by
/// reference, computed as follows:
/// \li <tt>T const(&)[N]</tt> becomes <tt>T const(&)[N]</tt>
/// \li <tt>T[N]</tt> becomes <tt>T(&)[N]</tt>
/// \li <tt>T(&)[N]</tt> becomes <tt>T(&)[N]</tt>
/// \li <tt>R(&)(A0,...)</tt> becomes <tt>R(&)(A0,...)</tt>
/// \li <tt>T const &</tt> becomes <tt>T const &</tt>
/// \li <tt>T &</tt> becomes <tt>T &</tt>
/// \li <tt>T</tt> becomes <tt>T &</tt>
typedef typename detail::term_traits<typename Expr::proto_child0>::reference type;
};
template<typename Expr>
struct value<Expr const &>
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::proto_child0 value_type;
/// The "const reference" type of the child, suitable for storage by
/// const reference, computed as follows:
/// \li <tt>T const(&)[N]</tt> becomes <tt>T const(&)[N]</tt>
/// \li <tt>T[N]</tt> becomes <tt>T const(&)[N]</tt>
/// \li <tt>T(&)[N]</tt> becomes <tt>T(&)[N]</tt>
/// \li <tt>R(&)(A0,...)</tt> becomes <tt>R(&)(A0,...)</tt>
/// \li <tt>T const &</tt> becomes <tt>T const &</tt>
/// \li <tt>T &</tt> becomes <tt>T &</tt>
/// \li <tt>T</tt> becomes <tt>T const &</tt>
typedef typename detail::term_traits<typename Expr::proto_child0>::const_reference type;
};
// TODO left<> and right<> force the instantiation of Expr.
// Couldn't we partially specialize them on proto::expr< T, A >
// and return A::child0 / A::child1?
/// \brief A metafunction that returns the type of the left child
/// of a binary Proto expression.
///
/// <tt>result_of::left\<Expr\></tt> is equivalent to
/// <tt>result_of::child_c\<Expr, 0\></tt>.
template<typename Expr>
struct left
: child_c<Expr, 0>
{};
/// \brief A metafunction that returns the type of the right child
/// of a binary Proto expression.
///
/// <tt>result_of::right\<Expr\></tt> is equivalent to
/// <tt>result_of::child_c\<Expr, 1\></tt>.
template<typename Expr>
struct right
: child_c<Expr, 1>
{};
} // namespace result_of
namespace op
{
/// \brief A metafunction for generating terminal expression types,
/// a grammar element for matching terminal expressions, and a
/// PrimitiveTransform that returns the current expression unchanged.
template<typename T>
struct terminal
: proto::transform<terminal<T>, int>
{
typedef proto::expr<proto::tag::terminal, term<T>, 0> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl : transform_impl<Expr, State, Data>
{
typedef Expr result_type;
/// \param e The current expression
/// \pre <tt>matches\<Expr, terminal\<T\> \>::::value</tt> is \c true.
/// \return \c e
/// \throw nothrow
#ifdef BOOST_HAS_DECLTYPE
result_type
#else
typename impl::expr_param
#endif
operator ()(
typename impl::expr_param e
, typename impl::state_param
, typename impl::data_param
) const
{
return e;
}
};
/// INTERNAL ONLY
typedef proto::tag::terminal proto_tag;
/// INTERNAL ONLY
typedef T proto_child0;
};
/// \brief A metafunction for generating ternary conditional expression types,
/// a grammar element for matching ternary conditional expressions, and a
/// PrimitiveTransform that dispatches to the <tt>pass_through\<\></tt>
/// transform.
template<typename T, typename U, typename V>
struct if_else_
: proto::transform<if_else_<T, U, V>, int>
{
typedef proto::expr<proto::tag::if_else_, list3<T, U, V>, 3> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl
: detail::pass_through_impl<if_else_, Expr, State, Data>
{};
/// INTERNAL ONLY
typedef proto::tag::if_else_ proto_tag;
/// INTERNAL ONLY
typedef T proto_child0;
/// INTERNAL ONLY
typedef U proto_child1;
/// INTERNAL ONLY
typedef V proto_child2;
};
/// \brief A metafunction for generating nullary expression types with a
/// specified tag type,
/// a grammar element for matching nullary expressions, and a
/// PrimitiveTransform that returns the current expression unchanged.
///
/// Use <tt>nullary_expr\<_, _\></tt> as a grammar element to match any
/// nullary expression.
template<typename Tag, typename T>
struct nullary_expr
: proto::transform<nullary_expr<Tag, T>, int>
{
typedef proto::expr<Tag, term<T>, 0> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl : transform_impl<Expr, State, Data>
{
typedef Expr result_type;
/// \param e The current expression
/// \pre <tt>matches\<Expr, nullary_expr\<Tag, T\> \>::::value</tt> is \c true.
/// \return \c e
/// \throw nothrow
#ifdef BOOST_HAS_DECLTYPE
result_type
#else
typename impl::expr_param
#endif
operator ()(
typename impl::expr_param e
, typename impl::state_param
, typename impl::data_param
) const
{
return e;
}
};
/// INTERNAL ONLY
typedef Tag proto_tag;
/// INTERNAL ONLY
typedef T proto_child0;
};
/// \brief A metafunction for generating unary expression types with a
/// specified tag type,
/// a grammar element for matching unary expressions, and a
/// PrimitiveTransform that dispatches to the <tt>pass_through\<\></tt>
/// transform.
///
/// Use <tt>unary_expr\<_, _\></tt> as a grammar element to match any
/// unary expression.
template<typename Tag, typename T>
struct unary_expr
: proto::transform<unary_expr<Tag, T>, int>
{
typedef proto::expr<Tag, list1<T>, 1> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl
: detail::pass_through_impl<unary_expr, Expr, State, Data>
{};
/// INTERNAL ONLY
typedef Tag proto_tag;
/// INTERNAL ONLY
typedef T proto_child0;
};
/// \brief A metafunction for generating binary expression types with a
/// specified tag type,
/// a grammar element for matching binary expressions, and a
/// PrimitiveTransform that dispatches to the <tt>pass_through\<\></tt>
/// transform.
///
/// Use <tt>binary_expr\<_, _, _\></tt> as a grammar element to match any
/// binary expression.
template<typename Tag, typename T, typename U>
struct binary_expr
: proto::transform<binary_expr<Tag, T, U>, int>
{
typedef proto::expr<Tag, list2<T, U>, 2> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl
: detail::pass_through_impl<binary_expr, Expr, State, Data>
{};
/// INTERNAL ONLY
typedef Tag proto_tag;
/// INTERNAL ONLY
typedef T proto_child0;
/// INTERNAL ONLY
typedef U proto_child1;
};
#define BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(Op) \
template<typename T> \
struct Op \
: proto::transform<Op<T>, int> \
{ \
typedef proto::expr<proto::tag::Op, list1<T>, 1> type; \
typedef type proto_base_expr; \
\
template<typename Expr, typename State, typename Data> \
struct impl \
: detail::pass_through_impl<Op, Expr, State, Data> \
{}; \
\
typedef proto::tag::Op proto_tag; \
typedef T proto_child0; \
}; \
/**/
#define BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(Op) \
template<typename T, typename U> \
struct Op \
: proto::transform<Op<T, U>, int> \
{ \
typedef proto::expr<proto::tag::Op, list2<T, U>, 2> type; \
typedef type proto_base_expr; \
\
template<typename Expr, typename State, typename Data> \
struct impl \
: detail::pass_through_impl<Op, Expr, State, Data> \
{}; \
\
typedef proto::tag::Op proto_tag; \
typedef T proto_child0; \
typedef U proto_child1; \
}; \
/**/
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(unary_plus)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(negate)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(dereference)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(complement)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(address_of)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(logical_not)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(pre_inc)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(pre_dec)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(post_inc)
BOOST_PROTO_DEFINE_UNARY_METAFUNCTION(post_dec)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(shift_left)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(shift_right)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(multiplies)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(divides)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(modulus)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(plus)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(minus)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(less)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(greater)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(less_equal)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(greater_equal)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(equal_to)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(not_equal_to)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(logical_or)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(logical_and)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_or)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_and)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_xor)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(comma)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(mem_ptr)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(shift_left_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(shift_right_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(multiplies_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(divides_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(modulus_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(plus_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(minus_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_or_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_and_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(bitwise_xor_assign)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(subscript)
BOOST_PROTO_DEFINE_BINARY_METAFUNCTION(member)
#undef BOOST_PROTO_DEFINE_UNARY_METAFUNCTION
#undef BOOST_PROTO_DEFINE_BINARY_METAFUNCTION
} // namespace op
#define BOOST_PROTO_CHILD(Z, N, DATA) \
/** INTERNAL ONLY */ \
typedef BOOST_PP_CAT(DATA, N) BOOST_PP_CAT(proto_child, N); \
/**/
#define BOOST_PP_ITERATION_PARAMS_1 (3, (0, BOOST_PROTO_MAX_ARITY, <boost/proto/traits.hpp>))
#include BOOST_PP_ITERATE()
#undef BOOST_PROTO_CHILD
#undef BOOST_PROTO_IMPLICIT_ARG
namespace functional
{
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c as_expr() function.
template<typename Domain /* = default_domain*/>
struct as_expr
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename T>
struct result<This(T)>
{
typedef typename remove_reference<T>::type unref_type;
typedef typename result_of::as_expr<unref_type, Domain>::type type;
};
/// \brief Wrap an object in a Proto terminal if it isn't a
/// Proto expression already.
/// \param t The object to wrap.
/// \return <tt>proto::as_expr\<Domain\>(t)</tt>
template<typename T>
typename result_of::as_expr<T, Domain>::reference
operator ()(T &t) const
{
return result_of::as_expr<T, Domain>::call(t);
}
/// \overload
///
template<typename T>
typename result_of::as_expr<T const, Domain>::reference
operator ()(T const &t) const
{
return result_of::as_expr<T const, Domain>::call(t);
}
#if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
template<typename T, std::size_t N_>
typename result_of::as_expr<T[N_], Domain>::reference
operator ()(T (&t)[N_]) const
{
return result_of::as_expr<T[N_], Domain>::call(t);
}
template<typename T, std::size_t N_>
typename result_of::as_expr<T const[N_], Domain>::reference
operator ()(T const (&t)[N_]) const
{
return result_of::as_expr<T const[N_], Domain>::call(t);
}
#endif
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c as_child() function.
template<typename Domain /* = default_domain*/>
struct as_child
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename T>
struct result<This(T)>
{
typedef typename remove_reference<T>::type unref_type;
typedef typename result_of::as_child<unref_type, Domain>::type type;
};
/// \brief Wrap an object in a Proto terminal if it isn't a
/// Proto expression already.
/// \param t The object to wrap.
/// \return <tt>proto::as_child\<Domain\>(t)</tt>
template<typename T>
typename result_of::as_child<T, Domain>::type
operator ()(T &t) const
{
return result_of::as_child<T, Domain>::call(t);
}
/// \overload
///
template<typename T>
typename result_of::as_child<T const, Domain>::type
operator ()(T const &t) const
{
return result_of::as_child<T const, Domain>::call(t);
}
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c child_c() function.
template<long N>
struct child_c
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr>
struct result<This(Expr)>
{
typedef typename result_of::child_c<Expr, N>::type type;
};
/// \brief Return the Nth child of the given expression.
/// \param expr The expression node.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true
/// \pre <tt>N \< Expr::proto_arity::value</tt>
/// \return <tt>proto::child_c\<N\>(expr)</tt>
/// \throw nothrow
template<typename Expr>
typename result_of::child_c<Expr &, N>::type
operator ()(Expr &e) const
{
return result_of::child_c<Expr &, N>::call(e);
}
/// \overload
///
template<typename Expr>
typename result_of::child_c<Expr const &, N>::type
operator ()(Expr const &e) const
{
return result_of::child_c<Expr const &, N>::call(e);
}
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c child() function.
///
/// A callable PolymorphicFunctionObject that is
/// equivalent to the \c child() function. \c N is required
/// to be an MPL Integral Constant.
template<typename N /* = mpl::long_<0>*/>
struct child
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr>
struct result<This(Expr)>
{
typedef typename result_of::child<Expr, N>::type type;
};
/// \brief Return the Nth child of the given expression.
/// \param expr The expression node.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true
/// \pre <tt>N::value \< Expr::proto_arity::value</tt>
/// \return <tt>proto::child\<N\>(expr)</tt>
/// \throw nothrow
template<typename Expr>
typename result_of::child<Expr &, N>::type
operator ()(Expr &e) const
{
return result_of::child<Expr &, N>::call(e);
}
/// \overload
///
template<typename Expr>
typename result_of::child<Expr const &, N>::type
operator ()(Expr const &e) const
{
return result_of::child<Expr const &, N>::call(e);
}
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c value() function.
struct value
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr>
struct result<This(Expr)>
{
typedef typename result_of::value<Expr>::type type;
};
/// \brief Return the value of the given terminal expression.
/// \param expr The terminal expression node.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true
/// \pre <tt>0 == Expr::proto_arity::value</tt>
/// \return <tt>proto::value(expr)</tt>
/// \throw nothrow
template<typename Expr>
typename result_of::value<Expr &>::type
operator ()(Expr &e) const
{
return e.proto_base().child0;
}
/// \overload
///
template<typename Expr>
typename result_of::value<Expr const &>::type
operator ()(Expr const &e) const
{
return e.proto_base().child0;
}
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c left() function.
struct left
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr>
struct result<This(Expr)>
{
typedef typename result_of::left<Expr>::type type;
};
/// \brief Return the left child of the given binary expression.
/// \param expr The expression node.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true
/// \pre <tt>2 == Expr::proto_arity::value</tt>
/// \return <tt>proto::left(expr)</tt>
/// \throw nothrow
template<typename Expr>
typename result_of::left<Expr &>::type
operator ()(Expr &e) const
{
return e.proto_base().child0;
}
/// \overload
///
template<typename Expr>
typename result_of::left<Expr const &>::type
operator ()(Expr const &e) const
{
return e.proto_base().child0;
}
};
/// \brief A callable PolymorphicFunctionObject that is
/// equivalent to the \c right() function.
struct right
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr>
struct result<This(Expr)>
{
typedef typename result_of::right<Expr>::type type;
};
/// \brief Return the right child of the given binary expression.
/// \param expr The expression node.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true
/// \pre <tt>2 == Expr::proto_arity::value</tt>
/// \return <tt>proto::right(expr)</tt>
/// \throw nothrow
template<typename Expr>
typename result_of::right<Expr &>::type
operator ()(Expr &e) const
{
return e.proto_base().child1;
}
template<typename Expr>
typename result_of::right<Expr const &>::type
operator ()(Expr const &e) const
{
return e.proto_base().child1;
}
};
}
/// \brief A function that wraps non-Proto expression types in Proto
/// terminals and leaves Proto expression types alone.
///
/// The <tt>as_expr()</tt> function turns objects into Proto terminals if
/// they are not Proto expression types already. Non-Proto types are
/// held by value, if possible. Types which are already Proto types are
/// left alone and returned by reference.
///
/// This function can be called either with an explicitly specified
/// \c Domain parameter (i.e., <tt>as_expr\<Domain\>(t)</tt>), or
/// without (i.e., <tt>as_expr(t)</tt>). If no domain is
/// specified, \c default_domain is assumed.
///
/// If <tt>is_expr\<T\>::::value</tt> is \c true, then the argument is
/// returned unmodified, by reference. Otherwise, the argument is wrapped
/// in a Proto terminal expression node according to the following rules.
/// If \c T is a function type, let \c A be <tt>T &</tt>. Otherwise, let
/// \c A be the type \c T stripped of cv-qualifiers. Then, \c as_expr()
/// returns <tt>Domain()(terminal\<A\>::::type::make(t))</tt>.
///
/// \param t The object to wrap.
template<typename T>
typename result_of::as_expr<T>::reference
as_expr(T &t BOOST_PROTO_DISABLE_IF_IS_CONST(T) BOOST_PROTO_DISABLE_IF_IS_FUNCTION(T))
{
return result_of::as_expr<T>::call(t);
}
/// \overload
///
template<typename T>
typename result_of::as_expr<T const>::reference
as_expr(T const &t)
{
return result_of::as_expr<T const>::call(t);
}
/// \overload
///
template<typename Domain, typename T>
typename result_of::as_expr<T, Domain>::reference
as_expr(T &t BOOST_PROTO_DISABLE_IF_IS_CONST(T) BOOST_PROTO_DISABLE_IF_IS_FUNCTION(T))
{
return result_of::as_expr<T, Domain>::call(t);
}
/// \overload
///
template<typename Domain, typename T>
typename result_of::as_expr<T const, Domain>::reference
as_expr(T const &t)
{
return result_of::as_expr<T const, Domain>::call(t);
}
/// \brief A function that wraps non-Proto expression types in Proto
/// terminals (by reference) and returns Proto expression types by
/// reference
///
/// The <tt>as_child()</tt> function turns objects into Proto terminals if
/// they are not Proto expression types already. Non-Proto types are
/// held by reference. Types which are already Proto types are simply
/// returned as-is.
///
/// This function can be called either with an explicitly specified
/// \c Domain parameter (i.e., <tt>as_child\<Domain\>(t)</tt>), or
/// without (i.e., <tt>as_child(t)</tt>). If no domain is
/// specified, \c default_domain is assumed.
///
/// If <tt>is_expr\<T\>::::value</tt> is \c true, then the argument is
/// returned as-is. Otherwise, \c as_child() returns
/// <tt>Domain()(terminal\<T &\>::::type::make(t))</tt>.
///
/// \param t The object to wrap.
template<typename T>
typename result_of::as_child<T>::type
as_child(T &t BOOST_PROTO_DISABLE_IF_IS_CONST(T) BOOST_PROTO_DISABLE_IF_IS_FUNCTION(T))
{
return result_of::as_child<T>::call(t);
}
/// \overload
///
template<typename T>
typename result_of::as_child<T const>::type
as_child(T const &t)
{
return result_of::as_child<T const>::call(t);
}
/// \overload
///
template<typename Domain, typename T>
typename result_of::as_child<T, Domain>::type
as_child(T &t BOOST_PROTO_DISABLE_IF_IS_CONST(T) BOOST_PROTO_DISABLE_IF_IS_FUNCTION(T))
{
return result_of::as_child<T, Domain>::call(t);
}
/// \overload
///
template<typename Domain, typename T>
typename result_of::as_child<T const, Domain>::type
as_child(T const &t)
{
return result_of::as_child<T const, Domain>::call(t);
}
/// \brief Return the Nth child of the specified Proto expression.
///
/// Return the Nth child of the specified Proto expression. If
/// \c N is not specified, as in \c child(expr), then \c N is assumed
/// to be <tt>mpl::long_\<0\></tt>. The child is returned by
/// reference.
///
/// \param expr The Proto expression.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true.
/// \pre \c N is an MPL Integral Constant.
/// \pre <tt>N::value \< Expr::proto_arity::value</tt>
/// \throw nothrow
/// \return A reference to the Nth child
template<typename N, typename Expr>
typename result_of::child<Expr &, N>::type
child(Expr &e BOOST_PROTO_DISABLE_IF_IS_CONST(Expr))
{
return result_of::child<Expr &, N>::call(e);
}
/// \overload
///
template<typename N, typename Expr>
typename result_of::child<Expr const &, N>::type
child(Expr const &e)
{
return result_of::child<Expr const &, N>::call(e);
}
/// \overload
///
template<typename Expr2>
typename detail::expr_traits<typename Expr2::proto_base_expr::proto_child0>::reference
child(Expr2 &expr2 BOOST_PROTO_DISABLE_IF_IS_CONST(Expr2))
{
return expr2.proto_base().child0;
}
/// \overload
///
template<typename Expr2>
typename detail::expr_traits<typename Expr2::proto_base_expr::proto_child0>::const_reference
child(Expr2 const &expr2)
{
return expr2.proto_base().child0;
}
/// \brief Return the Nth child of the specified Proto expression.
///
/// Return the Nth child of the specified Proto expression. The child
/// is returned by reference.
///
/// \param expr The Proto expression.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true.
/// \pre <tt>N \< Expr::proto_arity::value</tt>
/// \throw nothrow
/// \return A reference to the Nth child
template<long N, typename Expr>
typename result_of::child_c<Expr &, N>::type
child_c(Expr &e BOOST_PROTO_DISABLE_IF_IS_CONST(Expr))
{
return result_of::child_c<Expr &, N>::call(e);
}
/// \overload
///
template<long N, typename Expr>
typename result_of::child_c<Expr const &, N>::type
child_c(Expr const &e)
{
return result_of::child_c<Expr const &, N>::call(e);
}
/// \brief Return the value stored within the specified Proto
/// terminal expression.
///
/// Return the the value stored within the specified Proto
/// terminal expression. The value is returned by
/// reference.
///
/// \param expr The Proto terminal expression.
/// \pre <tt>N::value == 0</tt>
/// \throw nothrow
/// \return A reference to the terminal's value
template<typename Expr>
typename result_of::value<Expr &>::type
value(Expr &e BOOST_PROTO_DISABLE_IF_IS_CONST(Expr))
{
return e.proto_base().child0;
}
/// \overload
///
template<typename Expr>
typename result_of::value<Expr const &>::type
value(Expr const &e)
{
return e.proto_base().child0;
}
/// \brief Return the left child of the specified binary Proto
/// expression.
///
/// Return the left child of the specified binary Proto expression. The
/// child is returned by reference.
///
/// \param expr The Proto expression.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true.
/// \pre <tt>2 == Expr::proto_arity::value</tt>
/// \throw nothrow
/// \return A reference to the left child
template<typename Expr>
typename result_of::left<Expr &>::type
left(Expr &e BOOST_PROTO_DISABLE_IF_IS_CONST(Expr))
{
return e.proto_base().child0;
}
/// \overload
///
template<typename Expr>
typename result_of::left<Expr const &>::type
left(Expr const &e)
{
return e.proto_base().child0;
}
/// \brief Return the right child of the specified binary Proto
/// expression.
///
/// Return the right child of the specified binary Proto expression. The
/// child is returned by reference.
///
/// \param expr The Proto expression.
/// \pre <tt>is_expr\<Expr\>::::value</tt> is \c true.
/// \pre <tt>2 == Expr::proto_arity::value</tt>
/// \throw nothrow
/// \return A reference to the right child
template<typename Expr>
typename result_of::right<Expr &>::type
right(Expr &e BOOST_PROTO_DISABLE_IF_IS_CONST(Expr))
{
return e.proto_base().child1;
}
/// \overload
///
template<typename Expr>
typename result_of::right<Expr const &>::type
right(Expr const &e)
{
return e.proto_base().child1;
}
/// INTERNAL ONLY
///
template<typename Domain>
struct is_callable<functional::as_expr<Domain> >
: mpl::true_
{};
/// INTERNAL ONLY
///
template<typename Domain>
struct is_callable<functional::as_child<Domain> >
: mpl::true_
{};
/// INTERNAL ONLY
///
template<long N>
struct is_callable<functional::child_c<N> >
: mpl::true_
{};
/// INTERNAL ONLY
///
template<typename N>
struct is_callable<functional::child<N> >
: mpl::true_
{};
}}
#if BOOST_WORKAROUND( BOOST_MSVC, >= 1400 )
#pragma warning(pop)
#endif
#endif
#else // PP_IS_ITERATING
#define N BOOST_PP_ITERATION()
#if N > 0
namespace op
{
/// \brief A metafunction for generating function-call expression types,
/// a grammar element for matching function-call expressions, and a
/// PrimitiveTransform that dispatches to the <tt>pass_through\<\></tt>
/// transform.
template<BOOST_PP_ENUM_PARAMS(N, typename A)>
struct function
#if N != BOOST_PROTO_MAX_ARITY
<
BOOST_PP_ENUM_PARAMS(N, A)
BOOST_PP_ENUM_TRAILING_PARAMS(BOOST_PP_SUB(BOOST_PROTO_MAX_ARITY, N), void BOOST_PP_INTERCEPT)
>
#endif
: proto::transform<
function<
BOOST_PP_ENUM_PARAMS(N, A)
BOOST_PP_ENUM_TRAILING_PARAMS(BOOST_PP_SUB(BOOST_PROTO_MAX_ARITY, N), void BOOST_PP_INTERCEPT)
>
, int
>
{
typedef proto::expr<proto::tag::function, BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, A)>, N> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl
: detail::pass_through_impl<function, Expr, State, Data>
{};
/// INTERNAL ONLY
typedef proto::tag::function proto_tag;
BOOST_PP_REPEAT(N, BOOST_PROTO_CHILD, A)
BOOST_PP_REPEAT_FROM_TO(
N
, BOOST_PROTO_MAX_ARITY
, BOOST_PROTO_CHILD
, detail::if_vararg<BOOST_PP_CAT(A, BOOST_PP_DEC(N))> BOOST_PP_INTERCEPT
)
};
/// \brief A metafunction for generating n-ary expression types with a
/// specified tag type,
/// a grammar element for matching n-ary expressions, and a
/// PrimitiveTransform that dispatches to the <tt>pass_through\<\></tt>
/// transform.
///
/// Use <tt>nary_expr\<_, vararg\<_\> \></tt> as a grammar element to match any
/// n-ary expression; that is, any non-terminal.
template<typename Tag BOOST_PP_ENUM_TRAILING_PARAMS(N, typename A)>
struct nary_expr
#if N != BOOST_PROTO_MAX_ARITY
<
Tag
BOOST_PP_ENUM_TRAILING_PARAMS(N, A)
BOOST_PP_ENUM_TRAILING_PARAMS(BOOST_PP_SUB(BOOST_PROTO_MAX_ARITY, N), void BOOST_PP_INTERCEPT)
>
#endif
: proto::transform<
nary_expr<
Tag
BOOST_PP_ENUM_TRAILING_PARAMS(N, A)
BOOST_PP_ENUM_TRAILING_PARAMS(BOOST_PP_SUB(BOOST_PROTO_MAX_ARITY, N), void BOOST_PP_INTERCEPT)
>
, int
>
{
typedef proto::expr<Tag, BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, A)>, N> type;
typedef type proto_base_expr;
template<typename Expr, typename State, typename Data>
struct impl
: detail::pass_through_impl<nary_expr, Expr, State, Data>
{};
/// INTERNAL ONLY
typedef Tag proto_tag;
BOOST_PP_REPEAT(N, BOOST_PROTO_CHILD, A)
BOOST_PP_REPEAT_FROM_TO(
N
, BOOST_PROTO_MAX_ARITY
, BOOST_PROTO_CHILD
, detail::if_vararg<BOOST_PP_CAT(A, BOOST_PP_DEC(N))> BOOST_PP_INTERCEPT
)
};
} // namespace op
namespace detail
{
template<
template<BOOST_PP_ENUM_PARAMS(N, typename BOOST_PP_INTERCEPT)> class T
, BOOST_PP_ENUM_PARAMS(N, typename A)
>
struct is_callable_<T<BOOST_PP_ENUM_PARAMS(N, A)> BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(N)>
: is_same<BOOST_PP_CAT(A, BOOST_PP_DEC(N)), callable>
{};
}
#endif
namespace result_of
{
/// \brief A metafunction that returns the type of the Nth child
/// of a Proto expression.
///
/// A metafunction that returns the type of the Nth child
/// of a Proto expression. \c N must be less than
/// \c Expr::proto_arity::value.
template<typename Expr>
struct child_c<Expr, N>
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::BOOST_PP_CAT(proto_child, N) value_type;
/// The "value" type of the child, suitable for return by value,
/// computed as follows:
/// \li <tt>T const &</tt> becomes <tt>T</tt>
/// \li <tt>T &</tt> becomes <tt>T</tt>
/// \li <tt>T</tt> becomes <tt>T</tt>
typedef typename detail::expr_traits<typename Expr::BOOST_PP_CAT(proto_child, N)>::value_type type;
};
template<typename Expr>
struct child_c<Expr &, N>
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::BOOST_PP_CAT(proto_child, N) value_type;
/// The "reference" type of the child, suitable for return by
/// reference, computed as follows:
/// \li <tt>T const &</tt> becomes <tt>T const &</tt>
/// \li <tt>T &</tt> becomes <tt>T &</tt>
/// \li <tt>T</tt> becomes <tt>T &</tt>
typedef typename detail::expr_traits<typename Expr::BOOST_PP_CAT(proto_child, N)>::reference type;
/// INTERNAL ONLY
///
static type call(Expr &e)
{
return e.proto_base().BOOST_PP_CAT(child, N);
}
};
template<typename Expr>
struct child_c<Expr const &, N>
{
/// The raw type of the Nth child as it is stored within
/// \c Expr. This may be a value or a reference
typedef typename Expr::BOOST_PP_CAT(proto_child, N) value_type;
/// The "const reference" type of the child, suitable for return by
/// const reference, computed as follows:
/// \li <tt>T const &</tt> becomes <tt>T const &</tt>
/// \li <tt>T &</tt> becomes <tt>T &</tt>
/// \li <tt>T</tt> becomes <tt>T const &</tt>
typedef typename detail::expr_traits<typename Expr::BOOST_PP_CAT(proto_child, N)>::const_reference type;
/// INTERNAL ONLY
///
static type call(Expr const &e)
{
return e.proto_base().BOOST_PP_CAT(child, N);
}
};
}
#undef N
#endif
