You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
360 lines
9.7 KiB
360 lines
9.7 KiB
///////////////////////////////////////////////////////////////////////////////
|
|
/// \file arg.hpp
|
|
/// Contains definition of the argN transforms.
|
|
//
|
|
// 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_ARG_HPP_EAN_11_01_2007
|
|
#define BOOST_PROTO_TRANSFORM_ARG_HPP_EAN_11_01_2007
|
|
|
|
#include <boost/mpl/if.hpp>
|
|
#include <boost/proto/proto_fwd.hpp>
|
|
#include <boost/proto/traits.hpp>
|
|
#include <boost/proto/transform/impl.hpp>
|
|
#include <boost/type_traits/is_array.hpp>
|
|
#include <boost/proto/transform/env.hpp>
|
|
|
|
namespace boost { namespace proto
|
|
{
|
|
|
|
/// \brief A PrimitiveTransform that returns the current expression
|
|
/// unmodified
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// proto::terminal<int>::type & j = proto::_expr()(i);
|
|
/// assert( boost::addressof(i) == boost::addressof(j) );
|
|
/// \endcode
|
|
struct _expr : transform<_expr>
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl : transform_impl<Expr, State, Data>
|
|
{
|
|
typedef Expr result_type;
|
|
|
|
/// Returns the current expression.
|
|
/// \param e The current expression.
|
|
/// \return \c e
|
|
/// \throw nothrow
|
|
BOOST_PROTO_RETURN_TYPE_STRICT_LOOSE(result_type, typename impl::expr_param)
|
|
operator()(
|
|
typename impl::expr_param e
|
|
, typename impl::state_param
|
|
, typename impl::data_param
|
|
) const
|
|
{
|
|
return e;
|
|
}
|
|
};
|
|
};
|
|
|
|
/// \brief A PrimitiveTransform that returns the current state
|
|
/// unmodified
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// char ch = proto::_state()(i, 'a');
|
|
/// assert( ch == 'a' );
|
|
/// \endcode
|
|
struct _state : transform<_state>
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl : transform_impl<Expr, State, Data>
|
|
{
|
|
typedef State result_type;
|
|
|
|
/// Returns the current state.
|
|
/// \param s The current state.
|
|
/// \return \c s
|
|
/// \throw nothrow
|
|
BOOST_PROTO_RETURN_TYPE_STRICT_LOOSE(result_type, typename impl::state_param)
|
|
operator ()(
|
|
typename impl::expr_param
|
|
, typename impl::state_param s
|
|
, typename impl::data_param
|
|
) const
|
|
{
|
|
return s;
|
|
}
|
|
};
|
|
};
|
|
|
|
/// \brief A PrimitiveTransform that returns the current data
|
|
/// unmodified
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// std::string str("hello");
|
|
/// std::string & data = proto::_data()(i, 'a', str);
|
|
/// assert( &str == &data );
|
|
/// \endcode
|
|
struct _data : transform<_data>
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl
|
|
: mpl::if_c<
|
|
is_env<Data>::value
|
|
, _env_var<data_type>
|
|
, _env
|
|
>::type::template impl<Expr, State, Data>
|
|
{};
|
|
};
|
|
|
|
/// \brief A PrimitiveTransform that returns N-th child of the current
|
|
/// expression.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// proto::terminal<int>::type & j = proto::_child_c<0>()(-i);
|
|
/// assert( boost::addressof(i) == boost::addressof(j) );
|
|
/// \endcode
|
|
template<int N>
|
|
struct _child_c : transform<_child_c<N> >
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl : transform_impl<Expr, State, Data>
|
|
{
|
|
typedef
|
|
typename result_of::child_c<Expr, N>::type
|
|
result_type;
|
|
|
|
/// Returns the N-th child of \c e
|
|
/// \pre <tt>arity_of\<Expr\>::value \> N</tt>
|
|
/// \param e The current expression.
|
|
/// \return <tt>proto::child_c\<N\>(e)</tt>
|
|
/// \throw nothrow
|
|
#ifdef BOOST_PROTO_STRICT_RESULT_OF
|
|
result_type
|
|
#else
|
|
typename result_of::child_c<typename impl::expr_param, N>::type
|
|
#endif
|
|
operator ()(
|
|
typename impl::expr_param e
|
|
, typename impl::state_param
|
|
, typename impl::data_param
|
|
) const
|
|
{
|
|
return proto::child_c<N>(e);
|
|
}
|
|
};
|
|
};
|
|
|
|
/// \brief A PrimitiveTransform that returns the value of the
|
|
/// current terminal expression.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// int j = proto::_value()(i);
|
|
/// assert( 42 == j );
|
|
/// \endcode
|
|
struct _value : transform<_value>
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl : transform_impl<Expr, State, Data>
|
|
{
|
|
typedef
|
|
typename result_of::value<Expr>::type
|
|
result_type;
|
|
|
|
/// Returns the value of the specified terminal expression.
|
|
/// \pre <tt>arity_of\<Expr\>::value == 0</tt>.
|
|
/// \param e The current expression.
|
|
/// \return <tt>proto::value(e)</tt>
|
|
/// \throw nothrow
|
|
#ifdef BOOST_PROTO_STRICT_RESULT_OF
|
|
typename mpl::if_c<is_array<result_type>::value, result_type &, result_type>::type
|
|
#else
|
|
typename result_of::value<typename impl::expr_param>::type
|
|
#endif
|
|
operator ()(
|
|
typename impl::expr_param e
|
|
, typename impl::state_param
|
|
, typename impl::data_param
|
|
) const
|
|
{
|
|
return proto::value(e);
|
|
}
|
|
};
|
|
};
|
|
|
|
/// \brief A PrimitiveTransform that does nothing
|
|
/// and returns void.
|
|
struct _void : transform<_void>
|
|
{
|
|
template<typename Expr, typename State, typename Data>
|
|
struct impl : transform_impl<Expr, State, Data>
|
|
{
|
|
typedef void result_type;
|
|
|
|
/// Does nothing and returns void
|
|
void operator ()(
|
|
typename impl::expr_param
|
|
, typename impl::state_param
|
|
, typename impl::data_param
|
|
) const
|
|
{}
|
|
};
|
|
};
|
|
|
|
/// \brief A unary CallableTransform that wraps its argument
|
|
/// in a \c boost::reference_wrapper\<\>.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// boost::reference_wrapper<proto::terminal<int>::type> j
|
|
/// = proto::when<_, proto::_byref(_)>()(i);
|
|
/// assert( boost::addressof(i) == boost::addressof(j.get()) );
|
|
/// \endcode
|
|
struct _byref : callable
|
|
{
|
|
template<typename Sig>
|
|
struct result;
|
|
|
|
template<typename This, typename T>
|
|
struct result<This(T)>
|
|
{
|
|
typedef boost::reference_wrapper<T const> const type;
|
|
};
|
|
|
|
template<typename This, typename T>
|
|
struct result<This(T &)>
|
|
{
|
|
typedef boost::reference_wrapper<T> const type;
|
|
};
|
|
|
|
/// Wrap the parameter \c t in a \c boost::reference_wrapper\<\>
|
|
/// \param t The object to wrap
|
|
/// \return <tt>boost::ref(t)</tt>
|
|
/// \throw nothrow
|
|
template<typename T>
|
|
boost::reference_wrapper<T> const operator ()(T &t) const
|
|
{
|
|
return boost::reference_wrapper<T>(t);
|
|
}
|
|
|
|
/// \overload
|
|
///
|
|
template<typename T>
|
|
boost::reference_wrapper<T const> const operator ()(T const &t) const
|
|
{
|
|
return boost::reference_wrapper<T const>(t);
|
|
}
|
|
};
|
|
|
|
/// \brief A unary CallableTransform that strips references
|
|
/// and \c boost::reference_wrapper\<\> from its argument.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// \code
|
|
/// proto::terminal<int>::type i = {42};
|
|
/// int j = 67;
|
|
/// int k = proto::when<_, proto::_byval(proto::_state)>()(i, boost::ref(j));
|
|
/// assert( 67 == k );
|
|
/// \endcode
|
|
struct _byval : callable
|
|
{
|
|
template<typename Sig>
|
|
struct result;
|
|
|
|
template<typename This, typename T>
|
|
struct result<This(T)>
|
|
{
|
|
typedef T type;
|
|
};
|
|
|
|
template<typename This, typename T>
|
|
struct result<This(T &)>
|
|
: result<This(T)>
|
|
{};
|
|
|
|
template<typename This, typename T>
|
|
struct result<This(boost::reference_wrapper<T>)>
|
|
: result<This(T)>
|
|
{};
|
|
|
|
/// \param t The object to unref
|
|
/// \return <tt>t</tt>
|
|
/// \throw nothrow
|
|
template<typename T>
|
|
T operator ()(T const &t) const
|
|
{
|
|
return t;
|
|
}
|
|
|
|
/// \overload
|
|
///
|
|
template<typename T>
|
|
T operator ()(boost::reference_wrapper<T> const &t) const
|
|
{
|
|
return t;
|
|
}
|
|
};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_expr>
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_state>
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_data>
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<int N>
|
|
struct is_callable<_child_c<N> >
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_value>
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_byref>
|
|
: mpl::true_
|
|
{};
|
|
|
|
/// INTERNAL ONLY
|
|
///
|
|
template<>
|
|
struct is_callable<_byval>
|
|
: mpl::true_
|
|
{};
|
|
|
|
}}
|
|
|
|
#endif
|