/////////////////////////////////////////////////////////////////////////////// | |
// as_alternate.hpp | |
// | |
// 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_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_ALTERNATE_HPP_EAN_04_01_2007 | |
#define BOOST_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_ALTERNATE_HPP_EAN_04_01_2007 | |
// MS compatible compilers support #pragma once | |
#if defined(_MSC_VER) && (_MSC_VER >= 1020) | |
# pragma once | |
#endif | |
#include <boost/config.hpp> | |
#include <boost/mpl/assert.hpp> | |
#include <boost/type_traits/is_same.hpp> | |
#include <boost/proto/core.hpp> | |
#include <boost/xpressive/detail/detail_fwd.hpp> | |
#include <boost/xpressive/detail/static/static.hpp> | |
#include <boost/xpressive/detail/core/matcher/alternate_matcher.hpp> | |
#include <boost/xpressive/detail/utility/cons.hpp> | |
namespace boost { namespace xpressive | |
{ | |
namespace detail | |
{ | |
/////////////////////////////////////////////////////////////////////////////// | |
// alternates_list | |
// a fusion-compatible sequence of alternate expressions, that also keeps | |
// track of the list's width and purity. | |
template<typename Head, typename Tail> | |
struct alternates_list | |
: fusion::cons<Head, Tail> | |
{ | |
BOOST_STATIC_CONSTANT(std::size_t, width = Head::width == Tail::width ? Head::width : detail::unknown_width::value); | |
BOOST_STATIC_CONSTANT(bool, pure = Head::pure && Tail::pure); | |
alternates_list(Head const &head, Tail const &tail) | |
: fusion::cons<Head, Tail>(head, tail) | |
{ | |
} | |
}; | |
template<typename Head> | |
struct alternates_list<Head, fusion::nil> | |
: fusion::cons<Head, fusion::nil> | |
{ | |
BOOST_STATIC_CONSTANT(std::size_t, width = Head::width); | |
BOOST_STATIC_CONSTANT(bool, pure = Head::pure); | |
alternates_list(Head const &head, fusion::nil const &tail) | |
: fusion::cons<Head, fusion::nil>(head, tail) | |
{ | |
} | |
}; | |
} | |
namespace grammar_detail | |
{ | |
/////////////////////////////////////////////////////////////////////////////// | |
// in_alternate_list | |
template<typename Grammar, typename Callable = proto::callable> | |
struct in_alternate_list : proto::transform<in_alternate_list<Grammar, Callable> > | |
{ | |
template<typename Expr, typename State, typename Data> | |
struct impl : proto::transform_impl<Expr, State, Data> | |
{ | |
typedef | |
detail::alternates_list< | |
typename Grammar::template impl< | |
Expr | |
, detail::alternate_end_xpression | |
, Data | |
>::result_type | |
, State | |
> | |
result_type; | |
result_type operator ()( | |
typename impl::expr_param expr | |
, typename impl::state_param state | |
, typename impl::data_param data | |
) const | |
{ | |
return result_type( | |
typename Grammar::template impl<Expr, detail::alternate_end_xpression, Data>()( | |
expr | |
, detail::alternate_end_xpression() | |
, data | |
) | |
, state | |
); | |
} | |
}; | |
}; | |
/////////////////////////////////////////////////////////////////////////////// | |
// as_alternate_matcher | |
template<typename Grammar, typename Callable = proto::callable> | |
struct as_alternate_matcher : proto::transform<as_alternate_matcher<Grammar, Callable> > | |
{ | |
template<typename Expr, typename State, typename Data> | |
struct impl : proto::transform_impl<Expr, State, Data> | |
{ | |
typedef typename impl::data data_type; | |
typedef | |
detail::alternate_matcher< | |
typename Grammar::template impl<Expr, State, Data>::result_type | |
, typename data_type::traits_type | |
> | |
result_type; | |
result_type operator ()( | |
typename impl::expr_param expr | |
, typename impl::state_param state | |
, typename impl::data_param data | |
) const | |
{ | |
return result_type( | |
typename Grammar::template impl<Expr, State, Data>()(expr, state, data) | |
); | |
} | |
}; | |
}; | |
} | |
}} | |
#endif |