| /////////////////////////////////////////////////////////////////////////////// |
| // 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 |