static/transforms/as_modifier.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // as_modifier.hpp
0003 //
0004 //  Copyright 2008 Eric Niebler. Distributed under the Boost
0005 //  Software License, Version 1.0. (See accompanying file
0006 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007
0008 #ifndef BOOST_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_MODIFIER_HPP_EAN_04_05_2007
0009 #define BOOST_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_MODIFIER_HPP_EAN_04_05_2007
0010
0011 // MS compatible compilers support #pragma once
0012 #if defined(_MSC_VER)
0013 # pragma once
0014 #endif
0015
0016 #include <boost/mpl/sizeof.hpp>
0017 #include <boost/xpressive/detail/detail_fwd.hpp>
0018 #include <boost/xpressive/detail/static/static.hpp>
0019 #include <boost/proto/core.hpp>
0020
0021 #define UNCV(x) typename remove_const<x>::type
0022 #define UNREF(x) typename remove_reference<x>::type
0023 #define UNCVREF(x) UNCV(UNREF(x))
0024
0025 namespace boost { namespace xpressive { namespace detail
0026 {
0027     ///////////////////////////////////////////////////////////////////////////////
0028     // regex operator tags
0029     struct modifier_tag
0030     {};
0031
0032 }}}
0033
0034 namespace boost { namespace xpressive { namespace grammar_detail
0035 {
0036
0037     ///////////////////////////////////////////////////////////////////////////////
0038     // as_modifier
0039     template<typename Grammar, typename Callable = proto::callable>
0040     struct as_modifier : proto::transform<as_modifier<Grammar, Callable> >
0041     {
0042         template<typename Expr, typename State, typename Data>
0043         struct impl : proto::transform_impl<Expr, State, Data>
0044         {
0045             typedef
0046                 typename proto::result_of::value<
0047                     typename proto::result_of::left<typename impl::expr>::type
0048                 >::type
0049             modifier_type;
0050
0051             typedef
0052                 typename modifier_type::template apply<typename impl::data>::type
0053             visitor_type;
0054
0055             typedef
0056                 typename proto::result_of::right<Expr>::type
0057             expr_type;
0058
0059             typedef
0060                 typename Grammar::template impl<expr_type, State, visitor_type &>::result_type
0061             result_type;
0062
0063             result_type operator ()(
0064                 typename impl::expr_param expr
0065               , typename impl::state_param state
0066               , typename impl::data_param data
0067             ) const
0068             {
0069                 visitor_type new_visitor(proto::value(proto::left(expr)).call(data));
0070                 return typename Grammar::template impl<expr_type, State, visitor_type &>()(
0071                     proto::right(expr)
0072                   , state
0073                   , new_visitor
0074                 );
0075             }
0076         };
0077     };
0078
0079 }}}
0080
0081 #undef UNCV
0082 #undef UNREF
0083 #undef UNCVREF
0084
0085 #endif