home/lex/meta_compiler.hpp

0001 //  Copyright (c) 2001-2011 Hartmut Kaiser
0002 //  Copyright (c) 2001-2011 Joel de Guzman
0003 //
0004 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #if !defined(BOOST_SPIRIT_LEX_META_COMPILER_APR_20_2009_0756PM)
0008 #define BOOST_SPIRIT_LEX_META_COMPILER_APR_20_2009_0756PM
0009
0010 #if defined(_MSC_VER)
0011 #pragma once
0012 #endif
0013
0014 #include <boost/spirit/home/support/meta_compiler.hpp>
0015 #include <boost/spirit/home/lex/domain.hpp>
0016 #include <boost/spirit/home/lex/lexer_type.hpp>
0017 #include <boost/proto/tags.hpp>
0018 #include <boost/type_traits/remove_reference.hpp>
0019 #include <boost/utility/enable_if.hpp>
0020
0021 namespace boost { namespace spirit
0022 {
0023     template <typename T>
0024     struct use_terminal<lex::domain, T
0025       , typename enable_if<traits::is_lexer<T> >::type> // enables lexers
0026       : mpl::true_ {};
0027
0028     namespace lex
0029     {
0030         template <typename T, typename Modifiers, typename Enable = void>
0031         struct make_primitive // by default, return it as-is
0032         {
0033             typedef T result_type;
0034
0035             template <typename T_>
0036             T_& operator()(T_& val, unused_type) const
0037             {
0038                 return val;
0039             }
0040
0041             template <typename T_>
0042             T_ const& operator()(T_ const& val, unused_type) const
0043             {
0044                 return val;
0045             }
0046         };
0047
0048         template <typename Tag, typename Elements
0049           , typename Modifiers, typename Enable = void>
0050         struct make_composite;
0051     }
0052
0053     // Lex primitive meta-compiler
0054     template <>
0055     struct make_component<lex::domain, proto::tag::terminal>
0056     {
0057         template <typename Sig>
0058         struct result;
0059
0060         template <typename This, typename Elements, typename Modifiers>
0061         struct result<This(Elements, Modifiers)>
0062         {
0063             typedef typename lex::make_primitive<
0064                 typename remove_const<typename Elements::car_type>::type,
0065                 typename remove_reference<Modifiers>::type>::result_type
0066             type;
0067         };
0068
0069         template <typename Elements, typename Modifiers>
0070         typename result<make_component(Elements, Modifiers)>::type
0071         operator()(Elements const& elements, Modifiers const& modifiers) const
0072         {
0073             typedef typename remove_const<typename Elements::car_type>::type term;
0074             return lex::make_primitive<term, Modifiers>()(elements.car, modifiers);
0075         }
0076     };
0077
0078     // Lex composite meta-compiler
0079     template <typename Tag>
0080     struct make_component<lex::domain, Tag>
0081     {
0082         template <typename Sig>
0083         struct result;
0084
0085         template <typename This, typename Elements, typename Modifiers>
0086         struct result<This(Elements, Modifiers)>
0087         {
0088             typedef typename
0089                 lex::make_composite<Tag, Elements
0090                   , typename remove_reference<Modifiers>::type>::result_type
0091             type;
0092         };
0093
0094         template <typename Elements, typename Modifiers>
0095         typename result<make_component(Elements, Modifiers)>::type
0096         operator()(Elements const& elements, Modifiers const& modifiers) const
0097         {
0098             return lex::make_composite<Tag, Elements, Modifiers>()(
0099                 elements, modifiers);
0100         }
0101     };
0102
0103 }}
0104
0105 #endif