x3/directive/skip.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2014 Joel de Guzman
0003     Copyright (c) 2013 Agustin Berge
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 =============================================================================*/
0008 #if !defined(BOOST_SPIRIT_X3_SKIP_JANUARY_26_2008_0422PM)
0009 #define BOOST_SPIRIT_X3_SKIP_JANUARY_26_2008_0422PM
0010
0011 #include <boost/spirit/home/x3/support/context.hpp>
0012 #include <boost/spirit/home/x3/support/unused.hpp>
0013 #include <boost/spirit/home/x3/core/skip_over.hpp>
0014 #include <boost/spirit/home/x3/core/parser.hpp>
0015 #include <boost/utility/enable_if.hpp>
0016
0017 namespace boost { namespace spirit { namespace x3
0018 {
0019     template <typename Subject>
0020     struct reskip_directive : unary_parser<Subject, reskip_directive<Subject>>
0021     {
0022         typedef unary_parser<Subject, reskip_directive<Subject>> base_type;
0023         static bool const is_pass_through_unary = true;
0024         static bool const handles_container = Subject::handles_container;
0025
0026         constexpr reskip_directive(Subject const& subject)
0027           : base_type(subject) {}
0028
0029         template <typename Iterator, typename Context
0030           , typename RContext, typename Attribute>
0031         typename disable_if<has_skipper<Context>, bool>::type
0032         parse(Iterator& first, Iterator const& last
0033           , Context const& context, RContext& rcontext, Attribute& attr) const
0034         {
0035             auto const& skipper =
0036                 detail::get_unused_skipper(x3::get<skipper_tag>(context));
0037
0038             return this->subject.parse(
0039                 first, last
0040               , make_context<skipper_tag>(skipper, context)
0041               , rcontext
0042               , attr);
0043         }
0044         template <typename Iterator, typename Context
0045           , typename RContext, typename Attribute>
0046         typename enable_if<has_skipper<Context>, bool>::type
0047         parse(Iterator& first, Iterator const& last
0048           , Context const& context, RContext& rcontext, Attribute& attr) const
0049         {
0050             return this->subject.parse(
0051                 first, last
0052               , context
0053               , rcontext
0054               , attr);
0055         }
0056     };
0057
0058     template <typename Subject, typename Skipper>
0059     struct skip_directive : unary_parser<Subject, skip_directive<Subject, Skipper>>
0060     {
0061         typedef unary_parser<Subject, skip_directive<Subject, Skipper>> base_type;
0062         static bool const is_pass_through_unary = true;
0063         static bool const handles_container = Subject::handles_container;
0064
0065         constexpr skip_directive(Subject const& subject, Skipper const& skipper)
0066           : base_type(subject)
0067           , skipper(skipper)
0068         {}
0069
0070         template <typename Iterator, typename Context
0071           , typename RContext, typename Attribute>
0072         bool parse(Iterator& first, Iterator const& last
0073           , Context const& context, RContext& rcontext, Attribute& attr) const
0074         {
0075             return this->subject.parse(
0076                 first, last
0077               , make_context<skipper_tag>(skipper, context)
0078               , rcontext
0079               , attr);
0080         }
0081
0082         Skipper const skipper;
0083     };
0084
0085     struct reskip_gen
0086     {
0087         template <typename Skipper>
0088         struct skip_gen
0089         {
0090             constexpr skip_gen(Skipper const& skipper)
0091               : skipper_(skipper) {}
0092
0093             template <typename Subject>
0094             constexpr skip_directive<typename extension::as_parser<Subject>::value_type, Skipper>
0095             operator[](Subject const& subject) const
0096             {
0097                 return { as_parser(subject), skipper_ };
0098             }
0099
0100             Skipper skipper_;
0101         };
0102
0103         template <typename Skipper>
0104         constexpr skip_gen<Skipper> const operator()(Skipper const& skipper) const
0105         {
0106             return { skipper };
0107         }
0108
0109         template <typename Subject>
0110         constexpr reskip_directive<typename extension::as_parser<Subject>::value_type>
0111         operator[](Subject const& subject) const
0112         {
0113             return { as_parser(subject) };
0114         }
0115     };
0116
0117     constexpr auto skip = reskip_gen{};
0118 }}}
0119
0120 #endif