| 1 | /*============================================================================= |
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| 2 | Copyright (c) 2003 Joel de Guzman |
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| 3 | Copyright (c) 2003 Vaclav Vesely |
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| 4 | http://spirit.sourceforge.net/ |
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| 5 | |
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| 6 | Use, modification and distribution is subject to the Boost Software |
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| 7 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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| 8 | http://www.boost.org/LICENSE_1_0.txt) |
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| 9 | =============================================================================*/ |
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| 10 | #ifndef BOOST_SPIRIT_LAZY_HPP |
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| 11 | #define BOOST_SPIRIT_LAZY_HPP |
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| 12 | |
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| 13 | //////////////////////////////////////////////////////////////////////////////// |
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| 14 | #include <boost/spirit/core/parser.hpp> |
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| 15 | #include <boost/spirit/phoenix/actor.hpp> |
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| 16 | |
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| 17 | //////////////////////////////////////////////////////////////////////////////// |
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| 18 | |
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| 19 | namespace boost { namespace spirit |
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| 20 | { |
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| 21 | //////////////////////////////////////////////////////////////////////////// |
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| 22 | // |
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| 23 | // lazy_parser, holds phoenix actor which returns a spirit parser. |
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| 24 | // |
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| 25 | //////////////////////////////////////////////////////////////////////////// |
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| 26 | |
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| 27 | template<class ActorT> |
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| 28 | struct lazy_parser : parser<lazy_parser<ActorT> > |
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| 29 | { |
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| 30 | typedef lazy_parser<ActorT> self_t; |
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| 31 | typedef typename phoenix::actor_result< |
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| 32 | ActorT, phoenix::tuple<> >::plain_type actor_result_t; |
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| 33 | |
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| 34 | template<typename ScannerT> |
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| 35 | struct result |
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| 36 | { |
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| 37 | typedef typename |
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| 38 | parser_result<actor_result_t, ScannerT>::type |
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| 39 | type; |
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| 40 | }; |
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| 41 | |
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| 42 | lazy_parser(ActorT const& actor_) |
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| 43 | : actor(actor_) {} |
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| 44 | |
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| 45 | template<typename ScannerT> |
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| 46 | typename parser_result<self_t, ScannerT>::type |
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| 47 | parse(ScannerT const& scan) const |
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| 48 | { return actor().parse(scan); } |
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| 49 | |
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| 50 | ActorT actor; |
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| 51 | }; |
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| 52 | |
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| 53 | ////////////////////////////// |
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| 54 | // lazy_p, returns lazy_parser |
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| 55 | // Usage: lazy_p(actor) |
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| 56 | template<class ActorT> |
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| 57 | lazy_parser<ActorT> lazy_p(ActorT const& actor) |
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| 58 | { return lazy_parser<ActorT>(actor); } |
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| 59 | |
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| 60 | }} // namespace boost::spirit |
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| 61 | |
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| 62 | #endif // BOOST_SPIRIT_LAZY_HPP |
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