Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2002-2003 Joel de Guzman
Chris@16:     Copyright (c) 2002-2003 Martin Wille
Chris@16:     http://spirit.sourceforge.net/
Chris@16: 
Chris@16:   Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16:   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: =============================================================================*/
Chris@16: #ifndef BOOST_SPIRIT_WHILE_HPP
Chris@16: #define BOOST_SPIRIT_WHILE_HPP
Chris@16: 
Chris@16: #include <boost/spirit/home/classic/namespace.hpp>
Chris@16: #include <boost/spirit/home/classic/core/parser.hpp>
Chris@16: #include <boost/spirit/home/classic/core/composite/composite.hpp>
Chris@16: #include <boost/spirit/home/classic/dynamic/impl/conditions.ipp>
Chris@16: 
Chris@16: ////////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost { namespace spirit {
Chris@16: 
Chris@16: BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
Chris@16: 
Chris@16:     namespace impl {
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     // while parser
Chris@16:     // object are created by while_parser_gen and do_parser_gen
Chris@16:     template <typename ParsableT, typename CondT, bool is_do_parser>
Chris@16:     struct while_parser
Chris@16:         : public condition_evaluator< typename as_parser<CondT>::type >
Chris@16:         , public unary // the parent stores a copy of the body parser
Chris@16:         <
Chris@16:             typename as_parser<ParsableT>::type,
Chris@16:             parser<while_parser<ParsableT, CondT, is_do_parser> >
Chris@16:         >
Chris@16:     {
Chris@16:         typedef while_parser<ParsableT, CondT, is_do_parser> self_t;
Chris@16: 
Chris@16:         typedef as_parser<ParsableT>            as_parser_t;
Chris@16:         typedef typename as_parser_t::type      parser_t;
Chris@16:         typedef as_parser<CondT>                cond_as_parser_t;
Chris@16:         typedef typename cond_as_parser_t::type condition_t;
Chris@16: 
Chris@16:         typedef unary<parser_t, parser<self_t> > base_t;
Chris@16:         typedef condition_evaluator<condition_t> eval_t;
Chris@16: 
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // constructor, saves condition and body parser
Chris@16:         while_parser(ParsableT const &body, CondT const &cond)
Chris@16:             : eval_t(cond_as_parser_t::convert(cond))
Chris@16:             , base_t(as_parser_t::convert(body))
Chris@16:         {}
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // result type computer.
Chris@16:         template <typename ScannerT>
Chris@16:         struct result
Chris@16:         {
Chris@16:             typedef typename match_result
Chris@16:                 <ScannerT, nil_t>::type type;
Chris@16:         };
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // parse member function
Chris@16:         template <typename ScannerT>
Chris@16:         typename parser_result<self_t, ScannerT>::type
Chris@16:         parse(ScannerT const& scan) const
Chris@16:         {
Chris@16:             typedef typename parser_result<parser_t, ScannerT>::type sresult_t;
Chris@16:             typedef typename ScannerT::iterator_t                    iterator_t;
Chris@16: 
Chris@16:             iterator_t save(scan.first);
Chris@16:             std::size_t length = 0;
Chris@16:             int eval_length = 0;
Chris@16: 
Chris@16:             bool dont_check_condition = is_do_parser;
Chris@16: 
Chris@16:             while (dont_check_condition || (eval_length=this->evaluate(scan))>=0)
Chris@16:             {
Chris@16:                 dont_check_condition = false;
Chris@16:                 length += eval_length;
Chris@16:                 sresult_t tmp(this->subject().parse(scan));
Chris@16:                 if (tmp)
Chris@16:                 {
Chris@16:                     length+=tmp.length();
Chris@16:                 }
Chris@16:                 else
Chris@16:                 {
Chris@16:                     return scan.no_match();
Chris@16:                 }
Chris@16:             }
Chris@16:             return scan.create_match(length, nil_t(), save, scan.first);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     // while-parser generator, takes the body-parser in brackets
Chris@16:     // and returns the actual while-parser.
Chris@16:     template <typename CondT>
Chris@16:     struct while_parser_gen
Chris@16:     {
Chris@16:         //////////////////////////////
Chris@16:         // constructor, saves the condition for use by operator[]
Chris@16:         while_parser_gen(CondT const& cond_) : cond(cond_) {}
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // operator[] returns the actual while-parser object
Chris@16:         template <typename ParsableT>
Chris@16:         while_parser<ParsableT, CondT, false>
Chris@16:         operator[](ParsableT const &subject) const
Chris@16:         {
Chris@16:             return while_parser<ParsableT, CondT, false>(subject, cond);
Chris@16:         }
Chris@16:     private:
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // the condition is stored by reference here.
Chris@16:         // this should not cause any harm since object of type
Chris@16:         // while_parser_gen<> are only used as temporaries
Chris@16:         // the while-parser object constructed by the operator[]
Chris@16:         // stores a copy of the condition.
Chris@16:         CondT const &cond;
Chris@16:     };
Chris@16: 
Chris@16:     //////////////////////////////////
Chris@16:     // do-while-parser generator, takes the condition as
Chris@16:     // parameter to while_p member function and returns the
Chris@16:     // actual do-while-parser.
Chris@16:     template <typename ParsableT>
Chris@16:     struct do_while_parser_gen
Chris@16:     {
Chris@16:         //////////////////////////////
Chris@16:         // constructor. saves the body parser for use by while_p.
Chris@16:         explicit do_while_parser_gen(ParsableT const &body_parser)
Chris@16:             : body(body_parser)
Chris@16:         {}
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // while_p returns the actual while-parser object
Chris@16:         template <typename CondT>
Chris@16:         while_parser<ParsableT, CondT, true>
Chris@16:         while_p(CondT cond) const
Chris@16:         {
Chris@16:             return while_parser<ParsableT, CondT, true>(body, cond);
Chris@16:         }
Chris@16:     private:
Chris@16: 
Chris@16:         //////////////////////////////
Chris@16:         // the body is stored by reference here
Chris@16:         // this should not cause any harm since object of type
Chris@16:         // do_while_parser_gen<> are only used as temporaries
Chris@16:         // the while-parser object constructed by the while_p
Chris@16:         // member function stores a copy of the body parser.
Chris@16:         ParsableT const &body;
Chris@16:     };
Chris@16: 
Chris@16:     struct do_parser_gen
Chris@16:     {
Chris@16:         inline do_parser_gen() {}
Chris@16: 
Chris@16:         template <typename ParsableT>
Chris@16:         impl::do_while_parser_gen<ParsableT>
Chris@16:         operator[](ParsableT const& body) const
Chris@16:         {
Chris@16:             return impl::do_while_parser_gen<ParsableT>(body);
Chris@16:         }
Chris@16:     };
Chris@16: } // namespace impl
Chris@16: 
Chris@16: //////////////////////////////////
Chris@16: // while_p function, while-parser generator
Chris@16: // Usage: spirit::while_p(Condition)[Body]
Chris@16: template <typename CondT>
Chris@16: impl::while_parser_gen<CondT>
Chris@16: while_p(CondT const& cond)
Chris@16: {
Chris@16:     return impl::while_parser_gen<CondT>(cond);
Chris@16: }
Chris@16: 
Chris@16: //////////////////////////////////
Chris@16: // do_p functor, do-while-parser generator
Chris@16: // Usage: spirit::do_p[Body].while_p(Condition)
Chris@16: impl::do_parser_gen const do_p = impl::do_parser_gen();
Chris@16: 
Chris@16: BOOST_SPIRIT_CLASSIC_NAMESPACE_END
Chris@16: 
Chris@16: }} // namespace BOOST_SPIRIT_CLASSIC_NS
Chris@16: 
Chris@16: #endif // BOOST_SPIRIT_WHILE_HPP