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