sl@0: /*=============================================================================
sl@0:     Copyright (c) 1998-2003 Joel de Guzman
sl@0:     Copyright (c) 2002 Raghavendra Satish
sl@0:     Copyright (c) 2002 Jeff Westfahl
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: #if !defined(BOOST_SPIRIT_LOOPS_HPP)
sl@0: #define BOOST_SPIRIT_LOOPS_HPP
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: #include <boost/spirit/core/parser.hpp>
sl@0: #include <boost/spirit/core/composite/composite.hpp>
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: namespace boost { namespace spirit {
sl@0: 
sl@0:     ///////////////////////////////////////////////////////////////////////////
sl@0:     //
sl@0:     //  fixed_loop class
sl@0:     //
sl@0:     //      This class takes care of the construct:
sl@0:     //
sl@0:     //          repeat_p (exact) [p]
sl@0:     //
sl@0:     //      where 'p' is a parser and 'exact' is the number of times to
sl@0:     //      repeat. The parser iterates over the input exactly 'exact' times.
sl@0:     //      The parse function fails if the parser does not match the input
sl@0:     //      exactly 'exact' times.
sl@0:     //
sl@0:     //      This class is parametizable and can accept constant arguments
sl@0:     //      (e.g. repeat_p (5) [p]) as well as references to variables (e.g.
sl@0:     //      repeat_p (ref (n)) [p]).
sl@0:     //
sl@0:     ///////////////////////////////////////////////////////////////////////////
sl@0:     template <typename ParserT, typename ExactT>
sl@0:     class fixed_loop
sl@0:     : public unary<ParserT, parser <fixed_loop <ParserT, ExactT> > >
sl@0:     {
sl@0:     public:
sl@0: 
sl@0:         typedef fixed_loop<ParserT, ExactT>     self_t;
sl@0:         typedef unary<ParserT, parser<self_t> >  base_t;
sl@0: 
sl@0:         fixed_loop (ParserT const & subject, ExactT const & exact)
sl@0:         : base_t(subject), m_exact(exact) {}
sl@0: 
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<self_t, ScannerT>::type result_t;
sl@0:             result_t hit = scan.empty_match();
sl@0:             std::size_t n = m_exact;
sl@0: 
sl@0:             for (std::size_t i = 0; i < n; ++i)
sl@0:             {
sl@0:                 if (result_t next = this->subject().parse(scan))
sl@0:                 {
sl@0:                     scan.concat_match(hit, next);
sl@0:                 }
sl@0:                 else
sl@0:                 {
sl@0:                     return scan.no_match();
sl@0:                 }
sl@0:             }
sl@0: 
sl@0:             return hit;
sl@0:         }
sl@0: 
sl@0:         template <typename ScannerT>
sl@0:         struct result
sl@0:         {
sl@0:             typedef typename match_result<ScannerT, nil_t>::type type;
sl@0:         };
sl@0: 
sl@0:     private:
sl@0: 
sl@0:         ExactT m_exact;
sl@0:     };
sl@0: 
sl@0:     ///////////////////////////////////////////////////////////////////////////////
sl@0:     //
sl@0:     //  finite_loop class
sl@0:     //
sl@0:     //      This class takes care of the construct:
sl@0:     //
sl@0:     //          repeat_p (min, max) [p]
sl@0:     //
sl@0:     //      where 'p' is a parser, 'min' and 'max' specifies the minimum and
sl@0:     //      maximum iterations over 'p'. The parser iterates over the input
sl@0:     //      at least 'min' times and at most 'max' times. The parse function
sl@0:     //      fails if the parser does not match the input at least 'min' times
sl@0:     //      and at most 'max' times.
sl@0:     //
sl@0:     //      This class is parametizable and can accept constant arguments
sl@0:     //      (e.g. repeat_p (5, 10) [p]) as well as references to variables
sl@0:     //      (e.g. repeat_p (ref (n1), ref (n2)) [p]).
sl@0:     //
sl@0:     ///////////////////////////////////////////////////////////////////////////////
sl@0:     template <typename ParserT, typename MinT, typename MaxT>
sl@0:     class finite_loop
sl@0:     : public unary<ParserT, parser<finite_loop<ParserT, MinT, MaxT> > >
sl@0:     {
sl@0:     public:
sl@0: 
sl@0:         typedef finite_loop <ParserT, MinT, MaxT> self_t;
sl@0:         typedef unary<ParserT, parser<self_t> >   base_t;
sl@0: 
sl@0:         finite_loop (ParserT const & subject, MinT const & min, MaxT const & max)
sl@0:         : base_t(subject), m_min(min), m_max(max) {}
sl@0: 
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:             BOOST_SPIRIT_ASSERT(m_min <= m_max);
sl@0:             typedef typename parser_result<self_t, ScannerT>::type result_t;
sl@0:             result_t hit = scan.empty_match();
sl@0: 
sl@0:             std::size_t n1 = m_min;
sl@0:             std::size_t n2 = m_max;
sl@0: 
sl@0:             for (std::size_t i = 0; i < n2; ++i)
sl@0:             {
sl@0:                 typename ScannerT::iterator_t save = scan.first;
sl@0:                 result_t next = this->subject().parse(scan);
sl@0:  
sl@0:                 if (!next)
sl@0:                 {
sl@0:                     if (i >= n1)
sl@0:                     {
sl@0:                         scan.first = save;
sl@0:                         break;
sl@0:                     }
sl@0:                     else
sl@0:                     {
sl@0:                         return scan.no_match();
sl@0:                     }
sl@0:                 }
sl@0: 
sl@0:                 scan.concat_match(hit, next);
sl@0:             }
sl@0: 
sl@0:             return hit;
sl@0:         }
sl@0: 
sl@0:         template <typename ScannerT>
sl@0:         struct result
sl@0:         {
sl@0:             typedef typename match_result<ScannerT, nil_t>::type type;
sl@0:         };
sl@0: 
sl@0:     private:
sl@0: 
sl@0:         MinT    m_min;
sl@0:         MaxT    m_max;
sl@0:     };
sl@0: 
sl@0:     ///////////////////////////////////////////////////////////////////////////////
sl@0:     //
sl@0:     //  infinite_loop class
sl@0:     //
sl@0:     //      This class takes care of the construct:
sl@0:     //
sl@0:     //          repeat_p (min, more) [p]
sl@0:     //
sl@0:     //      where 'p' is a parser, 'min' is the minimum iteration over 'p'
sl@0:     //      and more specifies that the iteration should proceed
sl@0:     //      indefinitely. The parser iterates over the input at least 'min'
sl@0:     //      times and continues indefinitely until 'p' fails or all of the
sl@0:     //      input is parsed. The parse function fails if the parser does not
sl@0:     //      match the input at least 'min' times.
sl@0:     //
sl@0:     //      This class is parametizable and can accept constant arguments
sl@0:     //      (e.g. repeat_p (5, more) [p]) as well as references to variables
sl@0:     //      (e.g. repeat_p (ref (n), more) [p]).
sl@0:     //
sl@0:     ///////////////////////////////////////////////////////////////////////////////
sl@0: 
sl@0:     struct more_t {};
sl@0:     more_t const more = more_t ();
sl@0: 
sl@0:     template <typename ParserT, typename MinT>
sl@0:     class infinite_loop
sl@0:      : public unary<ParserT, parser<infinite_loop<ParserT, MinT> > >
sl@0:     {
sl@0:     public:
sl@0: 
sl@0:         typedef infinite_loop <ParserT, MinT>   self_t;
sl@0:         typedef unary<ParserT, parser<self_t> > base_t;
sl@0: 
sl@0:         infinite_loop (
sl@0:             ParserT const& subject,
sl@0:             MinT const& min,
sl@0:             more_t const&
sl@0:         )
sl@0:         : base_t(subject), m_min(min) {}
sl@0: 
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<self_t, ScannerT>::type result_t;
sl@0:             result_t hit = scan.empty_match();
sl@0:             std::size_t n = m_min;
sl@0: 
sl@0:             for (std::size_t i = 0; ; ++i)
sl@0:             {
sl@0:                 typename ScannerT::iterator_t save = scan.first;
sl@0:                 result_t next = this->subject().parse(scan);
sl@0: 
sl@0:                 if (!next)
sl@0:                 {
sl@0:                     if (i >= n)
sl@0:                     {
sl@0:                         scan.first = save;
sl@0:                         break;
sl@0:                     }
sl@0:                     else
sl@0:                     {
sl@0:                         return scan.no_match();
sl@0:                     }
sl@0:                 }
sl@0: 
sl@0:                 scan.concat_match(hit, next);
sl@0:             }
sl@0: 
sl@0:             return hit;
sl@0:         }
sl@0: 
sl@0:         template <typename ScannerT>
sl@0:         struct result
sl@0:         {
sl@0:             typedef typename match_result<ScannerT, nil_t>::type type;
sl@0:         };
sl@0: 
sl@0:         private:
sl@0: 
sl@0:         MinT m_min;
sl@0:     };
sl@0: 
sl@0:     template <typename ExactT>
sl@0:     struct fixed_loop_gen
sl@0:     {
sl@0:         fixed_loop_gen (ExactT const & exact)
sl@0:         : m_exact (exact) {}
sl@0: 
sl@0:         template <typename ParserT>
sl@0:         fixed_loop <ParserT, ExactT>
sl@0:         operator[](parser <ParserT> const & subject) const
sl@0:         {
sl@0:             return fixed_loop <ParserT, ExactT> (subject.derived (), m_exact);
sl@0:         }
sl@0: 
sl@0:         ExactT m_exact;
sl@0:     };
sl@0: 
sl@0:     namespace impl {
sl@0: 
sl@0:         template <typename ParserT, typename MinT, typename MaxT>
sl@0:         struct loop_traits
sl@0:         {
sl@0:             typedef typename mpl::if_<
sl@0:                 boost::is_same<MaxT, more_t>,
sl@0:                 infinite_loop<ParserT, MinT>,
sl@0:                 finite_loop<ParserT, MinT, MaxT>
sl@0:             >::type type;
sl@0:         };
sl@0: 
sl@0:     } // namespace impl
sl@0: 
sl@0:     template <typename MinT, typename MaxT>
sl@0:     struct nonfixed_loop_gen
sl@0:     {
sl@0:        nonfixed_loop_gen (MinT min, MaxT max)
sl@0:         : m_min (min), m_max (max) {}
sl@0: 
sl@0:        template <typename ParserT>
sl@0:        typename impl::loop_traits<ParserT, MinT, MaxT>::type
sl@0:        operator[](parser <ParserT> const & subject) const
sl@0:        {
sl@0:            typedef typename impl::loop_traits<ParserT, MinT, MaxT>::type ret_t;
sl@0:            return ret_t(
sl@0:                 subject.derived(),
sl@0:                 m_min,
sl@0:                 m_max);
sl@0:        }
sl@0: 
sl@0:        MinT m_min;
sl@0:        MaxT m_max;
sl@0:     };
sl@0: 
sl@0:     template <typename ExactT>
sl@0:     fixed_loop_gen <ExactT>
sl@0:     repeat_p(ExactT const & exact)
sl@0:     {
sl@0:         return fixed_loop_gen <ExactT> (exact);
sl@0:     }
sl@0: 
sl@0:     template <typename MinT, typename MaxT>
sl@0:     nonfixed_loop_gen <MinT, MaxT>
sl@0:     repeat_p(MinT const & min, MaxT const & max)
sl@0:     {
sl@0:         return nonfixed_loop_gen <MinT, MaxT> (min, max);
sl@0:     }
sl@0: 
sl@0: }} // namespace boost::spirit
sl@0: 
sl@0: #endif // #if !defined(BOOST_SPIRIT_LOOPS_HPP)