boost/spirit/utility/loops.hpp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
Copyright (c) 2002 Raghavendra Satish
Copyright (c) 2002 Jeff Westfahl
http://spirit.sourceforge.net/
Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#if !defined(BOOST_SPIRIT_LOOPS_HPP)
#define BOOST_SPIRIT_LOOPS_HPP
///////////////////////////////////////////////////////////////////////////////
#include <boost/spirit/core/parser.hpp>
#include <boost/spirit/core/composite/composite.hpp>
///////////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit {
///////////////////////////////////////////////////////////////////////////
//
// fixed_loop class
//
// This class takes care of the construct:
//
// repeat_p (exact) [p]
//
// where 'p' is a parser and 'exact' is the number of times to
// repeat. The parser iterates over the input exactly 'exact' times.
// The parse function fails if the parser does not match the input
// exactly 'exact' times.
//
// This class is parametizable and can accept constant arguments
// (e.g. repeat_p (5) [p]) as well as references to variables (e.g.
// repeat_p (ref (n)) [p]).
//
///////////////////////////////////////////////////////////////////////////
template <typename ParserT, typename ExactT>
class fixed_loop
: public unary<ParserT, parser <fixed_loop <ParserT, ExactT> > >
{
public:
typedef fixed_loop<ParserT, ExactT> self_t;
typedef unary<ParserT, parser<self_t> > base_t;
fixed_loop (ParserT const & subject, ExactT const & exact)
: base_t(subject), m_exact(exact) {}
template <typename ScannerT>
typename parser_result <self_t, ScannerT>::type
parse (ScannerT const & scan) const
{
typedef typename parser_result<self_t, ScannerT>::type result_t;
result_t hit = scan.empty_match();
std::size_t n = m_exact;
for (std::size_t i = 0; i < n; ++i)
{
if (result_t next = this->subject().parse(scan))
{
scan.concat_match(hit, next);
}
else
{
return scan.no_match();
}
}
return hit;
}
template <typename ScannerT>
struct result
{
typedef typename match_result<ScannerT, nil_t>::type type;
};
private:
ExactT m_exact;
};
///////////////////////////////////////////////////////////////////////////////
//
// finite_loop class
//
// This class takes care of the construct:
//
// repeat_p (min, max) [p]
//
// where 'p' is a parser, 'min' and 'max' specifies the minimum and
// maximum iterations over 'p'. The parser iterates over the input
// at least 'min' times and at most 'max' times. The parse function
// fails if the parser does not match the input at least 'min' times
// and at most 'max' times.
//
// This class is parametizable and can accept constant arguments
// (e.g. repeat_p (5, 10) [p]) as well as references to variables
// (e.g. repeat_p (ref (n1), ref (n2)) [p]).
//
///////////////////////////////////////////////////////////////////////////////
template <typename ParserT, typename MinT, typename MaxT>
class finite_loop
: public unary<ParserT, parser<finite_loop<ParserT, MinT, MaxT> > >
{
public:
typedef finite_loop <ParserT, MinT, MaxT> self_t;
typedef unary<ParserT, parser<self_t> > base_t;
finite_loop (ParserT const & subject, MinT const & min, MaxT const & max)
: base_t(subject), m_min(min), m_max(max) {}
template <typename ScannerT>
typename parser_result <self_t, ScannerT>::type
parse(ScannerT const & scan) const
{
BOOST_SPIRIT_ASSERT(m_min <= m_max);
typedef typename parser_result<self_t, ScannerT>::type result_t;
result_t hit = scan.empty_match();
std::size_t n1 = m_min;
std::size_t n2 = m_max;
for (std::size_t i = 0; i < n2; ++i)
{
typename ScannerT::iterator_t save = scan.first;
result_t next = this->subject().parse(scan);
if (!next)
{
if (i >= n1)
{
scan.first = save;
break;
}
else
{
return scan.no_match();
}
}
scan.concat_match(hit, next);
}
return hit;
}
template <typename ScannerT>
struct result
{
typedef typename match_result<ScannerT, nil_t>::type type;
};
private:
MinT m_min;
MaxT m_max;
};
///////////////////////////////////////////////////////////////////////////////
//
// infinite_loop class
//
// This class takes care of the construct:
//
// repeat_p (min, more) [p]
//
// where 'p' is a parser, 'min' is the minimum iteration over 'p'
// and more specifies that the iteration should proceed
// indefinitely. The parser iterates over the input at least 'min'
// times and continues indefinitely until 'p' fails or all of the
// input is parsed. The parse function fails if the parser does not
// match the input at least 'min' times.
//
// This class is parametizable and can accept constant arguments
// (e.g. repeat_p (5, more) [p]) as well as references to variables
// (e.g. repeat_p (ref (n), more) [p]).
//
///////////////////////////////////////////////////////////////////////////////
struct more_t {};
more_t const more = more_t ();
template <typename ParserT, typename MinT>
class infinite_loop
: public unary<ParserT, parser<infinite_loop<ParserT, MinT> > >
{
public:
typedef infinite_loop <ParserT, MinT> self_t;
typedef unary<ParserT, parser<self_t> > base_t;
infinite_loop (
ParserT const& subject,
MinT const& min,
more_t const&
)
: base_t(subject), m_min(min) {}
template <typename ScannerT>
typename parser_result <self_t, ScannerT>::type
parse(ScannerT const & scan) const
{
typedef typename parser_result<self_t, ScannerT>::type result_t;
result_t hit = scan.empty_match();
std::size_t n = m_min;
for (std::size_t i = 0; ; ++i)
{
typename ScannerT::iterator_t save = scan.first;
result_t next = this->subject().parse(scan);
if (!next)
{
if (i >= n)
{
scan.first = save;
break;
}
else
{
return scan.no_match();
}
}
scan.concat_match(hit, next);
}
return hit;
}
template <typename ScannerT>
struct result
{
typedef typename match_result<ScannerT, nil_t>::type type;
};
private:
MinT m_min;
};
template <typename ExactT>
struct fixed_loop_gen
{
fixed_loop_gen (ExactT const & exact)
: m_exact (exact) {}
template <typename ParserT>
fixed_loop <ParserT, ExactT>
operator[](parser <ParserT> const & subject) const
{
return fixed_loop <ParserT, ExactT> (subject.derived (), m_exact);
}
ExactT m_exact;
};
namespace impl {
template <typename ParserT, typename MinT, typename MaxT>
struct loop_traits
{
typedef typename mpl::if_<
boost::is_same<MaxT, more_t>,
infinite_loop<ParserT, MinT>,
finite_loop<ParserT, MinT, MaxT>
>::type type;
};
} // namespace impl
template <typename MinT, typename MaxT>
struct nonfixed_loop_gen
{
nonfixed_loop_gen (MinT min, MaxT max)
: m_min (min), m_max (max) {}
template <typename ParserT>
typename impl::loop_traits<ParserT, MinT, MaxT>::type
operator[](parser <ParserT> const & subject) const
{
typedef typename impl::loop_traits<ParserT, MinT, MaxT>::type ret_t;
return ret_t(
subject.derived(),
m_min,
m_max);
}
MinT m_min;
MaxT m_max;
};
template <typename ExactT>
fixed_loop_gen <ExactT>
repeat_p(ExactT const & exact)
{
return fixed_loop_gen <ExactT> (exact);
}
template <typename MinT, typename MaxT>
nonfixed_loop_gen <MinT, MaxT>
repeat_p(MinT const & min, MaxT const & max)
{
return nonfixed_loop_gen <MinT, MaxT> (min, max);
}
}} // namespace boost::spirit
#endif // #if !defined(BOOST_SPIRIT_LOOPS_HPP)
