boost/spirit/core/composite/positive.hpp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
Copyright (c) 2001 Daniel Nuffer
Copyright (c) 2002 Hartmut Kaiser
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_POSITIVE_HPP)
#define BOOST_SPIRIT_POSITIVE_HPP
#include <boost/spirit/core/parser.hpp>
#include <boost/spirit/core/primitives/primitives.hpp>
#include <boost/spirit/core/composite/composite.hpp>
#include <boost/spirit/meta/as_parser.hpp>
namespace boost { namespace spirit {
///////////////////////////////////////////////////////////////////////////
//
// positive class
//
// Handles expressions of the form:
//
// +a
//
// where a is a parser. The expression returns a composite
// parser that matches its subject one (1) or more times.
//
///////////////////////////////////////////////////////////////////////////
struct positive_parser_gen;
template <typename S>
struct positive
: public unary<S, parser<positive<S> > >
{
typedef positive<S> self_t;
typedef unary_parser_category parser_category_t;
typedef positive_parser_gen parser_generator_t;
typedef unary<S, parser<self_t> > base_t;
positive(S const& a)
: base_t(a) {}
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;
typedef typename ScannerT::iterator_t iterator_t;
result_t hit = this->subject().parse(scan);
if (hit)
{
for (;;)
{
iterator_t save = scan.first;
if (result_t next = this->subject().parse(scan))
{
scan.concat_match(hit, next);
}
else
{
scan.first = save;
break;
}
}
}
return hit;
}
};
struct positive_parser_gen
{
template <typename S>
struct result
{
typedef positive<S> type;
};
template <typename S>
static positive<S>
generate(parser<S> const& a)
{
return positive<S>(a.derived());
}
};
template <typename S>
inline positive<S>
operator+(parser<S> const& a);
}} // namespace boost::spirit
#endif
#include <boost/spirit/core/composite/impl/positive.ipp>
