/src/contrib/boost/spirit/home/classic/utility/flush_multi_pass.hpp

 1/*=============================================================================
 2    Copyright (c) 2001-2003 Daniel Nuffer
 3    http://spirit.sourceforge.net/
 4
 5  Distributed under the Boost Software License, Version 1.0. (See accompanying
 6  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 7=============================================================================*/
 8#ifndef BOOST_SPIRIT_FLUSH_MULTI_PASS_HPP
 9#define BOOST_SPIRIT_FLUSH_MULTI_PASS_HPP
10
11///////////////////////////////////////////////////////////////////////////////
12#include <boost/spirit/home/classic/namespace.hpp>
13#include <boost/spirit/home/classic/core.hpp>
14#include <boost/spirit/home/classic/iterator/multi_pass.hpp>
15
16///////////////////////////////////////////////////////////////////////////////
17namespace boost { namespace spirit {
18
19BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
20
21    namespace impl {
22
23        template <typename T>
24        void flush_iterator(T &) {}
25
26        template <typename T1, typename T2, typename T3, typename T4>
27        void flush_iterator(BOOST_SPIRIT_CLASSIC_NS::multi_pass<
28            T1, T2, T3, T4, BOOST_SPIRIT_CLASSIC_NS::multi_pass_policies::std_deque> &i)
29        {
30            i.clear_queue();
31        }
32
33    }   // namespace impl
34
35    ///////////////////////////////////////////////////////////////////////////
36    //
37    //  flush_multi_pass_parser
38    //
39    //      The flush_multi_pass_parser flushes an underlying
40    //      multi_pass_iterator during the normal parsing process. This may
41    //      be used at certain points during the parsing process, when it is
42    //      clear, that no backtracking is needed anymore and the input
43    //      gathered so far may be discarded.
44    //
45    ///////////////////////////////////////////////////////////////////////////
46    class flush_multi_pass_parser
47    :   public parser<flush_multi_pass_parser>
48    {
49    public:
50        typedef flush_multi_pass_parser this_t;
51
52        template <typename ScannerT>
53        typename parser_result<this_t, ScannerT>::type
54        parse(ScannerT const& scan) const
55        {
56            impl::flush_iterator(scan.first);
57            return scan.empty_match();
58        }
59    };
60
61    ///////////////////////////////////////////////////////////////////////////
62    //
63    //  predefined flush_multi_pass_p object
64    //
65    //      This object should may used to flush a multi_pass_iterator along
66    //      the way during the normal parsing process.
67    //
68    ///////////////////////////////////////////////////////////////////////////
69
70    flush_multi_pass_parser const
71        flush_multi_pass_p = flush_multi_pass_parser();
72
73BOOST_SPIRIT_CLASSIC_NAMESPACE_END
74
75}} // namespace BOOST_SPIRIT_CLASSIC_NS
76
77#endif // BOOST_SPIRIT_FLUSH_MULTI_PASS_HPP