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
78

source code of boost/libs/spirit/include/boost/spirit/home/classic/utility/flush_multi_pass.hpp