parser.h
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1 /*
2  * Copyright (C) 2003-2005 Tommi Maekitalo
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * As a special exception, you may use this file as part of a free
10  * software library without restriction. Specifically, if other files
11  * instantiate templates or use macros or inline functions from this
12  * file, or you compile this file and link it with other files to
13  * produce an executable, this file does not by itself cause the
14  * resulting executable to be covered by the GNU General Public
15  * License. This exception does not however invalidate any other
16  * reasons why the executable file might be covered by the GNU Library
17  * General Public License.
18  *
19  * This library is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22  * Lesser General Public License for more details.
23  *
24  * You should have received a copy of the GNU Lesser General Public
25  * License along with this library; if not, write to the Free Software
26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27  */
28 
29 
30 #ifndef TNT_PARSER_H
31 #define TNT_PARSER_H
32 
33 #include <iostream>
34 
36 
37 namespace tnt
38 {
39  class PrePostNop
40  {
41  protected:
42  void pre(char /* ch */) { }
43  bool post(bool ret) { return ret; }
44  };
45 
46  template <typename this_type, class PrePostProcessor = PrePostNop>
47  class Parser : public PrePostProcessor
48  {
49  protected:
50  typedef bool (this_type::*state_type)(char);
51 
52  state_type _state;
53  state_type _nextState;
54 
55  bool _failedFlag;
56 
57  bool state_skipws(char ch)
58  {
59  if (ch != ' ' && ch != '\t')
60  {
61  _state = _nextState;
62  return (static_cast<this_type*>(this)->*_state)(ch);
63  }
64  else
65  return false;
66  }
67 
68  void skipWs(state_type nextState)
69  {
70  _state = &Parser::state_skipws;
71  _nextState = nextState;
72  }
73 
74  public:
75  explicit Parser(state_type initialState)
76  : _state(initialState),
77  _nextState(0),
78  _failedFlag(false)
79  { }
80 
81  bool parse(char ch)
82  {
83  PrePostProcessor::pre(ch);
84  return PrePostProcessor::post(
85  (static_cast<this_type*>(this)->*_state)(ch) );
86  }
87 
88  bool parse(const char* str, unsigned size)
89  {
90  for (unsigned s = 0; s < size; ++s)
91  if (parse(str[s]))
92  return true;
93  return false;
94  }
95 
96  bool parse(std::istream& in)
97  {
98  std::streambuf* buf = in.rdbuf();
99  while (buf->sgetc() != std::ios::traits_type::eof())
100  if ( parse(buf->sbumpc()) )
101  return true;
102 
103  in.setstate(std::ios::eofbit);
104  return false;
105  }
106 
107  bool failed() const { return _failedFlag; }
108  };
109 }
110 
111 #endif // TNT_PARSER_H
112