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 
35 namespace tnt
36 {
37  class PrePostNop
38  {
39  protected:
40  void pre(char ch) { }
41  bool post(bool ret) { return ret; }
42  };
43 
44  template <typename this_type, class PrePostProcessor = PrePostNop>
45  class Parser : public PrePostProcessor
46  {
47  protected:
48 
49  typedef bool (this_type::*state_type)(char);
52 
53  bool failedFlag;
54 
55  bool state_skipws(char ch)
56  {
57  if (ch != ' ' && ch != '\t')
58  {
59  state = nextState;
60  return (static_cast<this_type*>(this)->*state)(ch);
61  }
62  else
63  return false;
64  }
65 
66  void skipWs(state_type nextState_)
67  {
69  nextState = nextState_;
70  }
71 
72  public:
73  explicit Parser(state_type initialState)
74  : state(initialState),
75  failedFlag(false)
76  { }
77 
78  bool parse(char ch)
79  {
80  PrePostProcessor::pre(ch);
81  return PrePostProcessor::post(
82  (static_cast<this_type*>(this)->*state)(ch) );
83  }
84 
85  bool parse(const char* str, unsigned size)
86  {
87  for (unsigned s = 0; s < size; ++s)
88  if (parse(str[s]))
89  return true;
90  return false;
91  }
92 
93  bool parse(std::istream& in)
94  {
95  std::streambuf* buf = in.rdbuf();
96  while (buf->sgetc() != std::ios::traits_type::eof())
97  if ( parse(buf->sbumpc()) )
98  return true;
99 
100  in.setstate(std::ios::eofbit);
101  return false;
102  }
103 
104  bool failed() const
105  {
106  return failedFlag;
107  }
108  };
109 }
110 
111 #endif // TNT_PARSER_H