regex-repeat-matcher.cpp
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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3  * Copyright (c) 2013-2019 Regents of the University of California.
4  *
5  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
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19  * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
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21  * @author Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>
22  */
23 
27 
28 #include <cstdlib>
29 #include <regex>
30 
31 namespace ndn {
32 
34  shared_ptr<RegexBackrefManager> backrefManager,
35  size_t indicator)
36  : RegexMatcher(expr, EXPR_REPEAT_PATTERN, std::move(backrefManager))
37  , m_indicator(indicator)
38 {
39  compile();
40 }
41 
42 void
44 {
45  if ('(' == m_expr[0]) {
46  auto matcher = make_shared<RegexBackrefMatcher>(m_expr.substr(0, m_indicator), m_backrefManager);
47  m_backrefManager->pushRef(matcher);
48  matcher->lateCompile();
49  m_matchers.push_back(std::move(matcher));
50  }
51  else {
52  m_matchers.push_back(make_shared<RegexComponentSetMatcher>(m_expr.substr(0, m_indicator),
54  }
55 
56  parseRepetition();
57 }
58 
59 bool
60 RegexRepeatMatcher::parseRepetition()
61 {
62  size_t exprSize = m_expr.size();
63  const size_t MAX_REPETITIONS = std::numeric_limits<size_t>::max();
64 
65  if (exprSize == m_indicator) {
66  m_repeatMin = 1;
67  m_repeatMax = 1;
68  return true;
69  }
70 
71  if (exprSize == (m_indicator + 1)) {
72  if ('?' == m_expr[m_indicator]) {
73  m_repeatMin = 0;
74  m_repeatMax = 1;
75  return true;
76  }
77  if ('+' == m_expr[m_indicator]) {
78  m_repeatMin = 1;
79  m_repeatMax = MAX_REPETITIONS;
80  return true;
81  }
82  if ('*' == m_expr[m_indicator]) {
83  m_repeatMin = 0;
84  m_repeatMax = MAX_REPETITIONS;
85  return true;
86  }
87  }
88  else {
89  std::string repeatStruct = m_expr.substr(m_indicator, exprSize - m_indicator);
90  size_t rsSize = repeatStruct.size();
91  size_t min = 0;
92  size_t max = 0;
93 
94  if (std::regex_match(repeatStruct, std::regex("\\{[0-9]+,[0-9]+\\}"))) {
95  size_t separator = repeatStruct.find_first_of(',', 0);
96  min = std::atoi(repeatStruct.substr(1, separator - 1).data());
97  max = std::atoi(repeatStruct.substr(separator + 1, rsSize - separator - 2).data());
98  }
99  else if (std::regex_match(repeatStruct, std::regex("\\{,[0-9]+\\}"))) {
100  size_t separator = repeatStruct.find_first_of(',', 0);
101  min = 0;
102  max = std::atoi(repeatStruct.substr(separator + 1, rsSize - separator - 2).data());
103  }
104  else if (std::regex_match(repeatStruct, std::regex("\\{[0-9]+,\\}"))) {
105  size_t separator = repeatStruct.find_first_of(',', 0);
106  min = std::atoi(repeatStruct.substr(1, separator).data());
107  max = MAX_REPETITIONS;
108  }
109  else if (std::regex_match(repeatStruct, std::regex("\\{[0-9]+\\}"))) {
110  min = std::atoi(repeatStruct.substr(1, rsSize - 1).data());
111  max = min;
112  }
113  else
114  NDN_THROW(Error("parseRepetition: unrecognized format " + m_expr));
115 
116  if (min > MAX_REPETITIONS || max > MAX_REPETITIONS || min > max)
117  NDN_THROW(Error("parseRepetition: wrong number " + m_expr));
118 
119  m_repeatMin = min;
120  m_repeatMax = max;
121 
122  return true;
123  }
124 
125  return false;
126 }
127 
128 bool
129 RegexRepeatMatcher::match(const Name& name, size_t offset, size_t len)
130 {
131  m_matchResult.clear();
132 
133  if (m_repeatMin == 0)
134  if (len == 0)
135  return true;
136 
137  if (recursiveMatch(0, name, offset, len)) {
138  for (size_t i = offset; i < offset + len; i++)
139  m_matchResult.push_back(name.get(i));
140  return true;
141  }
142 
143  return false;
144 }
145 
146 bool
147 RegexRepeatMatcher::recursiveMatch(size_t repeat, const Name& name, size_t offset, size_t len)
148 {
149  ssize_t tried = len;
150 
151  if (0 < len && repeat >= m_repeatMax) {
152  return false;
153  }
154 
155  if (0 == len && repeat < m_repeatMin) {
156  return false;
157  }
158 
159  if (0 == len && repeat >= m_repeatMin) {
160  return true;
161  }
162 
163  auto matcher = m_matchers[0];
164  while (tried >= 0) {
165  if (matcher->match(name, offset, tried) &&
166  recursiveMatch(repeat + 1, name, offset + tried, len - tried))
167  return true;
168  tried--;
169  }
170 
171  return false;
172 }
173 
174 } // namespace ndn
Definition: data.cpp:26
RegexRepeatMatcher(const std::string &expr, shared_ptr< RegexBackrefManager > backrefManager, size_t indicator)
STL namespace.
#define NDN_THROW(e)
Definition: exception.hpp:61
shared_ptr< RegexBackrefManager > m_backrefManager
bool match(const Name &name, size_t offset, size_t len) override
std::vector< shared_ptr< RegexMatcher > > m_matchers
std::vector< name::Component > m_matchResult
Represents an absolute name.
Definition: name.hpp:43
const std::string m_expr
void compile() override
Compile the regular expression to generate the more matchers when necessary.
const Component & get(ssize_t i) const
Get the component at the given index.
Definition: name.hpp:157