LLVM  4.0.0
Regex.cpp
Go to the documentation of this file.
1 //===-- Regex.cpp - Regular Expression matcher implementation -------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements a POSIX regular expression matcher.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Support/Regex.h"
15 #include "regex_impl.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/ADT/Twine.h"
19 #include <string>
20 using namespace llvm;
21 
22 Regex::Regex() : preg(nullptr), error(REG_BADPAT) {}
23 
24 Regex::Regex(StringRef regex, unsigned Flags) {
25  unsigned flags = 0;
26  preg = new llvm_regex();
27  preg->re_endp = regex.end();
28  if (Flags & IgnoreCase)
29  flags |= REG_ICASE;
30  if (Flags & Newline)
31  flags |= REG_NEWLINE;
32  if (!(Flags & BasicRegex))
33  flags |= REG_EXTENDED;
34  error = llvm_regcomp(preg, regex.data(), flags|REG_PEND);
35 }
36 
37 Regex::Regex(Regex &&regex) {
38  preg = regex.preg;
39  error = regex.error;
40  regex.preg = nullptr;
41  regex.error = REG_BADPAT;
42 }
43 
45  if (preg) {
46  llvm_regfree(preg);
47  delete preg;
48  }
49 }
50 
51 bool Regex::isValid(std::string &Error) {
52  if (!error)
53  return true;
54 
55  size_t len = llvm_regerror(error, preg, nullptr, 0);
56 
57  Error.resize(len - 1);
58  llvm_regerror(error, preg, &Error[0], len);
59  return false;
60 }
61 
62 /// getNumMatches - In a valid regex, return the number of parenthesized
63 /// matches it contains.
64 unsigned Regex::getNumMatches() const {
65  return preg->re_nsub;
66 }
67 
69  if (error)
70  return false;
71 
72  unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
73 
74  // pmatch needs to have at least one element.
76  pm.resize(nmatch > 0 ? nmatch : 1);
77  pm[0].rm_so = 0;
78  pm[0].rm_eo = String.size();
79 
80  int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND);
81 
82  if (rc == REG_NOMATCH)
83  return false;
84  if (rc != 0) {
85  // regexec can fail due to invalid pattern or running out of memory.
86  error = rc;
87  return false;
88  }
89 
90  // There was a match.
91 
92  if (Matches) { // match position requested
93  Matches->clear();
94 
95  for (unsigned i = 0; i != nmatch; ++i) {
96  if (pm[i].rm_so == -1) {
97  // this group didn't match
98  Matches->push_back(StringRef());
99  continue;
100  }
101  assert(pm[i].rm_eo >= pm[i].rm_so);
102  Matches->push_back(StringRef(String.data()+pm[i].rm_so,
103  pm[i].rm_eo-pm[i].rm_so));
104  }
105  }
106 
107  return true;
108 }
109 
111  std::string *Error) {
113 
114  // Reset error, if given.
115  if (Error && !Error->empty()) *Error = "";
116 
117  // Return the input if there was no match.
118  if (!match(String, &Matches))
119  return String;
120 
121  // Otherwise splice in the replacement string, starting with the prefix before
122  // the match.
123  std::string Res(String.begin(), Matches[0].begin());
124 
125  // Then the replacement string, honoring possible substitutions.
126  while (!Repl.empty()) {
127  // Skip to the next escape.
128  std::pair<StringRef, StringRef> Split = Repl.split('\\');
129 
130  // Add the skipped substring.
131  Res += Split.first;
132 
133  // Check for terminimation and trailing backslash.
134  if (Split.second.empty()) {
135  if (Repl.size() != Split.first.size() &&
136  Error && Error->empty())
137  *Error = "replacement string contained trailing backslash";
138  break;
139  }
140 
141  // Otherwise update the replacement string and interpret escapes.
142  Repl = Split.second;
143 
144  // FIXME: We should have a StringExtras function for mapping C99 escapes.
145  switch (Repl[0]) {
146  // Treat all unrecognized characters as self-quoting.
147  default:
148  Res += Repl[0];
149  Repl = Repl.substr(1);
150  break;
151 
152  // Single character escapes.
153  case 't':
154  Res += '\t';
155  Repl = Repl.substr(1);
156  break;
157  case 'n':
158  Res += '\n';
159  Repl = Repl.substr(1);
160  break;
161 
162  // Decimal escapes are backreferences.
163  case '0': case '1': case '2': case '3': case '4':
164  case '5': case '6': case '7': case '8': case '9': {
165  // Extract the backreference number.
166  StringRef Ref = Repl.slice(0, Repl.find_first_not_of("0123456789"));
167  Repl = Repl.substr(Ref.size());
168 
169  unsigned RefValue;
170  if (!Ref.getAsInteger(10, RefValue) &&
171  RefValue < Matches.size())
172  Res += Matches[RefValue];
173  else if (Error && Error->empty())
174  *Error = ("invalid backreference string '" + Twine(Ref) + "'").str();
175  break;
176  }
177  }
178  }
179 
180  // And finally the suffix.
181  Res += StringRef(Matches[0].end(), String.end() - Matches[0].end());
182 
183  return Res;
184 }
185 
186 // These are the special characters matched in functions like "p_ere_exp".
187 static const char RegexMetachars[] = "()^$|*+?.[]\\{}";
188 
190  // Check for regex metacharacters. This list was derived from our regex
191  // implementation in regcomp.c and double checked against the POSIX extended
192  // regular expression specification.
194 }
195 
197  std::string RegexStr;
198  for (unsigned i = 0, e = String.size(); i != e; ++i) {
199  if (strchr(RegexMetachars, String[i]))
200  RegexStr += '\\';
201  RegexStr += String[i];
202  }
203 
204  return RegexStr;
205 }
std::enable_if< std::numeric_limits< T >::is_signed, bool >::type getAsInteger(unsigned Radix, T &Result) const
Parse the current string as an integer of the specified radix.
Definition: StringRef.h:494
size_t re_nsub
Definition: regex_impl.h:50
void push_back(const T &Elt)
Definition: SmallVector.h:211
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:241
size_t i
#define REG_NEWLINE
Definition: regex_impl.h:60
static std::string escape(StringRef String)
Turn String into a regex by escaping its special characters.
Definition: Regex.cpp:196
int llvm_regcomp(llvm_regex_t *preg, const char *pattern, int cflags)
Definition: regcomp.c:165
void llvm_regfree(llvm_regex_t *)
Definition: regfree.c:50
#define REG_EXTENDED
Definition: regex_impl.h:57
struct fuzzer::@269 Flags
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
#define REG_BADPAT
Definition: regex_impl.h:67
const char * re_endp
Definition: regex_impl.h:51
bool isValid(std::string &Error)
isValid - returns the error encountered during regex compilation, or matching, if any...
Definition: Regex.cpp:51
size_t llvm_regerror(int errcode, const llvm_regex_t *preg, char *errbuf, size_t errbuf_size)
Definition: regerror.c:84
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE StringRef slice(size_t Start, size_t End) const
Return a reference to the substring from [Start, End).
Definition: StringRef.h:699
Compile for newline-sensitive matching.
Definition: Regex.h:39
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE size_t size() const
size - Get the string size.
Definition: StringRef.h:135
iterator begin() const
Definition: StringRef.h:103
#define REG_ICASE
Definition: regex_impl.h:58
Compile for matching that ignores upper/lower case distinctions.
Definition: Regex.h:33
#define rc(i)
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:115
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE StringRef substr(size_t Start, size_t N=npos) const
Return a reference to the substring from [Start, Start + N).
Definition: StringRef.h:587
static const char RegexMetachars[]
Definition: Regex.cpp:187
#define REG_STARTEND
Definition: regex_impl.h:88
static bool isLiteralERE(StringRef Str)
If this function returns true, ^Str$ is an extended regular expression that matches Str and only Str...
Definition: Regex.cpp:189
By default, the POSIX extended regular expression (ERE) syntax is assumed.
Definition: Regex.h:43
void pm(uint64_t &Value)
Adjusts a program memory address.
std::string sub(StringRef Repl, StringRef String, std::string *Error=nullptr)
sub - Return the result of replacing the first match of the regex in String with the Repl string...
Definition: Regex.cpp:110
LLVM_NODISCARD size_t find_first_not_of(char C, size_t From=0) const
Find the first character in the string that is not C or npos if not found.
Definition: StringRef.cpp:264
unsigned getNumMatches() const
getNumMatches - In a valid regex, return the number of parenthesized matches it contains.
Definition: Regex.cpp:64
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:843
LLVM_NODISCARD std::pair< StringRef, StringRef > split(char Separator) const
Split into two substrings around the first occurrence of a separator character.
Definition: StringRef.h:716
#define REG_NOMATCH
Definition: regex_impl.h:66
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:130
int llvm_regexec(const llvm_regex_t *, const char *, size_t, llvm_regmatch_t[], int)
Definition: regexec.c:141
#define REG_PEND
Definition: regex_impl.h:62
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:119
pointer data()
Return a pointer to the vector's buffer, even if empty().
Definition: SmallVector.h:142
static const size_t npos
Definition: StringRef.h:51
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:135
LLVM_NODISCARD size_t find_first_of(char C, size_t From=0) const
Find the first character in the string that is C, or npos if not found.
Definition: StringRef.h:392
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Lightweight error class with error context and mandatory checking.
iterator end() const
Definition: StringRef.h:105
Error error(const Twine &Message)
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:125
bool match(StringRef String, SmallVectorImpl< StringRef > *Matches=nullptr)
matches - Match the regex against a given String.
Definition: Regex.cpp:68
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:47
static void Split(std::vector< std::string > &V, StringRef S)
Split - Splits a string of comma separated items in to a vector of strings.
void resize(size_type N)
Definition: SmallVector.h:352