LLVM 19.0.0git
Regex.cpp
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1//===-- Regex.cpp - Regular Expression matcher implementation -------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements a POSIX regular expression matcher.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Support/Regex.h"
15#include "llvm/ADT/StringRef.h"
16#include "llvm/ADT/Twine.h"
17#include "regex_impl.h"
18
19#include <cassert>
20#include <string>
21
22using namespace llvm;
23
24Regex::Regex() : preg(nullptr), error(REG_BADPAT) {}
25
27 unsigned flags = 0;
28 preg = new llvm_regex();
29 preg->re_endp = regex.end();
30 if (Flags & IgnoreCase)
31 flags |= REG_ICASE;
32 if (Flags & Newline)
33 flags |= REG_NEWLINE;
34 if (!(Flags & BasicRegex))
35 flags |= REG_EXTENDED;
36 error = llvm_regcomp(preg, regex.data(), flags|REG_PEND);
37}
38
39Regex::Regex(StringRef regex, unsigned Flags)
40 : Regex(regex, static_cast<RegexFlags>(Flags)) {}
41
43 preg = regex.preg;
44 error = regex.error;
45 regex.preg = nullptr;
46 regex.error = REG_BADPAT;
47}
48
50 if (preg) {
51 llvm_regfree(preg);
52 delete preg;
53 }
54}
55
56namespace {
57
58/// Utility to convert a regex error code into a human-readable string.
59void RegexErrorToString(int error, struct llvm_regex *preg,
60 std::string &Error) {
61 size_t len = llvm_regerror(error, preg, nullptr, 0);
62
63 Error.resize(len - 1);
64 llvm_regerror(error, preg, &Error[0], len);
65}
66
67} // namespace
68
69bool Regex::isValid(std::string &Error) const {
70 if (!error)
71 return true;
72
73 RegexErrorToString(error, preg, Error);
74 return false;
75}
76
77/// getNumMatches - In a valid regex, return the number of parenthesized
78/// matches it contains.
79unsigned Regex::getNumMatches() const {
80 return preg->re_nsub;
81}
82
84 std::string *Error) const {
85 // Reset error, if given.
86 if (Error && !Error->empty())
87 *Error = "";
88
89 // Check if the regex itself didn't successfully compile.
90 if (Error ? !isValid(*Error) : !isValid())
91 return false;
92
93 unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
94
95 // Update null string to empty string.
96 if (String.data() == nullptr)
97 String = "";
98
99 // pmatch needs to have at least one element.
101 pm.resize(nmatch > 0 ? nmatch : 1);
102 pm[0].rm_so = 0;
103 pm[0].rm_eo = String.size();
104
105 int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND);
106
107 // Failure to match is not an error, it's just a normal return value.
108 // Any other error code is considered abnormal, and is logged in the Error.
109 if (rc == REG_NOMATCH)
110 return false;
111 if (rc != 0) {
112 if (Error)
113 RegexErrorToString(error, preg, *Error);
114 return false;
115 }
116
117 // There was a match.
118
119 if (Matches) { // match position requested
120 Matches->clear();
121
122 for (unsigned i = 0; i != nmatch; ++i) {
123 if (pm[i].rm_so == -1) {
124 // this group didn't match
125 Matches->push_back(StringRef());
126 continue;
127 }
128 assert(pm[i].rm_eo >= pm[i].rm_so);
129 Matches->push_back(StringRef(String.data()+pm[i].rm_so,
130 pm[i].rm_eo-pm[i].rm_so));
131 }
132 }
133
134 return true;
135}
136
138 std::string *Error) const {
140
141 // Return the input if there was no match.
142 if (!match(String, &Matches, Error))
143 return std::string(String);
144
145 // Otherwise splice in the replacement string, starting with the prefix before
146 // the match.
147 std::string Res(String.begin(), Matches[0].begin());
148
149 // Then the replacement string, honoring possible substitutions.
150 while (!Repl.empty()) {
151 // Skip to the next escape.
152 std::pair<StringRef, StringRef> Split = Repl.split('\\');
153
154 // Add the skipped substring.
155 Res += Split.first;
156
157 // Check for terminimation and trailing backslash.
158 if (Split.second.empty()) {
159 if (Repl.size() != Split.first.size() &&
160 Error && Error->empty())
161 *Error = "replacement string contained trailing backslash";
162 break;
163 }
164
165 // Otherwise update the replacement string and interpret escapes.
166 Repl = Split.second;
167
168 // FIXME: We should have a StringExtras function for mapping C99 escapes.
169 switch (Repl[0]) {
170
171 // Backreference with the "\g<ref>" syntax
172 case 'g':
173 if (Repl.size() >= 4 && Repl[1] == '<') {
174 size_t End = Repl.find('>');
175 StringRef Ref = Repl.slice(2, End);
176 unsigned RefValue;
177 if (End != StringRef::npos && !Ref.getAsInteger(10, RefValue)) {
178 Repl = Repl.substr(End + 1);
179 if (RefValue < Matches.size())
180 Res += Matches[RefValue];
181 else if (Error && Error->empty())
182 *Error =
183 ("invalid backreference string 'g<" + Twine(Ref) + ">'").str();
184 break;
185 }
186 }
187 [[fallthrough]];
188
189 // Treat all unrecognized characters as self-quoting.
190 default:
191 Res += Repl[0];
192 Repl = Repl.substr(1);
193 break;
194
195 // Single character escapes.
196 case 't':
197 Res += '\t';
198 Repl = Repl.substr(1);
199 break;
200 case 'n':
201 Res += '\n';
202 Repl = Repl.substr(1);
203 break;
204
205 // Decimal escapes are backreferences.
206 case '0': case '1': case '2': case '3': case '4':
207 case '5': case '6': case '7': case '8': case '9': {
208 // Extract the backreference number.
209 StringRef Ref = Repl.slice(0, Repl.find_first_not_of("0123456789"));
210 Repl = Repl.substr(Ref.size());
211
212 unsigned RefValue;
213 if (!Ref.getAsInteger(10, RefValue) &&
214 RefValue < Matches.size())
215 Res += Matches[RefValue];
216 else if (Error && Error->empty())
217 *Error = ("invalid backreference string '" + Twine(Ref) + "'").str();
218 break;
219 }
220 }
221 }
222
223 // And finally the suffix.
224 Res += StringRef(Matches[0].end(), String.end() - Matches[0].end());
225
226 return Res;
227}
228
229// These are the special characters matched in functions like "p_ere_exp".
230static const char RegexMetachars[] = "()^$|*+?.[]\\{}";
231
233 // Check for regex metacharacters. This list was derived from our regex
234 // implementation in regcomp.c and double checked against the POSIX extended
235 // regular expression specification.
236 return Str.find_first_of(RegexMetachars) == StringRef::npos;
237}
238
240 std::string RegexStr;
241 for (char C : String) {
242 if (strchr(RegexMetachars, C))
243 RegexStr += '\\';
244 RegexStr += C;
245 }
246
247 return RegexStr;
248}
bool End
Definition: ELF_riscv.cpp:480
#define rc(i)
static const char RegexMetachars[]
Definition: Regex.cpp:230
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file defines the SmallVector class.
#define error(X)
Lightweight error class with error context and mandatory checking.
Definition: Error.h:160
RegexFlags
Definition: Regex.h:30
@ Newline
Compile for newline-sensitive matching.
Definition: Regex.h:39
@ IgnoreCase
Compile for matching that ignores upper/lower case distinctions.
Definition: Regex.h:33
@ BasicRegex
By default, the POSIX extended regular expression (ERE) syntax is assumed.
Definition: Regex.h:43
static std::string escape(StringRef String)
Turn String into a regex by escaping its special characters.
Definition: Regex.cpp:239
bool isValid() const
Definition: Regex.h:67
std::string sub(StringRef Repl, StringRef String, std::string *Error=nullptr) const
sub - Return the result of replacing the first match of the regex in String with the Repl string.
Definition: Regex.cpp:137
static bool isLiteralERE(StringRef Str)
If this function returns true, ^Str$ is an extended regular expression that matches Str and only Str.
Definition: Regex.cpp:232
unsigned getNumMatches() const
getNumMatches - In a valid regex, return the number of parenthesized matches it contains.
Definition: Regex.cpp:79
bool match(StringRef String, SmallVectorImpl< StringRef > *Matches=nullptr, std::string *Error=nullptr) const
matches - Match the regex against a given String.
Definition: Regex.cpp:83
size_t size() const
Definition: SmallVector.h:91
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:586
void resize(size_type N)
Definition: SmallVector.h:651
void push_back(const T &Elt)
Definition: SmallVector.h:426
pointer data()
Return a pointer to the vector's buffer, even if empty().
Definition: SmallVector.h:299
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1209
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
std::pair< StringRef, StringRef > split(char Separator) const
Split into two substrings around the first occurrence of a separator character.
Definition: StringRef.h:685
constexpr StringRef substr(size_t Start, size_t N=npos) const
Return a reference to the substring from [Start, Start + N).
Definition: StringRef.h:556
constexpr bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:134
StringRef slice(size_t Start, size_t End) const
Return a reference to the substring from [Start, End).
Definition: StringRef.h:669
constexpr size_t size() const
size - Get the string size.
Definition: StringRef.h:137
constexpr const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:131
iterator end() const
Definition: StringRef.h:113
size_t find(char C, size_t From=0) const
Search for the first character C in the string.
Definition: StringRef.h:282
static constexpr size_t npos
Definition: StringRef.h:52
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:251
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Ref
The access may reference the value stored in memory.
int llvm_regcomp(llvm_regex_t *preg, const char *pattern, int cflags)
Definition: regcomp.c:293
size_t llvm_regerror(int errcode, const llvm_regex_t *preg, char *errbuf, size_t errbuf_size)
Definition: regerror.c:84
#define REG_ICASE
Definition: regex_impl.h:58
#define REG_NOMATCH
Definition: regex_impl.h:66
#define REG_STARTEND
Definition: regex_impl.h:88
void llvm_regfree(llvm_regex_t *)
Definition: regfree.c:50
#define REG_EXTENDED
Definition: regex_impl.h:57
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
#define REG_NEWLINE
Definition: regex_impl.h:60
#define REG_BADPAT
Definition: regex_impl.h:67
size_t re_nsub
Definition: regex_impl.h:50
const char * re_endp
Definition: regex_impl.h:51