1 //===-- Regex.cpp - Regular Expression matcher implementation -------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file implements a POSIX regular expression matcher.
11 //===----------------------------------------------------------------------===//
13 #include "llvm/Support/Regex.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/ADT/Twine.h"
19 // Important this comes last because it defines "_REGEX_H_". At least on
20 // Darwin, if included before any header that (transitively) includes
21 // xlocale.h, this will cause trouble, because of missing regex-related types.
22 #include "regex_impl.h"
26 Regex::Regex() : preg(nullptr), error(REG_BADPAT) {}
28 Regex::Regex(StringRef regex, unsigned Flags) {
30 preg = new llvm_regex();
31 preg->re_endp = regex.end();
32 if (Flags & IgnoreCase)
36 if (!(Flags & BasicRegex))
37 flags |= REG_EXTENDED;
38 error = llvm_regcomp(preg, regex.data(), flags|REG_PEND);
41 Regex::Regex(Regex &®ex) {
45 regex.error = REG_BADPAT;
55 bool Regex::isValid(std::string &Error) const {
59 size_t len = llvm_regerror(error, preg, nullptr, 0);
61 Error.resize(len - 1);
62 llvm_regerror(error, preg, &Error[0], len);
66 /// getNumMatches - In a valid regex, return the number of parenthesized
67 /// matches it contains.
68 unsigned Regex::getNumMatches() const {
72 bool Regex::match(StringRef String, SmallVectorImpl<StringRef> *Matches){
76 unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
78 // pmatch needs to have at least one element.
79 SmallVector<llvm_regmatch_t, 8> pm;
80 pm.resize(nmatch > 0 ? nmatch : 1);
82 pm[0].rm_eo = String.size();
84 int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND);
86 if (rc == REG_NOMATCH)
89 // regexec can fail due to invalid pattern or running out of memory.
96 if (Matches) { // match position requested
99 for (unsigned i = 0; i != nmatch; ++i) {
100 if (pm[i].rm_so == -1) {
101 // this group didn't match
102 Matches->push_back(StringRef());
105 assert(pm[i].rm_eo >= pm[i].rm_so);
106 Matches->push_back(StringRef(String.data()+pm[i].rm_so,
107 pm[i].rm_eo-pm[i].rm_so));
114 std::string Regex::sub(StringRef Repl, StringRef String,
115 std::string *Error) {
116 SmallVector<StringRef, 8> Matches;
118 // Reset error, if given.
119 if (Error && !Error->empty()) *Error = "";
121 // Return the input if there was no match.
122 if (!match(String, &Matches))
125 // Otherwise splice in the replacement string, starting with the prefix before
127 std::string Res(String.begin(), Matches[0].begin());
129 // Then the replacement string, honoring possible substitutions.
130 while (!Repl.empty()) {
131 // Skip to the next escape.
132 std::pair<StringRef, StringRef> Split = Repl.split('\\');
134 // Add the skipped substring.
137 // Check for terminimation and trailing backslash.
138 if (Split.second.empty()) {
139 if (Repl.size() != Split.first.size() &&
140 Error && Error->empty())
141 *Error = "replacement string contained trailing backslash";
145 // Otherwise update the replacement string and interpret escapes.
148 // FIXME: We should have a StringExtras function for mapping C99 escapes.
150 // Treat all unrecognized characters as self-quoting.
153 Repl = Repl.substr(1);
156 // Single character escapes.
159 Repl = Repl.substr(1);
163 Repl = Repl.substr(1);
166 // Decimal escapes are backreferences.
167 case '0': case '1': case '2': case '3': case '4':
168 case '5': case '6': case '7': case '8': case '9': {
169 // Extract the backreference number.
170 StringRef Ref = Repl.slice(0, Repl.find_first_not_of("0123456789"));
171 Repl = Repl.substr(Ref.size());
174 if (!Ref.getAsInteger(10, RefValue) &&
175 RefValue < Matches.size())
176 Res += Matches[RefValue];
177 else if (Error && Error->empty())
178 *Error = ("invalid backreference string '" + Twine(Ref) + "'").str();
184 // And finally the suffix.
185 Res += StringRef(Matches[0].end(), String.end() - Matches[0].end());
190 // These are the special characters matched in functions like "p_ere_exp".
191 static const char RegexMetachars[] = "()^$|*+?.[]\\{}";
193 bool Regex::isLiteralERE(StringRef Str) {
194 // Check for regex metacharacters. This list was derived from our regex
195 // implementation in regcomp.c and double checked against the POSIX extended
196 // regular expression specification.
197 return Str.find_first_of(RegexMetachars) == StringRef::npos;
200 std::string Regex::escape(StringRef String) {
201 std::string RegexStr;
202 for (unsigned i = 0, e = String.size(); i != e; ++i) {
203 if (strchr(RegexMetachars, String[i]))
205 RegexStr += String[i];