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(StringRef regex, unsigned Flags) { 23 unsigned flags = 0; 24 preg = new llvm_regex(); 25 preg->re_endp = regex.end(); 26 if (Flags & IgnoreCase) 27 flags |= REG_ICASE; 28 if (Flags & Newline) 29 flags |= REG_NEWLINE; 30 if (!(Flags & BasicRegex)) 31 flags |= REG_EXTENDED; 32 error = llvm_regcomp(preg, regex.data(), flags|REG_PEND); 33 } 34 35 Regex::~Regex() { 36 if (preg) { 37 llvm_regfree(preg); 38 delete preg; 39 } 40 } 41 42 bool Regex::isValid(std::string &Error) { 43 if (!error) 44 return true; 45 46 size_t len = llvm_regerror(error, preg, nullptr, 0); 47 48 Error.resize(len - 1); 49 llvm_regerror(error, preg, &Error[0], len); 50 return false; 51 } 52 53 /// getNumMatches - In a valid regex, return the number of parenthesized 54 /// matches it contains. 55 unsigned Regex::getNumMatches() const { 56 return preg->re_nsub; 57 } 58 59 bool Regex::match(StringRef String, SmallVectorImpl<StringRef> *Matches){ 60 unsigned nmatch = Matches ? preg->re_nsub+1 : 0; 61 62 // pmatch needs to have at least one element. 63 SmallVector<llvm_regmatch_t, 8> pm; 64 pm.resize(nmatch > 0 ? nmatch : 1); 65 pm[0].rm_so = 0; 66 pm[0].rm_eo = String.size(); 67 68 int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND); 69 70 if (rc == REG_NOMATCH) 71 return false; 72 if (rc != 0) { 73 // regexec can fail due to invalid pattern or running out of memory. 74 error = rc; 75 return false; 76 } 77 78 // There was a match. 79 80 if (Matches) { // match position requested 81 Matches->clear(); 82 83 for (unsigned i = 0; i != nmatch; ++i) { 84 if (pm[i].rm_so == -1) { 85 // this group didn't match 86 Matches->push_back(StringRef()); 87 continue; 88 } 89 assert(pm[i].rm_eo >= pm[i].rm_so); 90 Matches->push_back(StringRef(String.data()+pm[i].rm_so, 91 pm[i].rm_eo-pm[i].rm_so)); 92 } 93 } 94 95 return true; 96 } 97 98 std::string Regex::sub(StringRef Repl, StringRef String, 99 std::string *Error) { 100 SmallVector<StringRef, 8> Matches; 101 102 // Reset error, if given. 103 if (Error && !Error->empty()) *Error = ""; 104 105 // Return the input if there was no match. 106 if (!match(String, &Matches)) 107 return String; 108 109 // Otherwise splice in the replacement string, starting with the prefix before 110 // the match. 111 std::string Res(String.begin(), Matches[0].begin()); 112 113 // Then the replacement string, honoring possible substitutions. 114 while (!Repl.empty()) { 115 // Skip to the next escape. 116 std::pair<StringRef, StringRef> Split = Repl.split('\\'); 117 118 // Add the skipped substring. 119 Res += Split.first; 120 121 // Check for terminimation and trailing backslash. 122 if (Split.second.empty()) { 123 if (Repl.size() != Split.first.size() && 124 Error && Error->empty()) 125 *Error = "replacement string contained trailing backslash"; 126 break; 127 } 128 129 // Otherwise update the replacement string and interpret escapes. 130 Repl = Split.second; 131 132 // FIXME: We should have a StringExtras function for mapping C99 escapes. 133 switch (Repl[0]) { 134 // Treat all unrecognized characters as self-quoting. 135 default: 136 Res += Repl[0]; 137 Repl = Repl.substr(1); 138 break; 139 140 // Single character escapes. 141 case 't': 142 Res += '\t'; 143 Repl = Repl.substr(1); 144 break; 145 case 'n': 146 Res += '\n'; 147 Repl = Repl.substr(1); 148 break; 149 150 // Decimal escapes are backreferences. 151 case '0': case '1': case '2': case '3': case '4': 152 case '5': case '6': case '7': case '8': case '9': { 153 // Extract the backreference number. 154 StringRef Ref = Repl.slice(0, Repl.find_first_not_of("0123456789")); 155 Repl = Repl.substr(Ref.size()); 156 157 unsigned RefValue; 158 if (!Ref.getAsInteger(10, RefValue) && 159 RefValue < Matches.size()) 160 Res += Matches[RefValue]; 161 else if (Error && Error->empty()) 162 *Error = ("invalid backreference string '" + Twine(Ref) + "'").str(); 163 break; 164 } 165 } 166 } 167 168 // And finally the suffix. 169 Res += StringRef(Matches[0].end(), String.end() - Matches[0].end()); 170 171 return Res; 172 } 173 174 // These are the special characters matched in functions like "p_ere_exp". 175 static const char RegexMetachars[] = "()^$|*+?.[]\\{}"; 176 177 bool Regex::isLiteralERE(StringRef Str) { 178 // Check for regex metacharacters. This list was derived from our regex 179 // implementation in regcomp.c and double checked against the POSIX extended 180 // regular expression specification. 181 return Str.find_first_of(RegexMetachars) == StringRef::npos; 182 } 183 184 std::string Regex::escape(StringRef String) { 185 std::string RegexStr; 186 for (unsigned i = 0, e = String.size(); i != e; ++i) { 187 if (strchr(RegexMetachars, String[i])) 188 RegexStr += '\\'; 189 RegexStr += String[i]; 190 } 191 192 return RegexStr; 193 } 194
