1//===-- StringRef.cpp - Lightweight String References ---------------------===// 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#include "llvm/ADT/StringRef.h" 11#include "llvm/ADT/APInt.h" 12#include "llvm/ADT/Hashing.h" 13#include "llvm/ADT/edit_distance.h" 14#include <bitset> 15 16using namespace llvm; 17 18// MSVC emits references to this into the translation units which reference it. 19#ifndef _MSC_VER 20const size_t StringRef::npos; 21#endif 22 23static char ascii_tolower(char x) { 24 if (x >= 'A' && x <= 'Z') 25 return x - 'A' + 'a'; 26 return x; 27} 28 29static char ascii_toupper(char x) { 30 if (x >= 'a' && x <= 'z') 31 return x - 'a' + 'A'; 32 return x; 33} 34 35static bool ascii_isdigit(char x) { 36 return x >= '0' && x <= '9'; 37} 38 39// strncasecmp() is not available on non-POSIX systems, so define an 40// alternative function here. 41static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) { 42 for (size_t I = 0; I < Length; ++I) { 43 unsigned char LHC = ascii_tolower(LHS[I]); 44 unsigned char RHC = ascii_tolower(RHS[I]); 45 if (LHC != RHC) 46 return LHC < RHC ? -1 : 1; 47 } 48 return 0; 49} 50 51/// compare_lower - Compare strings, ignoring case. 52int StringRef::compare_lower(StringRef RHS) const { 53 if (int Res = ascii_strncasecmp(Data, RHS.Data, min(Length, RHS.Length))) 54 return Res; 55 if (Length == RHS.Length) 56 return 0; 57 return Length < RHS.Length ? -1 : 1; 58} 59 60/// Check if this string starts with the given \p Prefix, ignoring case. 61bool StringRef::startswith_lower(StringRef Prefix) const { 62 return Length >= Prefix.Length && 63 ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0; 64} 65 66/// Check if this string ends with the given \p Suffix, ignoring case. 67bool StringRef::endswith_lower(StringRef Suffix) const { 68 return Length >= Suffix.Length && 69 ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0; 70} 71 72/// compare_numeric - Compare strings, handle embedded numbers. 73int StringRef::compare_numeric(StringRef RHS) const { 74 for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) { 75 // Check for sequences of digits. 76 if (ascii_isdigit(Data[I]) && ascii_isdigit(RHS.Data[I])) { 77 // The longer sequence of numbers is considered larger. 78 // This doesn't really handle prefixed zeros well. 79 size_t J; 80 for (J = I + 1; J != E + 1; ++J) { 81 bool ld = J < Length && ascii_isdigit(Data[J]); 82 bool rd = J < RHS.Length && ascii_isdigit(RHS.Data[J]); 83 if (ld != rd) 84 return rd ? -1 : 1; 85 if (!rd) 86 break; 87 } 88 // The two number sequences have the same length (J-I), just memcmp them. 89 if (int Res = compareMemory(Data + I, RHS.Data + I, J - I)) 90 return Res < 0 ? -1 : 1; 91 // Identical number sequences, continue search after the numbers. 92 I = J - 1; 93 continue; 94 } 95 if (Data[I] != RHS.Data[I]) 96 return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1; 97 } 98 if (Length == RHS.Length) 99 return 0; 100 return Length < RHS.Length ? -1 : 1; 101} 102 103// Compute the edit distance between the two given strings. 104unsigned StringRef::edit_distance(llvm::StringRef Other, 105 bool AllowReplacements, 106 unsigned MaxEditDistance) const { 107 return llvm::ComputeEditDistance( 108 llvm::ArrayRef<char>(data(), size()), 109 llvm::ArrayRef<char>(Other.data(), Other.size()), 110 AllowReplacements, MaxEditDistance); 111} 112 113//===----------------------------------------------------------------------===// 114// String Operations 115//===----------------------------------------------------------------------===// 116 117std::string StringRef::lower() const { 118 std::string Result(size(), char()); 119 for (size_type i = 0, e = size(); i != e; ++i) { 120 Result[i] = ascii_tolower(Data[i]); 121 } 122 return Result; 123} 124 125std::string StringRef::upper() const { 126 std::string Result(size(), char()); 127 for (size_type i = 0, e = size(); i != e; ++i) { 128 Result[i] = ascii_toupper(Data[i]); 129 } 130 return Result; 131} 132 133//===----------------------------------------------------------------------===// 134// String Searching 135//===----------------------------------------------------------------------===// 136 137 138/// find - Search for the first string \arg Str in the string. 139/// 140/// \return - The index of the first occurrence of \arg Str, or npos if not 141/// found. 142size_t StringRef::find(StringRef Str, size_t From) const { 143 size_t N = Str.size(); 144 if (N > Length) 145 return npos; 146 147 // For short haystacks or unsupported needles fall back to the naive algorithm 148 if (Length < 16 || N > 255 || N == 0) { 149 for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i) 150 if (substr(i, N).equals(Str)) 151 return i; 152 return npos; 153 } 154 155 if (From >= Length) 156 return npos; 157 158 // Build the bad char heuristic table, with uint8_t to reduce cache thrashing. 159 uint8_t BadCharSkip[256]; 160 std::memset(BadCharSkip, N, 256); 161 for (unsigned i = 0; i != N-1; ++i) 162 BadCharSkip[(uint8_t)Str[i]] = N-1-i; 163 164 unsigned Len = Length-From, Pos = From; 165 while (Len >= N) { 166 if (substr(Pos, N).equals(Str)) // See if this is the correct substring. 167 return Pos; 168 169 // Otherwise skip the appropriate number of bytes. 170 uint8_t Skip = BadCharSkip[(uint8_t)(*this)[Pos+N-1]]; 171 Len -= Skip; 172 Pos += Skip; 173 } 174 175 return npos; 176} 177 178/// rfind - Search for the last string \arg Str in the string. 179/// 180/// \return - The index of the last occurrence of \arg Str, or npos if not 181/// found. 182size_t StringRef::rfind(StringRef Str) const { 183 size_t N = Str.size(); 184 if (N > Length) 185 return npos; 186 for (size_t i = Length - N + 1, e = 0; i != e;) { 187 --i; 188 if (substr(i, N).equals(Str)) 189 return i; 190 } 191 return npos; 192} 193 194/// find_first_of - Find the first character in the string that is in \arg 195/// Chars, or npos if not found. 196/// 197/// Note: O(size() + Chars.size()) 198StringRef::size_type StringRef::find_first_of(StringRef Chars, 199 size_t From) const { 200 std::bitset<1 << CHAR_BIT> CharBits; 201 for (size_type i = 0; i != Chars.size(); ++i) 202 CharBits.set((unsigned char)Chars[i]); 203 204 for (size_type i = min(From, Length), e = Length; i != e; ++i) 205 if (CharBits.test((unsigned char)Data[i])) 206 return i; 207 return npos; 208} 209 210/// find_first_not_of - Find the first character in the string that is not 211/// \arg C or npos if not found. 212StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const { 213 for (size_type i = min(From, Length), e = Length; i != e; ++i) 214 if (Data[i] != C) 215 return i; 216 return npos; 217} 218 219/// find_first_not_of - Find the first character in the string that is not 220/// in the string \arg Chars, or npos if not found. 221/// 222/// Note: O(size() + Chars.size()) 223StringRef::size_type StringRef::find_first_not_of(StringRef Chars, 224 size_t From) const { 225 std::bitset<1 << CHAR_BIT> CharBits; 226 for (size_type i = 0; i != Chars.size(); ++i) 227 CharBits.set((unsigned char)Chars[i]); 228 229 for (size_type i = min(From, Length), e = Length; i != e; ++i) 230 if (!CharBits.test((unsigned char)Data[i])) 231 return i; 232 return npos; 233} 234 235/// find_last_of - Find the last character in the string that is in \arg C, 236/// or npos if not found. 237/// 238/// Note: O(size() + Chars.size()) 239StringRef::size_type StringRef::find_last_of(StringRef Chars, 240 size_t From) const { 241 std::bitset<1 << CHAR_BIT> CharBits; 242 for (size_type i = 0; i != Chars.size(); ++i) 243 CharBits.set((unsigned char)Chars[i]); 244 245 for (size_type i = min(From, Length) - 1, e = -1; i != e; --i) 246 if (CharBits.test((unsigned char)Data[i])) 247 return i; 248 return npos; 249} 250 251/// find_last_not_of - Find the last character in the string that is not 252/// \arg C, or npos if not found. 253StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const { 254 for (size_type i = min(From, Length) - 1, e = -1; i != e; --i) 255 if (Data[i] != C) 256 return i; 257 return npos; 258} 259 260/// find_last_not_of - Find the last character in the string that is not in 261/// \arg Chars, or npos if not found. 262/// 263/// Note: O(size() + Chars.size()) 264StringRef::size_type StringRef::find_last_not_of(StringRef Chars, 265 size_t From) const { 266 std::bitset<1 << CHAR_BIT> CharBits; 267 for (size_type i = 0, e = Chars.size(); i != e; ++i) 268 CharBits.set((unsigned char)Chars[i]); 269 270 for (size_type i = min(From, Length) - 1, e = -1; i != e; --i) 271 if (!CharBits.test((unsigned char)Data[i])) 272 return i; 273 return npos; 274} 275 276void StringRef::split(SmallVectorImpl<StringRef> &A, 277 StringRef Separators, int MaxSplit, 278 bool KeepEmpty) const { 279 StringRef rest = *this; 280 281 // rest.data() is used to distinguish cases like "a," that splits into 282 // "a" + "" and "a" that splits into "a" + 0. 283 for (int splits = 0; 284 rest.data() != nullptr && (MaxSplit < 0 || splits < MaxSplit); 285 ++splits) { 286 std::pair<StringRef, StringRef> p = rest.split(Separators); 287 288 if (KeepEmpty || p.first.size() != 0) 289 A.push_back(p.first); 290 rest = p.second; 291 } 292 // If we have a tail left, add it. 293 if (rest.data() != nullptr && (rest.size() != 0 || KeepEmpty)) 294 A.push_back(rest); 295} 296 297//===----------------------------------------------------------------------===// 298// Helpful Algorithms 299//===----------------------------------------------------------------------===// 300 301/// count - Return the number of non-overlapped occurrences of \arg Str in 302/// the string. 303size_t StringRef::count(StringRef Str) const { 304 size_t Count = 0; 305 size_t N = Str.size(); 306 if (N > Length) 307 return 0; 308 for (size_t i = 0, e = Length - N + 1; i != e; ++i) 309 if (substr(i, N).equals(Str)) 310 ++Count; 311 return Count; 312} 313 314static unsigned GetAutoSenseRadix(StringRef &Str) { 315 if (Str.startswith("0x")) { 316 Str = Str.substr(2); 317 return 16; 318 } 319 320 if (Str.startswith("0b")) { 321 Str = Str.substr(2); 322 return 2; 323 } 324 325 if (Str.startswith("0o")) { 326 Str = Str.substr(2); 327 return 8; 328 } 329 330 if (Str.startswith("0")) 331 return 8; 332 333 return 10; 334} 335 336 337/// GetAsUnsignedInteger - Workhorse method that converts a integer character 338/// sequence of radix up to 36 to an unsigned long long value. 339bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix, 340 unsigned long long &Result) { 341 // Autosense radix if not specified. 342 if (Radix == 0) 343 Radix = GetAutoSenseRadix(Str); 344 345 // Empty strings (after the radix autosense) are invalid. 346 if (Str.empty()) return true; 347 348 // Parse all the bytes of the string given this radix. Watch for overflow. 349 Result = 0; 350 while (!Str.empty()) { 351 unsigned CharVal; 352 if (Str[0] >= '0' && Str[0] <= '9') 353 CharVal = Str[0]-'0'; 354 else if (Str[0] >= 'a' && Str[0] <= 'z') 355 CharVal = Str[0]-'a'+10; 356 else if (Str[0] >= 'A' && Str[0] <= 'Z') 357 CharVal = Str[0]-'A'+10; 358 else 359 return true; 360 361 // If the parsed value is larger than the integer radix, the string is 362 // invalid. 363 if (CharVal >= Radix) 364 return true; 365 366 // Add in this character. 367 unsigned long long PrevResult = Result; 368 Result = Result*Radix+CharVal; 369 370 // Check for overflow by shifting back and seeing if bits were lost. 371 if (Result/Radix < PrevResult) 372 return true; 373 374 Str = Str.substr(1); 375 } 376 377 return false; 378} 379 380bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix, 381 long long &Result) { 382 unsigned long long ULLVal; 383 384 // Handle positive strings first. 385 if (Str.empty() || Str.front() != '-') { 386 if (getAsUnsignedInteger(Str, Radix, ULLVal) || 387 // Check for value so large it overflows a signed value. 388 (long long)ULLVal < 0) 389 return true; 390 Result = ULLVal; 391 return false; 392 } 393 394 // Get the positive part of the value. 395 if (getAsUnsignedInteger(Str.substr(1), Radix, ULLVal) || 396 // Reject values so large they'd overflow as negative signed, but allow 397 // "-0". This negates the unsigned so that the negative isn't undefined 398 // on signed overflow. 399 (long long)-ULLVal > 0) 400 return true; 401 402 Result = -ULLVal; 403 return false; 404} 405 406bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const { 407 StringRef Str = *this; 408 409 // Autosense radix if not specified. 410 if (Radix == 0) 411 Radix = GetAutoSenseRadix(Str); 412 413 assert(Radix > 1 && Radix <= 36); 414 415 // Empty strings (after the radix autosense) are invalid. 416 if (Str.empty()) return true; 417 418 // Skip leading zeroes. This can be a significant improvement if 419 // it means we don't need > 64 bits. 420 while (!Str.empty() && Str.front() == '0') 421 Str = Str.substr(1); 422 423 // If it was nothing but zeroes.... 424 if (Str.empty()) { 425 Result = APInt(64, 0); 426 return false; 427 } 428 429 // (Over-)estimate the required number of bits. 430 unsigned Log2Radix = 0; 431 while ((1U << Log2Radix) < Radix) Log2Radix++; 432 bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix); 433 434 unsigned BitWidth = Log2Radix * Str.size(); 435 if (BitWidth < Result.getBitWidth()) 436 BitWidth = Result.getBitWidth(); // don't shrink the result 437 else if (BitWidth > Result.getBitWidth()) 438 Result = Result.zext(BitWidth); 439 440 APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix 441 if (!IsPowerOf2Radix) { 442 // These must have the same bit-width as Result. 443 RadixAP = APInt(BitWidth, Radix); 444 CharAP = APInt(BitWidth, 0); 445 } 446 447 // Parse all the bytes of the string given this radix. 448 Result = 0; 449 while (!Str.empty()) { 450 unsigned CharVal; 451 if (Str[0] >= '0' && Str[0] <= '9') 452 CharVal = Str[0]-'0'; 453 else if (Str[0] >= 'a' && Str[0] <= 'z') 454 CharVal = Str[0]-'a'+10; 455 else if (Str[0] >= 'A' && Str[0] <= 'Z') 456 CharVal = Str[0]-'A'+10; 457 else 458 return true; 459 460 // If the parsed value is larger than the integer radix, the string is 461 // invalid. 462 if (CharVal >= Radix) 463 return true; 464 465 // Add in this character. 466 if (IsPowerOf2Radix) { 467 Result <<= Log2Radix; 468 Result |= CharVal; 469 } else { 470 Result *= RadixAP; 471 CharAP = CharVal; 472 Result += CharAP; 473 } 474 475 Str = Str.substr(1); 476 } 477 478 return false; 479} 480 481 482// Implementation of StringRef hashing. 483hash_code llvm::hash_value(StringRef S) { 484 return hash_combine_range(S.begin(), S.end()); 485} 486