lib/Support/StringRef.cpp

   1 //===-- StringRef.cpp - Lightweight String References ---------------------===//
   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 #include "llvm/ADT/StringRef.h"
  10 #include "llvm/ADT/APFloat.h"
  11 #include "llvm/ADT/APInt.h"
  12 #include "llvm/ADT/Hashing.h"
  13 #include "llvm/ADT/StringExtras.h"
  14 #include "llvm/ADT/edit_distance.h"
  15 #include <bitset>
  16
  17 using namespace llvm;
  18
  19 // MSVC emits references to this into the translation units which reference it.
  20 #ifndef _MSC_VER
  21 const size_t StringRef::npos;
  22 #endif
  23
  24 // strncasecmp() is not available on non-POSIX systems, so define an
  25 // alternative function here.
  26 static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) {
  27   for (size_t I = 0; I < Length; ++I) {
  28     unsigned char LHC = toLower(LHS[I]);
  29     unsigned char RHC = toLower(RHS[I]);
  30     if (LHC != RHC)
  31       return LHC < RHC ? -1 : 1;
  32   }
  33   return 0;
  34 }
  35
  36 /// compare_lower - Compare strings, ignoring case.
  37 int StringRef::compare_lower(StringRef RHS) const {
  38   if (int Res = ascii_strncasecmp(Data, RHS.Data, std::min(Length, RHS.Length)))
  39     return Res;
  40   if (Length == RHS.Length)
  41     return 0;
  42   return Length < RHS.Length ? -1 : 1;
  43 }
  44
  45 /// Check if this string starts with the given \p Prefix, ignoring case.
  46 bool StringRef::startswith_lower(StringRef Prefix) const {
  47   return Length >= Prefix.Length &&
  48       ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;
  49 }
  50
  51 /// Check if this string ends with the given \p Suffix, ignoring case.
  52 bool StringRef::endswith_lower(StringRef Suffix) const {
  53   return Length >= Suffix.Length &&
  54       ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
  55 }
  56
  57 size_t StringRef::find_lower(char C, size_t From) const {
  58   char L = toLower(C);
  59   return find_if([L](char D) { return toLower(D) == L; }, From);
  60 }
  61
  62 /// compare_numeric - Compare strings, handle embedded numbers.
  63 int StringRef::compare_numeric(StringRef RHS) const {
  64   for (size_t I = 0, E = std::min(Length, RHS.Length); I != E; ++I) {
  65     // Check for sequences of digits.
  66     if (isDigit(Data[I]) && isDigit(RHS.Data[I])) {
  67       // The longer sequence of numbers is considered larger.
  68       // This doesn't really handle prefixed zeros well.
  69       size_t J;
  70       for (J = I + 1; J != E + 1; ++J) {
  71         bool ld = J < Length && isDigit(Data[J]);
  72         bool rd = J < RHS.Length && isDigit(RHS.Data[J]);
  73         if (ld != rd)
  74           return rd ? -1 : 1;
  75         if (!rd)
  76           break;
  77       }
  78       // The two number sequences have the same length (J-I), just memcmp them.
  79       if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))
  80         return Res < 0 ? -1 : 1;
  81       // Identical number sequences, continue search after the numbers.
  82       I = J - 1;
  83       continue;
  84     }
  85     if (Data[I] != RHS.Data[I])
  86       return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
  87   }
  88   if (Length == RHS.Length)
  89     return 0;
  90   return Length < RHS.Length ? -1 : 1;
  91 }
  92
  93 // Compute the edit distance between the two given strings.
  94 unsigned StringRef::edit_distance(llvm::StringRef Other,
  95                                   bool AllowReplacements,
  96                                   unsigned MaxEditDistance) const {
  97   return llvm::ComputeEditDistance(
  98       makeArrayRef(data(), size()),
  99       makeArrayRef(Other.data(), Other.size()),
 100       AllowReplacements, MaxEditDistance);
 101 }
 102
 103 //===----------------------------------------------------------------------===//
 104 // String Operations
 105 //===----------------------------------------------------------------------===//
 106
 107 std::string StringRef::lower() const {
 108   std::string Result(size(), char());
 109   for (size_type i = 0, e = size(); i != e; ++i) {
 110     Result[i] = toLower(Data[i]);
 111   }
 112   return Result;
 113 }
 114
 115 std::string StringRef::upper() const {
 116   std::string Result(size(), char());
 117   for (size_type i = 0, e = size(); i != e; ++i) {
 118     Result[i] = toUpper(Data[i]);
 119   }
 120   return Result;
 121 }
 122
 123 //===----------------------------------------------------------------------===//
 124 // String Searching
 125 //===----------------------------------------------------------------------===//
 126
 127
 128 /// find - Search for the first string \arg Str in the string.
 129 ///
 130 /// \return - The index of the first occurrence of \arg Str, or npos if not
 131 /// found.
 132 size_t StringRef::find(StringRef Str, size_t From) const {
 133   if (From > Length)
 134     return npos;
 135
 136   const char *Start = Data + From;
 137   size_t Size = Length - From;
 138
 139   const char *Needle = Str.data();
 140   size_t N = Str.size();
 141   if (N == 0)
 142     return From;
 143   if (Size < N)
 144     return npos;
 145   if (N == 1) {
 146     const char *Ptr = (const char *)::memchr(Start, Needle[0], Size);
 147     return Ptr == nullptr ? npos : Ptr - Data;
 148   }
 149
 150   const char *Stop = Start + (Size - N + 1);
 151
 152   // For short haystacks or unsupported needles fall back to the naive algorithm
 153   if (Size < 16 || N > 255) {
 154     do {
 155       if (std::memcmp(Start, Needle, N) == 0)
 156         return Start - Data;
 157       ++Start;
 158     } while (Start < Stop);
 159     return npos;
 160   }
 161
 162   // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
 163   uint8_t BadCharSkip[256];
 164   std::memset(BadCharSkip, N, 256);
 165   for (unsigned i = 0; i != N-1; ++i)
 166     BadCharSkip[(uint8_t)Str[i]] = N-1-i;
 167
 168   do {
 169     uint8_t Last = Start[N - 1];
 170     if (LLVM_UNLIKELY(Last == (uint8_t)Needle[N - 1]))
 171       if (std::memcmp(Start, Needle, N - 1) == 0)
 172         return Start - Data;
 173
 174     // Otherwise skip the appropriate number of bytes.
 175     Start += BadCharSkip[Last];
 176   } while (Start < Stop);
 177
 178   return npos;
 179 }
 180
 181 size_t StringRef::find_lower(StringRef Str, size_t From) const {
 182   StringRef This = substr(From);
 183   while (This.size() >= Str.size()) {
 184     if (This.startswith_lower(Str))
 185       return From;
 186     This = This.drop_front();
 187     ++From;
 188   }
 189   return npos;
 190 }
 191
 192 size_t StringRef::rfind_lower(char C, size_t From) const {
 193   From = std::min(From, Length);
 194   size_t i = From;
 195   while (i != 0) {
 196     --i;
 197     if (toLower(Data[i]) == toLower(C))
 198       return i;
 199   }
 200   return npos;
 201 }
 202
 203 /// rfind - Search for the last string \arg Str in the string.
 204 ///
 205 /// \return - The index of the last occurrence of \arg Str, or npos if not
 206 /// found.
 207 size_t StringRef::rfind(StringRef Str) const {
 208   size_t N = Str.size();
 209   if (N > Length)
 210     return npos;
 211   for (size_t i = Length - N + 1, e = 0; i != e;) {
 212     --i;
 213     if (substr(i, N).equals(Str))
 214       return i;
 215   }
 216   return npos;
 217 }
 218
 219 size_t StringRef::rfind_lower(StringRef Str) const {
 220   size_t N = Str.size();
 221   if (N > Length)
 222     return npos;
 223   for (size_t i = Length - N + 1, e = 0; i != e;) {
 224     --i;
 225     if (substr(i, N).equals_lower(Str))
 226       return i;
 227   }
 228   return npos;
 229 }
 230
 231 /// find_first_of - Find the first character in the string that is in \arg
 232 /// Chars, or npos if not found.
 233 ///
 234 /// Note: O(size() + Chars.size())
 235 StringRef::size_type StringRef::find_first_of(StringRef Chars,
 236                                               size_t From) const {
 237   std::bitset<1 << CHAR_BIT> CharBits;
 238   for (size_type i = 0; i != Chars.size(); ++i)
 239     CharBits.set((unsigned char)Chars[i]);
 240
 241   for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
 242     if (CharBits.test((unsigned char)Data[i]))
 243       return i;
 244   return npos;
 245 }
 246
 247 /// find_first_not_of - Find the first character in the string that is not
 248 /// \arg C or npos if not found.
 249 StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
 250   for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
 251     if (Data[i] != C)
 252       return i;
 253   return npos;
 254 }
 255
 256 /// find_first_not_of - Find the first character in the string that is not
 257 /// in the string \arg Chars, or npos if not found.
 258 ///
 259 /// Note: O(size() + Chars.size())
 260 StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
 261                                                   size_t From) const {
 262   std::bitset<1 << CHAR_BIT> CharBits;
 263   for (size_type i = 0; i != Chars.size(); ++i)
 264     CharBits.set((unsigned char)Chars[i]);
 265
 266   for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
 267     if (!CharBits.test((unsigned char)Data[i]))
 268       return i;
 269   return npos;
 270 }
 271
 272 /// find_last_of - Find the last character in the string that is in \arg C,
 273 /// or npos if not found.
 274 ///
 275 /// Note: O(size() + Chars.size())
 276 StringRef::size_type StringRef::find_last_of(StringRef Chars,
 277                                              size_t From) const {
 278   std::bitset<1 << CHAR_BIT> CharBits;
 279   for (size_type i = 0; i != Chars.size(); ++i)
 280     CharBits.set((unsigned char)Chars[i]);
 281
 282   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 283     if (CharBits.test((unsigned char)Data[i]))
 284       return i;
 285   return npos;
 286 }
 287
 288 /// find_last_not_of - Find the last character in the string that is not
 289 /// \arg C, or npos if not found.
 290 StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
 291   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 292     if (Data[i] != C)
 293       return i;
 294   return npos;
 295 }
 296
 297 /// find_last_not_of - Find the last character in the string that is not in
 298 /// \arg Chars, or npos if not found.
 299 ///
 300 /// Note: O(size() + Chars.size())
 301 StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
 302                                                  size_t From) const {
 303   std::bitset<1 << CHAR_BIT> CharBits;
 304   for (size_type i = 0, e = Chars.size(); i != e; ++i)
 305     CharBits.set((unsigned char)Chars[i]);
 306
 307   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 308     if (!CharBits.test((unsigned char)Data[i]))
 309       return i;
 310   return npos;
 311 }
 312
 313 void StringRef::split(SmallVectorImpl<StringRef> &A,
 314                       StringRef Separator, int MaxSplit,
 315                       bool KeepEmpty) const {
 316   StringRef S = *this;
 317
 318   // Count down from MaxSplit. When MaxSplit is -1, this will just split
 319   // "forever". This doesn't support splitting more than 2^31 times
 320   // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
 321   // but that seems unlikely to be useful.
 322   while (MaxSplit-- != 0) {
 323     size_t Idx = S.find(Separator);
 324     if (Idx == npos)
 325       break;
 326
 327     // Push this split.
 328     if (KeepEmpty || Idx > 0)
 329       A.push_back(S.slice(0, Idx));
 330
 331     // Jump forward.
 332     S = S.slice(Idx + Separator.size(), npos);
 333   }
 334
 335   // Push the tail.
 336   if (KeepEmpty || !S.empty())
 337     A.push_back(S);
 338 }
 339
 340 void StringRef::split(SmallVectorImpl<StringRef> &A, char Separator,
 341                       int MaxSplit, bool KeepEmpty) const {
 342   StringRef S = *this;
 343
 344   // Count down from MaxSplit. When MaxSplit is -1, this will just split
 345   // "forever". This doesn't support splitting more than 2^31 times
 346   // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
 347   // but that seems unlikely to be useful.
 348   while (MaxSplit-- != 0) {
 349     size_t Idx = S.find(Separator);
 350     if (Idx == npos)
 351       break;
 352
 353     // Push this split.
 354     if (KeepEmpty || Idx > 0)
 355       A.push_back(S.slice(0, Idx));
 356
 357     // Jump forward.
 358     S = S.slice(Idx + 1, npos);
 359   }
 360
 361   // Push the tail.
 362   if (KeepEmpty || !S.empty())
 363     A.push_back(S);
 364 }
 365
 366 //===----------------------------------------------------------------------===//
 367 // Helpful Algorithms
 368 //===----------------------------------------------------------------------===//
 369
 370 /// count - Return the number of non-overlapped occurrences of \arg Str in
 371 /// the string.
 372 size_t StringRef::count(StringRef Str) const {
 373   size_t Count = 0;
 374   size_t N = Str.size();
 375   if (N > Length)
 376     return 0;
 377   for (size_t i = 0, e = Length - N + 1; i != e; ++i)
 378     if (substr(i, N).equals(Str))
 379       ++Count;
 380   return Count;
 381 }
 382
 383 static unsigned GetAutoSenseRadix(StringRef &Str) {
 384   if (Str.empty())
 385     return 10;
 386
 387   if (Str.startswith("0x") || Str.startswith("0X")) {
 388     Str = Str.substr(2);
 389     return 16;
 390   }
 391
 392   if (Str.startswith("0b") || Str.startswith("0B")) {
 393     Str = Str.substr(2);
 394     return 2;
 395   }
 396
 397   if (Str.startswith("0o")) {
 398     Str = Str.substr(2);
 399     return 8;
 400   }
 401
 402   if (Str[0] == '0' && Str.size() > 1 && isDigit(Str[1])) {
 403     Str = Str.substr(1);
 404     return 8;
 405   }
 406
 407   return 10;
 408 }
 409
 410 bool llvm::consumeUnsignedInteger(StringRef &Str, unsigned Radix,
 411                                   unsigned long long &Result) {
 412   // Autosense radix if not specified.
 413   if (Radix == 0)
 414     Radix = GetAutoSenseRadix(Str);
 415
 416   // Empty strings (after the radix autosense) are invalid.
 417   if (Str.empty()) return true;
 418
 419   // Parse all the bytes of the string given this radix.  Watch for overflow.
 420   StringRef Str2 = Str;
 421   Result = 0;
 422   while (!Str2.empty()) {
 423     unsigned CharVal;
 424     if (Str2[0] >= '0' && Str2[0] <= '9')
 425       CharVal = Str2[0] - '0';
 426     else if (Str2[0] >= 'a' && Str2[0] <= 'z')
 427       CharVal = Str2[0] - 'a' + 10;
 428     else if (Str2[0] >= 'A' && Str2[0] <= 'Z')
 429       CharVal = Str2[0] - 'A' + 10;
 430     else
 431       break;
 432
 433     // If the parsed value is larger than the integer radix, we cannot
 434     // consume any more characters.
 435     if (CharVal >= Radix)
 436       break;
 437
 438     // Add in this character.
 439     unsigned long long PrevResult = Result;
 440     Result = Result * Radix + CharVal;
 441
 442     // Check for overflow by shifting back and seeing if bits were lost.
 443     if (Result / Radix < PrevResult)
 444       return true;
 445
 446     Str2 = Str2.substr(1);
 447   }
 448
 449   // We consider the operation a failure if no characters were consumed
 450   // successfully.
 451   if (Str.size() == Str2.size())
 452     return true;
 453
 454   Str = Str2;
 455   return false;
 456 }
 457
 458 bool llvm::consumeSignedInteger(StringRef &Str, unsigned Radix,
 459                                 long long &Result) {
 460   unsigned long long ULLVal;
 461
 462   // Handle positive strings first.
 463   if (Str.empty() || Str.front() != '-') {
 464     if (consumeUnsignedInteger(Str, Radix, ULLVal) ||
 465         // Check for value so large it overflows a signed value.
 466         (long long)ULLVal < 0)
 467       return true;
 468     Result = ULLVal;
 469     return false;
 470   }
 471
 472   // Get the positive part of the value.
 473   StringRef Str2 = Str.drop_front(1);
 474   if (consumeUnsignedInteger(Str2, Radix, ULLVal) ||
 475       // Reject values so large they'd overflow as negative signed, but allow
 476       // "-0".  This negates the unsigned so that the negative isn't undefined
 477       // on signed overflow.
 478       (long long)-ULLVal > 0)
 479     return true;
 480
 481   Str = Str2;
 482   Result = -ULLVal;
 483   return false;
 484 }
 485
 486 /// GetAsUnsignedInteger - Workhorse method that converts a integer character
 487 /// sequence of radix up to 36 to an unsigned long long value.
 488 bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
 489                                 unsigned long long &Result) {
 490   if (consumeUnsignedInteger(Str, Radix, Result))
 491     return true;
 492
 493   // For getAsUnsignedInteger, we require the whole string to be consumed or
 494   // else we consider it a failure.
 495   return !Str.empty();
 496 }
 497
 498 bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,
 499                               long long &Result) {
 500   if (consumeSignedInteger(Str, Radix, Result))
 501     return true;
 502
 503   // For getAsSignedInteger, we require the whole string to be consumed or else
 504   // we consider it a failure.
 505   return !Str.empty();
 506 }
 507
 508 bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
 509   StringRef Str = *this;
 510
 511   // Autosense radix if not specified.
 512   if (Radix == 0)
 513     Radix = GetAutoSenseRadix(Str);
 514
 515   assert(Radix > 1 && Radix <= 36);
 516
 517   // Empty strings (after the radix autosense) are invalid.
 518   if (Str.empty()) return true;
 519
 520   // Skip leading zeroes.  This can be a significant improvement if
 521   // it means we don't need > 64 bits.
 522   while (!Str.empty() && Str.front() == '0')
 523     Str = Str.substr(1);
 524
 525   // If it was nothing but zeroes....
 526   if (Str.empty()) {
 527     Result = APInt(64, 0);
 528     return false;
 529   }
 530
 531   // (Over-)estimate the required number of bits.
 532   unsigned Log2Radix = 0;
 533   while ((1U << Log2Radix) < Radix) Log2Radix++;
 534   bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);
 535
 536   unsigned BitWidth = Log2Radix * Str.size();
 537   if (BitWidth < Result.getBitWidth())
 538     BitWidth = Result.getBitWidth(); // don't shrink the result
 539   else if (BitWidth > Result.getBitWidth())
 540     Result = Result.zext(BitWidth);
 541
 542   APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
 543   if (!IsPowerOf2Radix) {
 544     // These must have the same bit-width as Result.
 545     RadixAP = APInt(BitWidth, Radix);
 546     CharAP = APInt(BitWidth, 0);
 547   }
 548
 549   // Parse all the bytes of the string given this radix.
 550   Result = 0;
 551   while (!Str.empty()) {
 552     unsigned CharVal;
 553     if (Str[0] >= '0' && Str[0] <= '9')
 554       CharVal = Str[0]-'0';
 555     else if (Str[0] >= 'a' && Str[0] <= 'z')
 556       CharVal = Str[0]-'a'+10;
 557     else if (Str[0] >= 'A' && Str[0] <= 'Z')
 558       CharVal = Str[0]-'A'+10;
 559     else
 560       return true;
 561
 562     // If the parsed value is larger than the integer radix, the string is
 563     // invalid.
 564     if (CharVal >= Radix)
 565       return true;
 566
 567     // Add in this character.
 568     if (IsPowerOf2Radix) {
 569       Result <<= Log2Radix;
 570       Result |= CharVal;
 571     } else {
 572       Result *= RadixAP;
 573       CharAP = CharVal;
 574       Result += CharAP;
 575     }
 576
 577     Str = Str.substr(1);
 578   }
 579
 580   return false;
 581 }
 582
 583 bool StringRef::getAsDouble(double &Result, bool AllowInexact) const {
 584   APFloat F(0.0);
 585   APFloat::opStatus Status =
 586       F.convertFromString(*this, APFloat::rmNearestTiesToEven);
 587   if (Status != APFloat::opOK) {
 588     if (!AllowInexact || !(Status & APFloat::opInexact))
 589       return true;
 590   }
 591
 592   Result = F.convertToDouble();
 593   return false;
 594 }
 595
 596 // Implementation of StringRef hashing.
 597 hash_code llvm::hash_value(StringRef S) {
 598   return hash_combine_range(S.begin(), S.end());
 599 }