llvm/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 "llvm/Support/Error.h"
  16 #include <bitset>
  17
  18 using namespace llvm;
  19
  20 // MSVC emits references to this into the translation units which reference it.
  21 #ifndef _MSC_VER
  22 constexpr size_t StringRef::npos;
  23 #endif
  24
  25 // strncasecmp() is not available on non-POSIX systems, so define an
  26 // alternative function here.
  27 static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) {
  28   for (size_t I = 0; I < Length; ++I) {
  29     unsigned char LHC = toLower(LHS[I]);
  30     unsigned char RHC = toLower(RHS[I]);
  31     if (LHC != RHC)
  32       return LHC < RHC ? -1 : 1;
  33   }
  34   return 0;
  35 }
  36
  37 int StringRef::compare_insensitive(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 bool StringRef::starts_with_insensitive(StringRef Prefix) const {
  46   return Length >= Prefix.Length &&
  47       ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;
  48 }
  49
  50 bool StringRef::ends_with_insensitive(StringRef Suffix) const {
  51   return Length >= Suffix.Length &&
  52       ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
  53 }
  54
  55 size_t StringRef::find_insensitive(char C, size_t From) const {
  56   char L = toLower(C);
  57   return find_if([L](char D) { return toLower(D) == L; }, From);
  58 }
  59
  60 /// compare_numeric - Compare strings, handle embedded numbers.
  61 int StringRef::compare_numeric(StringRef RHS) const {
  62   for (size_t I = 0, E = std::min(Length, RHS.Length); I != E; ++I) {
  63     // Check for sequences of digits.
  64     if (isDigit(Data[I]) && isDigit(RHS.Data[I])) {
  65       // The longer sequence of numbers is considered larger.
  66       // This doesn't really handle prefixed zeros well.
  67       size_t J;
  68       for (J = I + 1; J != E + 1; ++J) {
  69         bool ld = J < Length && isDigit(Data[J]);
  70         bool rd = J < RHS.Length && isDigit(RHS.Data[J]);
  71         if (ld != rd)
  72           return rd ? -1 : 1;
  73         if (!rd)
  74           break;
  75       }
  76       // The two number sequences have the same length (J-I), just memcmp them.
  77       if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))
  78         return Res < 0 ? -1 : 1;
  79       // Identical number sequences, continue search after the numbers.
  80       I = J - 1;
  81       continue;
  82     }
  83     if (Data[I] != RHS.Data[I])
  84       return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
  85   }
  86   if (Length == RHS.Length)
  87     return 0;
  88   return Length < RHS.Length ? -1 : 1;
  89 }
  90
  91 // Compute the edit distance between the two given strings.
  92 unsigned StringRef::edit_distance(llvm::StringRef Other,
  93                                   bool AllowReplacements,
  94                                   unsigned MaxEditDistance) const {
  95   return llvm::ComputeEditDistance(ArrayRef(data(), size()),
  96                                    ArrayRef(Other.data(), Other.size()),
  97                                    AllowReplacements, MaxEditDistance);
  98 }
  99
 100 unsigned llvm::StringRef::edit_distance_insensitive(
 101     StringRef Other, bool AllowReplacements, unsigned MaxEditDistance) const {
 102   return llvm::ComputeMappedEditDistance(
 103       ArrayRef(data(), size()), ArrayRef(Other.data(), Other.size()),
 104       llvm::toLower, AllowReplacements, MaxEditDistance);
 105 }
 106
 107 //===----------------------------------------------------------------------===//
 108 // String Operations
 109 //===----------------------------------------------------------------------===//
 110
 111 std::string StringRef::lower() const {
 112   return std::string(map_iterator(begin(), toLower),
 113                      map_iterator(end(), toLower));
 114 }
 115
 116 std::string StringRef::upper() const {
 117   return std::string(map_iterator(begin(), toUpper),
 118                      map_iterator(end(), toUpper));
 119 }
 120
 121 //===----------------------------------------------------------------------===//
 122 // String Searching
 123 //===----------------------------------------------------------------------===//
 124
 125
 126 /// find - Search for the first string \arg Str in the string.
 127 ///
 128 /// \return - The index of the first occurrence of \arg Str, or npos if not
 129 /// found.
 130 size_t StringRef::find(StringRef Str, size_t From) const {
 131   if (From > Length)
 132     return npos;
 133
 134   const char *Start = Data + From;
 135   size_t Size = Length - From;
 136
 137   const char *Needle = Str.data();
 138   size_t N = Str.size();
 139   if (N == 0)
 140     return From;
 141   if (Size < N)
 142     return npos;
 143   if (N == 1) {
 144     const char *Ptr = (const char *)::memchr(Start, Needle[0], Size);
 145     return Ptr == nullptr ? npos : Ptr - Data;
 146   }
 147
 148   const char *Stop = Start + (Size - N + 1);
 149
 150   if (N == 2) {
 151     // Provide a fast path for newline finding (CRLF case) in InclusionRewriter.
 152     // Not the most optimized strategy, but getting memcmp inlined should be
 153     // good enough.
 154     do {
 155       if (std::memcmp(Start, Needle, 2) == 0)
 156         return Start - Data;
 157       ++Start;
 158     } while (Start < Stop);
 159     return npos;
 160   }
 161
 162   // For short haystacks or unsupported needles fall back to the naive algorithm
 163   if (Size < 16 || N > 255) {
 164     do {
 165       if (std::memcmp(Start, Needle, N) == 0)
 166         return Start - Data;
 167       ++Start;
 168     } while (Start < Stop);
 169     return npos;
 170   }
 171
 172   // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
 173   uint8_t BadCharSkip[256];
 174   std::memset(BadCharSkip, N, 256);
 175   for (unsigned i = 0; i != N-1; ++i)
 176     BadCharSkip[(uint8_t)Str[i]] = N-1-i;
 177
 178   do {
 179     uint8_t Last = Start[N - 1];
 180     if (LLVM_UNLIKELY(Last == (uint8_t)Needle[N - 1]))
 181       if (std::memcmp(Start, Needle, N - 1) == 0)
 182         return Start - Data;
 183
 184     // Otherwise skip the appropriate number of bytes.
 185     Start += BadCharSkip[Last];
 186   } while (Start < Stop);
 187
 188   return npos;
 189 }
 190
 191 size_t StringRef::find_insensitive(StringRef Str, size_t From) const {
 192   StringRef This = substr(From);
 193   while (This.size() >= Str.size()) {
 194     if (This.starts_with_insensitive(Str))
 195       return From;
 196     This = This.drop_front();
 197     ++From;
 198   }
 199   return npos;
 200 }
 201
 202 size_t StringRef::rfind_insensitive(char C, size_t From) const {
 203   From = std::min(From, Length);
 204   size_t i = From;
 205   while (i != 0) {
 206     --i;
 207     if (toLower(Data[i]) == toLower(C))
 208       return i;
 209   }
 210   return npos;
 211 }
 212
 213 /// rfind - Search for the last string \arg Str in the string.
 214 ///
 215 /// \return - The index of the last occurrence of \arg Str, or npos if not
 216 /// found.
 217 size_t StringRef::rfind(StringRef Str) const {
 218   return std::string_view(*this).rfind(Str);
 219 }
 220
 221 size_t StringRef::rfind_insensitive(StringRef Str) const {
 222   size_t N = Str.size();
 223   if (N > Length)
 224     return npos;
 225   for (size_t i = Length - N + 1, e = 0; i != e;) {
 226     --i;
 227     if (substr(i, N).equals_insensitive(Str))
 228       return i;
 229   }
 230   return npos;
 231 }
 232
 233 /// find_first_of - Find the first character in the string that is in \arg
 234 /// Chars, or npos if not found.
 235 ///
 236 /// Note: O(size() + Chars.size())
 237 StringRef::size_type StringRef::find_first_of(StringRef Chars,
 238                                               size_t From) const {
 239   std::bitset<1 << CHAR_BIT> CharBits;
 240   for (char C : Chars)
 241     CharBits.set((unsigned char)C);
 242
 243   for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
 244     if (CharBits.test((unsigned char)Data[i]))
 245       return i;
 246   return npos;
 247 }
 248
 249 /// find_first_not_of - Find the first character in the string that is not
 250 /// \arg C or npos if not found.
 251 StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
 252   return std::string_view(*this).find_first_not_of(C, From);
 253 }
 254
 255 /// find_first_not_of - Find the first character in the string that is not
 256 /// in the string \arg Chars, or npos if not found.
 257 ///
 258 /// Note: O(size() + Chars.size())
 259 StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
 260                                                   size_t From) const {
 261   std::bitset<1 << CHAR_BIT> CharBits;
 262   for (char C : Chars)
 263     CharBits.set((unsigned char)C);
 264
 265   for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
 266     if (!CharBits.test((unsigned char)Data[i]))
 267       return i;
 268   return npos;
 269 }
 270
 271 /// find_last_of - Find the last character in the string that is in \arg C,
 272 /// or npos if not found.
 273 ///
 274 /// Note: O(size() + Chars.size())
 275 StringRef::size_type StringRef::find_last_of(StringRef Chars,
 276                                              size_t From) const {
 277   std::bitset<1 << CHAR_BIT> CharBits;
 278   for (char C : Chars)
 279     CharBits.set((unsigned char)C);
 280
 281   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 282     if (CharBits.test((unsigned char)Data[i]))
 283       return i;
 284   return npos;
 285 }
 286
 287 /// find_last_not_of - Find the last character in the string that is not
 288 /// \arg C, or npos if not found.
 289 StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
 290   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 291     if (Data[i] != C)
 292       return i;
 293   return npos;
 294 }
 295
 296 /// find_last_not_of - Find the last character in the string that is not in
 297 /// \arg Chars, or npos if not found.
 298 ///
 299 /// Note: O(size() + Chars.size())
 300 StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
 301                                                  size_t From) const {
 302   std::bitset<1 << CHAR_BIT> CharBits;
 303   for (char C : Chars)
 304     CharBits.set((unsigned char)C);
 305
 306   for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
 307     if (!CharBits.test((unsigned char)Data[i]))
 308       return i;
 309   return npos;
 310 }
 311
 312 void StringRef::split(SmallVectorImpl<StringRef> &A,
 313                       StringRef Separator, int MaxSplit,
 314                       bool KeepEmpty) const {
 315   StringRef S = *this;
 316
 317   // Count down from MaxSplit. When MaxSplit is -1, this will just split
 318   // "forever". This doesn't support splitting more than 2^31 times
 319   // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
 320   // but that seems unlikely to be useful.
 321   while (MaxSplit-- != 0) {
 322     size_t Idx = S.find(Separator);
 323     if (Idx == npos)
 324       break;
 325
 326     // Push this split.
 327     if (KeepEmpty || Idx > 0)
 328       A.push_back(S.slice(0, Idx));
 329
 330     // Jump forward.
 331     S = S.slice(Idx + Separator.size(), npos);
 332   }
 333
 334   // Push the tail.
 335   if (KeepEmpty || !S.empty())
 336     A.push_back(S);
 337 }
 338
 339 void StringRef::split(SmallVectorImpl<StringRef> &A, char Separator,
 340                       int MaxSplit, bool KeepEmpty) const {
 341   StringRef S = *this;
 342
 343   // Count down from MaxSplit. When MaxSplit is -1, this will just split
 344   // "forever". This doesn't support splitting more than 2^31 times
 345   // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
 346   // but that seems unlikely to be useful.
 347   while (MaxSplit-- != 0) {
 348     size_t Idx = S.find(Separator);
 349     if (Idx == npos)
 350       break;
 351
 352     // Push this split.
 353     if (KeepEmpty || Idx > 0)
 354       A.push_back(S.slice(0, Idx));
 355
 356     // Jump forward.
 357     S = S.slice(Idx + 1, npos);
 358   }
 359
 360   // Push the tail.
 361   if (KeepEmpty || !S.empty())
 362     A.push_back(S);
 363 }
 364
 365 //===----------------------------------------------------------------------===//
 366 // Helpful Algorithms
 367 //===----------------------------------------------------------------------===//
 368
 369 /// count - Return the number of non-overlapped occurrences of \arg Str in
 370 /// the string.
 371 size_t StringRef::count(StringRef Str) const {
 372   size_t Count = 0;
 373   size_t Pos = 0;
 374   size_t N = Str.size();
 375   // TODO: For an empty `Str` we return 0 for legacy reasons. Consider changing
 376   //       this to `Length + 1` which is more in-line with the function
 377   //       description.
 378   if (!N)
 379     return 0;
 380   while ((Pos = find(Str, Pos)) != npos) {
 381     ++Count;
 382     Pos += N;
 383   }
 384   return Count;
 385 }
 386
 387 static unsigned GetAutoSenseRadix(StringRef &Str) {
 388   if (Str.empty())
 389     return 10;
 390
 391   if (Str.startswith("0x") || Str.startswith("0X")) {
 392     Str = Str.substr(2);
 393     return 16;
 394   }
 395
 396   if (Str.startswith("0b") || Str.startswith("0B")) {
 397     Str = Str.substr(2);
 398     return 2;
 399   }
 400
 401   if (Str.startswith("0o")) {
 402     Str = Str.substr(2);
 403     return 8;
 404   }
 405
 406   if (Str[0] == '0' && Str.size() > 1 && isDigit(Str[1])) {
 407     Str = Str.substr(1);
 408     return 8;
 409   }
 410
 411   return 10;
 412 }
 413
 414 bool llvm::consumeUnsignedInteger(StringRef &Str, unsigned Radix,
 415                                   unsigned long long &Result) {
 416   // Autosense radix if not specified.
 417   if (Radix == 0)
 418     Radix = GetAutoSenseRadix(Str);
 419
 420   // Empty strings (after the radix autosense) are invalid.
 421   if (Str.empty()) return true;
 422
 423   // Parse all the bytes of the string given this radix.  Watch for overflow.
 424   StringRef Str2 = Str;
 425   Result = 0;
 426   while (!Str2.empty()) {
 427     unsigned CharVal;
 428     if (Str2[0] >= '0' && Str2[0] <= '9')
 429       CharVal = Str2[0] - '0';
 430     else if (Str2[0] >= 'a' && Str2[0] <= 'z')
 431       CharVal = Str2[0] - 'a' + 10;
 432     else if (Str2[0] >= 'A' && Str2[0] <= 'Z')
 433       CharVal = Str2[0] - 'A' + 10;
 434     else
 435       break;
 436
 437     // If the parsed value is larger than the integer radix, we cannot
 438     // consume any more characters.
 439     if (CharVal >= Radix)
 440       break;
 441
 442     // Add in this character.
 443     unsigned long long PrevResult = Result;
 444     Result = Result * Radix + CharVal;
 445
 446     // Check for overflow by shifting back and seeing if bits were lost.
 447     if (Result / Radix < PrevResult)
 448       return true;
 449
 450     Str2 = Str2.substr(1);
 451   }
 452
 453   // We consider the operation a failure if no characters were consumed
 454   // successfully.
 455   if (Str.size() == Str2.size())
 456     return true;
 457
 458   Str = Str2;
 459   return false;
 460 }
 461
 462 bool llvm::consumeSignedInteger(StringRef &Str, unsigned Radix,
 463                                 long long &Result) {
 464   unsigned long long ULLVal;
 465
 466   // Handle positive strings first.
 467   if (Str.empty() || Str.front() != '-') {
 468     if (consumeUnsignedInteger(Str, Radix, ULLVal) ||
 469         // Check for value so large it overflows a signed value.
 470         (long long)ULLVal < 0)
 471       return true;
 472     Result = ULLVal;
 473     return false;
 474   }
 475
 476   // Get the positive part of the value.
 477   StringRef Str2 = Str.drop_front(1);
 478   if (consumeUnsignedInteger(Str2, Radix, ULLVal) ||
 479       // Reject values so large they'd overflow as negative signed, but allow
 480       // "-0".  This negates the unsigned so that the negative isn't undefined
 481       // on signed overflow.
 482       (long long)-ULLVal > 0)
 483     return true;
 484
 485   Str = Str2;
 486   Result = -ULLVal;
 487   return false;
 488 }
 489
 490 /// GetAsUnsignedInteger - Workhorse method that converts a integer character
 491 /// sequence of radix up to 36 to an unsigned long long value.
 492 bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
 493                                 unsigned long long &Result) {
 494   if (consumeUnsignedInteger(Str, Radix, Result))
 495     return true;
 496
 497   // For getAsUnsignedInteger, we require the whole string to be consumed or
 498   // else we consider it a failure.
 499   return !Str.empty();
 500 }
 501
 502 bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,
 503                               long long &Result) {
 504   if (consumeSignedInteger(Str, Radix, Result))
 505     return true;
 506
 507   // For getAsSignedInteger, we require the whole string to be consumed or else
 508   // we consider it a failure.
 509   return !Str.empty();
 510 }
 511
 512 bool StringRef::consumeInteger(unsigned Radix, APInt &Result) {
 513   StringRef Str = *this;
 514
 515   // Autosense radix if not specified.
 516   if (Radix == 0)
 517     Radix = GetAutoSenseRadix(Str);
 518
 519   assert(Radix > 1 && Radix <= 36);
 520
 521   // Empty strings (after the radix autosense) are invalid.
 522   if (Str.empty()) return true;
 523
 524   // Skip leading zeroes.  This can be a significant improvement if
 525   // it means we don't need > 64 bits.
 526   while (!Str.empty() && Str.front() == '0')
 527     Str = Str.substr(1);
 528
 529   // If it was nothing but zeroes....
 530   if (Str.empty()) {
 531     Result = APInt(64, 0);
 532     *this = Str;
 533     return false;
 534   }
 535
 536   // (Over-)estimate the required number of bits.
 537   unsigned Log2Radix = 0;
 538   while ((1U << Log2Radix) < Radix) Log2Radix++;
 539   bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);
 540
 541   unsigned BitWidth = Log2Radix * Str.size();
 542   if (BitWidth < Result.getBitWidth())
 543     BitWidth = Result.getBitWidth(); // don't shrink the result
 544   else if (BitWidth > Result.getBitWidth())
 545     Result = Result.zext(BitWidth);
 546
 547   APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
 548   if (!IsPowerOf2Radix) {
 549     // These must have the same bit-width as Result.
 550     RadixAP = APInt(BitWidth, Radix);
 551     CharAP = APInt(BitWidth, 0);
 552   }
 553
 554   // Parse all the bytes of the string given this radix.
 555   Result = 0;
 556   while (!Str.empty()) {
 557     unsigned CharVal;
 558     if (Str[0] >= '0' && Str[0] <= '9')
 559       CharVal = Str[0]-'0';
 560     else if (Str[0] >= 'a' && Str[0] <= 'z')
 561       CharVal = Str[0]-'a'+10;
 562     else if (Str[0] >= 'A' && Str[0] <= 'Z')
 563       CharVal = Str[0]-'A'+10;
 564     else
 565       break;
 566
 567     // If the parsed value is larger than the integer radix, the string is
 568     // invalid.
 569     if (CharVal >= Radix)
 570       break;
 571
 572     // Add in this character.
 573     if (IsPowerOf2Radix) {
 574       Result <<= Log2Radix;
 575       Result |= CharVal;
 576     } else {
 577       Result *= RadixAP;
 578       CharAP = CharVal;
 579       Result += CharAP;
 580     }
 581
 582     Str = Str.substr(1);
 583   }
 584
 585   // We consider the operation a failure if no characters were consumed
 586   // successfully.
 587   if (size() == Str.size())
 588     return true;
 589
 590   *this = Str;
 591   return false;
 592 }
 593
 594 bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
 595   StringRef Str = *this;
 596   if (Str.consumeInteger(Radix, Result))
 597     return true;
 598
 599   // For getAsInteger, we require the whole string to be consumed or else we
 600   // consider it a failure.
 601   return !Str.empty();
 602 }
 603
 604 bool StringRef::getAsDouble(double &Result, bool AllowInexact) const {
 605   APFloat F(0.0);
 606   auto StatusOrErr = F.convertFromString(*this, APFloat::rmNearestTiesToEven);
 607   if (errorToBool(StatusOrErr.takeError()))
 608     return true;
 609
 610   APFloat::opStatus Status = *StatusOrErr;
 611   if (Status != APFloat::opOK) {
 612     if (!AllowInexact || !(Status & APFloat::opInexact))
 613       return true;
 614   }
 615
 616   Result = F.convertToDouble();
 617   return false;
 618 }
 619
 620 // Implementation of StringRef hashing.
 621 hash_code llvm::hash_value(StringRef S) {
 622   return hash_combine_range(S.begin(), S.end());
 623 }
 624
 625 unsigned DenseMapInfo<StringRef, void>::getHashValue(StringRef Val) {
 626   assert(Val.data() != getEmptyKey().data() &&
 627          "Cannot hash the empty key!");
 628   assert(Val.data() != getTombstoneKey().data() &&
 629          "Cannot hash the tombstone key!");
 630   return (unsigned)(hash_value(Val));
 631 }