llvm.org GIT mirror llvm / release_35 lib / Support / StringRef.cpp
release_35

Tree @release_35 (Download .tar.gz)

StringRef.cpp @release_35raw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
//===-- StringRef.cpp - Lightweight String References ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/edit_distance.h"
#include <bitset>

using namespace llvm;

// MSVC emits references to this into the translation units which reference it.
#ifndef _MSC_VER
const size_t StringRef::npos;
#endif

static char ascii_tolower(char x) {
  if (x >= 'A' && x <= 'Z')
    return x - 'A' + 'a';
  return x;
}

static char ascii_toupper(char x) {
  if (x >= 'a' && x <= 'z')
    return x - 'a' + 'A';
  return x;
}

static bool ascii_isdigit(char x) {
  return x >= '0' && x <= '9';
}

// strncasecmp() is not available on non-POSIX systems, so define an
// alternative function here.
static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) {
  for (size_t I = 0; I < Length; ++I) {
    unsigned char LHC = ascii_tolower(LHS[I]);
    unsigned char RHC = ascii_tolower(RHS[I]);
    if (LHC != RHC)
      return LHC < RHC ? -1 : 1;
  }
  return 0;
}

/// compare_lower - Compare strings, ignoring case.
int StringRef::compare_lower(StringRef RHS) const {
  if (int Res = ascii_strncasecmp(Data, RHS.Data, min(Length, RHS.Length)))
    return Res;
  if (Length == RHS.Length)
    return 0;
  return Length < RHS.Length ? -1 : 1;
}

/// Check if this string starts with the given \p Prefix, ignoring case.
bool StringRef::startswith_lower(StringRef Prefix) const {
  return Length >= Prefix.Length &&
      ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;
}

/// Check if this string ends with the given \p Suffix, ignoring case.
bool StringRef::endswith_lower(StringRef Suffix) const {
  return Length >= Suffix.Length &&
      ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
}

/// compare_numeric - Compare strings, handle embedded numbers.
int StringRef::compare_numeric(StringRef RHS) const {
  for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
    // Check for sequences of digits.
    if (ascii_isdigit(Data[I]) && ascii_isdigit(RHS.Data[I])) {
      // The longer sequence of numbers is considered larger.
      // This doesn't really handle prefixed zeros well.
      size_t J;
      for (J = I + 1; J != E + 1; ++J) {
        bool ld = J < Length && ascii_isdigit(Data[J]);
        bool rd = J < RHS.Length && ascii_isdigit(RHS.Data[J]);
        if (ld != rd)
          return rd ? -1 : 1;
        if (!rd)
          break;
      }
      // The two number sequences have the same length (J-I), just memcmp them.
      if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))
        return Res < 0 ? -1 : 1;
      // Identical number sequences, continue search after the numbers.
      I = J - 1;
      continue;
    }
    if (Data[I] != RHS.Data[I])
      return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
  }
  if (Length == RHS.Length)
    return 0;
  return Length < RHS.Length ? -1 : 1;
}

// Compute the edit distance between the two given strings.
unsigned StringRef::edit_distance(llvm::StringRef Other,
                                  bool AllowReplacements,
                                  unsigned MaxEditDistance) const {
  return llvm::ComputeEditDistance(
      llvm::ArrayRef<char>(data(), size()),
      llvm::ArrayRef<char>(Other.data(), Other.size()),
      AllowReplacements, MaxEditDistance);
}

//===----------------------------------------------------------------------===//
// String Operations
//===----------------------------------------------------------------------===//

std::string StringRef::lower() const {
  std::string Result(size(), char());
  for (size_type i = 0, e = size(); i != e; ++i) {
    Result[i] = ascii_tolower(Data[i]);
  }
  return Result;
}

std::string StringRef::upper() const {
  std::string Result(size(), char());
  for (size_type i = 0, e = size(); i != e; ++i) {
    Result[i] = ascii_toupper(Data[i]);
  }
  return Result;
}

//===----------------------------------------------------------------------===//
// String Searching
//===----------------------------------------------------------------------===//


/// find - Search for the first string \arg Str in the string.
///
/// \return - The index of the first occurrence of \arg Str, or npos if not
/// found.
size_t StringRef::find(StringRef Str, size_t From) const {
  size_t N = Str.size();
  if (N > Length)
    return npos;

  // For short haystacks or unsupported needles fall back to the naive algorithm
  if (Length < 16 || N > 255 || N == 0) {
    for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
      if (substr(i, N).equals(Str))
        return i;
    return npos;
  }

  if (From >= Length)
    return npos;

  // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
  uint8_t BadCharSkip[256];
  std::memset(BadCharSkip, N, 256);
  for (unsigned i = 0; i != N-1; ++i)
    BadCharSkip[(uint8_t)Str[i]] = N-1-i;

  unsigned Len = Length-From, Pos = From;
  while (Len >= N) {
    if (substr(Pos, N).equals(Str)) // See if this is the correct substring.
      return Pos;

    // Otherwise skip the appropriate number of bytes.
    uint8_t Skip = BadCharSkip[(uint8_t)(*this)[Pos+N-1]];
    Len -= Skip;
    Pos += Skip;
  }

  return npos;
}

/// rfind - Search for the last string \arg Str in the string.
///
/// \return - The index of the last occurrence of \arg Str, or npos if not
/// found.
size_t StringRef::rfind(StringRef Str) const {
  size_t N = Str.size();
  if (N > Length)
    return npos;
  for (size_t i = Length - N + 1, e = 0; i != e;) {
    --i;
    if (substr(i, N).equals(Str))
      return i;
  }
  return npos;
}

/// find_first_of - Find the first character in the string that is in \arg
/// Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
StringRef::size_type StringRef::find_first_of(StringRef Chars,
                                              size_t From) const {
  std::bitset<1 << CHAR_BIT> CharBits;
  for (size_type i = 0; i != Chars.size(); ++i)
    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = min(From, Length), e = Length; i != e; ++i)
    if (CharBits.test((unsigned char)Data[i]))
      return i;
  return npos;
}

/// find_first_not_of - Find the first character in the string that is not
/// \arg C or npos if not found.
StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
  for (size_type i = min(From, Length), e = Length; i != e; ++i)
    if (Data[i] != C)
      return i;
  return npos;
}

/// find_first_not_of - Find the first character in the string that is not
/// in the string \arg Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
                                                  size_t From) const {
  std::bitset<1 << CHAR_BIT> CharBits;
  for (size_type i = 0; i != Chars.size(); ++i)
    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = min(From, Length), e = Length; i != e; ++i)
    if (!CharBits.test((unsigned char)Data[i]))
      return i;
  return npos;
}

/// find_last_of - Find the last character in the string that is in \arg C,
/// or npos if not found.
///
/// Note: O(size() + Chars.size())
StringRef::size_type StringRef::find_last_of(StringRef Chars,
                                             size_t From) const {
  std::bitset<1 << CHAR_BIT> CharBits;
  for (size_type i = 0; i != Chars.size(); ++i)
    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
    if (CharBits.test((unsigned char)Data[i]))
      return i;
  return npos;
}

/// find_last_not_of - Find the last character in the string that is not
/// \arg C, or npos if not found.
StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
  for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
    if (Data[i] != C)
      return i;
  return npos;
}

/// find_last_not_of - Find the last character in the string that is not in
/// \arg Chars, or npos if not found.
///
/// Note: O(size() + Chars.size())
StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
                                                 size_t From) const {
  std::bitset<1 << CHAR_BIT> CharBits;
  for (size_type i = 0, e = Chars.size(); i != e; ++i)
    CharBits.set((unsigned char)Chars[i]);

  for (size_type i = min(From, Length) - 1, e = -1; i != e; --i)
    if (!CharBits.test((unsigned char)Data[i]))
      return i;
  return npos;
}

void StringRef::split(SmallVectorImpl<StringRef> &A,
                      StringRef Separators, int MaxSplit,
                      bool KeepEmpty) const {
  StringRef rest = *this;

  // rest.data() is used to distinguish cases like "a," that splits into
  // "a" + "" and "a" that splits into "a" + 0.
  for (int splits = 0;
       rest.data() != nullptr && (MaxSplit < 0 || splits < MaxSplit);
       ++splits) {
    std::pair<StringRef, StringRef> p = rest.split(Separators);

    if (KeepEmpty || p.first.size() != 0)
      A.push_back(p.first);
    rest = p.second;
  }
  // If we have a tail left, add it.
  if (rest.data() != nullptr && (rest.size() != 0 || KeepEmpty))
    A.push_back(rest);
}

//===----------------------------------------------------------------------===//
// Helpful Algorithms
//===----------------------------------------------------------------------===//

/// count - Return the number of non-overlapped occurrences of \arg Str in
/// the string.
size_t StringRef::count(StringRef Str) const {
  size_t Count = 0;
  size_t N = Str.size();
  if (N > Length)
    return 0;
  for (size_t i = 0, e = Length - N + 1; i != e; ++i)
    if (substr(i, N).equals(Str))
      ++Count;
  return Count;
}

static unsigned GetAutoSenseRadix(StringRef &Str) {
  if (Str.startswith("0x")) {
    Str = Str.substr(2);
    return 16;
  }
  
  if (Str.startswith("0b")) {
    Str = Str.substr(2);
    return 2;
  }

  if (Str.startswith("0o")) {
    Str = Str.substr(2);
    return 8;
  }

  if (Str.startswith("0"))
    return 8;
  
  return 10;
}


/// GetAsUnsignedInteger - Workhorse method that converts a integer character
/// sequence of radix up to 36 to an unsigned long long value.
bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
                                unsigned long long &Result) {
  // Autosense radix if not specified.
  if (Radix == 0)
    Radix = GetAutoSenseRadix(Str);

  // Empty strings (after the radix autosense) are invalid.
  if (Str.empty()) return true;

  // Parse all the bytes of the string given this radix.  Watch for overflow.
  Result = 0;
  while (!Str.empty()) {
    unsigned CharVal;
    if (Str[0] >= '0' && Str[0] <= '9')
      CharVal = Str[0]-'0';
    else if (Str[0] >= 'a' && Str[0] <= 'z')
      CharVal = Str[0]-'a'+10;
    else if (Str[0] >= 'A' && Str[0] <= 'Z')
      CharVal = Str[0]-'A'+10;
    else
      return true;

    // If the parsed value is larger than the integer radix, the string is
    // invalid.
    if (CharVal >= Radix)
      return true;

    // Add in this character.
    unsigned long long PrevResult = Result;
    Result = Result*Radix+CharVal;

    // Check for overflow by shifting back and seeing if bits were lost.
    if (Result/Radix < PrevResult)
      return true;

    Str = Str.substr(1);
  }

  return false;
}

bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,
                              long long &Result) {
  unsigned long long ULLVal;

  // Handle positive strings first.
  if (Str.empty() || Str.front() != '-') {
    if (getAsUnsignedInteger(Str, Radix, ULLVal) ||
        // Check for value so large it overflows a signed value.
        (long long)ULLVal < 0)
      return true;
    Result = ULLVal;
    return false;
  }

  // Get the positive part of the value.
  if (getAsUnsignedInteger(Str.substr(1), Radix, ULLVal) ||
      // Reject values so large they'd overflow as negative signed, but allow
      // "-0".  This negates the unsigned so that the negative isn't undefined
      // on signed overflow.
      (long long)-ULLVal > 0)
    return true;

  Result = -ULLVal;
  return false;
}

bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
  StringRef Str = *this;

  // Autosense radix if not specified.
  if (Radix == 0)
    Radix = GetAutoSenseRadix(Str);

  assert(Radix > 1 && Radix <= 36);

  // Empty strings (after the radix autosense) are invalid.
  if (Str.empty()) return true;

  // Skip leading zeroes.  This can be a significant improvement if
  // it means we don't need > 64 bits.
  while (!Str.empty() && Str.front() == '0')
    Str = Str.substr(1);

  // If it was nothing but zeroes....
  if (Str.empty()) {
    Result = APInt(64, 0);
    return false;
  }

  // (Over-)estimate the required number of bits.
  unsigned Log2Radix = 0;
  while ((1U << Log2Radix) < Radix) Log2Radix++;
  bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);

  unsigned BitWidth = Log2Radix * Str.size();
  if (BitWidth < Result.getBitWidth())
    BitWidth = Result.getBitWidth(); // don't shrink the result
  else if (BitWidth > Result.getBitWidth())
    Result = Result.zext(BitWidth);

  APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
  if (!IsPowerOf2Radix) {
    // These must have the same bit-width as Result.
    RadixAP = APInt(BitWidth, Radix);
    CharAP = APInt(BitWidth, 0);
  }

  // Parse all the bytes of the string given this radix.
  Result = 0;
  while (!Str.empty()) {
    unsigned CharVal;
    if (Str[0] >= '0' && Str[0] <= '9')
      CharVal = Str[0]-'0';
    else if (Str[0] >= 'a' && Str[0] <= 'z')
      CharVal = Str[0]-'a'+10;
    else if (Str[0] >= 'A' && Str[0] <= 'Z')
      CharVal = Str[0]-'A'+10;
    else
      return true;

    // If the parsed value is larger than the integer radix, the string is
    // invalid.
    if (CharVal >= Radix)
      return true;

    // Add in this character.
    if (IsPowerOf2Radix) {
      Result <<= Log2Radix;
      Result |= CharVal;
    } else {
      Result *= RadixAP;
      CharAP = CharVal;
      Result += CharAP;
    }

    Str = Str.substr(1);
  }

  return false;
}


// Implementation of StringRef hashing.
hash_code llvm::hash_value(StringRef S) {
  return hash_combine_range(S.begin(), S.end());
}