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.
ascii_strncasecmp(const char * LHS,const char * RHS,size_t Length)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
compare_insensitive(StringRef RHS) const37 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
startswith_insensitive(StringRef Prefix) const45 bool StringRef::startswith_insensitive(StringRef Prefix) const {
46 return Length >= Prefix.Length &&
47 ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;
48 }
49
endswith_insensitive(StringRef Suffix) const50 bool StringRef::endswith_insensitive(StringRef Suffix) const {
51 return Length >= Suffix.Length &&
52 ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
53 }
54
find_insensitive(char C,size_t From) const55 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.
compare_numeric(StringRef RHS) const61 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.
edit_distance(llvm::StringRef Other,bool AllowReplacements,unsigned MaxEditDistance) const92 unsigned StringRef::edit_distance(llvm::StringRef Other,
93 bool AllowReplacements,
94 unsigned MaxEditDistance) const {
95 return llvm::ComputeEditDistance(
96 makeArrayRef(data(), size()),
97 makeArrayRef(Other.data(), Other.size()),
98 AllowReplacements, MaxEditDistance);
99 }
100
101 //===----------------------------------------------------------------------===//
102 // String Operations
103 //===----------------------------------------------------------------------===//
104
lower() const105 std::string StringRef::lower() const {
106 return std::string(map_iterator(begin(), toLower),
107 map_iterator(end(), toLower));
108 }
109
upper() const110 std::string StringRef::upper() const {
111 return std::string(map_iterator(begin(), toUpper),
112 map_iterator(end(), toUpper));
113 }
114
115 //===----------------------------------------------------------------------===//
116 // String Searching
117 //===----------------------------------------------------------------------===//
118
119
120 /// find - Search for the first string \arg Str in the string.
121 ///
122 /// \return - The index of the first occurrence of \arg Str, or npos if not
123 /// found.
find(StringRef Str,size_t From) const124 size_t StringRef::find(StringRef Str, size_t From) const {
125 if (From > Length)
126 return npos;
127
128 const char *Start = Data + From;
129 size_t Size = Length - From;
130
131 const char *Needle = Str.data();
132 size_t N = Str.size();
133 if (N == 0)
134 return From;
135 if (Size < N)
136 return npos;
137 if (N == 1) {
138 const char *Ptr = (const char *)::memchr(Start, Needle[0], Size);
139 return Ptr == nullptr ? npos : Ptr - Data;
140 }
141
142 const char *Stop = Start + (Size - N + 1);
143
144 // For short haystacks or unsupported needles fall back to the naive algorithm
145 if (Size < 16 || N > 255) {
146 do {
147 if (std::memcmp(Start, Needle, N) == 0)
148 return Start - Data;
149 ++Start;
150 } while (Start < Stop);
151 return npos;
152 }
153
154 // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
155 uint8_t BadCharSkip[256];
156 std::memset(BadCharSkip, N, 256);
157 for (unsigned i = 0; i != N-1; ++i)
158 BadCharSkip[(uint8_t)Str[i]] = N-1-i;
159
160 do {
161 uint8_t Last = Start[N - 1];
162 if (LLVM_UNLIKELY(Last == (uint8_t)Needle[N - 1]))
163 if (std::memcmp(Start, Needle, N - 1) == 0)
164 return Start - Data;
165
166 // Otherwise skip the appropriate number of bytes.
167 Start += BadCharSkip[Last];
168 } while (Start < Stop);
169
170 return npos;
171 }
172
find_insensitive(StringRef Str,size_t From) const173 size_t StringRef::find_insensitive(StringRef Str, size_t From) const {
174 StringRef This = substr(From);
175 while (This.size() >= Str.size()) {
176 if (This.startswith_insensitive(Str))
177 return From;
178 This = This.drop_front();
179 ++From;
180 }
181 return npos;
182 }
183
rfind_insensitive(char C,size_t From) const184 size_t StringRef::rfind_insensitive(char C, size_t From) const {
185 From = std::min(From, Length);
186 size_t i = From;
187 while (i != 0) {
188 --i;
189 if (toLower(Data[i]) == toLower(C))
190 return i;
191 }
192 return npos;
193 }
194
195 /// rfind - Search for the last string \arg Str in the string.
196 ///
197 /// \return - The index of the last occurrence of \arg Str, or npos if not
198 /// found.
rfind(StringRef Str) const199 size_t StringRef::rfind(StringRef Str) const {
200 size_t N = Str.size();
201 if (N > Length)
202 return npos;
203 for (size_t i = Length - N + 1, e = 0; i != e;) {
204 --i;
205 if (substr(i, N).equals(Str))
206 return i;
207 }
208 return npos;
209 }
210
rfind_insensitive(StringRef Str) const211 size_t StringRef::rfind_insensitive(StringRef Str) const {
212 size_t N = Str.size();
213 if (N > Length)
214 return npos;
215 for (size_t i = Length - N + 1, e = 0; i != e;) {
216 --i;
217 if (substr(i, N).equals_insensitive(Str))
218 return i;
219 }
220 return npos;
221 }
222
223 /// find_first_of - Find the first character in the string that is in \arg
224 /// Chars, or npos if not found.
225 ///
226 /// Note: O(size() + Chars.size())
find_first_of(StringRef Chars,size_t From) const227 StringRef::size_type StringRef::find_first_of(StringRef Chars,
228 size_t From) const {
229 std::bitset<1 << CHAR_BIT> CharBits;
230 for (size_type i = 0; i != Chars.size(); ++i)
231 CharBits.set((unsigned char)Chars[i]);
232
233 for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
234 if (CharBits.test((unsigned char)Data[i]))
235 return i;
236 return npos;
237 }
238
239 /// find_first_not_of - Find the first character in the string that is not
240 /// \arg C or npos if not found.
find_first_not_of(char C,size_t From) const241 StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
242 for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
243 if (Data[i] != C)
244 return i;
245 return npos;
246 }
247
248 /// find_first_not_of - Find the first character in the string that is not
249 /// in the string \arg Chars, or npos if not found.
250 ///
251 /// Note: O(size() + Chars.size())
find_first_not_of(StringRef Chars,size_t From) const252 StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
253 size_t From) const {
254 std::bitset<1 << CHAR_BIT> CharBits;
255 for (size_type i = 0; i != Chars.size(); ++i)
256 CharBits.set((unsigned char)Chars[i]);
257
258 for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
259 if (!CharBits.test((unsigned char)Data[i]))
260 return i;
261 return npos;
262 }
263
264 /// find_last_of - Find the last character in the string that is in \arg C,
265 /// or npos if not found.
266 ///
267 /// Note: O(size() + Chars.size())
find_last_of(StringRef Chars,size_t From) const268 StringRef::size_type StringRef::find_last_of(StringRef Chars,
269 size_t From) const {
270 std::bitset<1 << CHAR_BIT> CharBits;
271 for (size_type i = 0; i != Chars.size(); ++i)
272 CharBits.set((unsigned char)Chars[i]);
273
274 for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
275 if (CharBits.test((unsigned char)Data[i]))
276 return i;
277 return npos;
278 }
279
280 /// find_last_not_of - Find the last character in the string that is not
281 /// \arg C, or npos if not found.
find_last_not_of(char C,size_t From) const282 StringRef::size_type StringRef::find_last_not_of(char C, size_t From) const {
283 for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
284 if (Data[i] != C)
285 return i;
286 return npos;
287 }
288
289 /// find_last_not_of - Find the last character in the string that is not in
290 /// \arg Chars, or npos if not found.
291 ///
292 /// Note: O(size() + Chars.size())
find_last_not_of(StringRef Chars,size_t From) const293 StringRef::size_type StringRef::find_last_not_of(StringRef Chars,
294 size_t From) const {
295 std::bitset<1 << CHAR_BIT> CharBits;
296 for (size_type i = 0, e = Chars.size(); i != e; ++i)
297 CharBits.set((unsigned char)Chars[i]);
298
299 for (size_type i = std::min(From, Length) - 1, e = -1; i != e; --i)
300 if (!CharBits.test((unsigned char)Data[i]))
301 return i;
302 return npos;
303 }
304
split(SmallVectorImpl<StringRef> & A,StringRef Separator,int MaxSplit,bool KeepEmpty) const305 void StringRef::split(SmallVectorImpl<StringRef> &A,
306 StringRef Separator, int MaxSplit,
307 bool KeepEmpty) const {
308 StringRef S = *this;
309
310 // Count down from MaxSplit. When MaxSplit is -1, this will just split
311 // "forever". This doesn't support splitting more than 2^31 times
312 // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
313 // but that seems unlikely to be useful.
314 while (MaxSplit-- != 0) {
315 size_t Idx = S.find(Separator);
316 if (Idx == npos)
317 break;
318
319 // Push this split.
320 if (KeepEmpty || Idx > 0)
321 A.push_back(S.slice(0, Idx));
322
323 // Jump forward.
324 S = S.slice(Idx + Separator.size(), npos);
325 }
326
327 // Push the tail.
328 if (KeepEmpty || !S.empty())
329 A.push_back(S);
330 }
331
split(SmallVectorImpl<StringRef> & A,char Separator,int MaxSplit,bool KeepEmpty) const332 void StringRef::split(SmallVectorImpl<StringRef> &A, char Separator,
333 int MaxSplit, bool KeepEmpty) const {
334 StringRef S = *this;
335
336 // Count down from MaxSplit. When MaxSplit is -1, this will just split
337 // "forever". This doesn't support splitting more than 2^31 times
338 // intentionally; if we ever want that we can make MaxSplit a 64-bit integer
339 // but that seems unlikely to be useful.
340 while (MaxSplit-- != 0) {
341 size_t Idx = S.find(Separator);
342 if (Idx == npos)
343 break;
344
345 // Push this split.
346 if (KeepEmpty || Idx > 0)
347 A.push_back(S.slice(0, Idx));
348
349 // Jump forward.
350 S = S.slice(Idx + 1, npos);
351 }
352
353 // Push the tail.
354 if (KeepEmpty || !S.empty())
355 A.push_back(S);
356 }
357
358 //===----------------------------------------------------------------------===//
359 // Helpful Algorithms
360 //===----------------------------------------------------------------------===//
361
362 /// count - Return the number of non-overlapped occurrences of \arg Str in
363 /// the string.
count(StringRef Str) const364 size_t StringRef::count(StringRef Str) const {
365 size_t Count = 0;
366 size_t N = Str.size();
367 if (!N || N > Length)
368 return 0;
369 for (size_t i = 0, e = Length - N + 1; i < e;) {
370 if (substr(i, N).equals(Str)) {
371 ++Count;
372 i += N;
373 }
374 else
375 ++i;
376 }
377 return Count;
378 }
379
GetAutoSenseRadix(StringRef & Str)380 static unsigned GetAutoSenseRadix(StringRef &Str) {
381 if (Str.empty())
382 return 10;
383
384 if (Str.startswith("0x") || Str.startswith("0X")) {
385 Str = Str.substr(2);
386 return 16;
387 }
388
389 if (Str.startswith("0b") || Str.startswith("0B")) {
390 Str = Str.substr(2);
391 return 2;
392 }
393
394 if (Str.startswith("0o")) {
395 Str = Str.substr(2);
396 return 8;
397 }
398
399 if (Str[0] == '0' && Str.size() > 1 && isDigit(Str[1])) {
400 Str = Str.substr(1);
401 return 8;
402 }
403
404 return 10;
405 }
406
consumeUnsignedInteger(StringRef & Str,unsigned Radix,unsigned long long & Result)407 bool llvm::consumeUnsignedInteger(StringRef &Str, unsigned Radix,
408 unsigned long long &Result) {
409 // Autosense radix if not specified.
410 if (Radix == 0)
411 Radix = GetAutoSenseRadix(Str);
412
413 // Empty strings (after the radix autosense) are invalid.
414 if (Str.empty()) return true;
415
416 // Parse all the bytes of the string given this radix. Watch for overflow.
417 StringRef Str2 = Str;
418 Result = 0;
419 while (!Str2.empty()) {
420 unsigned CharVal;
421 if (Str2[0] >= '0' && Str2[0] <= '9')
422 CharVal = Str2[0] - '0';
423 else if (Str2[0] >= 'a' && Str2[0] <= 'z')
424 CharVal = Str2[0] - 'a' + 10;
425 else if (Str2[0] >= 'A' && Str2[0] <= 'Z')
426 CharVal = Str2[0] - 'A' + 10;
427 else
428 break;
429
430 // If the parsed value is larger than the integer radix, we cannot
431 // consume any more characters.
432 if (CharVal >= Radix)
433 break;
434
435 // Add in this character.
436 unsigned long long PrevResult = Result;
437 Result = Result * Radix + CharVal;
438
439 // Check for overflow by shifting back and seeing if bits were lost.
440 if (Result / Radix < PrevResult)
441 return true;
442
443 Str2 = Str2.substr(1);
444 }
445
446 // We consider the operation a failure if no characters were consumed
447 // successfully.
448 if (Str.size() == Str2.size())
449 return true;
450
451 Str = Str2;
452 return false;
453 }
454
consumeSignedInteger(StringRef & Str,unsigned Radix,long long & Result)455 bool llvm::consumeSignedInteger(StringRef &Str, unsigned Radix,
456 long long &Result) {
457 unsigned long long ULLVal;
458
459 // Handle positive strings first.
460 if (Str.empty() || Str.front() != '-') {
461 if (consumeUnsignedInteger(Str, Radix, ULLVal) ||
462 // Check for value so large it overflows a signed value.
463 (long long)ULLVal < 0)
464 return true;
465 Result = ULLVal;
466 return false;
467 }
468
469 // Get the positive part of the value.
470 StringRef Str2 = Str.drop_front(1);
471 if (consumeUnsignedInteger(Str2, Radix, ULLVal) ||
472 // Reject values so large they'd overflow as negative signed, but allow
473 // "-0". This negates the unsigned so that the negative isn't undefined
474 // on signed overflow.
475 (long long)-ULLVal > 0)
476 return true;
477
478 Str = Str2;
479 Result = -ULLVal;
480 return false;
481 }
482
483 /// GetAsUnsignedInteger - Workhorse method that converts a integer character
484 /// sequence of radix up to 36 to an unsigned long long value.
getAsUnsignedInteger(StringRef Str,unsigned Radix,unsigned long long & Result)485 bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
486 unsigned long long &Result) {
487 if (consumeUnsignedInteger(Str, Radix, Result))
488 return true;
489
490 // For getAsUnsignedInteger, we require the whole string to be consumed or
491 // else we consider it a failure.
492 return !Str.empty();
493 }
494
getAsSignedInteger(StringRef Str,unsigned Radix,long long & Result)495 bool llvm::getAsSignedInteger(StringRef Str, unsigned Radix,
496 long long &Result) {
497 if (consumeSignedInteger(Str, Radix, Result))
498 return true;
499
500 // For getAsSignedInteger, we require the whole string to be consumed or else
501 // we consider it a failure.
502 return !Str.empty();
503 }
504
getAsInteger(unsigned Radix,APInt & Result) const505 bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
506 StringRef Str = *this;
507
508 // Autosense radix if not specified.
509 if (Radix == 0)
510 Radix = GetAutoSenseRadix(Str);
511
512 assert(Radix > 1 && Radix <= 36);
513
514 // Empty strings (after the radix autosense) are invalid.
515 if (Str.empty()) return true;
516
517 // Skip leading zeroes. This can be a significant improvement if
518 // it means we don't need > 64 bits.
519 while (!Str.empty() && Str.front() == '0')
520 Str = Str.substr(1);
521
522 // If it was nothing but zeroes....
523 if (Str.empty()) {
524 Result = APInt(64, 0);
525 return false;
526 }
527
528 // (Over-)estimate the required number of bits.
529 unsigned Log2Radix = 0;
530 while ((1U << Log2Radix) < Radix) Log2Radix++;
531 bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);
532
533 unsigned BitWidth = Log2Radix * Str.size();
534 if (BitWidth < Result.getBitWidth())
535 BitWidth = Result.getBitWidth(); // don't shrink the result
536 else if (BitWidth > Result.getBitWidth())
537 Result = Result.zext(BitWidth);
538
539 APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
540 if (!IsPowerOf2Radix) {
541 // These must have the same bit-width as Result.
542 RadixAP = APInt(BitWidth, Radix);
543 CharAP = APInt(BitWidth, 0);
544 }
545
546 // Parse all the bytes of the string given this radix.
547 Result = 0;
548 while (!Str.empty()) {
549 unsigned CharVal;
550 if (Str[0] >= '0' && Str[0] <= '9')
551 CharVal = Str[0]-'0';
552 else if (Str[0] >= 'a' && Str[0] <= 'z')
553 CharVal = Str[0]-'a'+10;
554 else if (Str[0] >= 'A' && Str[0] <= 'Z')
555 CharVal = Str[0]-'A'+10;
556 else
557 return true;
558
559 // If the parsed value is larger than the integer radix, the string is
560 // invalid.
561 if (CharVal >= Radix)
562 return true;
563
564 // Add in this character.
565 if (IsPowerOf2Radix) {
566 Result <<= Log2Radix;
567 Result |= CharVal;
568 } else {
569 Result *= RadixAP;
570 CharAP = CharVal;
571 Result += CharAP;
572 }
573
574 Str = Str.substr(1);
575 }
576
577 return false;
578 }
579
getAsDouble(double & Result,bool AllowInexact) const580 bool StringRef::getAsDouble(double &Result, bool AllowInexact) const {
581 APFloat F(0.0);
582 auto StatusOrErr = F.convertFromString(*this, APFloat::rmNearestTiesToEven);
583 if (errorToBool(StatusOrErr.takeError()))
584 return true;
585
586 APFloat::opStatus Status = *StatusOrErr;
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.
hash_value(StringRef S)597 hash_code llvm::hash_value(StringRef S) {
598 return hash_combine_range(S.begin(), S.end());
599 }
600