1//===- StringRef.h - Constant String Reference Wrapper ----------*- C++ -*-===//
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#ifndef LLVM_ADT_STRINGREF_H
10#define LLVM_ADT_STRINGREF_H
11
12#include "llvm/ADT/STLExtras.h"
13#include "llvm/ADT/iterator_range.h"
14#include "llvm/Support/Compiler.h"
15#include <algorithm>
16#include <cassert>
17#include <cstddef>
18#include <cstring>
19#include <limits>
20#include <string>
21#include <type_traits>
22#include <utility>
23
24namespace llvm {
25
26 class APInt;
27 class hash_code;
28 template <typename T> class SmallVectorImpl;
29 class StringRef;
30
31 /// Helper functions for StringRef::getAsInteger.
32 bool getAsUnsignedInteger(StringRef Str, unsigned Radix,
33 unsigned long long &Result);
34
35 bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result);
36
37 bool consumeUnsignedInteger(StringRef &Str, unsigned Radix,
38 unsigned long long &Result);
39 bool consumeSignedInteger(StringRef &Str, unsigned Radix, long long &Result);
40
41 /// StringRef - Represent a constant reference to a string, i.e. a character
42 /// array and a length, which need not be null terminated.
43 ///
44 /// This class does not own the string data, it is expected to be used in
45 /// situations where the character data resides in some other buffer, whose
46 /// lifetime extends past that of the StringRef. For this reason, it is not in
47 /// general safe to store a StringRef.
48 class StringRef {
49 public:
50 static const size_t npos = ~size_t(0);
51
52 using iterator = const char *;
53 using const_iterator = const char *;
54 using size_type = size_t;
55
56 private:
57 /// The start of the string, in an external buffer.
58 const char *Data = nullptr;
59
60 /// The length of the string.
61 size_t Length = 0;
62
63 // Workaround memcmp issue with null pointers (undefined behavior)
64 // by providing a specialized version
65 static int compareMemory(const char *Lhs, const char *Rhs, size_t Length) {
66 if (Length == 0) { return 0; }
67 return ::memcmp(Lhs,Rhs,Length);
68 }
69
70 public:
71 /// @name Constructors
72 /// @{
73
74 /// Construct an empty string ref.
75 /*implicit*/ StringRef() = default;
76
77 /// Disable conversion from nullptr. This prevents things like
78 /// if (S == nullptr)
79 StringRef(std::nullptr_t) = delete;
80
81 /// Construct a string ref from a cstring.
82 /*implicit*/ StringRef(const char *Str)
83 : Data(Str), Length(Str ? ::strlen(Str) : 0) {}
84
85 /// Construct a string ref from a pointer and length.
86 /*implicit*/ constexpr StringRef(const char *data, size_t length)
87 : Data(data), Length(length) {}
88
89 /// Construct a string ref from an std::string.
90 /*implicit*/ StringRef(const std::string &Str)
91 : Data(Str.data()), Length(Str.length()) {}
92
93 static StringRef withNullAsEmpty(const char *data) {
94 return StringRef(data ? data : "");
95 }
96
97 /// @}
98 /// @name Iterators
99 /// @{
100
101 iterator begin() const { return Data; }
102
103 iterator end() const { return Data + Length; }
104
105 const unsigned char *bytes_begin() const {
106 return reinterpret_cast<const unsigned char *>(begin());
107 }
108 const unsigned char *bytes_end() const {
109 return reinterpret_cast<const unsigned char *>(end());
110 }
111 iterator_range<const unsigned char *> bytes() const {
112 return make_range(bytes_begin(), bytes_end());
113 }
114
115 /// @}
116 /// @name String Operations
117 /// @{
118
119 /// data - Get a pointer to the start of the string (which may not be null
120 /// terminated).
121 LLVM_NODISCARD
122 const char *data() const { return Data; }
123
124 /// empty - Check if the string is empty.
125 LLVM_NODISCARD
126 bool empty() const { return Length == 0; }
127
128 /// size - Get the string size.
129 LLVM_NODISCARD
130 size_t size() const { return Length; }
131
132 /// front - Get the first character in the string.
133 LLVM_NODISCARD
134 char front() const {
135 assert(!empty());
136 return Data[0];
137 }
138
139 /// back - Get the last character in the string.
140 LLVM_NODISCARD
141 char back() const {
142 assert(!empty());
143 return Data[Length-1];
144 }
145
146 // copy - Allocate copy in Allocator and return StringRef to it.
147 template <typename Allocator>
148 LLVM_NODISCARD StringRef copy(Allocator &A) const {
149 // Don't request a length 0 copy from the allocator.
150 if (empty())
151 return StringRef();
152 char *S = A.template Allocate<char>(Length);
153 std::copy(begin(), end(), S);
154 return StringRef(S, Length);
155 }
156
157 /// equals - Check for string equality, this is more efficient than
158 /// compare() when the relative ordering of inequal strings isn't needed.
159 LLVM_NODISCARD
160 bool equals(StringRef RHS) const {
161 return (Length == RHS.Length &&
162 compareMemory(Data, RHS.Data, RHS.Length) == 0);
163 }
164
165 /// equals_lower - Check for string equality, ignoring case.
166 LLVM_NODISCARD
167 bool equals_lower(StringRef RHS) const {
168 return Length == RHS.Length && compare_lower(RHS) == 0;
169 }
170
171 /// compare - Compare two strings; the result is -1, 0, or 1 if this string
172 /// is lexicographically less than, equal to, or greater than the \p RHS.
173 LLVM_NODISCARD
174 int compare(StringRef RHS) const {
175 // Check the prefix for a mismatch.
176 if (int Res = compareMemory(Data, RHS.Data, std::min(Length, RHS.Length)))
177 return Res < 0 ? -1 : 1;
178
179 // Otherwise the prefixes match, so we only need to check the lengths.
180 if (Length == RHS.Length)
181 return 0;
182 return Length < RHS.Length ? -1 : 1;
183 }
184
185 /// compare_lower - Compare two strings, ignoring case.
186 LLVM_NODISCARD
187 int compare_lower(StringRef RHS) const;
188
189 /// compare_numeric - Compare two strings, treating sequences of digits as
190 /// numbers.
191 LLVM_NODISCARD
192 int compare_numeric(StringRef RHS) const;
193
194 /// Determine the edit distance between this string and another
195 /// string.
196 ///
197 /// \param Other the string to compare this string against.
198 ///
199 /// \param AllowReplacements whether to allow character
200 /// replacements (change one character into another) as a single
201 /// operation, rather than as two operations (an insertion and a
202 /// removal).
203 ///
204 /// \param MaxEditDistance If non-zero, the maximum edit distance that
205 /// this routine is allowed to compute. If the edit distance will exceed
206 /// that maximum, returns \c MaxEditDistance+1.
207 ///
208 /// \returns the minimum number of character insertions, removals,
209 /// or (if \p AllowReplacements is \c true) replacements needed to
210 /// transform one of the given strings into the other. If zero,
211 /// the strings are identical.
212 LLVM_NODISCARD
213 unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
214 unsigned MaxEditDistance = 0) const;
215
216 /// str - Get the contents as an std::string.
217 LLVM_NODISCARD
218 std::string str() const {
219 if (!Data) return std::string();
220 return std::string(Data, Length);
221 }
222
223 /// @}
224 /// @name Operator Overloads
225 /// @{
226
227 LLVM_NODISCARD
228 char operator[](size_t Index) const {
229 assert(Index < Length && "Invalid index!");
230 return Data[Index];
231 }
232
233 /// Disallow accidental assignment from a temporary std::string.
234 ///
235 /// The declaration here is extra complicated so that `stringRef = {}`
236 /// and `stringRef = "abc"` continue to select the move assignment operator.
237 template <typename T>
238 typename std::enable_if<std::is_same<T, std::string>::value,
239 StringRef>::type &
240 operator=(T &&Str) = delete;
241
242 /// @}
243 /// @name Type Conversions
244 /// @{
245
246 operator std::string() const {
247 return str();
248 }
249
250 /// @}
251 /// @name String Predicates
252 /// @{
253
254 /// Check if this string starts with the given \p Prefix.
255 LLVM_NODISCARD
256 bool startswith(StringRef Prefix) const {
257 return Length >= Prefix.Length &&
258 compareMemory(Data, Prefix.Data, Prefix.Length) == 0;
259 }
260
261 /// Check if this string starts with the given \p Prefix, ignoring case.
262 LLVM_NODISCARD
263 bool startswith_lower(StringRef Prefix) const;
264
265 /// Check if this string ends with the given \p Suffix.
266 LLVM_NODISCARD
267 bool endswith(StringRef Suffix) const {
268 return Length >= Suffix.Length &&
269 compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
270 }
271
272 /// Check if this string ends with the given \p Suffix, ignoring case.
273 LLVM_NODISCARD
274 bool endswith_lower(StringRef Suffix) const;
275
276 /// @}
277 /// @name String Searching
278 /// @{
279
280 /// Search for the first character \p C in the string.
281 ///
282 /// \returns The index of the first occurrence of \p C, or npos if not
283 /// found.
284 LLVM_NODISCARD
285 size_t find(char C, size_t From = 0) const {
286 size_t FindBegin = std::min(From, Length);
287 if (FindBegin < Length) { // Avoid calling memchr with nullptr.
288 // Just forward to memchr, which is faster than a hand-rolled loop.
289 if (const void *P = ::memchr(Data + FindBegin, C, Length - FindBegin))
290 return static_cast<const char *>(P) - Data;
291 }
292 return npos;
293 }
294
295 /// Search for the first character \p C in the string, ignoring case.
296 ///
297 /// \returns The index of the first occurrence of \p C, or npos if not
298 /// found.
299 LLVM_NODISCARD
300 size_t find_lower(char C, size_t From = 0) const;
301
302 /// Search for the first character satisfying the predicate \p F
303 ///
304 /// \returns The index of the first character satisfying \p F starting from
305 /// \p From, or npos if not found.
306 LLVM_NODISCARD
307 size_t find_if(function_ref<bool(char)> F, size_t From = 0) const {
308 StringRef S = drop_front(From);
309 while (!S.empty()) {
310 if (F(S.front()))
311 return size() - S.size();
312 S = S.drop_front();
313 }
314 return npos;
315 }
316
317 /// Search for the first character not satisfying the predicate \p F
318 ///
319 /// \returns The index of the first character not satisfying \p F starting
320 /// from \p From, or npos if not found.
321 LLVM_NODISCARD
322 size_t find_if_not(function_ref<bool(char)> F, size_t From = 0) const {
323 return find_if([F](char c) { return !F(c); }, From);
324 }
325
326 /// Search for the first string \p Str in the string.
327 ///
328 /// \returns The index of the first occurrence of \p Str, or npos if not
329 /// found.
330 LLVM_NODISCARD
331 size_t find(StringRef Str, size_t From = 0) const;
332
333 /// Search for the first string \p Str in the string, ignoring case.
334 ///
335 /// \returns The index of the first occurrence of \p Str, or npos if not
336 /// found.
337 LLVM_NODISCARD
338 size_t find_lower(StringRef Str, size_t From = 0) const;
339
340 /// Search for the last character \p C in the string.
341 ///
342 /// \returns The index of the last occurrence of \p C, or npos if not
343 /// found.
344 LLVM_NODISCARD
345 size_t rfind(char C, size_t From = npos) const {
346 From = std::min(From, Length);
347 size_t i = From;
348 while (i != 0) {
349 --i;
350 if (Data[i] == C)
351 return i;
352 }
353 return npos;
354 }
355
356 /// Search for the last character \p C in the string, ignoring case.
357 ///
358 /// \returns The index of the last occurrence of \p C, or npos if not
359 /// found.
360 LLVM_NODISCARD
361 size_t rfind_lower(char C, size_t From = npos) const;
362
363 /// Search for the last string \p Str in the string.
364 ///
365 /// \returns The index of the last occurrence of \p Str, or npos if not
366 /// found.
367 LLVM_NODISCARD
368 size_t rfind(StringRef Str) const;
369
370 /// Search for the last string \p Str in the string, ignoring case.
371 ///
372 /// \returns The index of the last occurrence of \p Str, or npos if not
373 /// found.
374 LLVM_NODISCARD
375 size_t rfind_lower(StringRef Str) const;
376
377 /// Find the first character in the string that is \p C, or npos if not
378 /// found. Same as find.
379 LLVM_NODISCARD
380 size_t find_first_of(char C, size_t From = 0) const {
381 return find(C, From);
382 }
383
384 /// Find the first character in the string that is in \p Chars, or npos if
385 /// not found.
386 ///
387 /// Complexity: O(size() + Chars.size())
388 LLVM_NODISCARD
389 size_t find_first_of(StringRef Chars, size_t From = 0) const;
390
391 /// Find the first character in the string that is not \p C or npos if not
392 /// found.
393 LLVM_NODISCARD
394 size_t find_first_not_of(char C, size_t From = 0) const;
395
396 /// Find the first character in the string that is not in the string
397 /// \p Chars, or npos if not found.
398 ///
399 /// Complexity: O(size() + Chars.size())
400 LLVM_NODISCARD
401 size_t find_first_not_of(StringRef Chars, size_t From = 0) const;
402
403 /// Find the last character in the string that is \p C, or npos if not
404 /// found.
405 LLVM_NODISCARD
406 size_t find_last_of(char C, size_t From = npos) const {
407 return rfind(C, From);
408 }
409
410 /// Find the last character in the string that is in \p C, or npos if not
411 /// found.
412 ///
413 /// Complexity: O(size() + Chars.size())
414 LLVM_NODISCARD
415 size_t find_last_of(StringRef Chars, size_t From = npos) const;
416
417 /// Find the last character in the string that is not \p C, or npos if not
418 /// found.
419 LLVM_NODISCARD
420 size_t find_last_not_of(char C, size_t From = npos) const;
421
422 /// Find the last character in the string that is not in \p Chars, or
423 /// npos if not found.
424 ///
425 /// Complexity: O(size() + Chars.size())
426 LLVM_NODISCARD
427 size_t find_last_not_of(StringRef Chars, size_t From = npos) const;
428
429 /// Return true if the given string is a substring of *this, and false
430 /// otherwise.
431 LLVM_NODISCARD
432 bool contains(StringRef Other) const { return find(Other) != npos; }
433
434 /// Return true if the given character is contained in *this, and false
435 /// otherwise.
436 LLVM_NODISCARD
437 bool contains(char C) const { return find_first_of(C) != npos; }
438
439 /// Return true if the given string is a substring of *this, and false
440 /// otherwise.
441 LLVM_NODISCARD
442 bool contains_lower(StringRef Other) const {
443 return find_lower(Other) != npos;
444 }
445
446 /// Return true if the given character is contained in *this, and false
447 /// otherwise.
448 LLVM_NODISCARD
449 bool contains_lower(char C) const { return find_lower(C) != npos; }
450
451 /// @}
452 /// @name Helpful Algorithms
453 /// @{
454
455 /// Return the number of occurrences of \p C in the string.
456 LLVM_NODISCARD
457 size_t count(char C) const {
458 size_t Count = 0;
459 for (size_t i = 0, e = Length; i != e; ++i)
460 if (Data[i] == C)
461 ++Count;
462 return Count;
463 }
464
465 /// Return the number of non-overlapped occurrences of \p Str in
466 /// the string.
467 size_t count(StringRef Str) const;
468
469 /// Parse the current string as an integer of the specified radix. If
470 /// \p Radix is specified as zero, this does radix autosensing using
471 /// extended C rules: 0 is octal, 0x is hex, 0b is binary.
472 ///
473 /// If the string is invalid or if only a subset of the string is valid,
474 /// this returns true to signify the error. The string is considered
475 /// erroneous if empty or if it overflows T.
476 template <typename T>
477 typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type
478 getAsInteger(unsigned Radix, T &Result) const {
479 long long LLVal;
480 if (getAsSignedInteger(*this, Radix, LLVal) ||
481 static_cast<T>(LLVal) != LLVal)
482 return true;
483 Result = LLVal;
484 return false;
485 }
486
487 template <typename T>
488 typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type
489 getAsInteger(unsigned Radix, T &Result) const {
490 unsigned long long ULLVal;
491 // The additional cast to unsigned long long is required to avoid the
492 // Visual C++ warning C4805: '!=' : unsafe mix of type 'bool' and type
493 // 'unsigned __int64' when instantiating getAsInteger with T = bool.
494 if (getAsUnsignedInteger(*this, Radix, ULLVal) ||
495 static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)
496 return true;
497 Result = ULLVal;
498 return false;
499 }
500
501 /// Parse the current string as an integer of the specified radix. If
502 /// \p Radix is specified as zero, this does radix autosensing using
503 /// extended C rules: 0 is octal, 0x is hex, 0b is binary.
504 ///
505 /// If the string does not begin with a number of the specified radix,
506 /// this returns true to signify the error. The string is considered
507 /// erroneous if empty or if it overflows T.
508 /// The portion of the string representing the discovered numeric value
509 /// is removed from the beginning of the string.
510 template <typename T>
511 typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type
512 consumeInteger(unsigned Radix, T &Result) {
513 long long LLVal;
514 if (consumeSignedInteger(*this, Radix, LLVal) ||
515 static_cast<long long>(static_cast<T>(LLVal)) != LLVal)
516 return true;
517 Result = LLVal;
518 return false;
519 }
520
521 template <typename T>
522 typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type
523 consumeInteger(unsigned Radix, T &Result) {
524 unsigned long long ULLVal;
525 if (consumeUnsignedInteger(*this, Radix, ULLVal) ||
526 static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)
527 return true;
528 Result = ULLVal;
529 return false;
530 }
531
532 /// Parse the current string as an integer of the specified \p Radix, or of
533 /// an autosensed radix if the \p Radix given is 0. The current value in
534 /// \p Result is discarded, and the storage is changed to be wide enough to
535 /// store the parsed integer.
536 ///
537 /// \returns true if the string does not solely consist of a valid
538 /// non-empty number in the appropriate base.
539 ///
540 /// APInt::fromString is superficially similar but assumes the
541 /// string is well-formed in the given radix.
542 bool getAsInteger(unsigned Radix, APInt &Result) const;
543
544 /// Parse the current string as an IEEE double-precision floating
545 /// point value. The string must be a well-formed double.
546 ///
547 /// If \p AllowInexact is false, the function will fail if the string
548 /// cannot be represented exactly. Otherwise, the function only fails
549 /// in case of an overflow or underflow.
550 bool getAsDouble(double &Result, bool AllowInexact = true) const;
551
552 /// @}
553 /// @name String Operations
554 /// @{
555
556 // Convert the given ASCII string to lowercase.
557 LLVM_NODISCARD
558 std::string lower() const;
559
560 /// Convert the given ASCII string to uppercase.
561 LLVM_NODISCARD
562 std::string upper() const;
563
564 /// @}
565 /// @name Substring Operations
566 /// @{
567
568 /// Return a reference to the substring from [Start, Start + N).
569 ///
570 /// \param Start The index of the starting character in the substring; if
571 /// the index is npos or greater than the length of the string then the
572 /// empty substring will be returned.
573 ///
574 /// \param N The number of characters to included in the substring. If N
575 /// exceeds the number of characters remaining in the string, the string
576 /// suffix (starting with \p Start) will be returned.
577 LLVM_NODISCARD
578 StringRef substr(size_t Start, size_t N = npos) const {
579 Start = std::min(Start, Length);
580 return StringRef(Data + Start, std::min(N, Length - Start));
581 }
582
583 /// Return a StringRef equal to 'this' but with only the first \p N
584 /// elements remaining. If \p N is greater than the length of the
585 /// string, the entire string is returned.
586 LLVM_NODISCARD
587 StringRef take_front(size_t N = 1) const {
588 if (N >= size())
589 return *this;
590 return drop_back(size() - N);
591 }
592
593 /// Return a StringRef equal to 'this' but with only the last \p N
594 /// elements remaining. If \p N is greater than the length of the
595 /// string, the entire string is returned.
596 LLVM_NODISCARD
597 StringRef take_back(size_t N = 1) const {
598 if (N >= size())
599 return *this;
600 return drop_front(size() - N);
601 }
602
603 /// Return the longest prefix of 'this' such that every character
604 /// in the prefix satisfies the given predicate.
605 LLVM_NODISCARD
606 StringRef take_while(function_ref<bool(char)> F) const {
607 return substr(0, find_if_not(F));
608 }
609
610 /// Return the longest prefix of 'this' such that no character in
611 /// the prefix satisfies the given predicate.
612 LLVM_NODISCARD
613 StringRef take_until(function_ref<bool(char)> F) const {
614 return substr(0, find_if(F));
615 }
616
617 /// Return a StringRef equal to 'this' but with the first \p N elements
618 /// dropped.
619 LLVM_NODISCARD
620 StringRef drop_front(size_t N = 1) const {
621 assert(size() >= N && "Dropping more elements than exist");
622 return substr(N);
623 }
624
625 /// Return a StringRef equal to 'this' but with the last \p N elements
626 /// dropped.
627 LLVM_NODISCARD
628 StringRef drop_back(size_t N = 1) const {
629 assert(size() >= N && "Dropping more elements than exist");
630 return substr(0, size()-N);
631 }
632
633 /// Return a StringRef equal to 'this', but with all characters satisfying
634 /// the given predicate dropped from the beginning of the string.
635 LLVM_NODISCARD
636 StringRef drop_while(function_ref<bool(char)> F) const {
637 return substr(find_if_not(F));
638 }
639
640 /// Return a StringRef equal to 'this', but with all characters not
641 /// satisfying the given predicate dropped from the beginning of the string.
642 LLVM_NODISCARD
643 StringRef drop_until(function_ref<bool(char)> F) const {
644 return substr(find_if(F));
645 }
646
647 /// Returns true if this StringRef has the given prefix and removes that
648 /// prefix.
649 bool consume_front(StringRef Prefix) {
650 if (!startswith(Prefix))
651 return false;
652
653 *this = drop_front(Prefix.size());
654 return true;
655 }
656
657 /// Returns true if this StringRef has the given suffix and removes that
658 /// suffix.
659 bool consume_back(StringRef Suffix) {
660 if (!endswith(Suffix))
661 return false;
662
663 *this = drop_back(Suffix.size());
664 return true;
665 }
666
667 /// Return a reference to the substring from [Start, End).
668 ///
669 /// \param Start The index of the starting character in the substring; if
670 /// the index is npos or greater than the length of the string then the
671 /// empty substring will be returned.
672 ///
673 /// \param End The index following the last character to include in the
674 /// substring. If this is npos or exceeds the number of characters
675 /// remaining in the string, the string suffix (starting with \p Start)
676 /// will be returned. If this is less than \p Start, an empty string will
677 /// be returned.
678 LLVM_NODISCARD
679 StringRef slice(size_t Start, size_t End) const {
680 Start = std::min(Start, Length);
681 End = std::min(std::max(Start, End), Length);
682 return StringRef(Data + Start, End - Start);
683 }
684
685 /// Split into two substrings around the first occurrence of a separator
686 /// character.
687 ///
688 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
689 /// such that (*this == LHS + Separator + RHS) is true and RHS is
690 /// maximal. If \p Separator is not in the string, then the result is a
691 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
692 ///
693 /// \param Separator The character to split on.
694 /// \returns The split substrings.
695 LLVM_NODISCARD
696 std::pair<StringRef, StringRef> split(char Separator) const {
697 return split(StringRef(&Separator, 1));
698 }
699
700 /// Split into two substrings around the first occurrence of a separator
701 /// string.
702 ///
703 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
704 /// such that (*this == LHS + Separator + RHS) is true and RHS is
705 /// maximal. If \p Separator is not in the string, then the result is a
706 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
707 ///
708 /// \param Separator - The string to split on.
709 /// \return - The split substrings.
710 LLVM_NODISCARD
711 std::pair<StringRef, StringRef> split(StringRef Separator) const {
712 size_t Idx = find(Separator);
713 if (Idx == npos)
714 return std::make_pair(*this, StringRef());
715 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
716 }
717
718 /// Split into two substrings around the last occurrence of a separator
719 /// string.
720 ///
721 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
722 /// such that (*this == LHS + Separator + RHS) is true and RHS is
723 /// minimal. If \p Separator is not in the string, then the result is a
724 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
725 ///
726 /// \param Separator - The string to split on.
727 /// \return - The split substrings.
728 LLVM_NODISCARD
729 std::pair<StringRef, StringRef> rsplit(StringRef Separator) const {
730 size_t Idx = rfind(Separator);
731 if (Idx == npos)
732 return std::make_pair(*this, StringRef());
733 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
734 }
735
736 /// Split into substrings around the occurrences of a separator string.
737 ///
738 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
739 /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1
740 /// elements are added to A.
741 /// If \p KeepEmpty is false, empty strings are not added to \p A. They
742 /// still count when considering \p MaxSplit
743 /// An useful invariant is that
744 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
745 ///
746 /// \param A - Where to put the substrings.
747 /// \param Separator - The string to split on.
748 /// \param MaxSplit - The maximum number of times the string is split.
749 /// \param KeepEmpty - True if empty substring should be added.
750 void split(SmallVectorImpl<StringRef> &A,
751 StringRef Separator, int MaxSplit = -1,
752 bool KeepEmpty = true) const;
753
754 /// Split into substrings around the occurrences of a separator character.
755 ///
756 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
757 /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1
758 /// elements are added to A.
759 /// If \p KeepEmpty is false, empty strings are not added to \p A. They
760 /// still count when considering \p MaxSplit
761 /// An useful invariant is that
762 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
763 ///
764 /// \param A - Where to put the substrings.
765 /// \param Separator - The string to split on.
766 /// \param MaxSplit - The maximum number of times the string is split.
767 /// \param KeepEmpty - True if empty substring should be added.
768 void split(SmallVectorImpl<StringRef> &A, char Separator, int MaxSplit = -1,
769 bool KeepEmpty = true) const;
770
771 /// Split into two substrings around the last occurrence of a separator
772 /// character.
773 ///
774 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
775 /// such that (*this == LHS + Separator + RHS) is true and RHS is
776 /// minimal. If \p Separator is not in the string, then the result is a
777 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
778 ///
779 /// \param Separator - The character to split on.
780 /// \return - The split substrings.
781 LLVM_NODISCARD
782 std::pair<StringRef, StringRef> rsplit(char Separator) const {
783 return rsplit(StringRef(&Separator, 1));
784 }
785
786 /// Return string with consecutive \p Char characters starting from the
787 /// the left removed.
788 LLVM_NODISCARD
789 StringRef ltrim(char Char) const {
790 return drop_front(std::min(Length, find_first_not_of(Char)));
791 }
792
793 /// Return string with consecutive characters in \p Chars starting from
794 /// the left removed.
795 LLVM_NODISCARD
796 StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
797 return drop_front(std::min(Length, find_first_not_of(Chars)));
798 }
799
800 /// Return string with consecutive \p Char characters starting from the
801 /// right removed.
802 LLVM_NODISCARD
803 StringRef rtrim(char Char) const {
804 return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));
805 }
806
807 /// Return string with consecutive characters in \p Chars starting from
808 /// the right removed.
809 LLVM_NODISCARD
810 StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
811 return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
812 }
813
814 /// Return string with consecutive \p Char characters starting from the
815 /// left and right removed.
816 LLVM_NODISCARD
817 StringRef trim(char Char) const {
818 return ltrim(Char).rtrim(Char);
819 }
820
821 /// Return string with consecutive characters in \p Chars starting from
822 /// the left and right removed.
823 LLVM_NODISCARD
824 StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
825 return ltrim(Chars).rtrim(Chars);
826 }
827
828 /// @}
829 };
830
831 /// A wrapper around a string literal that serves as a proxy for constructing
832 /// global tables of StringRefs with the length computed at compile time.
833 /// In order to avoid the invocation of a global constructor, StringLiteral
834 /// should *only* be used in a constexpr context, as such:
835 ///
836 /// constexpr StringLiteral S("test");
837 ///
838 class StringLiteral : public StringRef {
839 private:
840 constexpr StringLiteral(const char *Str, size_t N) : StringRef(Str, N) {
841 }
842
843 public:
844 template <size_t N>
845 constexpr StringLiteral(const char (&Str)[N])
846#if defined(__clang__) && __has_attribute(enable_if)
847#pragma clang diagnostic push
848#pragma clang diagnostic ignored "-Wgcc-compat"
849 __attribute((enable_if(__builtin_strlen(Str) == N - 1,
850 "invalid string literal")))
851#pragma clang diagnostic pop
852#endif
853 : StringRef(Str, N - 1) {
854 }
855
856 // Explicit construction for strings like "foo\0bar".
857 template <size_t N>
858 static constexpr StringLiteral withInnerNUL(const char (&Str)[N]) {
859 return StringLiteral(Str, N - 1);
860 }
861 };
862
863 /// @name StringRef Comparison Operators
864 /// @{
865
866 inline bool operator==(StringRef LHS, StringRef RHS) {
867 return LHS.equals(RHS);
868 }
869
870 inline bool operator!=(StringRef LHS, StringRef RHS) { return !(LHS == RHS); }
871
872 inline bool operator<(StringRef LHS, StringRef RHS) {
873 return LHS.compare(RHS) == -1;
874 }
875
876 inline bool operator<=(StringRef LHS, StringRef RHS) {
877 return LHS.compare(RHS) != 1;
878 }
879
880 inline bool operator>(StringRef LHS, StringRef RHS) {
881 return LHS.compare(RHS) == 1;
882 }
883
884 inline bool operator>=(StringRef LHS, StringRef RHS) {
885 return LHS.compare(RHS) != -1;
886 }
887
888 inline std::string &operator+=(std::string &buffer, StringRef string) {
889 return buffer.append(string.data(), string.size());
890 }
891
892 /// @}
893
894 /// Compute a hash_code for a StringRef.
895 LLVM_NODISCARD
896 hash_code hash_value(StringRef S);
897
898} // end namespace llvm
899
900#endif // LLVM_ADT_STRINGREF_H
901