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#if __cplusplus > 201402L
22#include <string_view>
23#endif
24#include <type_traits>
25#include <utility>
26
27// Declare the __builtin_strlen intrinsic for MSVC so it can be used in
28// constexpr context.
29#if defined(_MSC_VER)
30extern "C" size_t __builtin_strlen(const char *);
31#endif
32
33namespace llvm {
34
35 class APInt;
36 class hash_code;
37 template <typename T> class SmallVectorImpl;
38 class StringRef;
39
40 /// Helper functions for StringRef::getAsInteger.
41 bool getAsUnsignedInteger(StringRef Str, unsigned Radix,
42 unsigned long long &Result);
43
44 bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result);
45
46 bool consumeUnsignedInteger(StringRef &Str, unsigned Radix,
47 unsigned long long &Result);
48 bool consumeSignedInteger(StringRef &Str, unsigned Radix, long long &Result);
49
50 /// StringRef - Represent a constant reference to a string, i.e. a character
51 /// array and a length, which need not be null terminated.
52 ///
53 /// This class does not own the string data, it is expected to be used in
54 /// situations where the character data resides in some other buffer, whose
55 /// lifetime extends past that of the StringRef. For this reason, it is not in
56 /// general safe to store a StringRef.
57 class LLVM_GSL_POINTER StringRef {
58 public:
59 static constexpr size_t npos = ~size_t(0);
60
61 using iterator = const char *;
62 using const_iterator = const char *;
63 using size_type = size_t;
64
65 private:
66 /// The start of the string, in an external buffer.
67 const char *Data = nullptr;
68
69 /// The length of the string.
70 size_t Length = 0;
71
72 // Workaround memcmp issue with null pointers (undefined behavior)
73 // by providing a specialized version
74 static int compareMemory(const char *Lhs, const char *Rhs, size_t Length) {
75 if (Length == 0) { return 0; }
76 return ::memcmp(Lhs,Rhs,Length);
77 }
78
79 // Constexpr version of std::strlen.
80 static constexpr size_t strLen(const char *Str) {
81#if __cplusplus > 201402L
82 return std::char_traits<char>::length(Str);
83#elif __has_builtin(__builtin_strlen) || defined(__GNUC__) || \
84 (defined(_MSC_VER) && _MSC_VER >= 1916)
85 return __builtin_strlen(Str);
86#else
87 const char *Begin = Str;
88 while (*Str != '\0')
89 ++Str;
90 return Str - Begin;
91#endif
92 }
93
94 public:
95 /// @name Constructors
96 /// @{
97
98 /// Construct an empty string ref.
99 /*implicit*/ StringRef() = default;
100
101 /// Disable conversion from nullptr. This prevents things like
102 /// if (S == nullptr)
103 StringRef(std::nullptr_t) = delete;
104
105 /// Construct a string ref from a cstring.
106 /*implicit*/ constexpr StringRef(const char *Str)
107 : Data(Str), Length(Str ? strLen(Str) : 0) {}
108
109 /// Construct a string ref from a pointer and length.
110 /*implicit*/ constexpr StringRef(const char *data, size_t length)
111 : Data(data), Length(length) {}
112
113 /// Construct a string ref from an std::string.
114 /*implicit*/ StringRef(const std::string &Str)
115 : Data(Str.data()), Length(Str.length()) {}
116
117#if __cplusplus > 201402L
118 /// Construct a string ref from an std::string_view.
119 /*implicit*/ constexpr StringRef(std::string_view Str)
120 : Data(Str.data()), Length(Str.size()) {}
121#endif
122
123 static StringRef withNullAsEmpty(const char *data) {
124 return StringRef(data ? data : "");
125 }
126
127 /// @}
128 /// @name Iterators
129 /// @{
130
131 iterator begin() const { return Data; }
132
133 iterator end() const { return Data + Length; }
134
135 const unsigned char *bytes_begin() const {
136 return reinterpret_cast<const unsigned char *>(begin());
137 }
138 const unsigned char *bytes_end() const {
139 return reinterpret_cast<const unsigned char *>(end());
140 }
141 iterator_range<const unsigned char *> bytes() const {
142 return make_range(bytes_begin(), bytes_end());
143 }
144
145 /// @}
146 /// @name String Operations
147 /// @{
148
149 /// data - Get a pointer to the start of the string (which may not be null
150 /// terminated).
151 LLVM_NODISCARD
152 const char *data() const { return Data; }
153
154 /// empty - Check if the string is empty.
155 LLVM_NODISCARD
156 bool empty() const { return Length == 0; }
157
158 /// size - Get the string size.
159 LLVM_NODISCARD
160 size_t size() const { return Length; }
161
162 /// front - Get the first character in the string.
163 LLVM_NODISCARD
164 char front() const {
165 assert(!empty());
166 return Data[0];
167 }
168
169 /// back - Get the last character in the string.
170 LLVM_NODISCARD
171 char back() const {
172 assert(!empty());
173 return Data[Length-1];
174 }
175
176 // copy - Allocate copy in Allocator and return StringRef to it.
177 template <typename Allocator>
178 LLVM_NODISCARD StringRef copy(Allocator &A) const {
179 // Don't request a length 0 copy from the allocator.
180 if (empty())
181 return StringRef();
182 char *S = A.template Allocate<char>(Length);
183 std::copy(begin(), end(), S);
184 return StringRef(S, Length);
185 }
186
187 /// equals - Check for string equality, this is more efficient than
188 /// compare() when the relative ordering of inequal strings isn't needed.
189 LLVM_NODISCARD
190 bool equals(StringRef RHS) const {
191 return (Length == RHS.Length &&
192 compareMemory(Data, RHS.Data, RHS.Length) == 0);
193 }
194
195 /// equals_lower - Check for string equality, ignoring case.
196 LLVM_NODISCARD
197 bool equals_lower(StringRef RHS) const {
198 return Length == RHS.Length && compare_lower(RHS) == 0;
199 }
200
201 /// compare - Compare two strings; the result is -1, 0, or 1 if this string
202 /// is lexicographically less than, equal to, or greater than the \p RHS.
203 LLVM_NODISCARD
204 int compare(StringRef RHS) const {
205 // Check the prefix for a mismatch.
206 if (int Res = compareMemory(Data, RHS.Data, std::min(Length, RHS.Length)))
207 return Res < 0 ? -1 : 1;
208
209 // Otherwise the prefixes match, so we only need to check the lengths.
210 if (Length == RHS.Length)
211 return 0;
212 return Length < RHS.Length ? -1 : 1;
213 }
214
215 /// compare_lower - Compare two strings, ignoring case.
216 LLVM_NODISCARD
217 int compare_lower(StringRef RHS) const;
218
219 /// compare_numeric - Compare two strings, treating sequences of digits as
220 /// numbers.
221 LLVM_NODISCARD
222 int compare_numeric(StringRef RHS) const;
223
224 /// Determine the edit distance between this string and another
225 /// string.
226 ///
227 /// \param Other the string to compare this string against.
228 ///
229 /// \param AllowReplacements whether to allow character
230 /// replacements (change one character into another) as a single
231 /// operation, rather than as two operations (an insertion and a
232 /// removal).
233 ///
234 /// \param MaxEditDistance If non-zero, the maximum edit distance that
235 /// this routine is allowed to compute. If the edit distance will exceed
236 /// that maximum, returns \c MaxEditDistance+1.
237 ///
238 /// \returns the minimum number of character insertions, removals,
239 /// or (if \p AllowReplacements is \c true) replacements needed to
240 /// transform one of the given strings into the other. If zero,
241 /// the strings are identical.
242 LLVM_NODISCARD
243 unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
244 unsigned MaxEditDistance = 0) const;
245
246 /// str - Get the contents as an std::string.
247 LLVM_NODISCARD
248 std::string str() const {
249 if (!Data) return std::string();
250 return std::string(Data, Length);
251 }
252
253 /// @}
254 /// @name Operator Overloads
255 /// @{
256
257 LLVM_NODISCARD
258 char operator[](size_t Index) const {
259 assert(Index < Length && "Invalid index!");
260 return Data[Index];
261 }
262
263 /// Disallow accidental assignment from a temporary std::string.
264 ///
265 /// The declaration here is extra complicated so that `stringRef = {}`
266 /// and `stringRef = "abc"` continue to select the move assignment operator.
267 template <typename T>
268 std::enable_if_t<std::is_same<T, std::string>::value, StringRef> &
269 operator=(T &&Str) = delete;
270
271 /// @}
272 /// @name Type Conversions
273 /// @{
274
275 explicit operator std::string() const { return str(); }
276
277#if __cplusplus > 201402L
278 operator std::string_view() const {
279 return std::string_view(data(), size());
280 }
281#endif
282
283 /// @}
284 /// @name String Predicates
285 /// @{
286
287 /// Check if this string starts with the given \p Prefix.
288 LLVM_NODISCARD
289 bool startswith(StringRef Prefix) const {
290 return Length >= Prefix.Length &&
291 compareMemory(Data, Prefix.Data, Prefix.Length) == 0;
292 }
293
294 /// Check if this string starts with the given \p Prefix, ignoring case.
295 LLVM_NODISCARD
296 bool startswith_lower(StringRef Prefix) const;
297
298 /// Check if this string ends with the given \p Suffix.
299 LLVM_NODISCARD
300 bool endswith(StringRef Suffix) const {
301 return Length >= Suffix.Length &&
302 compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
303 }
304
305 /// Check if this string ends with the given \p Suffix, ignoring case.
306 LLVM_NODISCARD
307 bool endswith_lower(StringRef Suffix) const;
308
309 /// @}
310 /// @name String Searching
311 /// @{
312
313 /// Search for the first character \p C in the string.
314 ///
315 /// \returns The index of the first occurrence of \p C, or npos if not
316 /// found.
317 LLVM_NODISCARD
318 size_t find(char C, size_t From = 0) const {
319 size_t FindBegin = std::min(From, Length);
320 if (FindBegin < Length) { // Avoid calling memchr with nullptr.
321 // Just forward to memchr, which is faster than a hand-rolled loop.
322 if (const void *P = ::memchr(Data + FindBegin, C, Length - FindBegin))
323 return static_cast<const char *>(P) - Data;
324 }
325 return npos;
326 }
327
328 /// Search for the first character \p C in the string, ignoring case.
329 ///
330 /// \returns The index of the first occurrence of \p C, or npos if not
331 /// found.
332 LLVM_NODISCARD
333 size_t find_lower(char C, size_t From = 0) const;
334
335 /// Search for the first character satisfying the predicate \p F
336 ///
337 /// \returns The index of the first character satisfying \p F starting from
338 /// \p From, or npos if not found.
339 LLVM_NODISCARD
340 size_t find_if(function_ref<bool(char)> F, size_t From = 0) const {
341 StringRef S = drop_front(From);
342 while (!S.empty()) {
343 if (F(S.front()))
344 return size() - S.size();
345 S = S.drop_front();
346 }
347 return npos;
348 }
349
350 /// Search for the first character not satisfying the predicate \p F
351 ///
352 /// \returns The index of the first character not satisfying \p F starting
353 /// from \p From, or npos if not found.
354 LLVM_NODISCARD
355 size_t find_if_not(function_ref<bool(char)> F, size_t From = 0) const {
356 return find_if([F](char c) { return !F(c); }, From);
357 }
358
359 /// Search for the first string \p Str in the string.
360 ///
361 /// \returns The index of the first occurrence of \p Str, or npos if not
362 /// found.
363 LLVM_NODISCARD
364 size_t find(StringRef Str, size_t From = 0) const;
365
366 /// Search for the first string \p Str in the string, ignoring case.
367 ///
368 /// \returns The index of the first occurrence of \p Str, or npos if not
369 /// found.
370 LLVM_NODISCARD
371 size_t find_lower(StringRef Str, size_t From = 0) const;
372
373 /// Search for the last character \p C in the string.
374 ///
375 /// \returns The index of the last occurrence of \p C, or npos if not
376 /// found.
377 LLVM_NODISCARD
378 size_t rfind(char C, size_t From = npos) const {
379 From = std::min(From, Length);
380 size_t i = From;
381 while (i != 0) {
382 --i;
383 if (Data[i] == C)
384 return i;
385 }
386 return npos;
387 }
388
389 /// Search for the last character \p C in the string, ignoring case.
390 ///
391 /// \returns The index of the last occurrence of \p C, or npos if not
392 /// found.
393 LLVM_NODISCARD
394 size_t rfind_lower(char C, size_t From = npos) const;
395
396 /// Search for the last string \p Str in the string.
397 ///
398 /// \returns The index of the last occurrence of \p Str, or npos if not
399 /// found.
400 LLVM_NODISCARD
401 size_t rfind(StringRef Str) const;
402
403 /// Search for the last string \p Str in the string, ignoring case.
404 ///
405 /// \returns The index of the last occurrence of \p Str, or npos if not
406 /// found.
407 LLVM_NODISCARD
408 size_t rfind_lower(StringRef Str) const;
409
410 /// Find the first character in the string that is \p C, or npos if not
411 /// found. Same as find.
412 LLVM_NODISCARD
413 size_t find_first_of(char C, size_t From = 0) const {
414 return find(C, From);
415 }
416
417 /// Find the first character in the string that is in \p Chars, or npos if
418 /// not found.
419 ///
420 /// Complexity: O(size() + Chars.size())
421 LLVM_NODISCARD
422 size_t find_first_of(StringRef Chars, size_t From = 0) const;
423
424 /// Find the first character in the string that is not \p C or npos if not
425 /// found.
426 LLVM_NODISCARD
427 size_t find_first_not_of(char C, size_t From = 0) const;
428
429 /// Find the first character in the string that is not in the string
430 /// \p Chars, or npos if not found.
431 ///
432 /// Complexity: O(size() + Chars.size())
433 LLVM_NODISCARD
434 size_t find_first_not_of(StringRef Chars, size_t From = 0) const;
435
436 /// Find the last character in the string that is \p C, or npos if not
437 /// found.
438 LLVM_NODISCARD
439 size_t find_last_of(char C, size_t From = npos) const {
440 return rfind(C, From);
441 }
442
443 /// Find the last character in the string that is in \p C, or npos if not
444 /// found.
445 ///
446 /// Complexity: O(size() + Chars.size())
447 LLVM_NODISCARD
448 size_t find_last_of(StringRef Chars, size_t From = npos) const;
449
450 /// Find the last character in the string that is not \p C, or npos if not
451 /// found.
452 LLVM_NODISCARD
453 size_t find_last_not_of(char C, size_t From = npos) const;
454
455 /// Find the last character in the string that is not in \p Chars, or
456 /// npos if not found.
457 ///
458 /// Complexity: O(size() + Chars.size())
459 LLVM_NODISCARD
460 size_t find_last_not_of(StringRef Chars, size_t From = npos) const;
461
462 /// Return true if the given string is a substring of *this, and false
463 /// otherwise.
464 LLVM_NODISCARD
465 bool contains(StringRef Other) const { return find(Other) != npos; }
466
467 /// Return true if the given character is contained in *this, and false
468 /// otherwise.
469 LLVM_NODISCARD
470 bool contains(char C) const { return find_first_of(C) != npos; }
471
472 /// Return true if the given string is a substring of *this, and false
473 /// otherwise.
474 LLVM_NODISCARD
475 bool contains_lower(StringRef Other) const {
476 return find_lower(Other) != npos;
477 }
478
479 /// Return true if the given character is contained in *this, and false
480 /// otherwise.
481 LLVM_NODISCARD
482 bool contains_lower(char C) const { return find_lower(C) != npos; }
483
484 /// @}
485 /// @name Helpful Algorithms
486 /// @{
487
488 /// Return the number of occurrences of \p C in the string.
489 LLVM_NODISCARD
490 size_t count(char C) const {
491 size_t Count = 0;
492 for (size_t i = 0, e = Length; i != e; ++i)
493 if (Data[i] == C)
494 ++Count;
495 return Count;
496 }
497
498 /// Return the number of non-overlapped occurrences of \p Str in
499 /// the string.
500 size_t count(StringRef Str) const;
501
502 /// Parse the current string as an integer of the specified radix. If
503 /// \p Radix is specified as zero, this does radix autosensing using
504 /// extended C rules: 0 is octal, 0x is hex, 0b is binary.
505 ///
506 /// If the string is invalid or if only a subset of the string is valid,
507 /// this returns true to signify the error. The string is considered
508 /// erroneous if empty or if it overflows T.
509 template <typename T>
510 std::enable_if_t<std::numeric_limits<T>::is_signed, bool>
511 getAsInteger(unsigned Radix, T &Result) const {
512 long long LLVal;
513 if (getAsSignedInteger(*this, Radix, LLVal) ||
514 static_cast<T>(LLVal) != LLVal)
515 return true;
516 Result = LLVal;
517 return false;
518 }
519
520 template <typename T>
521 std::enable_if_t<!std::numeric_limits<T>::is_signed, bool>
522 getAsInteger(unsigned Radix, T &Result) const {
523 unsigned long long ULLVal;
524 // The additional cast to unsigned long long is required to avoid the
525 // Visual C++ warning C4805: '!=' : unsafe mix of type 'bool' and type
526 // 'unsigned __int64' when instantiating getAsInteger with T = bool.
527 if (getAsUnsignedInteger(*this, Radix, ULLVal) ||
528 static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)
529 return true;
530 Result = ULLVal;
531 return false;
532 }
533
534 /// Parse the current string as an integer of the specified radix. If
535 /// \p Radix is specified as zero, this does radix autosensing using
536 /// extended C rules: 0 is octal, 0x is hex, 0b is binary.
537 ///
538 /// If the string does not begin with a number of the specified radix,
539 /// this returns true to signify the error. The string is considered
540 /// erroneous if empty or if it overflows T.
541 /// The portion of the string representing the discovered numeric value
542 /// is removed from the beginning of the string.
543 template <typename T>
544 std::enable_if_t<std::numeric_limits<T>::is_signed, bool>
545 consumeInteger(unsigned Radix, T &Result) {
546 long long LLVal;
547 if (consumeSignedInteger(*this, Radix, LLVal) ||
548 static_cast<long long>(static_cast<T>(LLVal)) != LLVal)
549 return true;
550 Result = LLVal;
551 return false;
552 }
553
554 template <typename T>
555 std::enable_if_t<!std::numeric_limits<T>::is_signed, bool>
556 consumeInteger(unsigned Radix, T &Result) {
557 unsigned long long ULLVal;
558 if (consumeUnsignedInteger(*this, Radix, ULLVal) ||
559 static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)
560 return true;
561 Result = ULLVal;
562 return false;
563 }
564
565 /// Parse the current string as an integer of the specified \p Radix, or of
566 /// an autosensed radix if the \p Radix given is 0. The current value in
567 /// \p Result is discarded, and the storage is changed to be wide enough to
568 /// store the parsed integer.
569 ///
570 /// \returns true if the string does not solely consist of a valid
571 /// non-empty number in the appropriate base.
572 ///
573 /// APInt::fromString is superficially similar but assumes the
574 /// string is well-formed in the given radix.
575 bool getAsInteger(unsigned Radix, APInt &Result) const;
576
577 /// Parse the current string as an IEEE double-precision floating
578 /// point value. The string must be a well-formed double.
579 ///
580 /// If \p AllowInexact is false, the function will fail if the string
581 /// cannot be represented exactly. Otherwise, the function only fails
582 /// in case of an overflow or underflow, or an invalid floating point
583 /// representation.
584 bool getAsDouble(double &Result, bool AllowInexact = true) const;
585
586 /// @}
587 /// @name String Operations
588 /// @{
589
590 // Convert the given ASCII string to lowercase.
591 LLVM_NODISCARD
592 std::string lower() const;
593
594 /// Convert the given ASCII string to uppercase.
595 LLVM_NODISCARD
596 std::string upper() const;
597
598 /// @}
599 /// @name Substring Operations
600 /// @{
601
602 /// Return a reference to the substring from [Start, Start + N).
603 ///
604 /// \param Start The index of the starting character in the substring; if
605 /// the index is npos or greater than the length of the string then the
606 /// empty substring will be returned.
607 ///
608 /// \param N The number of characters to included in the substring. If N
609 /// exceeds the number of characters remaining in the string, the string
610 /// suffix (starting with \p Start) will be returned.
611 LLVM_NODISCARD
612 StringRef substr(size_t Start, size_t N = npos) const {
613 Start = std::min(Start, Length);
614 return StringRef(Data + Start, std::min(N, Length - Start));
615 }
616
617 /// Return a StringRef equal to 'this' but with only the first \p N
618 /// elements remaining. If \p N is greater than the length of the
619 /// string, the entire string is returned.
620 LLVM_NODISCARD
621 StringRef take_front(size_t N = 1) const {
622 if (N >= size())
623 return *this;
624 return drop_back(size() - N);
625 }
626
627 /// Return a StringRef equal to 'this' but with only the last \p N
628 /// elements remaining. If \p N is greater than the length of the
629 /// string, the entire string is returned.
630 LLVM_NODISCARD
631 StringRef take_back(size_t N = 1) const {
632 if (N >= size())
633 return *this;
634 return drop_front(size() - N);
635 }
636
637 /// Return the longest prefix of 'this' such that every character
638 /// in the prefix satisfies the given predicate.
639 LLVM_NODISCARD
640 StringRef take_while(function_ref<bool(char)> F) const {
641 return substr(0, find_if_not(F));
642 }
643
644 /// Return the longest prefix of 'this' such that no character in
645 /// the prefix satisfies the given predicate.
646 LLVM_NODISCARD
647 StringRef take_until(function_ref<bool(char)> F) const {
648 return substr(0, find_if(F));
649 }
650
651 /// Return a StringRef equal to 'this' but with the first \p N elements
652 /// dropped.
653 LLVM_NODISCARD
654 StringRef drop_front(size_t N = 1) const {
655 assert(size() >= N && "Dropping more elements than exist");
656 return substr(N);
657 }
658
659 /// Return a StringRef equal to 'this' but with the last \p N elements
660 /// dropped.
661 LLVM_NODISCARD
662 StringRef drop_back(size_t N = 1) const {
663 assert(size() >= N && "Dropping more elements than exist");
664 return substr(0, size()-N);
665 }
666
667 /// Return a StringRef equal to 'this', but with all characters satisfying
668 /// the given predicate dropped from the beginning of the string.
669 LLVM_NODISCARD
670 StringRef drop_while(function_ref<bool(char)> F) const {
671 return substr(find_if_not(F));
672 }
673
674 /// Return a StringRef equal to 'this', but with all characters not
675 /// satisfying the given predicate dropped from the beginning of the string.
676 LLVM_NODISCARD
677 StringRef drop_until(function_ref<bool(char)> F) const {
678 return substr(find_if(F));
679 }
680
681 /// Returns true if this StringRef has the given prefix and removes that
682 /// prefix.
683 bool consume_front(StringRef Prefix) {
684 if (!startswith(Prefix))
685 return false;
686
687 *this = drop_front(Prefix.size());
688 return true;
689 }
690
691 /// Returns true if this StringRef has the given suffix and removes that
692 /// suffix.
693 bool consume_back(StringRef Suffix) {
694 if (!endswith(Suffix))
695 return false;
696
697 *this = drop_back(Suffix.size());
698 return true;
699 }
700
701 /// Return a reference to the substring from [Start, End).
702 ///
703 /// \param Start The index of the starting character in the substring; if
704 /// the index is npos or greater than the length of the string then the
705 /// empty substring will be returned.
706 ///
707 /// \param End The index following the last character to include in the
708 /// substring. If this is npos or exceeds the number of characters
709 /// remaining in the string, the string suffix (starting with \p Start)
710 /// will be returned. If this is less than \p Start, an empty string will
711 /// be returned.
712 LLVM_NODISCARD
713 StringRef slice(size_t Start, size_t End) const {
714 Start = std::min(Start, Length);
715 End = std::min(std::max(Start, End), Length);
716 return StringRef(Data + Start, End - Start);
717 }
718
719 /// Split into two substrings around the first occurrence of a separator
720 /// character.
721 ///
722 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
723 /// such that (*this == LHS + Separator + RHS) is true and RHS is
724 /// maximal. If \p Separator is not in the string, then the result is a
725 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
726 ///
727 /// \param Separator The character to split on.
728 /// \returns The split substrings.
729 LLVM_NODISCARD
730 std::pair<StringRef, StringRef> split(char Separator) const {
731 return split(StringRef(&Separator, 1));
732 }
733
734 /// Split into two substrings around the first occurrence of a separator
735 /// string.
736 ///
737 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
738 /// such that (*this == LHS + Separator + RHS) is true and RHS is
739 /// maximal. If \p Separator is not in the string, then the result is a
740 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
741 ///
742 /// \param Separator - The string to split on.
743 /// \return - The split substrings.
744 LLVM_NODISCARD
745 std::pair<StringRef, StringRef> split(StringRef Separator) const {
746 size_t Idx = find(Separator);
747 if (Idx == npos)
748 return std::make_pair(*this, StringRef());
749 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
750 }
751
752 /// Split into two substrings around the last occurrence of a separator
753 /// string.
754 ///
755 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
756 /// such that (*this == LHS + Separator + RHS) is true and RHS is
757 /// minimal. If \p Separator is not in the string, then the result is a
758 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
759 ///
760 /// \param Separator - The string to split on.
761 /// \return - The split substrings.
762 LLVM_NODISCARD
763 std::pair<StringRef, StringRef> rsplit(StringRef Separator) const {
764 size_t Idx = rfind(Separator);
765 if (Idx == npos)
766 return std::make_pair(*this, StringRef());
767 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
768 }
769
770 /// Split into substrings around the occurrences of a separator string.
771 ///
772 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
773 /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1
774 /// elements are added to A.
775 /// If \p KeepEmpty is false, empty strings are not added to \p A. They
776 /// still count when considering \p MaxSplit
777 /// An useful invariant is that
778 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
779 ///
780 /// \param A - Where to put the substrings.
781 /// \param Separator - The string to split on.
782 /// \param MaxSplit - The maximum number of times the string is split.
783 /// \param KeepEmpty - True if empty substring should be added.
784 void split(SmallVectorImpl<StringRef> &A,
785 StringRef Separator, int MaxSplit = -1,
786 bool KeepEmpty = true) const;
787
788 /// Split into substrings around the occurrences of a separator character.
789 ///
790 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
791 /// \p MaxSplit splits are done and consequently <= \p MaxSplit + 1
792 /// elements are added to A.
793 /// If \p KeepEmpty is false, empty strings are not added to \p A. They
794 /// still count when considering \p MaxSplit
795 /// An useful invariant is that
796 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
797 ///
798 /// \param A - Where to put the substrings.
799 /// \param Separator - The string to split on.
800 /// \param MaxSplit - The maximum number of times the string is split.
801 /// \param KeepEmpty - True if empty substring should be added.
802 void split(SmallVectorImpl<StringRef> &A, char Separator, int MaxSplit = -1,
803 bool KeepEmpty = true) const;
804
805 /// Split into two substrings around the last occurrence of a separator
806 /// character.
807 ///
808 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
809 /// such that (*this == LHS + Separator + RHS) is true and RHS is
810 /// minimal. If \p Separator is not in the string, then the result is a
811 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
812 ///
813 /// \param Separator - The character to split on.
814 /// \return - The split substrings.
815 LLVM_NODISCARD
816 std::pair<StringRef, StringRef> rsplit(char Separator) const {
817 return rsplit(StringRef(&Separator, 1));
818 }
819
820 /// Return string with consecutive \p Char characters starting from the
821 /// the left removed.
822 LLVM_NODISCARD
823 StringRef ltrim(char Char) const {
824 return drop_front(std::min(Length, find_first_not_of(Char)));
825 }
826
827 /// Return string with consecutive characters in \p Chars starting from
828 /// the left removed.
829 LLVM_NODISCARD
830 StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
831 return drop_front(std::min(Length, find_first_not_of(Chars)));
832 }
833
834 /// Return string with consecutive \p Char characters starting from the
835 /// right removed.
836 LLVM_NODISCARD
837 StringRef rtrim(char Char) const {
838 return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));
839 }
840
841 /// Return string with consecutive characters in \p Chars starting from
842 /// the right removed.
843 LLVM_NODISCARD
844 StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
845 return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
846 }
847
848 /// Return string with consecutive \p Char characters starting from the
849 /// left and right removed.
850 LLVM_NODISCARD
851 StringRef trim(char Char) const {
852 return ltrim(Char).rtrim(Char);
853 }
854
855 /// Return string with consecutive characters in \p Chars starting from
856 /// the left and right removed.
857 LLVM_NODISCARD
858 StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
859 return ltrim(Chars).rtrim(Chars);
860 }
861
862 /// @}
863 };
864
865 /// A wrapper around a string literal that serves as a proxy for constructing
866 /// global tables of StringRefs with the length computed at compile time.
867 /// In order to avoid the invocation of a global constructor, StringLiteral
868 /// should *only* be used in a constexpr context, as such:
869 ///
870 /// constexpr StringLiteral S("test");
871 ///
872 class StringLiteral : public StringRef {
873 private:
874 constexpr StringLiteral(const char *Str, size_t N) : StringRef(Str, N) {
875 }
876
877 public:
878 template <size_t N>
879 constexpr StringLiteral(const char (&Str)[N])
880#if defined(__clang__) && __has_attribute(enable_if)
881#pragma clang diagnostic push
882#pragma clang diagnostic ignored "-Wgcc-compat"
883 __attribute((enable_if(__builtin_strlen(Str) == N - 1,
884 "invalid string literal")))
885#pragma clang diagnostic pop
886#endif
887 : StringRef(Str, N - 1) {
888 }
889
890 // Explicit construction for strings like "foo\0bar".
891 template <size_t N>
892 static constexpr StringLiteral withInnerNUL(const char (&Str)[N]) {
893 return StringLiteral(Str, N - 1);
894 }
895 };
896
897 /// @name StringRef Comparison Operators
898 /// @{
899
900 inline bool operator==(StringRef LHS, StringRef RHS) {
901 return LHS.equals(RHS);
902 }
903
904 inline bool operator!=(StringRef LHS, StringRef RHS) { return !(LHS == RHS); }
905
906 inline bool operator<(StringRef LHS, StringRef RHS) {
907 return LHS.compare(RHS) == -1;
908 }
909
910 inline bool operator<=(StringRef LHS, StringRef RHS) {
911 return LHS.compare(RHS) != 1;
912 }
913
914 inline bool operator>(StringRef LHS, StringRef RHS) {
915 return LHS.compare(RHS) == 1;
916 }
917
918 inline bool operator>=(StringRef LHS, StringRef RHS) {
919 return LHS.compare(RHS) != -1;
920 }
921
922 inline std::string &operator+=(std::string &buffer, StringRef string) {
923 return buffer.append(string.data(), string.size());
924 }
925
926 /// @}
927
928 /// Compute a hash_code for a StringRef.
929 LLVM_NODISCARD
930 hash_code hash_value(StringRef S);
931
932} // end namespace llvm
933
934#endif // LLVM_ADT_STRINGREF_H
935