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) 30 extern "C" size_t __builtin_strlen(const char *); 31 #endif 32 33 namespace 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 compareMemory(const char * Lhs,const char * Rhs,size_t Length)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. strLen(const char * Str)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. StringRef(const char * Str)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. StringRef(const char * data,size_t 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. StringRef(const std::string & Str)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. StringRef(std::string_view Str)119 /*implicit*/ constexpr StringRef(std::string_view Str) 120 : Data(Str.data()), Length(Str.size()) {} 121 #endif 122 withNullAsEmpty(const char * data)123 static StringRef withNullAsEmpty(const char *data) { 124 return StringRef(data ? data : ""); 125 } 126 127 /// @} 128 /// @name Iterators 129 /// @{ 130 begin()131 iterator begin() const { return Data; } 132 end()133 iterator end() const { return Data + Length; } 134 bytes_begin()135 const unsigned char *bytes_begin() const { 136 return reinterpret_cast<const unsigned char *>(begin()); 137 } bytes_end()138 const unsigned char *bytes_end() const { 139 return reinterpret_cast<const unsigned char *>(end()); 140 } bytes()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 data()152 const char *data() const { return Data; } 153 154 /// empty - Check if the string is empty. 155 LLVM_NODISCARD empty()156 bool empty() const { return Length == 0; } 157 158 /// size - Get the string size. 159 LLVM_NODISCARD size()160 size_t size() const { return Length; } 161 162 /// front - Get the first character in the string. 163 LLVM_NODISCARD front()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 back()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> copy(Allocator & A)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 equals(StringRef RHS)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 equals_lower(StringRef RHS)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 compare(StringRef RHS)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 str()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 string()275 explicit operator std::string() const { return str(); } 276 277 #if __cplusplus > 201402L string_view()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 startswith(StringRef Prefix)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 endswith(StringRef Suffix)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 contains(StringRef Other)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 contains(char C)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 contains_lower(StringRef Other)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 contains_lower(char C)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 count(char C)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> getAsInteger(unsigned Radix,T & Result)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> getAsInteger(unsigned Radix,T & Result)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> consumeInteger(unsigned Radix,T & Result)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> consumeInteger(unsigned Radix,T & Result)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 take_while(function_ref<bool (char)> F)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 take_until(function_ref<bool (char)> F)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 drop_while(function_ref<bool (char)> F)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 drop_until(function_ref<bool (char)> F)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. consume_front(StringRef 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. consume_back(StringRef 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 slice(size_t Start,size_t End)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 split(char Separator)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 split(StringRef Separator)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 rsplit(StringRef Separator)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 rsplit(char Separator)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 ltrim(char Char)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 rtrim(char Char)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 trim(char Char)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: StringLiteral(const char * Str,size_t N)874 constexpr StringLiteral(const char *Str, size_t N) : StringRef(Str, N) { 875 } 876 877 public: 878 template <size_t N> StringLiteral(const char (& Str)[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> withInnerNUL(const char (& Str)[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