1 //===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef LLVM_ADT_STRINGREF_H 11 #define LLVM_ADT_STRINGREF_H 12 13 #include <algorithm> 14 #include <cassert> 15 #include <cstring> 16 #include <limits> 17 #include <string> 18 #include <utility> 19 20 namespace llvm { 21 template <typename T> 22 class SmallVectorImpl; 23 class APInt; 24 class hash_code; 25 class StringRef; 26 27 /// Helper functions for StringRef::getAsInteger. 28 bool getAsUnsignedInteger(StringRef Str, unsigned Radix, 29 unsigned long long &Result); 30 31 bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result); 32 33 /// StringRef - Represent a constant reference to a string, i.e. a character 34 /// array and a length, which need not be null terminated. 35 /// 36 /// This class does not own the string data, it is expected to be used in 37 /// situations where the character data resides in some other buffer, whose 38 /// lifetime extends past that of the StringRef. For this reason, it is not in 39 /// general safe to store a StringRef. 40 class StringRef { 41 public: 42 typedef const char *iterator; 43 typedef const char *const_iterator; 44 static const size_t npos = ~size_t(0); 45 typedef size_t size_type; 46 47 private: 48 /// The start of the string, in an external buffer. 49 const char *Data; 50 51 /// The length of the string. 52 size_t Length; 53 54 // Workaround PR5482: nearly all gcc 4.x miscompile StringRef and std::min() 55 // Changing the arg of min to be an integer, instead of a reference to an 56 // integer works around this bug. 57 static size_t min(size_t a, size_t b) { return a < b ? a : b; } 58 static size_t max(size_t a, size_t b) { return a > b ? a : b; } 59 60 // Workaround memcmp issue with null pointers (undefined behavior) 61 // by providing a specialized version 62 static int compareMemory(const char *Lhs, const char *Rhs, size_t Length) { 63 if (Length == 0) { return 0; } 64 return ::memcmp(Lhs,Rhs,Length); 65 } 66 67 public: 68 /// @name Constructors 69 /// @{ 70 71 /// Construct an empty string ref. 72 /*implicit*/ StringRef() : Data(nullptr), Length(0) {} 73 74 /// Construct a string ref from a cstring. 75 /*implicit*/ StringRef(const char *Str) 76 : Data(Str) { 77 assert(Str && "StringRef cannot be built from a NULL argument"); 78 Length = ::strlen(Str); // invoking strlen(NULL) is undefined behavior 79 } 80 81 /// Construct a string ref from a pointer and length. 82 /*implicit*/ StringRef(const char *data, size_t length) 83 : Data(data), Length(length) { 84 assert((data || length == 0) && 85 "StringRef cannot be built from a NULL argument with non-null length"); 86 } 87 88 /// Construct a string ref from an std::string. 89 /*implicit*/ StringRef(const std::string &Str) 90 : Data(Str.data()), Length(Str.length()) {} 91 92 /// @} 93 /// @name Iterators 94 /// @{ 95 96 iterator begin() const { return Data; } 97 98 iterator end() const { return Data + Length; } 99 100 /// @} 101 /// @name String Operations 102 /// @{ 103 104 /// data - Get a pointer to the start of the string (which may not be null 105 /// terminated). 106 const char *data() const { return Data; } 107 108 /// empty - Check if the string is empty. 109 bool empty() const { return Length == 0; } 110 111 /// size - Get the string size. 112 size_t size() const { return Length; } 113 114 /// front - Get the first character in the string. 115 char front() const { 116 assert(!empty()); 117 return Data[0]; 118 } 119 120 /// back - Get the last character in the string. 121 char back() const { 122 assert(!empty()); 123 return Data[Length-1]; 124 } 125 126 // copy - Allocate copy in Allocator and return StringRef to it. 127 template <typename Allocator> StringRef copy(Allocator &A) { 128 char *S = A.template Allocate<char>(Length); 129 std::copy(begin(), end(), S); 130 return StringRef(S, Length); 131 } 132 133 /// equals - Check for string equality, this is more efficient than 134 /// compare() when the relative ordering of inequal strings isn't needed. 135 bool equals(StringRef RHS) const { 136 return (Length == RHS.Length && 137 compareMemory(Data, RHS.Data, RHS.Length) == 0); 138 } 139 140 /// equals_lower - Check for string equality, ignoring case. 141 bool equals_lower(StringRef RHS) const { 142 return Length == RHS.Length && compare_lower(RHS) == 0; 143 } 144 145 /// compare - Compare two strings; the result is -1, 0, or 1 if this string 146 /// is lexicographically less than, equal to, or greater than the \p RHS. 147 int compare(StringRef RHS) const { 148 // Check the prefix for a mismatch. 149 if (int Res = compareMemory(Data, RHS.Data, min(Length, RHS.Length))) 150 return Res < 0 ? -1 : 1; 151 152 // Otherwise the prefixes match, so we only need to check the lengths. 153 if (Length == RHS.Length) 154 return 0; 155 return Length < RHS.Length ? -1 : 1; 156 } 157 158 /// compare_lower - Compare two strings, ignoring case. 159 int compare_lower(StringRef RHS) const; 160 161 /// compare_numeric - Compare two strings, treating sequences of digits as 162 /// numbers. 163 int compare_numeric(StringRef RHS) const; 164 165 /// \brief Determine the edit distance between this string and another 166 /// string. 167 /// 168 /// \param Other the string to compare this string against. 169 /// 170 /// \param AllowReplacements whether to allow character 171 /// replacements (change one character into another) as a single 172 /// operation, rather than as two operations (an insertion and a 173 /// removal). 174 /// 175 /// \param MaxEditDistance If non-zero, the maximum edit distance that 176 /// this routine is allowed to compute. If the edit distance will exceed 177 /// that maximum, returns \c MaxEditDistance+1. 178 /// 179 /// \returns the minimum number of character insertions, removals, 180 /// or (if \p AllowReplacements is \c true) replacements needed to 181 /// transform one of the given strings into the other. If zero, 182 /// the strings are identical. 183 unsigned edit_distance(StringRef Other, bool AllowReplacements = true, 184 unsigned MaxEditDistance = 0) const; 185 186 /// str - Get the contents as an std::string. 187 std::string str() const { 188 if (!Data) return std::string(); 189 return std::string(Data, Length); 190 } 191 192 /// @} 193 /// @name Operator Overloads 194 /// @{ 195 196 char operator[](size_t Index) const { 197 assert(Index < Length && "Invalid index!"); 198 return Data[Index]; 199 } 200 201 /// @} 202 /// @name Type Conversions 203 /// @{ 204 205 operator std::string() const { 206 return str(); 207 } 208 209 /// @} 210 /// @name String Predicates 211 /// @{ 212 213 /// Check if this string starts with the given \p Prefix. 214 bool startswith(StringRef Prefix) const { 215 return Length >= Prefix.Length && 216 compareMemory(Data, Prefix.Data, Prefix.Length) == 0; 217 } 218 219 /// Check if this string starts with the given \p Prefix, ignoring case. 220 bool startswith_lower(StringRef Prefix) const; 221 222 /// Check if this string ends with the given \p Suffix. 223 bool endswith(StringRef Suffix) const { 224 return Length >= Suffix.Length && 225 compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0; 226 } 227 228 /// Check if this string ends with the given \p Suffix, ignoring case. 229 bool endswith_lower(StringRef Suffix) const; 230 231 /// @} 232 /// @name String Searching 233 /// @{ 234 235 /// Search for the first character \p C in the string. 236 /// 237 /// \returns The index of the first occurrence of \p C, or npos if not 238 /// found. 239 size_t find(char C, size_t From = 0) const { 240 for (size_t i = min(From, Length), e = Length; i != e; ++i) 241 if (Data[i] == C) 242 return i; 243 return npos; 244 } 245 246 /// Search for the first string \p Str in the string. 247 /// 248 /// \returns The index of the first occurrence of \p Str, or npos if not 249 /// found. 250 size_t find(StringRef Str, size_t From = 0) const; 251 252 /// Search for the last character \p C in the string. 253 /// 254 /// \returns The index of the last occurrence of \p C, or npos if not 255 /// found. 256 size_t rfind(char C, size_t From = npos) const { 257 From = min(From, Length); 258 size_t i = From; 259 while (i != 0) { 260 --i; 261 if (Data[i] == C) 262 return i; 263 } 264 return npos; 265 } 266 267 /// Search for the last string \p Str in the string. 268 /// 269 /// \returns The index of the last occurrence of \p Str, or npos if not 270 /// found. 271 size_t rfind(StringRef Str) const; 272 273 /// Find the first character in the string that is \p C, or npos if not 274 /// found. Same as find. 275 size_t find_first_of(char C, size_t From = 0) const { 276 return find(C, From); 277 } 278 279 /// Find the first character in the string that is in \p Chars, or npos if 280 /// not found. 281 /// 282 /// Complexity: O(size() + Chars.size()) 283 size_t find_first_of(StringRef Chars, size_t From = 0) const; 284 285 /// Find the first character in the string that is not \p C or npos if not 286 /// found. 287 size_t find_first_not_of(char C, size_t From = 0) const; 288 289 /// Find the first character in the string that is not in the string 290 /// \p Chars, or npos if not found. 291 /// 292 /// Complexity: O(size() + Chars.size()) 293 size_t find_first_not_of(StringRef Chars, size_t From = 0) const; 294 295 /// Find the last character in the string that is \p C, or npos if not 296 /// found. 297 size_t find_last_of(char C, size_t From = npos) const { 298 return rfind(C, From); 299 } 300 301 /// Find the last character in the string that is in \p C, or npos if not 302 /// found. 303 /// 304 /// Complexity: O(size() + Chars.size()) 305 size_t find_last_of(StringRef Chars, size_t From = npos) const; 306 307 /// Find the last character in the string that is not \p C, or npos if not 308 /// found. 309 size_t find_last_not_of(char C, size_t From = npos) const; 310 311 /// Find the last character in the string that is not in \p Chars, or 312 /// npos if not found. 313 /// 314 /// Complexity: O(size() + Chars.size()) 315 size_t find_last_not_of(StringRef Chars, size_t From = npos) const; 316 317 /// @} 318 /// @name Helpful Algorithms 319 /// @{ 320 321 /// Return the number of occurrences of \p C in the string. 322 size_t count(char C) const { 323 size_t Count = 0; 324 for (size_t i = 0, e = Length; i != e; ++i) 325 if (Data[i] == C) 326 ++Count; 327 return Count; 328 } 329 330 /// Return the number of non-overlapped occurrences of \p Str in 331 /// the string. 332 size_t count(StringRef Str) const; 333 334 /// Parse the current string as an integer of the specified radix. If 335 /// \p Radix is specified as zero, this does radix autosensing using 336 /// extended C rules: 0 is octal, 0x is hex, 0b is binary. 337 /// 338 /// If the string is invalid or if only a subset of the string is valid, 339 /// this returns true to signify the error. The string is considered 340 /// erroneous if empty or if it overflows T. 341 template <typename T> 342 typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type 343 getAsInteger(unsigned Radix, T &Result) const { 344 long long LLVal; 345 if (getAsSignedInteger(*this, Radix, LLVal) || 346 static_cast<T>(LLVal) != LLVal) 347 return true; 348 Result = LLVal; 349 return false; 350 } 351 352 template <typename T> 353 typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type 354 getAsInteger(unsigned Radix, T &Result) const { 355 unsigned long long ULLVal; 356 if (getAsUnsignedInteger(*this, Radix, ULLVal) || 357 static_cast<T>(ULLVal) != ULLVal) 358 return true; 359 Result = ULLVal; 360 return false; 361 } 362 363 /// Parse the current string as an integer of the specified \p Radix, or of 364 /// an autosensed radix if the \p Radix given is 0. The current value in 365 /// \p Result is discarded, and the storage is changed to be wide enough to 366 /// store the parsed integer. 367 /// 368 /// \returns true if the string does not solely consist of a valid 369 /// non-empty number in the appropriate base. 370 /// 371 /// APInt::fromString is superficially similar but assumes the 372 /// string is well-formed in the given radix. 373 bool getAsInteger(unsigned Radix, APInt &Result) const; 374 375 /// @} 376 /// @name String Operations 377 /// @{ 378 379 // Convert the given ASCII string to lowercase. 380 std::string lower() const; 381 382 /// Convert the given ASCII string to uppercase. 383 std::string upper() const; 384 385 /// @} 386 /// @name Substring Operations 387 /// @{ 388 389 /// Return a reference to the substring from [Start, Start + N). 390 /// 391 /// \param Start The index of the starting character in the substring; if 392 /// the index is npos or greater than the length of the string then the 393 /// empty substring will be returned. 394 /// 395 /// \param N The number of characters to included in the substring. If N 396 /// exceeds the number of characters remaining in the string, the string 397 /// suffix (starting with \p Start) will be returned. 398 StringRef substr(size_t Start, size_t N = npos) const { 399 Start = min(Start, Length); 400 return StringRef(Data + Start, min(N, Length - Start)); 401 } 402 403 /// Return a StringRef equal to 'this' but with the first \p N elements 404 /// dropped. 405 StringRef drop_front(size_t N = 1) const { 406 assert(size() >= N && "Dropping more elements than exist"); 407 return substr(N); 408 } 409 410 /// Return a StringRef equal to 'this' but with the last \p N elements 411 /// dropped. 412 StringRef drop_back(size_t N = 1) const { 413 assert(size() >= N && "Dropping more elements than exist"); 414 return substr(0, size()-N); 415 } 416 417 /// Return a reference to the substring from [Start, End). 418 /// 419 /// \param Start The index of the starting character in the substring; if 420 /// the index is npos or greater than the length of the string then the 421 /// empty substring will be returned. 422 /// 423 /// \param End The index following the last character to include in the 424 /// substring. If this is npos, or less than \p Start, or exceeds the 425 /// number of characters remaining in the string, the string suffix 426 /// (starting with \p Start) will be returned. 427 StringRef slice(size_t Start, size_t End) const { 428 Start = min(Start, Length); 429 End = min(max(Start, End), Length); 430 return StringRef(Data + Start, End - Start); 431 } 432 433 /// Split into two substrings around the first occurrence of a separator 434 /// character. 435 /// 436 /// If \p Separator is in the string, then the result is a pair (LHS, RHS) 437 /// such that (*this == LHS + Separator + RHS) is true and RHS is 438 /// maximal. If \p Separator is not in the string, then the result is a 439 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 440 /// 441 /// \param Separator The character to split on. 442 /// \returns The split substrings. 443 std::pair<StringRef, StringRef> split(char Separator) const { 444 size_t Idx = find(Separator); 445 if (Idx == npos) 446 return std::make_pair(*this, StringRef()); 447 return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); 448 } 449 450 /// Split into two substrings around the first occurrence of a separator 451 /// string. 452 /// 453 /// If \p Separator is in the string, then the result is a pair (LHS, RHS) 454 /// such that (*this == LHS + Separator + RHS) is true and RHS is 455 /// maximal. If \p Separator is not in the string, then the result is a 456 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 457 /// 458 /// \param Separator - The string to split on. 459 /// \return - The split substrings. 460 std::pair<StringRef, StringRef> split(StringRef Separator) const { 461 size_t Idx = find(Separator); 462 if (Idx == npos) 463 return std::make_pair(*this, StringRef()); 464 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos)); 465 } 466 467 /// Split into substrings around the occurrences of a separator string. 468 /// 469 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most 470 /// \p MaxSplit splits are done and consequently <= \p MaxSplit 471 /// elements are added to A. 472 /// If \p KeepEmpty is false, empty strings are not added to \p A. They 473 /// still count when considering \p MaxSplit 474 /// An useful invariant is that 475 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true 476 /// 477 /// \param A - Where to put the substrings. 478 /// \param Separator - The string to split on. 479 /// \param MaxSplit - The maximum number of times the string is split. 480 /// \param KeepEmpty - True if empty substring should be added. 481 void split(SmallVectorImpl<StringRef> &A, 482 StringRef Separator, int MaxSplit = -1, 483 bool KeepEmpty = true) const; 484 485 /// Split into two substrings around the last occurrence of a separator 486 /// character. 487 /// 488 /// If \p Separator is in the string, then the result is a pair (LHS, RHS) 489 /// such that (*this == LHS + Separator + RHS) is true and RHS is 490 /// minimal. If \p Separator is not in the string, then the result is a 491 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 492 /// 493 /// \param Separator - The character to split on. 494 /// \return - The split substrings. 495 std::pair<StringRef, StringRef> rsplit(char Separator) const { 496 size_t Idx = rfind(Separator); 497 if (Idx == npos) 498 return std::make_pair(*this, StringRef()); 499 return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); 500 } 501 502 /// Return string with consecutive characters in \p Chars starting from 503 /// the left removed. 504 StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const { 505 return drop_front(std::min(Length, find_first_not_of(Chars))); 506 } 507 508 /// Return string with consecutive characters in \p Chars starting from 509 /// the right removed. 510 StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const { 511 return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1)); 512 } 513 514 /// Return string with consecutive characters in \p Chars starting from 515 /// the left and right removed. 516 StringRef trim(StringRef Chars = " \t\n\v\f\r") const { 517 return ltrim(Chars).rtrim(Chars); 518 } 519 520 /// @} 521 }; 522 523 /// @name StringRef Comparison Operators 524 /// @{ 525 526 inline bool operator==(StringRef LHS, StringRef RHS) { 527 return LHS.equals(RHS); 528 } 529 530 inline bool operator!=(StringRef LHS, StringRef RHS) { 531 return !(LHS == RHS); 532 } 533 534 inline bool operator<(StringRef LHS, StringRef RHS) { 535 return LHS.compare(RHS) == -1; 536 } 537 538 inline bool operator<=(StringRef LHS, StringRef RHS) { 539 return LHS.compare(RHS) != 1; 540 } 541 542 inline bool operator>(StringRef LHS, StringRef RHS) { 543 return LHS.compare(RHS) == 1; 544 } 545 546 inline bool operator>=(StringRef LHS, StringRef RHS) { 547 return LHS.compare(RHS) != -1; 548 } 549 550 inline std::string &operator+=(std::string &buffer, StringRef string) { 551 return buffer.append(string.data(), string.size()); 552 } 553 554 /// @} 555 556 /// \brief Compute a hash_code for a StringRef. 557 hash_code hash_value(StringRef S); 558 559 // StringRefs can be treated like a POD type. 560 template <typename T> struct isPodLike; 561 template <> struct isPodLike<StringRef> { static const bool value = true; }; 562 } 563 564 #endif 565
