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