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