StringRef.h revision 218893
10SN/A//===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===// 2157SN/A// 30SN/A// The LLVM Compiler Infrastructure 40SN/A// 50SN/A// This file is distributed under the University of Illinois Open Source 60SN/A// License. See LICENSE.TXT for details. 7157SN/A// 80SN/A//===----------------------------------------------------------------------===// 9157SN/A 100SN/A#ifndef LLVM_ADT_STRINGREF_H 110SN/A#define LLVM_ADT_STRINGREF_H 120SN/A 130SN/A#include <cassert> 140SN/A#include <cstring> 150SN/A#include <utility> 160SN/A#include <string> 170SN/A 180SN/Anamespace llvm { 190SN/A template<typename T> 200SN/A class SmallVectorImpl; 21157SN/A class APInt; 22157SN/A 23157SN/A /// StringRef - Represent a constant reference to a string, i.e. a character 240SN/A /// array and a length, which need not be null terminated. 250SN/A /// 260SN/A /// This class does not own the string data, it is expected to be used in 270SN/A /// situations where the character data resides in some other buffer, whose 280SN/A /// lifetime extends past that of the StringRef. For this reason, it is not in 290SN/A /// general safe to store a StringRef. 300SN/A class StringRef { 310SN/A public: 320SN/A 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 public: 51 /// @name Constructors 52 /// @{ 53 54 /// Construct an empty string ref. 55 /*implicit*/ StringRef() : Data(0), Length(0) {} 56 57 /// Construct a string ref from a cstring. 58 /*implicit*/ StringRef(const char *Str) 59 : Data(Str), Length(::strlen(Str)) {} 60 61 /// Construct a string ref from a pointer and length. 62 /*implicit*/ StringRef(const char *data, size_t length) 63 : Data(data), Length(length) {} 64 65 /// Construct a string ref from an std::string. 66 /*implicit*/ StringRef(const std::string &Str) 67 : Data(Str.data()), Length(Str.length()) {} 68 69 /// @} 70 /// @name Iterators 71 /// @{ 72 73 iterator begin() const { return Data; } 74 75 iterator end() const { return Data + Length; } 76 77 /// @} 78 /// @name String Operations 79 /// @{ 80 81 /// data - Get a pointer to the start of the string (which may not be null 82 /// terminated). 83 const char *data() const { return Data; } 84 85 /// empty - Check if the string is empty. 86 bool empty() const { return Length == 0; } 87 88 /// size - Get the string size. 89 size_t size() const { return Length; } 90 91 /// front - Get the first character in the string. 92 char front() const { 93 assert(!empty()); 94 return Data[0]; 95 } 96 97 /// back - Get the last character in the string. 98 char back() const { 99 assert(!empty()); 100 return Data[Length-1]; 101 } 102 103 /// equals - Check for string equality, this is more efficient than 104 /// compare() when the relative ordering of inequal strings isn't needed. 105 bool equals(StringRef RHS) const { 106 return (Length == RHS.Length && 107 memcmp(Data, RHS.Data, RHS.Length) == 0); 108 } 109 110 /// equals_lower - Check for string equality, ignoring case. 111 bool equals_lower(StringRef RHS) const { 112 return Length == RHS.Length && compare_lower(RHS) == 0; 113 } 114 115 /// compare - Compare two strings; the result is -1, 0, or 1 if this string 116 /// is lexicographically less than, equal to, or greater than the \arg RHS. 117 int compare(StringRef RHS) const { 118 // Check the prefix for a mismatch. 119 if (int Res = memcmp(Data, RHS.Data, min(Length, RHS.Length))) 120 return Res < 0 ? -1 : 1; 121 122 // Otherwise the prefixes match, so we only need to check the lengths. 123 if (Length == RHS.Length) 124 return 0; 125 return Length < RHS.Length ? -1 : 1; 126 } 127 128 /// compare_lower - Compare two strings, ignoring case. 129 int compare_lower(StringRef RHS) const; 130 131 /// compare_numeric - Compare two strings, treating sequences of digits as 132 /// numbers. 133 int compare_numeric(StringRef RHS) const; 134 135 /// \brief Determine the edit distance between this string and another 136 /// string. 137 /// 138 /// \param Other the string to compare this string against. 139 /// 140 /// \param AllowReplacements whether to allow character 141 /// replacements (change one character into another) as a single 142 /// operation, rather than as two operations (an insertion and a 143 /// removal). 144 /// 145 /// \param MaxEditDistance If non-zero, the maximum edit distance that 146 /// this routine is allowed to compute. If the edit distance will exceed 147 /// that maximum, returns \c MaxEditDistance+1. 148 /// 149 /// \returns the minimum number of character insertions, removals, 150 /// or (if \p AllowReplacements is \c true) replacements needed to 151 /// transform one of the given strings into the other. If zero, 152 /// the strings are identical. 153 unsigned edit_distance(StringRef Other, bool AllowReplacements = true, 154 unsigned MaxEditDistance = 0); 155 156 /// str - Get the contents as an std::string. 157 std::string str() const { 158 if (Data == 0) return std::string(); 159 return std::string(Data, Length); 160 } 161 162 /// @} 163 /// @name Operator Overloads 164 /// @{ 165 166 char operator[](size_t Index) const { 167 assert(Index < Length && "Invalid index!"); 168 return Data[Index]; 169 } 170 171 /// @} 172 /// @name Type Conversions 173 /// @{ 174 175 operator std::string() const { 176 return str(); 177 } 178 179 /// @} 180 /// @name String Predicates 181 /// @{ 182 183 /// startswith - Check if this string starts with the given \arg Prefix. 184 bool startswith(StringRef Prefix) const { 185 return Length >= Prefix.Length && 186 memcmp(Data, Prefix.Data, Prefix.Length) == 0; 187 } 188 189 /// endswith - Check if this string ends with the given \arg Suffix. 190 bool endswith(StringRef Suffix) const { 191 return Length >= Suffix.Length && 192 memcmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0; 193 } 194 195 /// @} 196 /// @name String Searching 197 /// @{ 198 199 /// find - Search for the first character \arg C in the string. 200 /// 201 /// \return - The index of the first occurrence of \arg C, or npos if not 202 /// found. 203 size_t find(char C, size_t From = 0) const { 204 for (size_t i = min(From, Length), e = Length; i != e; ++i) 205 if (Data[i] == C) 206 return i; 207 return npos; 208 } 209 210 /// find - Search for the first string \arg Str in the string. 211 /// 212 /// \return - The index of the first occurrence of \arg Str, or npos if not 213 /// found. 214 size_t find(StringRef Str, size_t From = 0) const; 215 216 /// rfind - Search for the last character \arg C in the string. 217 /// 218 /// \return - The index of the last occurrence of \arg C, or npos if not 219 /// found. 220 size_t rfind(char C, size_t From = npos) const { 221 From = min(From, Length); 222 size_t i = From; 223 while (i != 0) { 224 --i; 225 if (Data[i] == C) 226 return i; 227 } 228 return npos; 229 } 230 231 /// rfind - Search for the last string \arg Str in the string. 232 /// 233 /// \return - The index of the last occurrence of \arg Str, or npos if not 234 /// found. 235 size_t rfind(StringRef Str) const; 236 237 /// find_first_of - Find the first character in the string that is \arg C, 238 /// or npos if not found. Same as find. 239 size_type find_first_of(char C, size_t From = 0) const { 240 return find(C, From); 241 } 242 243 /// find_first_of - Find the first character in the string that is in \arg 244 /// Chars, or npos if not found. 245 /// 246 /// Note: O(size() + Chars.size()) 247 size_type find_first_of(StringRef Chars, size_t From = 0) const; 248 249 /// find_first_not_of - Find the first character in the string that is not 250 /// \arg C or npos if not found. 251 size_type find_first_not_of(char C, size_t From = 0) const; 252 253 /// find_first_not_of - Find the first character in the string that is not 254 /// in the string \arg Chars, or npos if not found. 255 /// 256 /// Note: O(size() + Chars.size()) 257 size_type find_first_not_of(StringRef Chars, size_t From = 0) const; 258 259 /// find_last_of - Find the last character in the string that is \arg C, or 260 /// npos if not found. 261 size_type find_last_of(char C, size_t From = npos) const { 262 return rfind(C, From); 263 } 264 265 /// find_last_of - Find the last character in the string that is in \arg C, 266 /// or npos if not found. 267 /// 268 /// Note: O(size() + Chars.size()) 269 size_type find_last_of(StringRef Chars, size_t From = npos) const; 270 271 /// @} 272 /// @name Helpful Algorithms 273 /// @{ 274 275 /// count - Return the number of occurrences of \arg C in the string. 276 size_t count(char C) const { 277 size_t Count = 0; 278 for (size_t i = 0, e = Length; i != e; ++i) 279 if (Data[i] == C) 280 ++Count; 281 return Count; 282 } 283 284 /// count - Return the number of non-overlapped occurrences of \arg Str in 285 /// the string. 286 size_t count(StringRef Str) const; 287 288 /// getAsInteger - Parse the current string as an integer of the specified 289 /// radix. If Radix is specified as zero, this does radix autosensing using 290 /// extended C rules: 0 is octal, 0x is hex, 0b is binary. 291 /// 292 /// If the string is invalid or if only a subset of the string is valid, 293 /// this returns true to signify the error. The string is considered 294 /// erroneous if empty. 295 /// 296 bool getAsInteger(unsigned Radix, long long &Result) const; 297 bool getAsInteger(unsigned Radix, unsigned long long &Result) const; 298 bool getAsInteger(unsigned Radix, int &Result) const; 299 bool getAsInteger(unsigned Radix, unsigned &Result) const; 300 301 // TODO: Provide overloads for int/unsigned that check for overflow. 302 303 /// getAsInteger - Parse the current string as an integer of the 304 /// specified radix, or of an autosensed radix if the radix given 305 /// is 0. The current value in Result is discarded, and the 306 /// storage is changed to be wide enough to store the parsed 307 /// integer. 308 /// 309 /// Returns true if the string does not solely consist of a valid 310 /// non-empty number in the appropriate base. 311 /// 312 /// APInt::fromString is superficially similar but assumes the 313 /// string is well-formed in the given radix. 314 bool getAsInteger(unsigned Radix, APInt &Result) const; 315 316 /// @} 317 /// @name Substring Operations 318 /// @{ 319 320 /// substr - Return a reference to the substring from [Start, Start + N). 321 /// 322 /// \param Start - The index of the starting character in the substring; if 323 /// the index is npos or greater than the length of the string then the 324 /// empty substring will be returned. 325 /// 326 /// \param N - The number of characters to included in the substring. If N 327 /// exceeds the number of characters remaining in the string, the string 328 /// suffix (starting with \arg Start) will be returned. 329 StringRef substr(size_t Start, size_t N = npos) const { 330 Start = min(Start, Length); 331 return StringRef(Data + Start, min(N, Length - Start)); 332 } 333 334 /// slice - Return a reference to the substring from [Start, End). 335 /// 336 /// \param Start - The index of the starting character in the substring; if 337 /// the index is npos or greater than the length of the string then the 338 /// empty substring will be returned. 339 /// 340 /// \param End - The index following the last character to include in the 341 /// substring. If this is npos, or less than \arg Start, or exceeds the 342 /// number of characters remaining in the string, the string suffix 343 /// (starting with \arg Start) will be returned. 344 StringRef slice(size_t Start, size_t End) const { 345 Start = min(Start, Length); 346 End = min(max(Start, End), Length); 347 return StringRef(Data + Start, End - Start); 348 } 349 350 /// split - Split into two substrings around the first occurrence of a 351 /// separator character. 352 /// 353 /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) 354 /// such that (*this == LHS + Separator + RHS) is true and RHS is 355 /// maximal. If \arg Separator is not in the string, then the result is a 356 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 357 /// 358 /// \param Separator - The character to split on. 359 /// \return - The split substrings. 360 std::pair<StringRef, StringRef> split(char Separator) const { 361 size_t Idx = find(Separator); 362 if (Idx == npos) 363 return std::make_pair(*this, StringRef()); 364 return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); 365 } 366 367 /// split - Split into two substrings around the first occurrence of a 368 /// separator string. 369 /// 370 /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) 371 /// such that (*this == LHS + Separator + RHS) is true and RHS is 372 /// maximal. If \arg Separator is not in the string, then the result is a 373 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 374 /// 375 /// \param Separator - The string to split on. 376 /// \return - The split substrings. 377 std::pair<StringRef, StringRef> split(StringRef Separator) const { 378 size_t Idx = find(Separator); 379 if (Idx == npos) 380 return std::make_pair(*this, StringRef()); 381 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos)); 382 } 383 384 /// split - Split into substrings around the occurrences of a separator 385 /// string. 386 /// 387 /// Each substring is stored in \arg A. If \arg MaxSplit is >= 0, at most 388 /// \arg MaxSplit splits are done and consequently <= \arg MaxSplit 389 /// elements are added to A. 390 /// If \arg KeepEmpty is false, empty strings are not added to \arg A. They 391 /// still count when considering \arg MaxSplit 392 /// An useful invariant is that 393 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true 394 /// 395 /// \param A - Where to put the substrings. 396 /// \param Separator - The string to split on. 397 /// \param MaxSplit - The maximum number of times the string is split. 398 /// \param KeepEmpty - True if empty substring should be added. 399 void split(SmallVectorImpl<StringRef> &A, 400 StringRef Separator, int MaxSplit = -1, 401 bool KeepEmpty = true) const; 402 403 /// rsplit - Split into two substrings around the last occurrence of a 404 /// separator character. 405 /// 406 /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) 407 /// such that (*this == LHS + Separator + RHS) is true and RHS is 408 /// minimal. If \arg Separator is not in the string, then the result is a 409 /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). 410 /// 411 /// \param Separator - The character to split on. 412 /// \return - The split substrings. 413 std::pair<StringRef, StringRef> rsplit(char Separator) const { 414 size_t Idx = rfind(Separator); 415 if (Idx == npos) 416 return std::make_pair(*this, StringRef()); 417 return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); 418 } 419 420 /// @} 421 }; 422 423 /// @name StringRef Comparison Operators 424 /// @{ 425 426 inline bool operator==(StringRef LHS, StringRef RHS) { 427 return LHS.equals(RHS); 428 } 429 430 inline bool operator!=(StringRef LHS, StringRef RHS) { 431 return !(LHS == RHS); 432 } 433 434 inline bool operator<(StringRef LHS, StringRef RHS) { 435 return LHS.compare(RHS) == -1; 436 } 437 438 inline bool operator<=(StringRef LHS, StringRef RHS) { 439 return LHS.compare(RHS) != 1; 440 } 441 442 inline bool operator>(StringRef LHS, StringRef RHS) { 443 return LHS.compare(RHS) == 1; 444 } 445 446 inline bool operator>=(StringRef LHS, StringRef RHS) { 447 return LHS.compare(RHS) != -1; 448 } 449 450 /// @} 451 452 // StringRefs can be treated like a POD type. 453 template <typename T> struct isPodLike; 454 template <> struct isPodLike<StringRef> { static const bool value = true; }; 455 456} 457 458#endif 459