1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // Copied from strings/stringpiece.h with modifications 5 // 6 // A string-like object that points to a sized piece of memory. 7 // 8 // You can use StringPiece as a function or method parameter. A StringPiece 9 // parameter can receive a double-quoted string literal argument, a "const 10 // char*" argument, a string argument, or a StringPiece argument with no data 11 // copying. Systematic use of StringPiece for arguments reduces data 12 // copies and strlen() calls. 13 // 14 // Prefer passing StringPieces by value: 15 // void MyFunction(StringPiece arg); 16 // If circumstances require, you may also pass by const reference: 17 // void MyFunction(const StringPiece& arg); // not preferred 18 // Both of these have the same lifetime semantics. Passing by value 19 // generates slightly smaller code. For more discussion, Googlers can see 20 // the thread go/stringpiecebyvalue on c-users. 21 // 22 // StringPiece16 is similar to StringPiece but for base::string16 instead of 23 // std::string. We do not define as large of a subset of the STL functions 24 // from basic_string as in StringPiece, but this can be changed if these 25 // functions (find, find_first_of, etc.) are found to be useful in this context. 26 // 27 28 #ifndef BASE_STRINGS_STRING_PIECE_H_ 29 #define BASE_STRINGS_STRING_PIECE_H_ 30 31 #include <stddef.h> 32 33 #include <iosfwd> 34 #include <string> 35 36 #include "base/base_export.h" 37 #include "base/basictypes.h" 38 #include "base/containers/hash_tables.h" 39 #include "base/strings/string16.h" 40 41 namespace base { 42 43 template <typename STRING_TYPE> class BasicStringPiece; 44 typedef BasicStringPiece<std::string> StringPiece; 45 typedef BasicStringPiece<string16> StringPiece16; 46 47 // internal -------------------------------------------------------------------- 48 49 // Many of the StringPiece functions use different implementations for the 50 // 8-bit and 16-bit versions, and we don't want lots of template expansions in 51 // this (very common) header that will slow down compilation. 52 // 53 // So here we define overloaded functions called by the StringPiece template. 54 // For those that share an implementation, the two versions will expand to a 55 // template internal to the .cc file. 56 namespace internal { 57 58 BASE_EXPORT void CopyToString(const StringPiece& self, std::string* target); 59 BASE_EXPORT void CopyToString(const StringPiece16& self, string16* target); 60 61 BASE_EXPORT void AppendToString(const StringPiece& self, std::string* target); 62 BASE_EXPORT void AppendToString(const StringPiece16& self, string16* target); 63 64 BASE_EXPORT size_t copy(const StringPiece& self, 65 char* buf, 66 size_t n, 67 size_t pos); 68 BASE_EXPORT size_t copy(const StringPiece16& self, 69 char16* buf, 70 size_t n, 71 size_t pos); 72 73 BASE_EXPORT size_t find(const StringPiece& self, 74 const StringPiece& s, 75 size_t pos); 76 BASE_EXPORT size_t find(const StringPiece16& self, 77 const StringPiece16& s, 78 size_t pos); 79 BASE_EXPORT size_t find(const StringPiece& self, 80 char c, 81 size_t pos); 82 BASE_EXPORT size_t find(const StringPiece16& self, 83 char16 c, 84 size_t pos); 85 86 BASE_EXPORT size_t rfind(const StringPiece& self, 87 const StringPiece& s, 88 size_t pos); 89 BASE_EXPORT size_t rfind(const StringPiece16& self, 90 const StringPiece16& s, 91 size_t pos); 92 BASE_EXPORT size_t rfind(const StringPiece& self, 93 char c, 94 size_t pos); 95 BASE_EXPORT size_t rfind(const StringPiece16& self, 96 char16 c, 97 size_t pos); 98 99 BASE_EXPORT size_t find_first_of(const StringPiece& self, 100 const StringPiece& s, 101 size_t pos); 102 BASE_EXPORT size_t find_first_of(const StringPiece16& self, 103 const StringPiece16& s, 104 size_t pos); 105 106 BASE_EXPORT size_t find_first_not_of(const StringPiece& self, 107 const StringPiece& s, 108 size_t pos); 109 BASE_EXPORT size_t find_first_not_of(const StringPiece16& self, 110 const StringPiece16& s, 111 size_t pos); 112 BASE_EXPORT size_t find_first_not_of(const StringPiece& self, 113 char c, 114 size_t pos); 115 BASE_EXPORT size_t find_first_not_of(const StringPiece16& self, 116 char16 c, 117 size_t pos); 118 119 BASE_EXPORT size_t find_last_of(const StringPiece& self, 120 const StringPiece& s, 121 size_t pos); 122 BASE_EXPORT size_t find_last_of(const StringPiece16& self, 123 const StringPiece16& s, 124 size_t pos); 125 BASE_EXPORT size_t find_last_of(const StringPiece& self, 126 char c, 127 size_t pos); 128 BASE_EXPORT size_t find_last_of(const StringPiece16& self, 129 char16 c, 130 size_t pos); 131 132 BASE_EXPORT size_t find_last_not_of(const StringPiece& self, 133 const StringPiece& s, 134 size_t pos); 135 BASE_EXPORT size_t find_last_not_of(const StringPiece16& self, 136 const StringPiece16& s, 137 size_t pos); 138 BASE_EXPORT size_t find_last_not_of(const StringPiece16& self, 139 char16 c, 140 size_t pos); 141 BASE_EXPORT size_t find_last_not_of(const StringPiece& self, 142 char c, 143 size_t pos); 144 145 BASE_EXPORT StringPiece substr(const StringPiece& self, 146 size_t pos, 147 size_t n); 148 BASE_EXPORT StringPiece16 substr(const StringPiece16& self, 149 size_t pos, 150 size_t n); 151 152 } // namespace internal 153 154 // BasicStringPiece ------------------------------------------------------------ 155 156 // Defines the types, methods, operators, and data members common to both 157 // StringPiece and StringPiece16. Do not refer to this class directly, but 158 // rather to BasicStringPiece, StringPiece, or StringPiece16. 159 // 160 // This is templatized by string class type rather than character type, so 161 // BasicStringPiece<std::string> or BasicStringPiece<base::string16>. 162 template <typename STRING_TYPE> class BasicStringPiece { 163 public: 164 // Standard STL container boilerplate. 165 typedef size_t size_type; 166 typedef typename STRING_TYPE::value_type value_type; 167 typedef const value_type* pointer; 168 typedef const value_type& reference; 169 typedef const value_type& const_reference; 170 typedef ptrdiff_t difference_type; 171 typedef const value_type* const_iterator; 172 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 173 174 static const size_type npos; 175 176 public: 177 // We provide non-explicit singleton constructors so users can pass 178 // in a "const char*" or a "string" wherever a "StringPiece" is 179 // expected (likewise for char16, string16, StringPiece16). 180 BasicStringPiece() : ptr_(NULL), length_(0) {} 181 BasicStringPiece(const value_type* str) 182 : ptr_(str), 183 length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {} 184 BasicStringPiece(const STRING_TYPE& str) 185 : ptr_(str.data()), length_(str.size()) {} 186 BasicStringPiece(const value_type* offset, size_type len) 187 : ptr_(offset), length_(len) {} 188 BasicStringPiece(const typename STRING_TYPE::const_iterator& begin, 189 const typename STRING_TYPE::const_iterator& end) 190 : ptr_((end > begin) ? &(*begin) : NULL), 191 length_((end > begin) ? (size_type)(end - begin) : 0) {} 192 193 // data() may return a pointer to a buffer with embedded NULs, and the 194 // returned buffer may or may not be null terminated. Therefore it is 195 // typically a mistake to pass data() to a routine that expects a NUL 196 // terminated string. 197 const value_type* data() const { return ptr_; } 198 size_type size() const { return length_; } 199 size_type length() const { return length_; } 200 bool empty() const { return length_ == 0; } 201 202 void clear() { 203 ptr_ = NULL; 204 length_ = 0; 205 } 206 void set(const value_type* data, size_type len) { 207 ptr_ = data; 208 length_ = len; 209 } 210 void set(const value_type* str) { 211 ptr_ = str; 212 length_ = str ? STRING_TYPE::traits_type::length(str) : 0; 213 } 214 215 value_type operator[](size_type i) const { return ptr_[i]; } 216 217 void remove_prefix(size_type n) { 218 ptr_ += n; 219 length_ -= n; 220 } 221 222 void remove_suffix(size_type n) { 223 length_ -= n; 224 } 225 226 int compare(const BasicStringPiece<STRING_TYPE>& x) const { 227 int r = wordmemcmp( 228 ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_)); 229 if (r == 0) { 230 if (length_ < x.length_) r = -1; 231 else if (length_ > x.length_) r = +1; 232 } 233 return r; 234 } 235 236 STRING_TYPE as_string() const { 237 // std::string doesn't like to take a NULL pointer even with a 0 size. 238 return empty() ? STRING_TYPE() : STRING_TYPE(data(), size()); 239 } 240 241 const_iterator begin() const { return ptr_; } 242 const_iterator end() const { return ptr_ + length_; } 243 const_reverse_iterator rbegin() const { 244 return const_reverse_iterator(ptr_ + length_); 245 } 246 const_reverse_iterator rend() const { 247 return const_reverse_iterator(ptr_); 248 } 249 250 size_type max_size() const { return length_; } 251 size_type capacity() const { return length_; } 252 253 static int wordmemcmp(const value_type* p, 254 const value_type* p2, 255 size_type N) { 256 return STRING_TYPE::traits_type::compare(p, p2, N); 257 } 258 259 // Sets the value of the given string target type to be the current string. 260 // This saves a temporary over doing |a = b.as_string()| 261 void CopyToString(STRING_TYPE* target) const { 262 internal::CopyToString(*this, target); 263 } 264 265 void AppendToString(STRING_TYPE* target) const { 266 internal::AppendToString(*this, target); 267 } 268 269 size_type copy(value_type* buf, size_type n, size_type pos = 0) const { 270 return internal::copy(*this, buf, n, pos); 271 } 272 273 // Does "this" start with "x" 274 bool starts_with(const BasicStringPiece& x) const { 275 return ((this->length_ >= x.length_) && 276 (wordmemcmp(this->ptr_, x.ptr_, x.length_) == 0)); 277 } 278 279 // Does "this" end with "x" 280 bool ends_with(const BasicStringPiece& x) const { 281 return ((this->length_ >= x.length_) && 282 (wordmemcmp(this->ptr_ + (this->length_-x.length_), 283 x.ptr_, x.length_) == 0)); 284 } 285 286 // find: Search for a character or substring at a given offset. 287 size_type find(const BasicStringPiece<STRING_TYPE>& s, 288 size_type pos = 0) const { 289 return internal::find(*this, s, pos); 290 } 291 size_type find(value_type c, size_type pos = 0) const { 292 return internal::find(*this, c, pos); 293 } 294 295 // rfind: Reverse find. 296 size_type rfind(const BasicStringPiece& s, 297 size_type pos = BasicStringPiece::npos) const { 298 return internal::rfind(*this, s, pos); 299 } 300 size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const { 301 return internal::rfind(*this, c, pos); 302 } 303 304 // find_first_of: Find the first occurence of one of a set of characters. 305 size_type find_first_of(const BasicStringPiece& s, 306 size_type pos = 0) const { 307 return internal::find_first_of(*this, s, pos); 308 } 309 size_type find_first_of(value_type c, size_type pos = 0) const { 310 return find(c, pos); 311 } 312 313 // find_first_not_of: Find the first occurence not of a set of characters. 314 size_type find_first_not_of(const BasicStringPiece& s, 315 size_type pos = 0) const { 316 return internal::find_first_not_of(*this, s, pos); 317 } 318 size_type find_first_not_of(value_type c, size_type pos = 0) const { 319 return internal::find_first_not_of(*this, c, pos); 320 } 321 322 // find_last_of: Find the last occurence of one of a set of characters. 323 size_type find_last_of(const BasicStringPiece& s, 324 size_type pos = BasicStringPiece::npos) const { 325 return internal::find_last_of(*this, s, pos); 326 } 327 size_type find_last_of(value_type c, 328 size_type pos = BasicStringPiece::npos) const { 329 return rfind(c, pos); 330 } 331 332 // find_last_not_of: Find the last occurence not of a set of characters. 333 size_type find_last_not_of(const BasicStringPiece& s, 334 size_type pos = BasicStringPiece::npos) const { 335 return internal::find_last_not_of(*this, s, pos); 336 } 337 size_type find_last_not_of(value_type c, 338 size_type pos = BasicStringPiece::npos) const { 339 return internal::find_last_not_of(*this, c, pos); 340 } 341 342 // substr. 343 BasicStringPiece substr(size_type pos, 344 size_type n = BasicStringPiece::npos) const { 345 return internal::substr(*this, pos, n); 346 } 347 348 protected: 349 const value_type* ptr_; 350 size_type length_; 351 }; 352 353 template <typename STRING_TYPE> 354 const typename BasicStringPiece<STRING_TYPE>::size_type 355 BasicStringPiece<STRING_TYPE>::npos = 356 typename BasicStringPiece<STRING_TYPE>::size_type(-1); 357 358 // MSVC doesn't like complex extern templates and DLLs. 359 #if !defined(COMPILER_MSVC) 360 extern template class BASE_EXPORT BasicStringPiece<std::string>; 361 extern template class BASE_EXPORT BasicStringPiece<string16>; 362 #endif 363 364 // StingPiece operators -------------------------------------------------------- 365 366 BASE_EXPORT bool operator==(const StringPiece& x, const StringPiece& y); 367 368 inline bool operator!=(const StringPiece& x, const StringPiece& y) { 369 return !(x == y); 370 } 371 372 inline bool operator<(const StringPiece& x, const StringPiece& y) { 373 const int r = StringPiece::wordmemcmp( 374 x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size())); 375 return ((r < 0) || ((r == 0) && (x.size() < y.size()))); 376 } 377 378 inline bool operator>(const StringPiece& x, const StringPiece& y) { 379 return y < x; 380 } 381 382 inline bool operator<=(const StringPiece& x, const StringPiece& y) { 383 return !(x > y); 384 } 385 386 inline bool operator>=(const StringPiece& x, const StringPiece& y) { 387 return !(x < y); 388 } 389 390 // StringPiece16 operators ----------------------------------------------------- 391 392 inline bool operator==(const StringPiece16& x, const StringPiece16& y) { 393 if (x.size() != y.size()) 394 return false; 395 396 return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0; 397 } 398 399 inline bool operator!=(const StringPiece16& x, const StringPiece16& y) { 400 return !(x == y); 401 } 402 403 inline bool operator<(const StringPiece16& x, const StringPiece16& y) { 404 const int r = StringPiece16::wordmemcmp( 405 x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size())); 406 return ((r < 0) || ((r == 0) && (x.size() < y.size()))); 407 } 408 409 inline bool operator>(const StringPiece16& x, const StringPiece16& y) { 410 return y < x; 411 } 412 413 inline bool operator<=(const StringPiece16& x, const StringPiece16& y) { 414 return !(x > y); 415 } 416 417 inline bool operator>=(const StringPiece16& x, const StringPiece16& y) { 418 return !(x < y); 419 } 420 421 BASE_EXPORT std::ostream& operator<<(std::ostream& o, 422 const StringPiece& piece); 423 424 } // namespace base 425 426 // Hashing --------------------------------------------------------------------- 427 428 // We provide appropriate hash functions so StringPiece and StringPiece16 can 429 // be used as keys in hash sets and maps. 430 431 // This hash function is copied from base/containers/hash_tables.h. We don't 432 // use the ones already defined for string and string16 directly because it 433 // would require the string constructors to be called, which we don't want. 434 #define HASH_STRING_PIECE(StringPieceType, string_piece) \ 435 std::size_t result = 0; \ 436 for (StringPieceType::const_iterator i = string_piece.begin(); \ 437 i != string_piece.end(); ++i) \ 438 result = (result * 131) + *i; \ 439 return result; \ 440 441 namespace BASE_HASH_NAMESPACE { 442 #if defined(COMPILER_GCC) 443 444 template<> 445 struct hash<base::StringPiece> { 446 std::size_t operator()(const base::StringPiece& sp) const { 447 HASH_STRING_PIECE(base::StringPiece, sp); 448 } 449 }; 450 template<> 451 struct hash<base::StringPiece16> { 452 std::size_t operator()(const base::StringPiece16& sp16) const { 453 HASH_STRING_PIECE(base::StringPiece16, sp16); 454 } 455 }; 456 457 #elif defined(COMPILER_MSVC) 458 459 inline size_t hash_value(const base::StringPiece& sp) { 460 HASH_STRING_PIECE(base::StringPiece, sp); 461 } 462 inline size_t hash_value(const base::StringPiece16& sp16) { 463 HASH_STRING_PIECE(base::StringPiece16, sp16); 464 } 465 466 #endif // COMPILER 467 468 } // namespace BASE_HASH_NAMESPACE 469 470 #endif // BASE_STRINGS_STRING_PIECE_H_ 471
