1 // Copyright 2013 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 // 5 // This file defines utility functions for working with strings. 6 7 #ifndef BASE_STRINGS_STRING_UTIL_H_ 8 #define BASE_STRINGS_STRING_UTIL_H_ 9 10 #include <ctype.h> 11 #include <stdarg.h> // va_list 12 13 #include <string> 14 #include <vector> 15 16 #include "base/base_export.h" 17 #include "base/basictypes.h" 18 #include "base/compiler_specific.h" 19 #include "base/strings/string16.h" 20 #include "base/strings/string_piece.h" // For implicit conversions. 21 22 namespace base { 23 24 // C standard-library functions like "strncasecmp" and "snprintf" that aren't 25 // cross-platform are provided as "base::strncasecmp", and their prototypes 26 // are listed below. These functions are then implemented as inline calls 27 // to the platform-specific equivalents in the platform-specific headers. 28 29 // Compares the two strings s1 and s2 without regard to case using 30 // the current locale; returns 0 if they are equal, 1 if s1 > s2, and -1 if 31 // s2 > s1 according to a lexicographic comparison. 32 int strcasecmp(const char* s1, const char* s2); 33 34 // Compares up to count characters of s1 and s2 without regard to case using 35 // the current locale; returns 0 if they are equal, 1 if s1 > s2, and -1 if 36 // s2 > s1 according to a lexicographic comparison. 37 int strncasecmp(const char* s1, const char* s2, size_t count); 38 39 // Same as strncmp but for char16 strings. 40 int strncmp16(const char16* s1, const char16* s2, size_t count); 41 42 // Wrapper for vsnprintf that always null-terminates and always returns the 43 // number of characters that would be in an untruncated formatted 44 // string, even when truncation occurs. 45 int vsnprintf(char* buffer, size_t size, const char* format, va_list arguments) 46 PRINTF_FORMAT(3, 0); 47 48 // Some of these implementations need to be inlined. 49 50 // We separate the declaration from the implementation of this inline 51 // function just so the PRINTF_FORMAT works. 52 inline int snprintf(char* buffer, size_t size, const char* format, ...) 53 PRINTF_FORMAT(3, 4); 54 inline int snprintf(char* buffer, size_t size, const char* format, ...) { 55 va_list arguments; 56 va_start(arguments, format); 57 int result = vsnprintf(buffer, size, format, arguments); 58 va_end(arguments); 59 return result; 60 } 61 62 // BSD-style safe and consistent string copy functions. 63 // Copies |src| to |dst|, where |dst_size| is the total allocated size of |dst|. 64 // Copies at most |dst_size|-1 characters, and always NULL terminates |dst|, as 65 // long as |dst_size| is not 0. Returns the length of |src| in characters. 66 // If the return value is >= dst_size, then the output was truncated. 67 // NOTE: All sizes are in number of characters, NOT in bytes. 68 BASE_EXPORT size_t strlcpy(char* dst, const char* src, size_t dst_size); 69 BASE_EXPORT size_t wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size); 70 71 // Scan a wprintf format string to determine whether it's portable across a 72 // variety of systems. This function only checks that the conversion 73 // specifiers used by the format string are supported and have the same meaning 74 // on a variety of systems. It doesn't check for other errors that might occur 75 // within a format string. 76 // 77 // Nonportable conversion specifiers for wprintf are: 78 // - 's' and 'c' without an 'l' length modifier. %s and %c operate on char 79 // data on all systems except Windows, which treat them as wchar_t data. 80 // Use %ls and %lc for wchar_t data instead. 81 // - 'S' and 'C', which operate on wchar_t data on all systems except Windows, 82 // which treat them as char data. Use %ls and %lc for wchar_t data 83 // instead. 84 // - 'F', which is not identified by Windows wprintf documentation. 85 // - 'D', 'O', and 'U', which are deprecated and not available on all systems. 86 // Use %ld, %lo, and %lu instead. 87 // 88 // Note that there is no portable conversion specifier for char data when 89 // working with wprintf. 90 // 91 // This function is intended to be called from base::vswprintf. 92 BASE_EXPORT bool IsWprintfFormatPortable(const wchar_t* format); 93 94 // ASCII-specific tolower. The standard library's tolower is locale sensitive, 95 // so we don't want to use it here. 96 template <class Char> inline Char ToLowerASCII(Char c) { 97 return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c; 98 } 99 100 // ASCII-specific toupper. The standard library's toupper is locale sensitive, 101 // so we don't want to use it here. 102 template <class Char> inline Char ToUpperASCII(Char c) { 103 return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c; 104 } 105 106 // Function objects to aid in comparing/searching strings. 107 108 template<typename Char> struct CaseInsensitiveCompare { 109 public: 110 bool operator()(Char x, Char y) const { 111 // TODO(darin): Do we really want to do locale sensitive comparisons here? 112 // See http://crbug.com/24917 113 return tolower(x) == tolower(y); 114 } 115 }; 116 117 template<typename Char> struct CaseInsensitiveCompareASCII { 118 public: 119 bool operator()(Char x, Char y) const { 120 return ToLowerASCII(x) == ToLowerASCII(y); 121 } 122 }; 123 124 // These threadsafe functions return references to globally unique empty 125 // strings. 126 // 127 // It is likely faster to construct a new empty string object (just a few 128 // instructions to set the length to 0) than to get the empty string singleton 129 // returned by these functions (which requires threadsafe singleton access). 130 // 131 // Therefore, DO NOT USE THESE AS A GENERAL-PURPOSE SUBSTITUTE FOR DEFAULT 132 // CONSTRUCTORS. There is only one case where you should use these: functions 133 // which need to return a string by reference (e.g. as a class member 134 // accessor), and don't have an empty string to use (e.g. in an error case). 135 // These should not be used as initializers, function arguments, or return 136 // values for functions which return by value or outparam. 137 BASE_EXPORT const std::string& EmptyString(); 138 BASE_EXPORT const string16& EmptyString16(); 139 140 // Contains the set of characters representing whitespace in the corresponding 141 // encoding. Null-terminated. 142 BASE_EXPORT extern const wchar_t kWhitespaceWide[]; 143 BASE_EXPORT extern const char16 kWhitespaceUTF16[]; 144 BASE_EXPORT extern const char kWhitespaceASCII[]; 145 146 // Null-terminated string representing the UTF-8 byte order mark. 147 BASE_EXPORT extern const char kUtf8ByteOrderMark[]; 148 149 // Removes characters in |remove_chars| from anywhere in |input|. Returns true 150 // if any characters were removed. |remove_chars| must be null-terminated. 151 // NOTE: Safe to use the same variable for both |input| and |output|. 152 BASE_EXPORT bool RemoveChars(const string16& input, 153 const base::StringPiece16& remove_chars, 154 string16* output); 155 BASE_EXPORT bool RemoveChars(const std::string& input, 156 const base::StringPiece& remove_chars, 157 std::string* output); 158 159 // Replaces characters in |replace_chars| from anywhere in |input| with 160 // |replace_with|. Each character in |replace_chars| will be replaced with 161 // the |replace_with| string. Returns true if any characters were replaced. 162 // |replace_chars| must be null-terminated. 163 // NOTE: Safe to use the same variable for both |input| and |output|. 164 BASE_EXPORT bool ReplaceChars(const string16& input, 165 const base::StringPiece16& replace_chars, 166 const string16& replace_with, 167 string16* output); 168 BASE_EXPORT bool ReplaceChars(const std::string& input, 169 const base::StringPiece& replace_chars, 170 const std::string& replace_with, 171 std::string* output); 172 173 // Removes characters in |trim_chars| from the beginning and end of |input|. 174 // |trim_chars| must be null-terminated. 175 // NOTE: Safe to use the same variable for both |input| and |output|. 176 BASE_EXPORT bool TrimString(const string16& input, 177 const base::StringPiece16& trim_chars, 178 string16* output); 179 BASE_EXPORT bool TrimString(const std::string& input, 180 const base::StringPiece& trim_chars, 181 std::string* output); 182 183 // Truncates a string to the nearest UTF-8 character that will leave 184 // the string less than or equal to the specified byte size. 185 BASE_EXPORT void TruncateUTF8ToByteSize(const std::string& input, 186 const size_t byte_size, 187 std::string* output); 188 189 // Trims any whitespace from either end of the input string. Returns where 190 // whitespace was found. 191 // The non-wide version has two functions: 192 // * TrimWhitespaceASCII() 193 // This function is for ASCII strings and only looks for ASCII whitespace; 194 // Please choose the best one according to your usage. 195 // NOTE: Safe to use the same variable for both input and output. 196 enum TrimPositions { 197 TRIM_NONE = 0, 198 TRIM_LEADING = 1 << 0, 199 TRIM_TRAILING = 1 << 1, 200 TRIM_ALL = TRIM_LEADING | TRIM_TRAILING, 201 }; 202 BASE_EXPORT TrimPositions TrimWhitespace(const string16& input, 203 TrimPositions positions, 204 base::string16* output); 205 BASE_EXPORT TrimPositions TrimWhitespaceASCII(const std::string& input, 206 TrimPositions positions, 207 std::string* output); 208 209 // Deprecated. This function is only for backward compatibility and calls 210 // TrimWhitespaceASCII(). 211 BASE_EXPORT TrimPositions TrimWhitespace(const std::string& input, 212 TrimPositions positions, 213 std::string* output); 214 215 // Searches for CR or LF characters. Removes all contiguous whitespace 216 // strings that contain them. This is useful when trying to deal with text 217 // copied from terminals. 218 // Returns |text|, with the following three transformations: 219 // (1) Leading and trailing whitespace is trimmed. 220 // (2) If |trim_sequences_with_line_breaks| is true, any other whitespace 221 // sequences containing a CR or LF are trimmed. 222 // (3) All other whitespace sequences are converted to single spaces. 223 BASE_EXPORT string16 CollapseWhitespace( 224 const string16& text, 225 bool trim_sequences_with_line_breaks); 226 BASE_EXPORT std::string CollapseWhitespaceASCII( 227 const std::string& text, 228 bool trim_sequences_with_line_breaks); 229 230 // Returns true if |input| is empty or contains only characters found in 231 // |characters|. 232 BASE_EXPORT bool ContainsOnlyChars(const StringPiece& input, 233 const StringPiece& characters); 234 BASE_EXPORT bool ContainsOnlyChars(const StringPiece16& input, 235 const StringPiece16& characters); 236 237 // Returns true if the specified string matches the criteria. How can a wide 238 // string be 8-bit or UTF8? It contains only characters that are < 256 (in the 239 // first case) or characters that use only 8-bits and whose 8-bit 240 // representation looks like a UTF-8 string (the second case). 241 // 242 // Note that IsStringUTF8 checks not only if the input is structurally 243 // valid but also if it doesn't contain any non-character codepoint 244 // (e.g. U+FFFE). It's done on purpose because all the existing callers want 245 // to have the maximum 'discriminating' power from other encodings. If 246 // there's a use case for just checking the structural validity, we have to 247 // add a new function for that. 248 BASE_EXPORT bool IsStringUTF8(const std::string& str); 249 BASE_EXPORT bool IsStringASCII(const StringPiece& str); 250 BASE_EXPORT bool IsStringASCII(const string16& str); 251 252 } // namespace base 253 254 #if defined(OS_WIN) 255 #include "base/strings/string_util_win.h" 256 #elif defined(OS_POSIX) 257 #include "base/strings/string_util_posix.h" 258 #else 259 #error Define string operations appropriately for your platform 260 #endif 261 262 // Converts the elements of the given string. This version uses a pointer to 263 // clearly differentiate it from the non-pointer variant. 264 template <class str> inline void StringToLowerASCII(str* s) { 265 for (typename str::iterator i = s->begin(); i != s->end(); ++i) 266 *i = base::ToLowerASCII(*i); 267 } 268 269 template <class str> inline str StringToLowerASCII(const str& s) { 270 // for std::string and std::wstring 271 str output(s); 272 StringToLowerASCII(&output); 273 return output; 274 } 275 276 // Converts the elements of the given string. This version uses a pointer to 277 // clearly differentiate it from the non-pointer variant. 278 template <class str> inline void StringToUpperASCII(str* s) { 279 for (typename str::iterator i = s->begin(); i != s->end(); ++i) 280 *i = base::ToUpperASCII(*i); 281 } 282 283 template <class str> inline str StringToUpperASCII(const str& s) { 284 // for std::string and std::wstring 285 str output(s); 286 StringToUpperASCII(&output); 287 return output; 288 } 289 290 // Compare the lower-case form of the given string against the given ASCII 291 // string. This is useful for doing checking if an input string matches some 292 // token, and it is optimized to avoid intermediate string copies. This API is 293 // borrowed from the equivalent APIs in Mozilla. 294 BASE_EXPORT bool LowerCaseEqualsASCII(const std::string& a, const char* b); 295 BASE_EXPORT bool LowerCaseEqualsASCII(const base::string16& a, const char* b); 296 297 // Same thing, but with string iterators instead. 298 BASE_EXPORT bool LowerCaseEqualsASCII(std::string::const_iterator a_begin, 299 std::string::const_iterator a_end, 300 const char* b); 301 BASE_EXPORT bool LowerCaseEqualsASCII(base::string16::const_iterator a_begin, 302 base::string16::const_iterator a_end, 303 const char* b); 304 BASE_EXPORT bool LowerCaseEqualsASCII(const char* a_begin, 305 const char* a_end, 306 const char* b); 307 BASE_EXPORT bool LowerCaseEqualsASCII(const base::char16* a_begin, 308 const base::char16* a_end, 309 const char* b); 310 311 // Performs a case-sensitive string compare. The behavior is undefined if both 312 // strings are not ASCII. 313 BASE_EXPORT bool EqualsASCII(const base::string16& a, const base::StringPiece& b); 314 315 // Returns true if str starts with search, or false otherwise. 316 BASE_EXPORT bool StartsWithASCII(const std::string& str, 317 const std::string& search, 318 bool case_sensitive); 319 BASE_EXPORT bool StartsWith(const base::string16& str, 320 const base::string16& search, 321 bool case_sensitive); 322 323 // Returns true if str ends with search, or false otherwise. 324 BASE_EXPORT bool EndsWith(const std::string& str, 325 const std::string& search, 326 bool case_sensitive); 327 BASE_EXPORT bool EndsWith(const base::string16& str, 328 const base::string16& search, 329 bool case_sensitive); 330 331 332 // Determines the type of ASCII character, independent of locale (the C 333 // library versions will change based on locale). 334 template <typename Char> 335 inline bool IsAsciiWhitespace(Char c) { 336 return c == ' ' || c == '\r' || c == '\n' || c == '\t'; 337 } 338 template <typename Char> 339 inline bool IsAsciiAlpha(Char c) { 340 return ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z')); 341 } 342 template <typename Char> 343 inline bool IsAsciiDigit(Char c) { 344 return c >= '0' && c <= '9'; 345 } 346 347 template <typename Char> 348 inline bool IsHexDigit(Char c) { 349 return (c >= '0' && c <= '9') || 350 (c >= 'A' && c <= 'F') || 351 (c >= 'a' && c <= 'f'); 352 } 353 354 template <typename Char> 355 inline Char HexDigitToInt(Char c) { 356 DCHECK(IsHexDigit(c)); 357 if (c >= '0' && c <= '9') 358 return c - '0'; 359 if (c >= 'A' && c <= 'F') 360 return c - 'A' + 10; 361 if (c >= 'a' && c <= 'f') 362 return c - 'a' + 10; 363 return 0; 364 } 365 366 // Returns true if it's a whitespace character. 367 inline bool IsWhitespace(wchar_t c) { 368 return wcschr(base::kWhitespaceWide, c) != NULL; 369 } 370 371 // Return a byte string in human-readable format with a unit suffix. Not 372 // appropriate for use in any UI; use of FormatBytes and friends in ui/base is 373 // highly recommended instead. TODO(avi): Figure out how to get callers to use 374 // FormatBytes instead; remove this. 375 BASE_EXPORT base::string16 FormatBytesUnlocalized(int64 bytes); 376 377 // Starting at |start_offset| (usually 0), replace the first instance of 378 // |find_this| with |replace_with|. 379 BASE_EXPORT void ReplaceFirstSubstringAfterOffset( 380 base::string16* str, 381 size_t start_offset, 382 const base::string16& find_this, 383 const base::string16& replace_with); 384 BASE_EXPORT void ReplaceFirstSubstringAfterOffset( 385 std::string* str, 386 size_t start_offset, 387 const std::string& find_this, 388 const std::string& replace_with); 389 390 // Starting at |start_offset| (usually 0), look through |str| and replace all 391 // instances of |find_this| with |replace_with|. 392 // 393 // This does entire substrings; use std::replace in <algorithm> for single 394 // characters, for example: 395 // std::replace(str.begin(), str.end(), 'a', 'b'); 396 BASE_EXPORT void ReplaceSubstringsAfterOffset( 397 base::string16* str, 398 size_t start_offset, 399 const base::string16& find_this, 400 const base::string16& replace_with); 401 BASE_EXPORT void ReplaceSubstringsAfterOffset(std::string* str, 402 size_t start_offset, 403 const std::string& find_this, 404 const std::string& replace_with); 405 406 // Reserves enough memory in |str| to accommodate |length_with_null| characters, 407 // sets the size of |str| to |length_with_null - 1| characters, and returns a 408 // pointer to the underlying contiguous array of characters. This is typically 409 // used when calling a function that writes results into a character array, but 410 // the caller wants the data to be managed by a string-like object. It is 411 // convenient in that is can be used inline in the call, and fast in that it 412 // avoids copying the results of the call from a char* into a string. 413 // 414 // |length_with_null| must be at least 2, since otherwise the underlying string 415 // would have size 0, and trying to access &((*str)[0]) in that case can result 416 // in a number of problems. 417 // 418 // Internally, this takes linear time because the resize() call 0-fills the 419 // underlying array for potentially all 420 // (|length_with_null - 1| * sizeof(string_type::value_type)) bytes. Ideally we 421 // could avoid this aspect of the resize() call, as we expect the caller to 422 // immediately write over this memory, but there is no other way to set the size 423 // of the string, and not doing that will mean people who access |str| rather 424 // than str.c_str() will get back a string of whatever size |str| had on entry 425 // to this function (probably 0). 426 template <class string_type> 427 inline typename string_type::value_type* WriteInto(string_type* str, 428 size_t length_with_null) { 429 DCHECK_GT(length_with_null, 1u); 430 str->reserve(length_with_null); 431 str->resize(length_with_null - 1); 432 return &((*str)[0]); 433 } 434 435 //----------------------------------------------------------------------------- 436 437 // Splits a string into its fields delimited by any of the characters in 438 // |delimiters|. Each field is added to the |tokens| vector. Returns the 439 // number of tokens found. 440 BASE_EXPORT size_t Tokenize(const base::string16& str, 441 const base::string16& delimiters, 442 std::vector<base::string16>* tokens); 443 BASE_EXPORT size_t Tokenize(const std::string& str, 444 const std::string& delimiters, 445 std::vector<std::string>* tokens); 446 BASE_EXPORT size_t Tokenize(const base::StringPiece& str, 447 const base::StringPiece& delimiters, 448 std::vector<base::StringPiece>* tokens); 449 450 // Does the opposite of SplitString(). 451 BASE_EXPORT base::string16 JoinString(const std::vector<base::string16>& parts, 452 base::char16 s); 453 BASE_EXPORT std::string JoinString( 454 const std::vector<std::string>& parts, char s); 455 456 // Join |parts| using |separator|. 457 BASE_EXPORT std::string JoinString( 458 const std::vector<std::string>& parts, 459 const std::string& separator); 460 BASE_EXPORT base::string16 JoinString( 461 const std::vector<base::string16>& parts, 462 const base::string16& separator); 463 464 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively. 465 // Additionally, any number of consecutive '$' characters is replaced by that 466 // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be 467 // NULL. This only allows you to use up to nine replacements. 468 BASE_EXPORT base::string16 ReplaceStringPlaceholders( 469 const base::string16& format_string, 470 const std::vector<base::string16>& subst, 471 std::vector<size_t>* offsets); 472 473 BASE_EXPORT std::string ReplaceStringPlaceholders( 474 const base::StringPiece& format_string, 475 const std::vector<std::string>& subst, 476 std::vector<size_t>* offsets); 477 478 // Single-string shortcut for ReplaceStringHolders. |offset| may be NULL. 479 BASE_EXPORT base::string16 ReplaceStringPlaceholders( 480 const base::string16& format_string, 481 const base::string16& a, 482 size_t* offset); 483 484 // Returns true if the string passed in matches the pattern. The pattern 485 // string can contain wildcards like * and ? 486 // The backslash character (\) is an escape character for * and ? 487 // We limit the patterns to having a max of 16 * or ? characters. 488 // ? matches 0 or 1 character, while * matches 0 or more characters. 489 BASE_EXPORT bool MatchPattern(const base::StringPiece& string, 490 const base::StringPiece& pattern); 491 BASE_EXPORT bool MatchPattern(const base::string16& string, 492 const base::string16& pattern); 493 494 // Hack to convert any char-like type to its unsigned counterpart. 495 // For example, it will convert char, signed char and unsigned char to unsigned 496 // char. 497 template<typename T> 498 struct ToUnsigned { 499 typedef T Unsigned; 500 }; 501 502 template<> 503 struct ToUnsigned<char> { 504 typedef unsigned char Unsigned; 505 }; 506 template<> 507 struct ToUnsigned<signed char> { 508 typedef unsigned char Unsigned; 509 }; 510 template<> 511 struct ToUnsigned<wchar_t> { 512 #if defined(WCHAR_T_IS_UTF16) 513 typedef unsigned short Unsigned; 514 #elif defined(WCHAR_T_IS_UTF32) 515 typedef uint32 Unsigned; 516 #endif 517 }; 518 template<> 519 struct ToUnsigned<short> { 520 typedef unsigned short Unsigned; 521 }; 522 523 #endif // BASE_STRINGS_STRING_UTIL_H_ 524