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 #include <stddef.h> 13 #include <stdint.h> 14 15 #include <string> 16 #include <vector> 17 18 #include "base/base_export.h" 19 #include "base/compiler_specific.h" 20 #include "base/strings/string16.h" 21 #include "base/strings/string_piece.h" // For implicit conversions. 22 #include "build/build_config.h" 23 24 // On Android, bionic's stdio.h defines an snprintf macro when being built with 25 // clang. Undefine it here so it won't collide with base::snprintf(). 26 #undef snprintf 27 28 namespace base { 29 30 // C standard-library functions that aren't cross-platform are provided as 31 // "base::...", and their prototypes are listed below. These functions are 32 // then implemented as inline calls to the platform-specific equivalents in the 33 // platform-specific headers. 34 35 // Wrapper for vsnprintf that always null-terminates and always returns the 36 // number of characters that would be in an untruncated formatted 37 // string, even when truncation occurs. 38 int vsnprintf(char* buffer, size_t size, const char* format, va_list arguments) 39 PRINTF_FORMAT(3, 0); 40 41 // Some of these implementations need to be inlined. 42 43 // We separate the declaration from the implementation of this inline 44 // function just so the PRINTF_FORMAT works. 45 inline int snprintf(char* buffer, 46 size_t size, 47 _Printf_format_string_ const char* format, 48 ...) PRINTF_FORMAT(3, 4); 49 inline int snprintf(char* buffer, 50 size_t size, 51 _Printf_format_string_ const char* format, 52 ...) { 53 va_list arguments; 54 va_start(arguments, format); 55 int result = vsnprintf(buffer, size, format, arguments); 56 va_end(arguments); 57 return result; 58 } 59 60 // BSD-style safe and consistent string copy functions. 61 // Copies |src| to |dst|, where |dst_size| is the total allocated size of |dst|. 62 // Copies at most |dst_size|-1 characters, and always NULL terminates |dst|, as 63 // long as |dst_size| is not 0. Returns the length of |src| in characters. 64 // If the return value is >= dst_size, then the output was truncated. 65 // NOTE: All sizes are in number of characters, NOT in bytes. 66 BASE_EXPORT size_t strlcpy(char* dst, const char* src, size_t dst_size); 67 BASE_EXPORT size_t wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size); 68 69 // Scan a wprintf format string to determine whether it's portable across a 70 // variety of systems. This function only checks that the conversion 71 // specifiers used by the format string are supported and have the same meaning 72 // on a variety of systems. It doesn't check for other errors that might occur 73 // within a format string. 74 // 75 // Nonportable conversion specifiers for wprintf are: 76 // - 's' and 'c' without an 'l' length modifier. %s and %c operate on char 77 // data on all systems except Windows, which treat them as wchar_t data. 78 // Use %ls and %lc for wchar_t data instead. 79 // - 'S' and 'C', which operate on wchar_t data on all systems except Windows, 80 // which treat them as char data. Use %ls and %lc for wchar_t data 81 // instead. 82 // - 'F', which is not identified by Windows wprintf documentation. 83 // - 'D', 'O', and 'U', which are deprecated and not available on all systems. 84 // Use %ld, %lo, and %lu instead. 85 // 86 // Note that there is no portable conversion specifier for char data when 87 // working with wprintf. 88 // 89 // This function is intended to be called from base::vswprintf. 90 BASE_EXPORT bool IsWprintfFormatPortable(const wchar_t* format); 91 92 // ASCII-specific tolower. The standard library's tolower is locale sensitive, 93 // so we don't want to use it here. 94 inline char ToLowerASCII(char c) { 95 return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c; 96 } 97 inline char16 ToLowerASCII(char16 c) { 98 return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c; 99 } 100 101 // ASCII-specific toupper. The standard library's toupper is locale sensitive, 102 // so we don't want to use it here. 103 inline char ToUpperASCII(char c) { 104 return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c; 105 } 106 inline char16 ToUpperASCII(char16 c) { 107 return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c; 108 } 109 110 // Converts the given string to it's ASCII-lowercase equivalent. 111 BASE_EXPORT std::string ToLowerASCII(StringPiece str); 112 BASE_EXPORT string16 ToLowerASCII(StringPiece16 str); 113 114 // Converts the given string to it's ASCII-uppercase equivalent. 115 BASE_EXPORT std::string ToUpperASCII(StringPiece str); 116 BASE_EXPORT string16 ToUpperASCII(StringPiece16 str); 117 118 // Functor for case-insensitive ASCII comparisons for STL algorithms like 119 // std::search. 120 // 121 // Note that a full Unicode version of this functor is not possible to write 122 // because case mappings might change the number of characters, depend on 123 // context (combining accents), and require handling UTF-16. If you need 124 // proper Unicode support, use base::i18n::ToLower/FoldCase and then just 125 // use a normal operator== on the result. 126 template<typename Char> struct CaseInsensitiveCompareASCII { 127 public: 128 bool operator()(Char x, Char y) const { 129 return ToLowerASCII(x) == ToLowerASCII(y); 130 } 131 }; 132 133 // Like strcasecmp for case-insensitive ASCII characters only. Returns: 134 // -1 (a < b) 135 // 0 (a == b) 136 // 1 (a > b) 137 // (unlike strcasecmp which can return values greater or less than 1/-1). For 138 // full Unicode support, use base::i18n::ToLower or base::i18h::FoldCase 139 // and then just call the normal string operators on the result. 140 BASE_EXPORT int CompareCaseInsensitiveASCII(StringPiece a, StringPiece b); 141 BASE_EXPORT int CompareCaseInsensitiveASCII(StringPiece16 a, StringPiece16 b); 142 143 // Equality for ASCII case-insensitive comparisons. For full Unicode support, 144 // use base::i18n::ToLower or base::i18h::FoldCase and then compare with either 145 // == or !=. 146 BASE_EXPORT bool EqualsCaseInsensitiveASCII(StringPiece a, StringPiece b); 147 BASE_EXPORT bool EqualsCaseInsensitiveASCII(StringPiece16 a, StringPiece16 b); 148 149 // These threadsafe functions return references to globally unique empty 150 // strings. 151 // 152 // It is likely faster to construct a new empty string object (just a few 153 // instructions to set the length to 0) than to get the empty string singleton 154 // returned by these functions (which requires threadsafe singleton access). 155 // 156 // Therefore, DO NOT USE THESE AS A GENERAL-PURPOSE SUBSTITUTE FOR DEFAULT 157 // CONSTRUCTORS. There is only one case where you should use these: functions 158 // which need to return a string by reference (e.g. as a class member 159 // accessor), and don't have an empty string to use (e.g. in an error case). 160 // These should not be used as initializers, function arguments, or return 161 // values for functions which return by value or outparam. 162 BASE_EXPORT const std::string& EmptyString(); 163 BASE_EXPORT const string16& EmptyString16(); 164 165 // Contains the set of characters representing whitespace in the corresponding 166 // encoding. Null-terminated. The ASCII versions are the whitespaces as defined 167 // by HTML5, and don't include control characters. 168 BASE_EXPORT extern const wchar_t kWhitespaceWide[]; // Includes Unicode. 169 BASE_EXPORT extern const char16 kWhitespaceUTF16[]; // Includes Unicode. 170 BASE_EXPORT extern const char kWhitespaceASCII[]; 171 BASE_EXPORT extern const char16 kWhitespaceASCIIAs16[]; // No unicode. 172 173 // Null-terminated string representing the UTF-8 byte order mark. 174 BASE_EXPORT extern const char kUtf8ByteOrderMark[]; 175 176 // Removes characters in |remove_chars| from anywhere in |input|. Returns true 177 // if any characters were removed. |remove_chars| must be null-terminated. 178 // NOTE: Safe to use the same variable for both |input| and |output|. 179 BASE_EXPORT bool RemoveChars(const string16& input, 180 const StringPiece16& remove_chars, 181 string16* output); 182 BASE_EXPORT bool RemoveChars(const std::string& input, 183 const StringPiece& remove_chars, 184 std::string* output); 185 186 // Replaces characters in |replace_chars| from anywhere in |input| with 187 // |replace_with|. Each character in |replace_chars| will be replaced with 188 // the |replace_with| string. Returns true if any characters were replaced. 189 // |replace_chars| must be null-terminated. 190 // NOTE: Safe to use the same variable for both |input| and |output|. 191 BASE_EXPORT bool ReplaceChars(const string16& input, 192 const StringPiece16& replace_chars, 193 const string16& replace_with, 194 string16* output); 195 BASE_EXPORT bool ReplaceChars(const std::string& input, 196 const StringPiece& replace_chars, 197 const std::string& replace_with, 198 std::string* output); 199 200 enum TrimPositions { 201 TRIM_NONE = 0, 202 TRIM_LEADING = 1 << 0, 203 TRIM_TRAILING = 1 << 1, 204 TRIM_ALL = TRIM_LEADING | TRIM_TRAILING, 205 }; 206 207 // Removes characters in |trim_chars| from the beginning and end of |input|. 208 // The 8-bit version only works on 8-bit characters, not UTF-8. 209 // 210 // It is safe to use the same variable for both |input| and |output| (this is 211 // the normal usage to trim in-place). 212 BASE_EXPORT bool TrimString(const string16& input, 213 StringPiece16 trim_chars, 214 string16* output); 215 BASE_EXPORT bool TrimString(const std::string& input, 216 StringPiece trim_chars, 217 std::string* output); 218 219 // StringPiece versions of the above. The returned pieces refer to the original 220 // buffer. 221 BASE_EXPORT StringPiece16 TrimString(StringPiece16 input, 222 const StringPiece16& trim_chars, 223 TrimPositions positions); 224 BASE_EXPORT StringPiece TrimString(StringPiece input, 225 const StringPiece& trim_chars, 226 TrimPositions positions); 227 228 // Truncates a string to the nearest UTF-8 character that will leave 229 // the string less than or equal to the specified byte size. 230 BASE_EXPORT void TruncateUTF8ToByteSize(const std::string& input, 231 const size_t byte_size, 232 std::string* output); 233 234 // Trims any whitespace from either end of the input string. 235 // 236 // The StringPiece versions return a substring referencing the input buffer. 237 // The ASCII versions look only for ASCII whitespace. 238 // 239 // The std::string versions return where whitespace was found. 240 // NOTE: Safe to use the same variable for both input and output. 241 BASE_EXPORT TrimPositions TrimWhitespace(const string16& input, 242 TrimPositions positions, 243 string16* output); 244 BASE_EXPORT StringPiece16 TrimWhitespace(StringPiece16 input, 245 TrimPositions positions); 246 BASE_EXPORT TrimPositions TrimWhitespaceASCII(const std::string& input, 247 TrimPositions positions, 248 std::string* output); 249 BASE_EXPORT StringPiece TrimWhitespaceASCII(StringPiece input, 250 TrimPositions positions); 251 252 // Searches for CR or LF characters. Removes all contiguous whitespace 253 // strings that contain them. This is useful when trying to deal with text 254 // copied from terminals. 255 // Returns |text|, with the following three transformations: 256 // (1) Leading and trailing whitespace is trimmed. 257 // (2) If |trim_sequences_with_line_breaks| is true, any other whitespace 258 // sequences containing a CR or LF are trimmed. 259 // (3) All other whitespace sequences are converted to single spaces. 260 BASE_EXPORT string16 CollapseWhitespace( 261 const string16& text, 262 bool trim_sequences_with_line_breaks); 263 BASE_EXPORT std::string CollapseWhitespaceASCII( 264 const std::string& text, 265 bool trim_sequences_with_line_breaks); 266 267 // Returns true if |input| is empty or contains only characters found in 268 // |characters|. 269 BASE_EXPORT bool ContainsOnlyChars(const StringPiece& input, 270 const StringPiece& characters); 271 BASE_EXPORT bool ContainsOnlyChars(const StringPiece16& input, 272 const StringPiece16& characters); 273 274 // Returns true if the specified string matches the criteria. How can a wide 275 // string be 8-bit or UTF8? It contains only characters that are < 256 (in the 276 // first case) or characters that use only 8-bits and whose 8-bit 277 // representation looks like a UTF-8 string (the second case). 278 // 279 // Note that IsStringUTF8 checks not only if the input is structurally 280 // valid but also if it doesn't contain any non-character codepoint 281 // (e.g. U+FFFE). It's done on purpose because all the existing callers want 282 // to have the maximum 'discriminating' power from other encodings. If 283 // there's a use case for just checking the structural validity, we have to 284 // add a new function for that. 285 // 286 // IsStringASCII assumes the input is likely all ASCII, and does not leave early 287 // if it is not the case. 288 BASE_EXPORT bool IsStringUTF8(const StringPiece& str); 289 BASE_EXPORT bool IsStringASCII(const StringPiece& str); 290 BASE_EXPORT bool IsStringASCII(const StringPiece16& str); 291 // A convenience adaptor for WebStrings, as they don't convert into 292 // StringPieces directly. 293 BASE_EXPORT bool IsStringASCII(const string16& str); 294 #if defined(WCHAR_T_IS_UTF32) 295 BASE_EXPORT bool IsStringASCII(const std::wstring& str); 296 #endif 297 298 // Compare the lower-case form of the given string against the given 299 // previously-lower-cased ASCII string (typically a constant). 300 BASE_EXPORT bool LowerCaseEqualsASCII(StringPiece str, 301 StringPiece lowecase_ascii); 302 BASE_EXPORT bool LowerCaseEqualsASCII(StringPiece16 str, 303 StringPiece lowecase_ascii); 304 305 // Performs a case-sensitive string compare of the given 16-bit string against 306 // the given 8-bit ASCII string (typically a constant). The behavior is 307 // undefined if the |ascii| string is not ASCII. 308 BASE_EXPORT bool EqualsASCII(StringPiece16 str, StringPiece ascii); 309 310 // Indicates case sensitivity of comparisons. Only ASCII case insensitivity 311 // is supported. Full Unicode case-insensitive conversions would need to go in 312 // base/i18n so it can use ICU. 313 // 314 // If you need to do Unicode-aware case-insensitive StartsWith/EndsWith, it's 315 // best to call base::i18n::ToLower() or base::i18n::FoldCase() (see 316 // base/i18n/case_conversion.h for usage advice) on the arguments, and then use 317 // the results to a case-sensitive comparison. 318 enum class CompareCase { 319 SENSITIVE, 320 INSENSITIVE_ASCII, 321 }; 322 323 BASE_EXPORT bool StartsWith(StringPiece str, 324 StringPiece search_for, 325 CompareCase case_sensitivity); 326 BASE_EXPORT bool StartsWith(StringPiece16 str, 327 StringPiece16 search_for, 328 CompareCase case_sensitivity); 329 BASE_EXPORT bool EndsWith(StringPiece str, 330 StringPiece search_for, 331 CompareCase case_sensitivity); 332 BASE_EXPORT bool EndsWith(StringPiece16 str, 333 StringPiece16 search_for, 334 CompareCase case_sensitivity); 335 336 // Determines the type of ASCII character, independent of locale (the C 337 // library versions will change based on locale). 338 template <typename Char> 339 inline bool IsAsciiWhitespace(Char c) { 340 return c == ' ' || c == '\r' || c == '\n' || c == '\t'; 341 } 342 template <typename Char> 343 inline bool IsAsciiAlpha(Char c) { 344 return ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z')); 345 } 346 template <typename Char> 347 inline bool IsAsciiDigit(Char c) { 348 return c >= '0' && c <= '9'; 349 } 350 351 template <typename Char> 352 inline bool IsHexDigit(Char c) { 353 return (c >= '0' && c <= '9') || 354 (c >= 'A' && c <= 'F') || 355 (c >= 'a' && c <= 'f'); 356 } 357 358 // Returns the integer corresponding to the given hex character. For example: 359 // '4' -> 4 360 // 'a' -> 10 361 // 'B' -> 11 362 // Assumes the input is a valid hex character. DCHECKs in debug builds if not. 363 BASE_EXPORT char HexDigitToInt(wchar_t c); 364 365 // Returns true if it's a Unicode whitespace character. 366 BASE_EXPORT bool IsUnicodeWhitespace(wchar_t c); 367 368 // Return a byte string in human-readable format with a unit suffix. Not 369 // appropriate for use in any UI; use of FormatBytes and friends in ui/base is 370 // highly recommended instead. TODO(avi): Figure out how to get callers to use 371 // FormatBytes instead; remove this. 372 BASE_EXPORT string16 FormatBytesUnlocalized(int64_t bytes); 373 374 // Starting at |start_offset| (usually 0), replace the first instance of 375 // |find_this| with |replace_with|. 376 BASE_EXPORT void ReplaceFirstSubstringAfterOffset( 377 base::string16* str, 378 size_t start_offset, 379 StringPiece16 find_this, 380 StringPiece16 replace_with); 381 BASE_EXPORT void ReplaceFirstSubstringAfterOffset( 382 std::string* str, 383 size_t start_offset, 384 StringPiece find_this, 385 StringPiece replace_with); 386 387 // Starting at |start_offset| (usually 0), look through |str| and replace all 388 // instances of |find_this| with |replace_with|. 389 // 390 // This does entire substrings; use std::replace in <algorithm> for single 391 // characters, for example: 392 // std::replace(str.begin(), str.end(), 'a', 'b'); 393 BASE_EXPORT void ReplaceSubstringsAfterOffset( 394 string16* str, 395 size_t start_offset, 396 StringPiece16 find_this, 397 StringPiece16 replace_with); 398 BASE_EXPORT void ReplaceSubstringsAfterOffset( 399 std::string* str, 400 size_t start_offset, 401 StringPiece find_this, 402 StringPiece replace_with); 403 404 // Reserves enough memory in |str| to accommodate |length_with_null| characters, 405 // sets the size of |str| to |length_with_null - 1| characters, and returns a 406 // pointer to the underlying contiguous array of characters. This is typically 407 // used when calling a function that writes results into a character array, but 408 // the caller wants the data to be managed by a string-like object. It is 409 // convenient in that is can be used inline in the call, and fast in that it 410 // avoids copying the results of the call from a char* into a string. 411 // 412 // |length_with_null| must be at least 2, since otherwise the underlying string 413 // would have size 0, and trying to access &((*str)[0]) in that case can result 414 // in a number of problems. 415 // 416 // Internally, this takes linear time because the resize() call 0-fills the 417 // underlying array for potentially all 418 // (|length_with_null - 1| * sizeof(string_type::value_type)) bytes. Ideally we 419 // could avoid this aspect of the resize() call, as we expect the caller to 420 // immediately write over this memory, but there is no other way to set the size 421 // of the string, and not doing that will mean people who access |str| rather 422 // than str.c_str() will get back a string of whatever size |str| had on entry 423 // to this function (probably 0). 424 BASE_EXPORT char* WriteInto(std::string* str, size_t length_with_null); 425 BASE_EXPORT char16* WriteInto(string16* str, size_t length_with_null); 426 #ifndef OS_WIN 427 BASE_EXPORT wchar_t* WriteInto(std::wstring* str, size_t length_with_null); 428 #endif 429 430 // Does the opposite of SplitString(). 431 BASE_EXPORT std::string JoinString(const std::vector<std::string>& parts, 432 StringPiece separator); 433 BASE_EXPORT string16 JoinString(const std::vector<string16>& parts, 434 StringPiece16 separator); 435 436 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively. 437 // Additionally, any number of consecutive '$' characters is replaced by that 438 // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be 439 // NULL. This only allows you to use up to nine replacements. 440 BASE_EXPORT string16 ReplaceStringPlaceholders( 441 const string16& format_string, 442 const std::vector<string16>& subst, 443 std::vector<size_t>* offsets); 444 445 BASE_EXPORT std::string ReplaceStringPlaceholders( 446 const StringPiece& format_string, 447 const std::vector<std::string>& subst, 448 std::vector<size_t>* offsets); 449 450 // Single-string shortcut for ReplaceStringHolders. |offset| may be NULL. 451 BASE_EXPORT string16 ReplaceStringPlaceholders(const string16& format_string, 452 const string16& a, 453 size_t* offset); 454 455 } // namespace base 456 457 #if defined(OS_WIN) 458 #include "base/strings/string_util_win.h" 459 #elif defined(OS_POSIX) 460 #include "base/strings/string_util_posix.h" 461 #else 462 #error Define string operations appropriately for your platform 463 #endif 464 465 #endif // BASE_STRINGS_STRING_UTIL_H_ 466