| // Copyright 2013 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| // |
| // This file defines utility functions for working with strings. |
| |
| #ifndef BASE_STRINGS_STRING_UTIL_H_ |
| #define BASE_STRINGS_STRING_UTIL_H_ |
| |
| #include <ctype.h> |
| #include <stdarg.h> // va_list |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <initializer_list> |
| #include <string> |
| #include <type_traits> |
| #include <vector> |
| |
| #include "polyfills/base/base_export.h" |
| #include "polyfills/base/check_op.h" |
| #include "base/compiler_specific.h" |
| #include "base/containers/span.h" |
| #include "base/cxx20_to_address.h" |
| #include "base/strings/string_piece.h" // For implicit conversions. |
| #include "build/build_config.h" |
| |
| namespace gurl_base { |
| |
| // C standard-library functions that aren't cross-platform are provided as |
| // "gurl_base::...", and their prototypes are listed below. These functions are |
| // then implemented as inline calls to the platform-specific equivalents in the |
| // platform-specific headers. |
| |
| // Wrapper for vsnprintf that always null-terminates and always returns the |
| // number of characters that would be in an untruncated formatted |
| // string, even when truncation occurs. |
| int vsnprintf(char* buffer, size_t size, const char* format, va_list arguments) |
| PRINTF_FORMAT(3, 0); |
| |
| // Some of these implementations need to be inlined. |
| |
| // We separate the declaration from the implementation of this inline |
| // function just so the PRINTF_FORMAT works. |
| inline int snprintf(char* buffer, size_t size, const char* format, ...) |
| PRINTF_FORMAT(3, 4); |
| inline int snprintf(char* buffer, size_t size, const char* format, ...) { |
| va_list arguments; |
| va_start(arguments, format); |
| int result = vsnprintf(buffer, size, format, arguments); |
| va_end(arguments); |
| return result; |
| } |
| |
| // BSD-style safe and consistent string copy functions. |
| // Copies |src| to |dst|, where |dst_size| is the total allocated size of |dst|. |
| // Copies at most |dst_size|-1 characters, and always NULL terminates |dst|, as |
| // long as |dst_size| is not 0. Returns the length of |src| in characters. |
| // If the return value is >= dst_size, then the output was truncated. |
| // NOTE: All sizes are in number of characters, NOT in bytes. |
| BASE_EXPORT size_t strlcpy(char* dst, const char* src, size_t dst_size); |
| BASE_EXPORT size_t wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size); |
| |
| // Scan a wprintf format string to determine whether it's portable across a |
| // variety of systems. This function only checks that the conversion |
| // specifiers used by the format string are supported and have the same meaning |
| // on a variety of systems. It doesn't check for other errors that might occur |
| // within a format string. |
| // |
| // Nonportable conversion specifiers for wprintf are: |
| // - 's' and 'c' without an 'l' length modifier. %s and %c operate on char |
| // data on all systems except Windows, which treat them as wchar_t data. |
| // Use %ls and %lc for wchar_t data instead. |
| // - 'S' and 'C', which operate on wchar_t data on all systems except Windows, |
| // which treat them as char data. Use %ls and %lc for wchar_t data |
| // instead. |
| // - 'F', which is not identified by Windows wprintf documentation. |
| // - 'D', 'O', and 'U', which are deprecated and not available on all systems. |
| // Use %ld, %lo, and %lu instead. |
| // |
| // Note that there is no portable conversion specifier for char data when |
| // working with wprintf. |
| // |
| // This function is intended to be called from gurl_base::vswprintf. |
| BASE_EXPORT bool IsWprintfFormatPortable(const wchar_t* format); |
| |
| // Simplified implementation of C++20's std::basic_string_view(It, End). |
| // Reference: https://wg21.link/string.view.cons |
| template <typename CharT, typename Iter> |
| constexpr BasicStringPiece<CharT> MakeBasicStringPiece(Iter begin, Iter end) { |
| GURL_DCHECK_GE(end - begin, 0); |
| return {gurl_base::to_address(begin), static_cast<size_t>(end - begin)}; |
| } |
| |
| // Explicit instantiations of MakeBasicStringPiece for the BasicStringPiece |
| // aliases defined in base/strings/string_piece_forward.h |
| template <typename Iter> |
| constexpr StringPiece MakeStringPiece(Iter begin, Iter end) { |
| return MakeBasicStringPiece<char>(begin, end); |
| } |
| |
| template <typename Iter> |
| constexpr StringPiece16 MakeStringPiece16(Iter begin, Iter end) { |
| return MakeBasicStringPiece<char16_t>(begin, end); |
| } |
| |
| template <typename Iter> |
| constexpr WStringPiece MakeWStringPiece(Iter begin, Iter end) { |
| return MakeBasicStringPiece<wchar_t>(begin, end); |
| } |
| |
| // ASCII-specific tolower. The standard library's tolower is locale sensitive, |
| // so we don't want to use it here. |
| template <typename CharT, |
| typename = std::enable_if_t<std::is_integral<CharT>::value>> |
| CharT ToLowerASCII(CharT c) { |
| return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c; |
| } |
| |
| // ASCII-specific toupper. The standard library's toupper is locale sensitive, |
| // so we don't want to use it here. |
| template <typename CharT, |
| typename = std::enable_if_t<std::is_integral<CharT>::value>> |
| CharT ToUpperASCII(CharT c) { |
| return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c; |
| } |
| |
| // Converts the given string to it's ASCII-lowercase equivalent. |
| BASE_EXPORT std::string ToLowerASCII(StringPiece str); |
| BASE_EXPORT std::u16string ToLowerASCII(StringPiece16 str); |
| |
| // Converts the given string to it's ASCII-uppercase equivalent. |
| BASE_EXPORT std::string ToUpperASCII(StringPiece str); |
| BASE_EXPORT std::u16string ToUpperASCII(StringPiece16 str); |
| |
| // Functor for case-insensitive ASCII comparisons for STL algorithms like |
| // std::search. |
| // |
| // Note that a full Unicode version of this functor is not possible to write |
| // because case mappings might change the number of characters, depend on |
| // context (combining accents), and require handling UTF-16. If you need |
| // proper Unicode support, use gurl_base::i18n::ToLower/FoldCase and then just |
| // use a normal operator== on the result. |
| template<typename Char> struct CaseInsensitiveCompareASCII { |
| public: |
| bool operator()(Char x, Char y) const { |
| return ToLowerASCII(x) == ToLowerASCII(y); |
| } |
| }; |
| |
| // Like strcasecmp for case-insensitive ASCII characters only. Returns: |
| // -1 (a < b) |
| // 0 (a == b) |
| // 1 (a > b) |
| // (unlike strcasecmp which can return values greater or less than 1/-1). For |
| // full Unicode support, use gurl_base::i18n::ToLower or gurl_base::i18h::FoldCase |
| // and then just call the normal string operators on the result. |
| BASE_EXPORT int CompareCaseInsensitiveASCII(StringPiece a, StringPiece b); |
| BASE_EXPORT int CompareCaseInsensitiveASCII(StringPiece16 a, StringPiece16 b); |
| |
| // Equality for ASCII case-insensitive comparisons. For full Unicode support, |
| // use gurl_base::i18n::ToLower or gurl_base::i18h::FoldCase and then compare with either |
| // == or !=. |
| BASE_EXPORT bool EqualsCaseInsensitiveASCII(StringPiece a, StringPiece b); |
| BASE_EXPORT bool EqualsCaseInsensitiveASCII(StringPiece16 a, StringPiece16 b); |
| |
| // These threadsafe functions return references to globally unique empty |
| // strings. |
| // |
| // It is likely faster to construct a new empty string object (just a few |
| // instructions to set the length to 0) than to get the empty string instance |
| // returned by these functions (which requires threadsafe static access). |
| // |
| // Therefore, DO NOT USE THESE AS A GENERAL-PURPOSE SUBSTITUTE FOR DEFAULT |
| // CONSTRUCTORS. There is only one case where you should use these: functions |
| // which need to return a string by reference (e.g. as a class member |
| // accessor), and don't have an empty string to use (e.g. in an error case). |
| // These should not be used as initializers, function arguments, or return |
| // values for functions which return by value or outparam. |
| BASE_EXPORT const std::string& EmptyString(); |
| BASE_EXPORT const std::u16string& EmptyString16(); |
| |
| // Contains the set of characters representing whitespace in the corresponding |
| // encoding. Null-terminated. The ASCII versions are the whitespaces as defined |
| // by HTML5, and don't include control characters. |
| BASE_EXPORT extern const wchar_t kWhitespaceWide[]; // Includes Unicode. |
| BASE_EXPORT extern const char16_t kWhitespaceUTF16[]; // Includes Unicode. |
| BASE_EXPORT extern const char16_t |
| kWhitespaceNoCrLfUTF16[]; // Unicode w/o CR/LF. |
| BASE_EXPORT extern const char kWhitespaceASCII[]; |
| BASE_EXPORT extern const char16_t kWhitespaceASCIIAs16[]; // No unicode. |
| |
| // Null-terminated string representing the UTF-8 byte order mark. |
| BASE_EXPORT extern const char kUtf8ByteOrderMark[]; |
| |
| // Removes characters in |remove_chars| from anywhere in |input|. Returns true |
| // if any characters were removed. |remove_chars| must be null-terminated. |
| // NOTE: Safe to use the same variable for both |input| and |output|. |
| BASE_EXPORT bool RemoveChars(StringPiece16 input, |
| StringPiece16 remove_chars, |
| std::u16string* output); |
| BASE_EXPORT bool RemoveChars(StringPiece input, |
| StringPiece remove_chars, |
| std::string* output); |
| |
| // Replaces characters in |replace_chars| from anywhere in |input| with |
| // |replace_with|. Each character in |replace_chars| will be replaced with |
| // the |replace_with| string. Returns true if any characters were replaced. |
| // |replace_chars| must be null-terminated. |
| // NOTE: Safe to use the same variable for both |input| and |output|. |
| BASE_EXPORT bool ReplaceChars(StringPiece16 input, |
| StringPiece16 replace_chars, |
| StringPiece16 replace_with, |
| std::u16string* output); |
| BASE_EXPORT bool ReplaceChars(StringPiece input, |
| StringPiece replace_chars, |
| StringPiece replace_with, |
| std::string* output); |
| |
| enum TrimPositions { |
| TRIM_NONE = 0, |
| TRIM_LEADING = 1 << 0, |
| TRIM_TRAILING = 1 << 1, |
| TRIM_ALL = TRIM_LEADING | TRIM_TRAILING, |
| }; |
| |
| // Removes characters in |trim_chars| from the beginning and end of |input|. |
| // The 8-bit version only works on 8-bit characters, not UTF-8. Returns true if |
| // any characters were removed. |
| // |
| // It is safe to use the same variable for both |input| and |output| (this is |
| // the normal usage to trim in-place). |
| BASE_EXPORT bool TrimString(StringPiece16 input, |
| StringPiece16 trim_chars, |
| std::u16string* output); |
| BASE_EXPORT bool TrimString(StringPiece input, |
| StringPiece trim_chars, |
| std::string* output); |
| |
| // StringPiece versions of the above. The returned pieces refer to the original |
| // buffer. |
| BASE_EXPORT StringPiece16 TrimString(StringPiece16 input, |
| StringPiece16 trim_chars, |
| TrimPositions positions); |
| BASE_EXPORT StringPiece TrimString(StringPiece input, |
| StringPiece trim_chars, |
| TrimPositions positions); |
| |
| // Truncates a string to the nearest UTF-8 character that will leave |
| // the string less than or equal to the specified byte size. |
| BASE_EXPORT void TruncateUTF8ToByteSize(const std::string& input, |
| const size_t byte_size, |
| std::string* output); |
| |
| // Trims any whitespace from either end of the input string. |
| // |
| // The StringPiece versions return a substring referencing the input buffer. |
| // The ASCII versions look only for ASCII whitespace. |
| // |
| // The std::string versions return where whitespace was found. |
| // NOTE: Safe to use the same variable for both input and output. |
| BASE_EXPORT TrimPositions TrimWhitespace(StringPiece16 input, |
| TrimPositions positions, |
| std::u16string* output); |
| BASE_EXPORT StringPiece16 TrimWhitespace(StringPiece16 input, |
| TrimPositions positions); |
| BASE_EXPORT TrimPositions TrimWhitespaceASCII(StringPiece input, |
| TrimPositions positions, |
| std::string* output); |
| BASE_EXPORT StringPiece TrimWhitespaceASCII(StringPiece input, |
| TrimPositions positions); |
| |
| // Searches for CR or LF characters. Removes all contiguous whitespace |
| // strings that contain them. This is useful when trying to deal with text |
| // copied from terminals. |
| // Returns |text|, with the following three transformations: |
| // (1) Leading and trailing whitespace is trimmed. |
| // (2) If |trim_sequences_with_line_breaks| is true, any other whitespace |
| // sequences containing a CR or LF are trimmed. |
| // (3) All other whitespace sequences are converted to single spaces. |
| BASE_EXPORT std::u16string CollapseWhitespace( |
| StringPiece16 text, |
| bool trim_sequences_with_line_breaks); |
| BASE_EXPORT std::string CollapseWhitespaceASCII( |
| StringPiece text, |
| bool trim_sequences_with_line_breaks); |
| |
| // Returns true if |input| is empty or contains only characters found in |
| // |characters|. |
| BASE_EXPORT bool ContainsOnlyChars(StringPiece input, StringPiece characters); |
| BASE_EXPORT bool ContainsOnlyChars(StringPiece16 input, |
| StringPiece16 characters); |
| |
| // Returns true if |str| is structurally valid UTF-8 and also doesn't |
| // contain any non-character code point (e.g. U+10FFFE). Prohibiting |
| // non-characters increases the likelihood of detecting non-UTF-8 in |
| // real-world text, for callers which do not need to accept |
| // non-characters in strings. |
| BASE_EXPORT bool IsStringUTF8(StringPiece str); |
| |
| // Returns true if |str| contains valid UTF-8, allowing non-character |
| // code points. |
| BASE_EXPORT bool IsStringUTF8AllowingNoncharacters(StringPiece str); |
| |
| // Returns true if |str| contains only valid ASCII character values. |
| // Note 1: IsStringASCII executes in time determined solely by the |
| // length of the string, not by its contents, so it is robust against |
| // timing attacks for all strings of equal length. |
| // Note 2: IsStringASCII assumes the input is likely all ASCII, and |
| // does not leave early if it is not the case. |
| BASE_EXPORT bool IsStringASCII(StringPiece str); |
| BASE_EXPORT bool IsStringASCII(StringPiece16 str); |
| |
| #if defined(WCHAR_T_IS_UTF32) |
| BASE_EXPORT bool IsStringASCII(WStringPiece str); |
| #endif |
| |
| // Compare the lower-case form of the given string against the given |
| // previously-lower-cased ASCII string (typically a constant). |
| BASE_EXPORT bool LowerCaseEqualsASCII(StringPiece str, |
| StringPiece lowercase_ascii); |
| BASE_EXPORT bool LowerCaseEqualsASCII(StringPiece16 str, |
| StringPiece lowercase_ascii); |
| |
| // Performs a case-sensitive string compare of the given 16-bit string against |
| // the given 8-bit ASCII string (typically a constant). The behavior is |
| // undefined if the |ascii| string is not ASCII. |
| BASE_EXPORT bool EqualsASCII(StringPiece16 str, StringPiece ascii); |
| |
| // Indicates case sensitivity of comparisons. Only ASCII case insensitivity |
| // is supported. Full Unicode case-insensitive conversions would need to go in |
| // base/i18n so it can use ICU. |
| // |
| // If you need to do Unicode-aware case-insensitive StartsWith/EndsWith, it's |
| // best to call gurl_base::i18n::ToLower() or gurl_base::i18n::FoldCase() (see |
| // base/i18n/case_conversion.h for usage advice) on the arguments, and then use |
| // the results to a case-sensitive comparison. |
| enum class CompareCase { |
| SENSITIVE, |
| INSENSITIVE_ASCII, |
| }; |
| |
| BASE_EXPORT bool StartsWith( |
| StringPiece str, |
| StringPiece search_for, |
| CompareCase case_sensitivity = CompareCase::SENSITIVE); |
| BASE_EXPORT bool StartsWith( |
| StringPiece16 str, |
| StringPiece16 search_for, |
| CompareCase case_sensitivity = CompareCase::SENSITIVE); |
| BASE_EXPORT bool EndsWith( |
| StringPiece str, |
| StringPiece search_for, |
| CompareCase case_sensitivity = CompareCase::SENSITIVE); |
| BASE_EXPORT bool EndsWith( |
| StringPiece16 str, |
| StringPiece16 search_for, |
| CompareCase case_sensitivity = CompareCase::SENSITIVE); |
| |
| // Determines the type of ASCII character, independent of locale (the C |
| // library versions will change based on locale). |
| template <typename Char> |
| inline bool IsAsciiWhitespace(Char c) { |
| return c == ' ' || c == '\r' || c == '\n' || c == '\t' || c == '\f'; |
| } |
| template <typename Char> |
| inline bool IsAsciiAlpha(Char c) { |
| return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'); |
| } |
| template <typename Char> |
| inline bool IsAsciiUpper(Char c) { |
| return c >= 'A' && c <= 'Z'; |
| } |
| template <typename Char> |
| inline bool IsAsciiLower(Char c) { |
| return c >= 'a' && c <= 'z'; |
| } |
| template <typename Char> |
| inline bool IsAsciiDigit(Char c) { |
| return c >= '0' && c <= '9'; |
| } |
| template <typename Char> |
| inline bool IsAsciiPrintable(Char c) { |
| return c >= ' ' && c <= '~'; |
| } |
| |
| template <typename Char> |
| inline bool IsHexDigit(Char c) { |
| return (c >= '0' && c <= '9') || |
| (c >= 'A' && c <= 'F') || |
| (c >= 'a' && c <= 'f'); |
| } |
| |
| // Returns the integer corresponding to the given hex character. For example: |
| // '4' -> 4 |
| // 'a' -> 10 |
| // 'B' -> 11 |
| // Assumes the input is a valid hex character. DCHECKs in debug builds if not. |
| BASE_EXPORT char HexDigitToInt(wchar_t c); |
| |
| // Returns true if it's a Unicode whitespace character. |
| BASE_EXPORT bool IsUnicodeWhitespace(wchar_t c); |
| |
| // Return a byte string in human-readable format with a unit suffix. Not |
| // appropriate for use in any UI; use of FormatBytes and friends in ui/base is |
| // highly recommended instead. TODO(avi): Figure out how to get callers to use |
| // FormatBytes instead; remove this. |
| BASE_EXPORT std::u16string FormatBytesUnlocalized(int64_t bytes); |
| |
| // Starting at |start_offset| (usually 0), replace the first instance of |
| // |find_this| with |replace_with|. |
| BASE_EXPORT void ReplaceFirstSubstringAfterOffset(std::u16string* str, |
| size_t start_offset, |
| StringPiece16 find_this, |
| StringPiece16 replace_with); |
| BASE_EXPORT void ReplaceFirstSubstringAfterOffset( |
| std::string* str, |
| size_t start_offset, |
| StringPiece find_this, |
| StringPiece replace_with); |
| |
| // Starting at |start_offset| (usually 0), look through |str| and replace all |
| // instances of |find_this| with |replace_with|. |
| // |
| // This does entire substrings; use std::replace in <algorithm> for single |
| // characters, for example: |
| // std::replace(str.begin(), str.end(), 'a', 'b'); |
| BASE_EXPORT void ReplaceSubstringsAfterOffset(std::u16string* str, |
| size_t start_offset, |
| StringPiece16 find_this, |
| StringPiece16 replace_with); |
| BASE_EXPORT void ReplaceSubstringsAfterOffset( |
| std::string* str, |
| size_t start_offset, |
| StringPiece find_this, |
| StringPiece replace_with); |
| |
| // Reserves enough memory in |str| to accommodate |length_with_null| characters, |
| // sets the size of |str| to |length_with_null - 1| characters, and returns a |
| // pointer to the underlying contiguous array of characters. This is typically |
| // used when calling a function that writes results into a character array, but |
| // the caller wants the data to be managed by a string-like object. It is |
| // convenient in that is can be used inline in the call, and fast in that it |
| // avoids copying the results of the call from a char* into a string. |
| // |
| // Internally, this takes linear time because the resize() call 0-fills the |
| // underlying array for potentially all |
| // (|length_with_null - 1| * sizeof(string_type::value_type)) bytes. Ideally we |
| // could avoid this aspect of the resize() call, as we expect the caller to |
| // immediately write over this memory, but there is no other way to set the size |
| // of the string, and not doing that will mean people who access |str| rather |
| // than str.c_str() will get back a string of whatever size |str| had on entry |
| // to this function (probably 0). |
| BASE_EXPORT char* WriteInto(std::string* str, size_t length_with_null); |
| BASE_EXPORT char16_t* WriteInto(std::u16string* str, size_t length_with_null); |
| |
| // Joins a list of strings into a single string, inserting |separator| (which |
| // may be empty) in between all elements. |
| // |
| // Note this is inverse of SplitString()/SplitStringPiece() defined in |
| // string_split.h. |
| // |
| // If possible, callers should build a vector of StringPieces and use the |
| // StringPiece variant, so that they do not create unnecessary copies of |
| // strings. For example, instead of using SplitString, modifying the vector, |
| // then using JoinString, use SplitStringPiece followed by JoinString so that no |
| // copies of those strings are created until the final join operation. |
| // |
| // Use StrCat (in base/strings/strcat.h) if you don't need a separator. |
| BASE_EXPORT std::string JoinString(span<const std::string> parts, |
| StringPiece separator); |
| BASE_EXPORT std::u16string JoinString(span<const std::u16string> parts, |
| StringPiece16 separator); |
| BASE_EXPORT std::string JoinString(span<const StringPiece> parts, |
| StringPiece separator); |
| BASE_EXPORT std::u16string JoinString(span<const StringPiece16> parts, |
| StringPiece16 separator); |
| // Explicit initializer_list overloads are required to break ambiguity when used |
| // with a literal initializer list (otherwise the compiler would not be able to |
| // decide between the string and StringPiece overloads). |
| BASE_EXPORT std::string JoinString(std::initializer_list<StringPiece> parts, |
| StringPiece separator); |
| BASE_EXPORT std::u16string JoinString( |
| std::initializer_list<StringPiece16> parts, |
| StringPiece16 separator); |
| |
| // Replace $1-$2-$3..$9 in the format string with values from |subst|. |
| // Additionally, any number of consecutive '$' characters is replaced by that |
| // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be |
| // NULL. This only allows you to use up to nine replacements. |
| BASE_EXPORT std::u16string ReplaceStringPlaceholders( |
| StringPiece16 format_string, |
| const std::vector<std::u16string>& subst, |
| std::vector<size_t>* offsets); |
| |
| BASE_EXPORT std::string ReplaceStringPlaceholders( |
| StringPiece format_string, |
| const std::vector<std::string>& subst, |
| std::vector<size_t>* offsets); |
| |
| // Single-string shortcut for ReplaceStringHolders. |offset| may be NULL. |
| BASE_EXPORT std::u16string ReplaceStringPlaceholders( |
| const std::u16string& format_string, |
| const std::u16string& a, |
| size_t* offset); |
| |
| } // namespace base |
| |
| #if BUILDFLAG(IS_WIN) |
| #include "base/strings/string_util_win.h" |
| #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) |
| #include "base/strings/string_util_posix.h" |
| #else |
| #error Define string operations appropriately for your platform |
| #endif |
| |
| #endif // BASE_STRINGS_STRING_UTIL_H_ |