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+// 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 <vector>
+
+#include "base/base_export.h"
+#include "base/compiler_specific.h"
+#include "base/stl_util.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_piece.h" // For implicit conversions.
+#include "build/build_config.h"
+
+namespace base {
+
+// C standard-library functions that aren't cross-platform are provided as
+// "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 base::vswprintf.
+BASE_EXPORT bool IsWprintfFormatPortable(const wchar_t* format);
+
+// ASCII-specific tolower. The standard library's tolower is locale sensitive,
+// so we don't want to use it here.
+inline char ToLowerASCII(char c) {
+ return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c;
+}
+inline char16 ToLowerASCII(char16 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.
+inline char ToUpperASCII(char c) {
+ return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c;
+}
+inline char16 ToUpperASCII(char16 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 string16 ToLowerASCII(StringPiece16 str);
+
+// Converts the given string to it's ASCII-uppercase equivalent.
+BASE_EXPORT std::string ToUpperASCII(StringPiece str);
+BASE_EXPORT string16 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 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 base::i18n::ToLower or 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 base::i18n::ToLower or 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 string16& 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 kWhitespaceUTF16[]; // Includes Unicode.
+BASE_EXPORT extern const char16 kWhitespaceNoCrLfUTF16[]; // Unicode w/o CR/LF.
+BASE_EXPORT extern const char kWhitespaceASCII[];
+BASE_EXPORT extern const char16 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(const string16& input,
+ StringPiece16 remove_chars,
+ string16* output);
+BASE_EXPORT bool RemoveChars(const std::string& 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(const string16& input,
+ StringPiece16 replace_chars,
+ StringPiece16 replace_with,
+ string16* output);
+BASE_EXPORT bool ReplaceChars(const std::string& 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,
+ string16* 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);
+
+#if defined(WCHAR_T_IS_UTF16)
+// Utility functions to access the underlying string buffer as a wide char
+// pointer.
+//
+// Note: These functions violate strict aliasing when char16 and wchar_t are
+// unrelated types. We thus pass -fno-strict-aliasing to the compiler on
+// non-Windows platforms [1], and rely on it being off in Clang's CL mode [2].
+//
+// [1] https://crrev.com/b9a0976622/build/config/compiler/BUILD.gn#244
+// [2]
+// https://github.com/llvm/llvm-project/blob/1e28a66/clang/lib/Driver/ToolChains/Clang.cpp#L3949
+inline wchar_t* as_writable_wcstr(char16* str) {
+ return reinterpret_cast<wchar_t*>(str);
+}
+
+inline wchar_t* as_writable_wcstr(string16& str) {
+ return reinterpret_cast<wchar_t*>(data(str));
+}
+
+inline const wchar_t* as_wcstr(const char16* str) {
+ return reinterpret_cast<const wchar_t*>(str);
+}
+
+inline const wchar_t* as_wcstr(StringPiece16 str) {
+ return reinterpret_cast<const wchar_t*>(str.data());
+}
+
+// Utility functions to access the underlying string buffer as a char16 pointer.
+inline char16* as_writable_u16cstr(wchar_t* str) {
+ return reinterpret_cast<char16*>(str);
+}
+
+inline char16* as_writable_u16cstr(std::wstring& str) {
+ return reinterpret_cast<char16*>(data(str));
+}
+
+inline const char16* as_u16cstr(const wchar_t* str) {
+ return reinterpret_cast<const char16*>(str);
+}
+
+inline const char16* as_u16cstr(WStringPiece str) {
+ return reinterpret_cast<const char16*>(str.data());
+}
+
+// Utility functions to convert between base::WStringPiece and
+// base::StringPiece16.
+inline WStringPiece AsWStringPiece(StringPiece16 str) {
+ return WStringPiece(as_wcstr(str.data()), str.size());
+}
+
+inline StringPiece16 AsStringPiece16(WStringPiece str) {
+ return StringPiece16(as_u16cstr(str.data()), str.size());
+}
+
+inline std::wstring AsWString(StringPiece16 str) {
+ return std::wstring(as_wcstr(str.data()), str.size());
+}
+
+inline string16 AsString16(WStringPiece str) {
+ return string16(as_u16cstr(str.data()), str.size());
+}
+#endif // defined(WCHAR_T_IS_UTF16)
+
+// 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,
+ string16* 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 string16 CollapseWhitespace(
+ const string16& text,
+ bool trim_sequences_with_line_breaks);
+BASE_EXPORT std::string CollapseWhitespaceASCII(
+ const std::string& 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 lowecase_ascii);
+BASE_EXPORT bool LowerCaseEqualsASCII(StringPiece16 str,
+ StringPiece lowecase_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 base::i18n::ToLower() or 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);
+BASE_EXPORT bool StartsWith(StringPiece16 str,
+ StringPiece16 search_for,
+ CompareCase case_sensitivity);
+BASE_EXPORT bool EndsWith(StringPiece str,
+ StringPiece search_for,
+ CompareCase case_sensitivity);
+BASE_EXPORT bool EndsWith(StringPiece16 str,
+ StringPiece16 search_for,
+ CompareCase case_sensitivity);
+
+// 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 string16 FormatBytesUnlocalized(int64_t bytes);
+
+// Starting at |start_offset| (usually 0), replace the first instance of
+// |find_this| with |replace_with|.
+BASE_EXPORT void ReplaceFirstSubstringAfterOffset(
+ base::string16* 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(
+ string16* 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* WriteInto(string16* str, size_t length_with_null);
+
+// Joins a vector or 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(const std::vector<std::string>& parts,
+ StringPiece separator);
+BASE_EXPORT string16 JoinString(const std::vector<string16>& parts,
+ StringPiece16 separator);
+BASE_EXPORT std::string JoinString(const std::vector<StringPiece>& parts,
+ StringPiece separator);
+BASE_EXPORT string16 JoinString(const std::vector<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 string16 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 string16 ReplaceStringPlaceholders(
+ const string16& format_string,
+ const std::vector<string16>& 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 string16 ReplaceStringPlaceholders(const string16& format_string,
+ const string16& a,
+ size_t* offset);
+
+#if defined(OS_WIN) && defined(BASE_STRING16_IS_STD_U16STRING)
+BASE_EXPORT TrimPositions TrimWhitespace(WStringPiece input,
+ TrimPositions positions,
+ std::wstring* output);
+
+BASE_EXPORT WStringPiece TrimWhitespace(WStringPiece input,
+ TrimPositions positions);
+
+BASE_EXPORT bool TrimString(WStringPiece input,
+ WStringPiece trim_chars,
+ std::wstring* output);
+
+BASE_EXPORT WStringPiece TrimString(WStringPiece input,
+ WStringPiece trim_chars,
+ TrimPositions positions);
+
+BASE_EXPORT wchar_t* WriteInto(std::wstring* str, size_t length_with_null);
+#endif
+
+} // namespace base
+
+#if defined(OS_WIN)
+#include "base/strings/string_util_win.h"
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
+#include "base/strings/string_util_posix.h"
+#else
+#error Define string operations appropriately for your platform
+#endif
+
+#endif // BASE_STRINGS_STRING_UTIL_H_