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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 <string>

 #include <vector>

 #include "base/base_export.h"

 #include "base/basictypes.h"

 #include "base/compiler_specific.h"

 #include "base/strings/string16.h"

 #include "base/strings/string_piece.h"  // For implicit conversions.

 // Safe standard library wrappers for all platforms.

 namespace base {

 // C standard-library functions like "strncasecmp" and "snprintf" that aren't

 // cross-platform are provided as "base::strncasecmp", and their prototypes

 // are listed below.  These functions are then implemented as inline calls

 // to the platform-specific equivalents in the platform-specific headers.

 // Compares the two strings s1 and s2 without regard to case using

 // the current locale; returns 0 if they are equal, 1 if s1 > s2, and -1 if

 // s2 > s1 according to a lexicographic comparison.

 int strcasecmp(const char* s1, const char* s2);

 // Compares up to count characters of s1 and s2 without regard to case using

 // the current locale; returns 0 if they are equal, 1 if s1 > s2, and -1 if

 // s2 > s1 according to a lexicographic comparison.

 int strncasecmp(const char* s1, const char* s2, size_t count);

 // Same as strncmp but for char16 strings.

 int strncmp16(const char16* s1, const char16* s2, size_t count);

 // 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);

 // vswprintf always null-terminates, but when truncation occurs, it will either

 // return -1 or the number of characters that would be in an untruncated

 // formatted string.  The actual return value depends on the underlying

 // C library's vswprintf implementation.

 int vswprintf(wchar_t* buffer, size_t size,

               const wchar_t* format, va_list arguments)

     WPRINTF_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;

 }

 // We separate the declaration from the implementation of this inline

 // function just so the WPRINTF_FORMAT works.

 inline int swprintf(wchar_t* buffer, size_t size, const wchar_t* format, ...)

     WPRINTF_FORMAT(3, 4);

 inline int swprintf(wchar_t* buffer, size_t size, const wchar_t* format, ...) {

   va_list arguments;

   va_start(arguments, format);

   int result = vswprintf(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.

 template <class Char> inline Char ToLowerASCII(Char 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 <class Char> inline Char ToUpperASCII(Char c) {

   return (c >= 'a' && c <= 'z') ? (c + ('A' - 'a')) : c;

 }

 // Function objects to aid in comparing/searching strings.

 template<typename Char> struct CaseInsensitiveCompare {

  public:

   bool operator()(Char x, Char y) const {

     // TODO(darin): Do we really want to do locale sensitive comparisons here?

     // See http://crbug.com/24917

     return tolower(x) == tolower(y);

   }

 };

 template<typename Char> struct CaseInsensitiveCompareASCII {

  public:

   bool operator()(Char x, Char y) const {

     return ToLowerASCII(x) == ToLowerASCII(y);

   }

 };

 }  // namespace base

 #if defined(OS_WIN)

 #include "base/strings/string_util_win.h"

 #elif defined(OS_POSIX)

 #include "base/strings/string_util_posix.h"

 #else

 #error Define string operations appropriately for your platform

 #endif

 // These threadsafe functions return references to globally unique empty

 // strings.

 //

 // 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::wstring& EmptyWString();

 BASE_EXPORT const string16& EmptyString16();

 BASE_EXPORT extern const wchar_t kWhitespaceWide[];

 BASE_EXPORT extern const char16 kWhitespaceUTF16[];

 BASE_EXPORT extern const char kWhitespaceASCII[];

 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,

                              const char16 remove_chars[],

                              string16* output);

 BASE_EXPORT bool RemoveChars(const std::string& input,

                              const char 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,

                               const char16 replace_chars[],

                               const string16& replace_with,

                               string16* output);

 BASE_EXPORT bool ReplaceChars(const std::string& input,

                               const char replace_chars[],

                               const std::string& replace_with,

                               std::string* output);

 // Removes characters in |trim_chars| from the beginning and end of |input|.

 // |trim_chars| must be null-terminated.

 // NOTE: Safe to use the same variable for both |input| and |output|.

 BASE_EXPORT bool TrimString(const std::wstring& input,

                             const wchar_t trim_chars[],

                             std::wstring* output);

 BASE_EXPORT bool TrimString(const string16& input,

                             const char16 trim_chars[],

                             string16* output);

 BASE_EXPORT bool TrimString(const std::string& input,

                             const char trim_chars[],

                             std::string* output);

 // 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.  Returns where

 // whitespace was found.

 // The non-wide version has two functions:

 // * TrimWhitespaceASCII()

 //   This function is for ASCII strings and only looks for ASCII whitespace;

 // Please choose the best one according to your usage.

 // NOTE: Safe to use the same variable for both input and output.

 enum TrimPositions {

   TRIM_NONE     = 0,

   TRIM_LEADING  = 1 << 0,

   TRIM_TRAILING = 1 << 1,

   TRIM_ALL      = TRIM_LEADING | TRIM_TRAILING,

 };

 BASE_EXPORT TrimPositions TrimWhitespace(const string16& input,

                                          TrimPositions positions,

                                          string16* output);

 BASE_EXPORT TrimPositions TrimWhitespaceASCII(const std::string& input,

                                               TrimPositions positions,

                                               std::string* output);

 // Deprecated. This function is only for backward compatibility and calls

 // TrimWhitespaceASCII().

 BASE_EXPORT TrimPositions TrimWhitespace(const std::string& input,

                                          TrimPositions positions,

                                          std::string* output);

 // 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::wstring CollapseWhitespace(

     const std::wstring& text,

     bool trim_sequences_with_line_breaks);

 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 the passed string is empty or contains only white-space

 // characters.

 BASE_EXPORT bool ContainsOnlyWhitespaceASCII(const std::string& str);

 BASE_EXPORT bool ContainsOnlyWhitespace(const string16& str);

 // Returns true if |input| is empty or contains only characters found in

 // |characters|.

 BASE_EXPORT bool ContainsOnlyChars(const std::wstring& input,

                                    const std::wstring& characters);

 BASE_EXPORT bool ContainsOnlyChars(const string16& input,

                                    const string16& characters);

 BASE_EXPORT bool ContainsOnlyChars(const std::string& input,

                                    const std::string& characters);

 // Converts to 7-bit ASCII by truncating. The result must be known to be ASCII

 // beforehand.

 BASE_EXPORT std::string WideToASCII(const std::wstring& wide);

 BASE_EXPORT std::string UTF16ToASCII(const string16& utf16);

 // Converts the given wide string to the corresponding Latin1. This will fail

 // (return false) if any characters are more than 255.

 BASE_EXPORT bool WideToLatin1(const std::wstring& wide, std::string* latin1);

 // Returns true if the specified string matches the criteria. How can a wide

 // string be 8-bit or UTF8? It contains only characters that are < 256 (in the

 // first case) or characters that use only 8-bits and whose 8-bit

 // representation looks like a UTF-8 string (the second case).

 //

 // Note that IsStringUTF8 checks not only if the input is structurally

 // valid but also if it doesn't contain any non-character codepoint

 // (e.g. U+FFFE). It's done on purpose because all the existing callers want

 // to have the maximum 'discriminating' power from other encodings. If

 // there's a use case for just checking the structural validity, we have to

 // add a new function for that.

 BASE_EXPORT bool IsStringUTF8(const std::string& str);

 BASE_EXPORT bool IsStringASCII(const std::wstring& str);

 BASE_EXPORT bool IsStringASCII(const string16& str);

 // Converts the elements of the given string.  This version uses a pointer to

 // clearly differentiate it from the non-pointer variant.

 template <class str> inline void StringToLowerASCII(str* s) {

   for (typename str::iterator i = s->begin(); i != s->end(); ++i)

     *i = base::ToLowerASCII(*i);

 }

 template <class str> inline str StringToLowerASCII(const str& s) {

   // for std::string and std::wstring

   str output(s);

   StringToLowerASCII(&output);

   return output;

 }

 // Converts the elements of the given string.  This version uses a pointer to

 // clearly differentiate it from the non-pointer variant.

 template <class str> inline void StringToUpperASCII(str* s) {

   for (typename str::iterator i = s->begin(); i != s->end(); ++i)

     *i = base::ToUpperASCII(*i);

 }

 template <class str> inline str StringToUpperASCII(const str& s) {

   // for std::string and std::wstring

   str output(s);

   StringToUpperASCII(&output);

   return output;

 }

 // Compare the lower-case form of the given string against the given ASCII

 // string.  This is useful for doing checking if an input string matches some

 // token, and it is optimized to avoid intermediate string copies.  This API is

 // borrowed from the equivalent APIs in Mozilla.

 BASE_EXPORT bool LowerCaseEqualsASCII(const std::string& a, const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(const std::wstring& a, const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(const string16& a, const char* b);

 // Same thing, but with string iterators instead.

 BASE_EXPORT bool LowerCaseEqualsASCII(std::string::const_iterator a_begin,

                                       std::string::const_iterator a_end,

                                       const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(std::wstring::const_iterator a_begin,

                                       std::wstring::const_iterator a_end,

                                       const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(string16::const_iterator a_begin,

                                       string16::const_iterator a_end,

                                       const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(const char* a_begin,

                                       const char* a_end,

                                       const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(const wchar_t* a_begin,

                                       const wchar_t* a_end,

                                       const char* b);

 BASE_EXPORT bool LowerCaseEqualsASCII(const char16* a_begin,

                                       const char16* a_end,

                                       const char* b);

 // Performs a case-sensitive string compare. The behavior is undefined if both

 // strings are not ASCII.

 BASE_EXPORT bool EqualsASCII(const string16& a, const base::StringPiece& b);

 // Returns true if str starts with search, or false otherwise.

 BASE_EXPORT bool StartsWithASCII(const std::string& str,

                                  const std::string& search,

                                  bool case_sensitive);

 BASE_EXPORT bool StartsWith(const std::wstring& str,

                             const std::wstring& search,

                             bool case_sensitive);

 BASE_EXPORT bool StartsWith(const string16& str,

                             const string16& search,

                             bool case_sensitive);

 // Returns true if str ends with search, or false otherwise.

 BASE_EXPORT bool EndsWith(const std::string& str,

                           const std::string& search,

                           bool case_sensitive);

 BASE_EXPORT bool EndsWith(const std::wstring& str,

                           const std::wstring& search,

                           bool case_sensitive);

 BASE_EXPORT bool EndsWith(const string16& str,

                           const string16& search,

                           bool case_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';

 }

 template <typename Char>

 inline bool IsAsciiAlpha(Char c) {

   return ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'));

 }

 template <typename Char>

 inline bool IsAsciiDigit(Char c) {

   return c >= '0' && c <= '9';

 }

 template <typename Char>

 inline bool IsHexDigit(Char c) {

   return (c >= '0' && c <= '9') ||

          (c >= 'A' && c <= 'F') ||

          (c >= 'a' && c <= 'f');

 }

 template <typename Char>

 inline Char HexDigitToInt(Char c) {

   DCHECK(IsHexDigit(c));

   if (c >= '0' && c <= '9')

     return c - '0';

   if (c >= 'A' && c <= 'F')

     return c - 'A' + 10;

   if (c >= 'a' && c <= 'f')

     return c - 'a' + 10;

   return 0;

 }

 // Returns true if it's a whitespace character.

 inline bool IsWhitespace(wchar_t c) {

   return wcschr(kWhitespaceWide, c) != NULL;

 }

 // 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 bytes);

 // Starting at |start_offset| (usually 0), replace the first instance of

 // |find_this| with |replace_with|.

 BASE_EXPORT void ReplaceFirstSubstringAfterOffset(

     string16* str,

     string16::size_type start_offset,

     const string16& find_this,

     const string16& replace_with);

 BASE_EXPORT void ReplaceFirstSubstringAfterOffset(

     std::string* str,

     std::string::size_type start_offset,

     const std::string& find_this,

     const std::string& 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,

     string16::size_type start_offset,

     const string16& find_this,

     const string16& replace_with);

 BASE_EXPORT void ReplaceSubstringsAfterOffset(

     std::string* str,

     std::string::size_type start_offset,

     const std::string& find_this,

     const std::string& 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.

 //

 // |length_with_null| must be at least 2, since otherwise the underlying string

 // would have size 0, and trying to access &((*str)[0]) in that case can result

 // in a number of problems.

 //

 // 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).

 template <class string_type>

 inline typename string_type::value_type* WriteInto(string_type* str,

                                                    size_t length_with_null) {

   DCHECK_GT(length_with_null, 1u);

   str->reserve(length_with_null);

   str->resize(length_with_null - 1);

   return &((*str)[0]);

 }

 //-----------------------------------------------------------------------------

 // Splits a string into its fields delimited by any of the characters in

 // |delimiters|.  Each field is added to the |tokens| vector.  Returns the

 // number of tokens found.

 BASE_EXPORT size_t Tokenize(const std::wstring& str,

                             const std::wstring& delimiters,

                             std::vector<std::wstring>* tokens);

 BASE_EXPORT size_t Tokenize(const string16& str,

                             const string16& delimiters,

                             std::vector<string16>* tokens);

 BASE_EXPORT size_t Tokenize(const std::string& str,

                             const std::string& delimiters,

                             std::vector<std::string>* tokens);

 BASE_EXPORT size_t Tokenize(const base::StringPiece& str,

                             const base::StringPiece& delimiters,

                             std::vector<base::StringPiece>* tokens);

 // Does the opposite of SplitString().

 BASE_EXPORT string16 JoinString(const std::vector<string16>& parts, char16 s);

 BASE_EXPORT std::string JoinString(

     const std::vector<std::string>& parts, char s);

 // Join |parts| using |separator|.

 BASE_EXPORT std::string JoinString(

     const std::vector<std::string>& parts,

     const std::string& separator);

 BASE_EXPORT string16 JoinString(

     const std::vector<string16>& parts,

     const string16& separator);

 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively.

 // 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(

     const base::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);

 // Returns true if the string passed in matches the pattern. The pattern

 // string can contain wildcards like * and ?

 // The backslash character (\) is an escape character for * and ?

 // We limit the patterns to having a max of 16 * or ? characters.

 // ? matches 0 or 1 character, while * matches 0 or more characters.

 BASE_EXPORT bool MatchPattern(const base::StringPiece& string,

                               const base::StringPiece& pattern);

 BASE_EXPORT bool MatchPattern(const string16& string, const string16& pattern);

 // Hack to convert any char-like type to its unsigned counterpart.

 // For example, it will convert char, signed char and unsigned char to unsigned

 // char.

 template<typename T>

 struct ToUnsigned {

   typedef T Unsigned;

 };

 template<>

 struct ToUnsigned<char> {

   typedef unsigned char Unsigned;

 };

 template<>

 struct ToUnsigned<signed char> {

   typedef unsigned char Unsigned;

 };

 template<>

 struct ToUnsigned<wchar_t> {

 #if defined(WCHAR_T_IS_UTF16)

   typedef unsigned short Unsigned;

 #elif defined(WCHAR_T_IS_UTF32)

   typedef uint32 Unsigned;

 #endif

 };

 template<>

 struct ToUnsigned<short> {

   typedef unsigned short Unsigned;

 };

 #endif  // BASE_STRINGS_STRING_UTIL_H_