text: // 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);
  
  // 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.
  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);
    }
  };
  
  // 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 singleton
  // returned by these functions (which requires threadsafe singleton 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.
  BASE_EXPORT extern const wchar_t kWhitespaceWide[];
  BASE_EXPORT extern const char16 kWhitespaceUTF16[];
  BASE_EXPORT extern const char kWhitespaceASCII[];
  
  // 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,
                               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 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,
                                           base::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);
  
  }  // 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
  
  // 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 base::string16 CollapseWhitespace(
      const base::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 base::string16& str);
  
  // Returns true if |input| is empty or contains only characters found in
  // |characters|.
  BASE_EXPORT bool ContainsOnlyChars(const base::string16& input,
                                     const base::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 base::string16& utf16);
  
  // 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 base::StringPiece& str);
  BASE_EXPORT bool IsStringASCII(const base::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 base::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(base::string16::const_iterator a_begin,
                                        base::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 base::char16* a_begin,
                                        const base::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 base::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 base::string16& str,
                              const base::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 base::string16& str,
                            const base::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(base::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 base::string16 FormatBytesUnlocalized(int64 bytes);
  
  // Starting at |start_offset| (usually 0), replace the first instance of
  // |find_this| with |replace_with|.
  BASE_EXPORT void ReplaceFirstSubstringAfterOffset(
      base::string16* str,
      base::string16::size_type start_offset,
      const base::string16& find_this,
      const base::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(
      base::string16* str,
      base::string16::size_type start_offset,
      const base::string16& find_this,
      const base::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 base::string16& str,
                              const base::string16& delimiters,
                              std::vector<base::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 base::string16 JoinString(const std::vector<base::string16>& parts,
                                        base::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 base::string16 JoinString(
      const std::vector<base::string16>& parts,
      const base::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 base::string16 ReplaceStringPlaceholders(
      const base::string16& format_string,
      const std::vector<base::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 base::string16 ReplaceStringPlaceholders(
      const base::string16& format_string,
      const base::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 base::string16& string,
                                const base::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_
  