string.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "stdafx.h"
#include "debug.h"
#include "core/alloc_func.hpp"
#include "core/math_func.hpp"
#include "string_func.h"
#include "string_base.h"
 
#include "table/control_codes.h"
 
#include <stdarg.h>
#include <ctype.h> /* required for tolower() */
#include <sstream>
#include <iomanip>
 
#ifdef _MSC_VER
#include <errno.h> // required by vsnprintf implementation for MSVC
#endif
 
#ifdef _WIN32
#include "os/windows/win32.h"
#endif
 
#ifdef WITH_UNISCRIBE
#include "os/windows/string_uniscribe.h"
#endif
 
#ifdef WITH_ICU_I18N
/* Required by strnatcmp. */
#include <unicode/ustring.h>
#include "language.h"
#include "gfx_func.h"
#endif /* WITH_ICU_I18N */
 
#if defined(WITH_COCOA)
#include "os/macosx/string_osx.h"
#endif
 
/* The function vsnprintf is used internally to perform the required formatting
 * tasks. As such this one must be allowed, and makes sure it's terminated. */
#include "safeguards.h"
#undef vsnprintf
 
int CDECL vseprintf(char *str, const char *last, const char *format, va_list ap)
{
  ptrdiff_t diff = last - str;
  if (diff < 0) return 0;
  return std::min(static_cast<int>(diff), vsnprintf(str, diff + 1, format, ap));
}
 
char *strecat(char *dst, const char *src, const char *last)
{
  assert(dst <= last);
  while (*dst != '\0') {
    if (dst == last) return dst;
    dst++;
  }
 
  return strecpy(dst, src, last);
}
 
 
char *strecpy(char *dst, const char *src, const char *last)
{
  assert(dst <= last);
  while (dst != last && *src != '\0') {
    *dst++ = *src++;
  }
  *dst = '\0';
 
  if (dst == last && *src != '\0') {
#if defined(STRGEN) || defined(SETTINGSGEN)
    error("String too long for destination buffer");
#else /* STRGEN || SETTINGSGEN */
    Debug(misc, 0, "String too long for destination buffer");
#endif /* STRGEN || SETTINGSGEN */
  }
  return dst;
}
 
char *stredup(const char *s, const char *last)
{
  size_t len = last == nullptr ? strlen(s) : ttd_strnlen(s, last - s + 1);
  char *tmp = CallocT<char>(len + 1);
  memcpy(tmp, s, len);
  return tmp;
}
 
char *CDECL str_fmt(const char *str, ...)
{
  char buf[4096];
  va_list va;
 
  va_start(va, str);
  int len = vseprintf(buf, lastof(buf), str, va);
  va_end(va);
  char *p = MallocT<char>(len + 1);
  memcpy(p, buf, len + 1);
  return p;
}
 
std::string FormatArrayAsHex(span<const byte> data)
{
  std::ostringstream ss;
  ss << std::uppercase << std::setfill('0') << std::setw(2) << std::hex;
 
  for (auto b : data) {
    ss << b;
  }
 
  return ss.str();
}
 
void str_fix_scc_encoded(char *str, const char *last)
{
  while (str <= last && *str != '\0') {
    size_t len = Utf8EncodedCharLen(*str);
    if ((len == 0 && str + 4 > last) || str + len > last) break;
 
    WChar c;
    Utf8Decode(&c, str);
    if (c == '\0') break;
 
    if (c == 0xE028 || c == 0xE02A) {
      c = SCC_ENCODED;
    }
    str += Utf8Encode(str, c);
  }
  *str = '\0';
}
 
 
template <class T>
static void StrMakeValidInPlace(T &dst, const char *str, const char *last, StringValidationSettings settings)
{
  /* Assume the ABSOLUTE WORST to be in str as it comes from the outside. */
 
  while (str <= last && *str != '\0') {
    size_t len = Utf8EncodedCharLen(*str);
    WChar c;
    /* If the first byte does not look like the first byte of an encoded
     * character, i.e. encoded length is 0, then this byte is definitely bad
     * and it should be skipped.
     * When the first byte looks like the first byte of an encoded character,
     * then the remaining bytes in the string are checked whether the whole
     * encoded character can be there. If that is not the case, this byte is
     * skipped.
     * Finally we attempt to decode the encoded character, which does certain
     * extra validations to see whether the correct number of bytes were used
     * to encode the character. If that is not the case, the byte is probably
     * invalid and it is skipped. We could emit a question mark, but then the
     * logic below cannot just copy bytes, it would need to re-encode the
     * decoded characters as the length in bytes may have changed.
     *
     * The goals here is to get as much valid Utf8 encoded characters from the
     * source string to the destination string.
     *
     * Note: a multi-byte encoded termination ('\0') will trigger the encoded
     * char length and the decoded length to differ, so it will be ignored as
     * invalid character data. If it were to reach the termination, then we
     * would also reach the "last" byte of the string and a normal '\0'
     * termination will be placed after it.
     */
    if (len == 0 || str + len > last || len != Utf8Decode(&c, str)) {
      /* Maybe the next byte is still a valid character? */
      str++;
      continue;
    }
 
    if ((IsPrintable(c) && (c < SCC_SPRITE_START || c > SCC_SPRITE_END)) || ((settings & SVS_ALLOW_CONTROL_CODE) != 0 && c == SCC_ENCODED)) {
      /* Copy the character back. Even if dst is current the same as str
       * (i.e. no characters have been changed) this is quicker than
       * moving the pointers ahead by len */
      do {
        *dst++ = *str++;
      } while (--len != 0);
    } else if ((settings & SVS_ALLOW_NEWLINE) != 0 && c == '\n') {
      *dst++ = *str++;
    } else {
      if ((settings & SVS_ALLOW_NEWLINE) != 0 && c == '\r' && str[1] == '\n') {
        str += len;
        continue;
      }
      /* Replace the undesirable character with a question mark */
      str += len;
      if ((settings & SVS_REPLACE_WITH_QUESTION_MARK) != 0) *dst++ = '?';
    }
  }
 
  /* String termination, if needed, is left to the caller of this function. */
}
 
void StrMakeValidInPlace(char *str, const char *last, StringValidationSettings settings)
{
  char *dst = str;
  StrMakeValidInPlace(dst, str, last, settings);
  *dst = '\0';
}
 
void StrMakeValidInPlace(char *str, StringValidationSettings settings)
{
  /* We know it is '\0' terminated. */
  StrMakeValidInPlace(str, str + strlen(str), settings);
}
 
std::string StrMakeValid(const std::string &str, StringValidationSettings settings)
{
  auto buf = str.data();
  auto last = buf + str.size();
 
  std::ostringstream dst;
  std::ostreambuf_iterator<char> dst_iter(dst);
  StrMakeValidInPlace(dst_iter, buf, last, settings);
 
  return dst.str();
}
 
bool StrValid(const char *str, const char *last)
{
  /* Assume the ABSOLUTE WORST to be in str as it comes from the outside. */
 
  while (str <= last && *str != '\0') {
    size_t len = Utf8EncodedCharLen(*str);
    /* Encoded length is 0 if the character isn't known.
     * The length check is needed to prevent Utf8Decode to read
     * over the terminating '\0' if that happens to be placed
     * within the encoding of an UTF8 character. */
    if (len == 0 || str + len > last) return false;
 
    WChar c;
    len = Utf8Decode(&c, str);
    if (!IsPrintable(c) || (c >= SCC_SPRITE_START && c <= SCC_SPRITE_END)) {
      return false;
    }
 
    str += len;
  }
 
  return *str == '\0';
}
 
static void StrLeftTrimInPlace(std::string &str)
{
  size_t pos = str.find_first_not_of(' ');
  str.erase(0, pos);
}
 
static void StrRightTrimInPlace(std::string &str)
{
  size_t pos = str.find_last_not_of(' ');
  if (pos != std::string::npos) str.erase(pos + 1);
}
 
void StrTrimInPlace(std::string &str)
{
  StrLeftTrimInPlace(str);
  StrRightTrimInPlace(str);
}
 
bool StrStartsWith(const std::string_view str, const std::string_view prefix)
{
  size_t prefix_len = prefix.size();
  if (str.size() < prefix_len) return false;
  return str.compare(0, prefix_len, prefix, 0, prefix_len) == 0;
}
 
bool StrEndsWith(const std::string_view str, const std::string_view suffix)
{
  size_t suffix_len = suffix.size();
  if (str.size() < suffix_len) return false;
  return str.compare(str.size() - suffix_len, suffix_len, suffix, 0, suffix_len) == 0;
}
 
 
void str_strip_colours(char *str)
{
  char *dst = str;
  WChar c;
  size_t len;
 
  for (len = Utf8Decode(&c, str); c != '\0'; len = Utf8Decode(&c, str)) {
    if (c < SCC_BLUE || c > SCC_BLACK) {
      /* Copy the character back. Even if dst is current the same as str
       * (i.e. no characters have been changed) this is quicker than
       * moving the pointers ahead by len */
      do {
        *dst++ = *str++;
      } while (--len != 0);
    } else {
      /* Just skip (strip) the colour codes */
      str += len;
    }
  }
  *dst = '\0';
}
 
size_t Utf8StringLength(const char *s)
{
  size_t len = 0;
  const char *t = s;
  while (Utf8Consume(&t) != 0) len++;
  return len;
}
 
size_t Utf8StringLength(const std::string &str)
{
  return Utf8StringLength(str.c_str());
}
 
bool strtolower(char *str)
{
  bool changed = false;
  for (; *str != '\0'; str++) {
    char new_str = tolower(*str);
    changed |= new_str != *str;
    *str = new_str;
  }
  return changed;
}
 
bool strtolower(std::string &str, std::string::size_type offs)
{
  bool changed = false;
  for (auto ch = str.begin() + offs; ch != str.end(); ++ch) {
    auto new_ch = static_cast<char>(tolower(static_cast<unsigned char>(*ch)));
    changed |= new_ch != *ch;
    *ch = new_ch;
  }
  return changed;
}
 
bool IsValidChar(WChar key, CharSetFilter afilter)
{
  switch (afilter) {
    case CS_ALPHANUMERAL:  return IsPrintable(key);
    case CS_NUMERAL:       return (key >= '0' && key <= '9');
    case CS_NUMERAL_SPACE: return (key >= '0' && key <= '9') || key == ' ';
    case CS_ALPHA:         return IsPrintable(key) && !(key >= '0' && key <= '9');
    case CS_HEXADECIMAL:   return (key >= '0' && key <= '9') || (key >= 'a' && key <= 'f') || (key >= 'A' && key <= 'F');
    default: NOT_REACHED();
  }
}
 
#ifdef _WIN32
#if defined(_MSC_VER) && _MSC_VER < 1900
 
int CDECL vsnprintf(char *str, size_t size, const char *format, va_list ap)
{
  if (size == 0) return 0;
 
  errno = 0;
  int ret = _vsnprintf(str, size, format, ap);
 
  if (ret < 0) {
    if (errno != ERANGE) {
      /* There's a formatting error, better get that looked
       * at properly instead of ignoring it. */
      NOT_REACHED();
    }
  } else if ((size_t)ret < size) {
    /* The buffer is big enough for the number of
     * characters stored (excluding null), i.e.
     * the string has been null-terminated. */
    return ret;
  }
 
  /* The buffer is too small for _vsnprintf to write the
   * null-terminator at its end and return size. */
  str[size - 1] = '\0';
  return (int)size;
}
#endif /* _MSC_VER */
 
#endif /* _WIN32 */
 
int CDECL seprintf(char *str, const char *last, const char *format, ...)
{
  va_list ap;
 
  va_start(ap, format);
  int ret = vseprintf(str, last, format, ap);
  va_end(ap);
  return ret;
}
 
 
char *md5sumToString(char *buf, const char *last, const uint8 md5sum[16])
{
  char *p = buf;
 
  for (uint i = 0; i < 16; i++) {
    p += seprintf(p, last, "%02X", md5sum[i]);
  }
 
  return p;
}
 
 
/* UTF-8 handling routines */
 
 
size_t Utf8Decode(WChar *c, const char *s)
{
  assert(c != nullptr);
 
  if (!HasBit(s[0], 7)) {
    /* Single byte character: 0xxxxxxx */
    *c = s[0];
    return 1;
  } else if (GB(s[0], 5, 3) == 6) {
    if (IsUtf8Part(s[1])) {
      /* Double byte character: 110xxxxx 10xxxxxx */
      *c = GB(s[0], 0, 5) << 6 | GB(s[1], 0, 6);
      if (*c >= 0x80) return 2;
    }
  } else if (GB(s[0], 4, 4) == 14) {
    if (IsUtf8Part(s[1]) && IsUtf8Part(s[2])) {
      /* Triple byte character: 1110xxxx 10xxxxxx 10xxxxxx */
      *c = GB(s[0], 0, 4) << 12 | GB(s[1], 0, 6) << 6 | GB(s[2], 0, 6);
      if (*c >= 0x800) return 3;
    }
  } else if (GB(s[0], 3, 5) == 30) {
    if (IsUtf8Part(s[1]) && IsUtf8Part(s[2]) && IsUtf8Part(s[3])) {
      /* 4 byte character: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
      *c = GB(s[0], 0, 3) << 18 | GB(s[1], 0, 6) << 12 | GB(s[2], 0, 6) << 6 | GB(s[3], 0, 6);
      if (*c >= 0x10000 && *c <= 0x10FFFF) return 4;
    }
  }
 
  /* Debug(misc, 1, "[utf8] invalid UTF-8 sequence"); */
  *c = '?';
  return 1;
}
 
 
template <class T>
inline size_t Utf8Encode(T buf, WChar c)
{
  if (c < 0x80) {
    *buf = c;
    return 1;
  } else if (c < 0x800) {
    *buf++ = 0xC0 + GB(c,  6, 5);
    *buf   = 0x80 + GB(c,  0, 6);
    return 2;
  } else if (c < 0x10000) {
    *buf++ = 0xE0 + GB(c, 12, 4);
    *buf++ = 0x80 + GB(c,  6, 6);
    *buf   = 0x80 + GB(c,  0, 6);
    return 3;
  } else if (c < 0x110000) {
    *buf++ = 0xF0 + GB(c, 18, 3);
    *buf++ = 0x80 + GB(c, 12, 6);
    *buf++ = 0x80 + GB(c,  6, 6);
    *buf   = 0x80 + GB(c,  0, 6);
    return 4;
  }
 
  /* Debug(misc, 1, "[utf8] can't UTF-8 encode value 0x{:X}", c); */
  *buf = '?';
  return 1;
}
 
size_t Utf8Encode(char *buf, WChar c)
{
  return Utf8Encode<char *>(buf, c);
}
 
size_t Utf8Encode(std::ostreambuf_iterator<char> &buf, WChar c)
{
  return Utf8Encode<std::ostreambuf_iterator<char> &>(buf, c);
}
 
size_t Utf8TrimString(char *s, size_t maxlen)
{
  size_t length = 0;
 
  for (const char *ptr = strchr(s, '\0'); *s != '\0';) {
    size_t len = Utf8EncodedCharLen(*s);
    /* Silently ignore invalid UTF8 sequences, our only concern trimming */
    if (len == 0) len = 1;
 
    /* Take care when a hard cutoff was made for the string and
     * the last UTF8 sequence is invalid */
    if (length + len >= maxlen || (s + len > ptr)) break;
    s += len;
    length += len;
  }
 
  *s = '\0';
  return length;
}
 
#ifdef DEFINE_STRCASESTR
char *strcasestr(const char *haystack, const char *needle)
{
  size_t hay_len = strlen(haystack);
  size_t needle_len = strlen(needle);
  while (hay_len >= needle_len) {
    if (strncasecmp(haystack, needle, needle_len) == 0) return const_cast<char *>(haystack);
 
    haystack++;
    hay_len--;
  }
 
  return nullptr;
}
#endif /* DEFINE_STRCASESTR */
 
static const char *SkipGarbage(const char *str)
{
  while (*str != '\0' && (*str < '0' || IsInsideMM(*str, ';', '@' + 1) || IsInsideMM(*str, '[', '`' + 1) || IsInsideMM(*str, '{', '~' + 1))) str++;
  return str;
}
 
int strnatcmp(const char *s1, const char *s2, bool ignore_garbage_at_front)
{
  if (ignore_garbage_at_front) {
    s1 = SkipGarbage(s1);
    s2 = SkipGarbage(s2);
  }
 
#ifdef WITH_ICU_I18N
  if (_current_collator) {
    UErrorCode status = U_ZERO_ERROR;
    int result = _current_collator->compareUTF8(s1, s2, status);
    if (U_SUCCESS(status)) return result;
  }
#endif /* WITH_ICU_I18N */
 
#if defined(_WIN32) && !defined(STRGEN) && !defined(SETTINGSGEN)
  int res = OTTDStringCompare(s1, s2);
  if (res != 0) return res - 2; // Convert to normal C return values.
#endif
 
#if defined(WITH_COCOA) && !defined(STRGEN) && !defined(SETTINGSGEN)
  int res = MacOSStringCompare(s1, s2);
  if (res != 0) return res - 2; // Convert to normal C return values.
#endif
 
  /* Do a normal comparison if ICU is missing or if we cannot create a collator. */
  return strcasecmp(s1, s2);
}
 
#ifdef WITH_UNISCRIBE
 
/* static */ StringIterator *StringIterator::Create()
{
  return new UniscribeStringIterator();
}
 
#elif defined(WITH_ICU_I18N)
 
#include <unicode/utext.h>
#include <unicode/brkiter.h>
 
class IcuStringIterator : public StringIterator
{
  icu::BreakIterator *char_itr; 
  icu::BreakIterator *word_itr; 
 
  std::vector<UChar> utf16_str;      
  std::vector<size_t> utf16_to_utf8; 
 
public:
  IcuStringIterator() : char_itr(nullptr), word_itr(nullptr)
  {
    UErrorCode status = U_ZERO_ERROR;
    this->char_itr = icu::BreakIterator::createCharacterInstance(icu::Locale(_current_language != nullptr ? _current_language->isocode : "en"), status);
    this->word_itr = icu::BreakIterator::createWordInstance(icu::Locale(_current_language != nullptr ? _current_language->isocode : "en"), status);
 
    this->utf16_str.push_back('\0');
    this->utf16_to_utf8.push_back(0);
  }
 
  ~IcuStringIterator() override
  {
    delete this->char_itr;
    delete this->word_itr;
  }
 
  void SetString(const char *s) override
  {
    const char *string_base = s;
 
    /* Unfortunately current ICU versions only provide rudimentary support
     * for word break iterators (especially for CJK languages) in combination
     * with UTF-8 input. As a work around we have to convert the input to
     * UTF-16 and create a mapping back to UTF-8 character indices. */
    this->utf16_str.clear();
    this->utf16_to_utf8.clear();
 
    while (*s != '\0') {
      size_t idx = s - string_base;
 
      WChar c = Utf8Consume(&s);
      if (c < 0x10000) {
        this->utf16_str.push_back((UChar)c);
      } else {
        /* Make a surrogate pair. */
        this->utf16_str.push_back((UChar)(0xD800 + ((c - 0x10000) >> 10)));
        this->utf16_str.push_back((UChar)(0xDC00 + ((c - 0x10000) & 0x3FF)));
        this->utf16_to_utf8.push_back(idx);
      }
      this->utf16_to_utf8.push_back(idx);
    }
    this->utf16_str.push_back('\0');
    this->utf16_to_utf8.push_back(s - string_base);
 
    UText text = UTEXT_INITIALIZER;
    UErrorCode status = U_ZERO_ERROR;
    utext_openUChars(&text, this->utf16_str.data(), this->utf16_str.size() - 1, &status);
    this->char_itr->setText(&text, status);
    this->word_itr->setText(&text, status);
    this->char_itr->first();
    this->word_itr->first();
  }
 
  size_t SetCurPosition(size_t pos) override
  {
    /* Convert incoming position to an UTF-16 string index. */
    uint utf16_pos = 0;
    for (uint i = 0; i < this->utf16_to_utf8.size(); i++) {
      if (this->utf16_to_utf8[i] == pos) {
        utf16_pos = i;
        break;
      }
    }
 
    /* isBoundary has the documented side-effect of setting the current
     * position to the first valid boundary equal to or greater than
     * the passed value. */
    this->char_itr->isBoundary(utf16_pos);
    return this->utf16_to_utf8[this->char_itr->current()];
  }
 
  size_t Next(IterType what) override
  {
    int32_t pos;
    switch (what) {
      case ITER_CHARACTER:
        pos = this->char_itr->next();
        break;
 
      case ITER_WORD:
        pos = this->word_itr->following(this->char_itr->current());
        /* The ICU word iterator considers both the start and the end of a word a valid
         * break point, but we only want word starts. Move to the next location in
         * case the new position points to whitespace. */
        while (pos != icu::BreakIterator::DONE &&
            IsWhitespace(Utf16DecodeChar((const uint16 *)&this->utf16_str[pos]))) {
          int32_t new_pos = this->word_itr->next();
          /* Don't set it to DONE if it was valid before. Otherwise we'll return END
           * even though the iterator wasn't at the end of the string before. */
          if (new_pos == icu::BreakIterator::DONE) break;
          pos = new_pos;
        }
 
        this->char_itr->isBoundary(pos);
        break;
 
      default:
        NOT_REACHED();
    }
 
    return pos == icu::BreakIterator::DONE ? END : this->utf16_to_utf8[pos];
  }
 
  size_t Prev(IterType what) override
  {
    int32_t pos;
    switch (what) {
      case ITER_CHARACTER:
        pos = this->char_itr->previous();
        break;
 
      case ITER_WORD:
        pos = this->word_itr->preceding(this->char_itr->current());
        /* The ICU word iterator considers both the start and the end of a word a valid
         * break point, but we only want word starts. Move to the previous location in
         * case the new position points to whitespace. */
        while (pos != icu::BreakIterator::DONE &&
            IsWhitespace(Utf16DecodeChar((const uint16 *)&this->utf16_str[pos]))) {
          int32_t new_pos = this->word_itr->previous();
          /* Don't set it to DONE if it was valid before. Otherwise we'll return END
           * even though the iterator wasn't at the start of the string before. */
          if (new_pos == icu::BreakIterator::DONE) break;
          pos = new_pos;
        }
 
        this->char_itr->isBoundary(pos);
        break;
 
      default:
        NOT_REACHED();
    }
 
    return pos == icu::BreakIterator::DONE ? END : this->utf16_to_utf8[pos];
  }
};
 
/* static */ StringIterator *StringIterator::Create()
{
  return new IcuStringIterator();
}
 
#else
 
class DefaultStringIterator : public StringIterator
{
  const char *string; 
  size_t len;         
  size_t cur_pos;     
 
public:
  DefaultStringIterator() : string(nullptr), len(0), cur_pos(0)
  {
  }
 
  virtual void SetString(const char *s)
  {
    this->string = s;
    this->len = strlen(s);
    this->cur_pos = 0;
  }
 
  virtual size_t SetCurPosition(size_t pos)
  {
    assert(this->string != nullptr && pos <= this->len);
    /* Sanitize in case we get a position inside an UTF-8 sequence. */
    while (pos > 0 && IsUtf8Part(this->string[pos])) pos--;
    return this->cur_pos = pos;
  }
 
  virtual size_t Next(IterType what)
  {
    assert(this->string != nullptr);
 
    /* Already at the end? */
    if (this->cur_pos >= this->len) return END;
 
    switch (what) {
      case ITER_CHARACTER: {
        WChar c;
        this->cur_pos += Utf8Decode(&c, this->string + this->cur_pos);
        return this->cur_pos;
      }
 
      case ITER_WORD: {
        WChar c;
        /* Consume current word. */
        size_t offs = Utf8Decode(&c, this->string + this->cur_pos);
        while (this->cur_pos < this->len && !IsWhitespace(c)) {
          this->cur_pos += offs;
          offs = Utf8Decode(&c, this->string + this->cur_pos);
        }
        /* Consume whitespace to the next word. */
        while (this->cur_pos < this->len && IsWhitespace(c)) {
          this->cur_pos += offs;
          offs = Utf8Decode(&c, this->string + this->cur_pos);
        }
 
        return this->cur_pos;
      }
 
      default:
        NOT_REACHED();
    }
 
    return END;
  }
 
  virtual size_t Prev(IterType what)
  {
    assert(this->string != nullptr);
 
    /* Already at the beginning? */
    if (this->cur_pos == 0) return END;
 
    switch (what) {
      case ITER_CHARACTER:
        return this->cur_pos = Utf8PrevChar(this->string + this->cur_pos) - this->string;
 
      case ITER_WORD: {
        const char *s = this->string + this->cur_pos;
        WChar c;
        /* Consume preceding whitespace. */
        do {
          s = Utf8PrevChar(s);
          Utf8Decode(&c, s);
        } while (s > this->string && IsWhitespace(c));
        /* Consume preceding word. */
        while (s > this->string && !IsWhitespace(c)) {
          s = Utf8PrevChar(s);
          Utf8Decode(&c, s);
        }
        /* Move caret back to the beginning of the word. */
        if (IsWhitespace(c)) Utf8Consume(&s);
 
        return this->cur_pos = s - this->string;
      }
 
      default:
        NOT_REACHED();
    }
 
    return END;
  }
};
 
#if defined(WITH_COCOA) && !defined(STRGEN) && !defined(SETTINGSGEN)
/* static */ StringIterator *StringIterator::Create()
{
  StringIterator *i = OSXStringIterator::Create();
  if (i != nullptr) return i;
 
  return new DefaultStringIterator();
}
#else
/* static */ StringIterator *StringIterator::Create()
{
  return new DefaultStringIterator();
}
#endif /* defined(WITH_COCOA) && !defined(STRGEN) && !defined(SETTINGSGEN) */
 
#endif