Function parseXPathSteps

lib/KOReaderSync/ProgressMapper.cpp:134–184

Parse the XPath segment between /body/DocFragment[N]/body/ and the terminal position into an ordered sequence of steps. Returns step count, 0 on failure. Example input: "/body/DocFragment[1]/body/div[1]/ul/li[4]/text()[1].51" Fills steps with: {div,1}, {ul,1}, {li,4}

// Example input: "/body/DocFragment[1]/body/div[1]/ul/li[4]/text()[1].51"
// Fills steps with: {div,1}, {ul,1}, {li,4}
int parseXPathSteps(const std::string& xpath, XPathStep steps[MAX_XPATH_DEPTH]) {
  static const char kBodyFrag[] = "/body/DocFragment[";
  const size_t fragPos = xpath.find(kBodyFrag);
  if (fragPos == std::string::npos) return 0;
  const size_t afterBracket = xpath.find(']', fragPos + strlen(kBodyFrag));
  if (afterBracket == std::string::npos) return 0;
  static const char kBody[] = "/body/";
  if (xpath.compare(afterBracket + 1, strlen(kBody), kBody) != 0) return 0;
  size_t pos = afterBracket + 1 + strlen(kBody);

  size_t stepsEnd = xpath.rfind("/text()");
  if (stepsEnd == std::string::npos) {
    stepsEnd = xpath.rfind('.');
    if (stepsEnd == std::string::npos || stepsEnd <= pos || stepsEnd + 1 >= xpath.size()) return 0;
    for (size_t i = stepsEnd + 1; i < xpath.size(); i++) {
      if (xpath[i] < '0' || xpath[i] > '9') return 0;
    }
  }
  if (stepsEnd <= pos) return 0;

  int count = 0;
  while (pos < stepsEnd && count < MAX_XPATH_DEPTH) {
    const size_t slash = xpath.find('/', pos);
    const size_t segEnd = (slash < stepsEnd) ? slash : stepsEnd;

    XPathStep& step = steps[count];
    const size_t bracket = xpath.find('[', pos);
    const size_t nameEnd = (bracket != std::string::npos && bracket < segEnd) ? bracket : segEnd;
    const size_t nameLen = nameEnd - pos;
    if (nameLen == 0 || nameLen >= sizeof(step.tag)) return 0;
    memcpy(step.tag, xpath.c_str() + pos, nameLen);
    step.tag[nameLen] = '\0';

    if (bracket != std::string::npos && bracket < segEnd) {
      const size_t closeBracket = xpath.find(']', bracket + 1);
      if (closeBracket == std::string::npos || closeBracket > segEnd) return 0;
      int idx = 0;
      for (size_t i = bracket + 1; i < closeBracket; i++) {
        if (xpath[i] < '0' || xpath[i] > '9') return 0;
        idx = idx * 10 + (xpath[i] - '0');
      }
      step.siblingIndex = idx;
    } else {
      step.siblingIndex = 1;
    }

    count++;
    pos = (slash < stepsEnd) ? slash + 1 : stepsEnd;
  }
  return count;
}

class ParagraphStreamer final : public Print {
  size_t bytesWritten = 0;