Function MatchRepetitionAndRegexAtHead

tests/gtest/gtest-all.cc:10587–10609

Matches a repeated regex atom followed by a valid simple regular expression. The regex atom is defined as c if escaped is false, or \c otherwise. repeat is the repetition meta character (?, *, or +). The behavior is undefined if str contains too many characters to be indexable by size_t, in which case the test will probably time out anyway. We are fine with this limitation as std::string has i

// probably time out anyway.  We are fine with this limitation as
// std::string has it too.
bool MatchRepetitionAndRegexAtHead(
    bool escaped, char c, char repeat, const char* regex,
    const char* str) {
  const size_t min_count = (repeat == '+') ? 1 : 0;
  const size_t max_count = (repeat == '?') ? 1 :
      static_cast<size_t>(-1) - 1;
  // We cannot call numeric_limits::max() as it conflicts with the
  // max() macro on Windows.

  for (size_t i = 0; i <= max_count; ++i) {
    // We know that the atom matches each of the first i characters in str.
    if (i >= min_count && MatchRegexAtHead(regex, str + i)) {
      // We have enough matches at the head, and the tail matches too.
      // Since we only care about *whether* the pattern matches str
      // (as opposed to *how* it matches), there is no need to find a
      // greedy match.
      return true;
    }
    if (str[i] == '\0' || !AtomMatchesChar(escaped, c, str[i]))
      return false;
  }
  return false;
}

// Returns true iff regex matches a prefix of str.  regex must be a
// valid simple regular expression and not start with "^", or the