Method PushRepetition

extern/re2/re2/parse.cc:568–601

Pushes a repetition regexp onto the stack. A valid argument for the operator must already be on the stack.

// Pushes a repetition regexp onto the stack.
// A valid argument for the operator must already be on the stack.
bool Regexp::ParseState::PushRepetition(int min, int max,
                                        const StringPiece& s,
                                        bool nongreedy) {
  if ((max != -1 && max < min) || min > kMaxRepeat || max > kMaxRepeat) {
    status_->set_code(kRegexpRepeatSize);
    status_->set_error_arg(s);
    return false;
  }
  if (stacktop_ == NULL || IsMarker(stacktop_->op())) {
    status_->set_code(kRegexpRepeatArgument);
    status_->set_error_arg(s);
    return false;
  }
  Regexp::ParseFlags fl = flags_;
  if (nongreedy)
    fl = fl ^ NonGreedy;
  Regexp* re = new Regexp(kRegexpRepeat, fl);
  re->min_ = min;
  re->max_ = max;
  re->AllocSub(1);
  re->down_ = stacktop_->down_;
  re->sub()[0] = FinishRegexp(stacktop_);
  re->simple_ = re->ComputeSimple();
  stacktop_ = re;
  if (min >= 2 || max >= 2) {
    RepetitionWalker w;
    if (w.Walk(stacktop_, kMaxRepeat) == 0) {
      status_->set_code(kRegexpRepeatSize);
      status_->set_error_arg(s);
      return false;
    }
  }
  return true;
}

// Checks whether a particular regexp op is a marker.
bool Regexp::ParseState::IsMarker(RegexpOp op) {