nodeForPathSegments method Null safety

Implementation

RouteNode? nodeForPathSegments(
  Iterator<String> requestSegments,
  RequestPath path,
) {
  if (!requestSegments.moveNext()) {
    return this;
  }

  final nextSegment = requestSegments.current;

  if (equalityChildren.containsKey(nextSegment)) {
    return equalityChildren[nextSegment]!
        .nodeForPathSegments(requestSegments, path);
  }

  for (final node in patternedChildren) {
    if (node.patternMatcher == null) {
      // This is a variable with no regular expression
      return node.nodeForPathSegments(requestSegments, path);
    }

    if (node.patternMatcher!.firstMatch(nextSegment) != null) {
      // This segment has a regular expression
      return node.nodeForPathSegments(requestSegments, path);
    }
  }

  // If this is null, then we return null from this method
  // and the router knows we didn't find a match.
  return takeAllChild;
}