bool visitSelector()

in lib/src/query_selector.dart [64:124]
43 lines of code
18 McCabe index (conditional complexity)

  bool visitSelector(Selector node) {
    final old = _element;
    var result = true;

    // Note: evaluate selectors right-to-left as it's more efficient.
    int? combinator;
    for (var s in node.simpleSelectorSequences.reversed) {
      if (combinator == null) {
        result = s.simpleSelector.visit(this) as bool;
      } else if (combinator == TokenKind.COMBINATOR_DESCENDANT) {
        // descendant combinator
        // http://dev.w3.org/csswg/selectors-4/#descendant-combinators
        do {
          _element = _element!.parent;
        } while (_element != null && !(s.simpleSelector.visit(this) as bool));

        if (_element == null) result = false;
      } else if (combinator == TokenKind.COMBINATOR_TILDE) {
        // Following-sibling combinator
        // http://dev.w3.org/csswg/selectors-4/#general-sibling-combinators
        do {
          _element = _element!.previousElementSibling;
        } while (_element != null && !(s.simpleSelector.visit(this) as bool));

        if (_element == null) result = false;
      }

      if (!result) break;

      switch (s.combinator) {
        case TokenKind.COMBINATOR_PLUS:
          // Next-sibling combinator
          // http://dev.w3.org/csswg/selectors-4/#adjacent-sibling-combinators
          _element = _element!.previousElementSibling;
          break;
        case TokenKind.COMBINATOR_GREATER:
          // Child combinator
          // http://dev.w3.org/csswg/selectors-4/#child-combinators
          _element = _element!.parent;
          break;
        case TokenKind.COMBINATOR_DESCENDANT:
        case TokenKind.COMBINATOR_TILDE:
          // We need to iterate through all siblings or parents.
          // For now, just remember what the combinator was.
          combinator = s.combinator;
          break;
        case TokenKind.COMBINATOR_NONE:
          break;
        default:
          throw _unsupported(node);
      }

      if (_element == null) {
        result = false;
        break;
      }
    }

    _element = old;
    return result;
  }