@Nullable
  public ZenCodingNode parse() {
    ZenCodingNode add = parseAddOrMore();
    if (add == null) {
      return null;
    }

    ZenCodingNode result = add;

    while (true) {
      ZenCodingToken token = getToken();
      if (token != ZenCodingTokens.PIPE) {
        return result;
      }

      advance();
      token = getToken();
      if (!(token instanceof IdentifierToken)) {
        return null;
      }

      final String filterSuffix = ((IdentifierToken) token).getText();
      if (!ZenCodingUtil.checkFilterSuffix(filterSuffix)) {
        return null;
      }

      advance();
      result = new FilterNode(result, filterSuffix);
    }
  }
  @Nullable
  protected ZenCodingNode parseTemplate() {
    ZenCodingToken token = getToken();
    if (!(token instanceof IdentifierToken)) {
      return null;
    }
    String templateKey = ((IdentifierToken) token).getText();
    advance();

    TemplateImpl template = myCallback.findApplicableTemplate(templateKey);
    if (template == null && !ZenCodingUtil.isXML11ValidQName(templateKey)) {
      return null;
    }

    final TemplateToken templateToken = new TemplateToken(templateKey);
    if (!setTemplate(templateToken, template)) {
      return null;
    }
    return new TemplateNode(templateToken);
  }