private function validateChildrenExpression()

in src/core/Node.hack [634:703]
60 lines of code
14 McCabe index (conditional complexity)

  private function validateChildrenExpression(
    ReflectionXHPChildrenExpression $expr,
    int $index,
  ): (bool, int) {
    switch ($expr->getType()) {
      case XHPChildrenExpressionType::SINGLE:
        // Exactly once -- :fb_thing
        return $this->validateChildrenRule($expr, $index);
      case XHPChildrenExpressionType::ANY_NUMBER:
        // Zero or more times -- :fb_thing*
        do {
          list($ret, $index) = $this->validateChildrenRule($expr, $index);
        } while ($ret);
        return tuple(true, $index);

      case XHPChildrenExpressionType::ZERO_OR_ONE:
        // Zero or one times -- :fb_thing?
        list($_, $index) = $this->validateChildrenRule($expr, $index);
        return tuple(true, $index);

      case XHPChildrenExpressionType::ONE_OR_MORE:
        // One or more times -- :fb_thing+
        list($ret, $index) = $this->validateChildrenRule($expr, $index);
        if (!$ret) {
          return tuple(false, $index);
        }
        do {
          list($ret, $index) = $this->validateChildrenRule($expr, $index);
        } while ($ret);
        return tuple(true, $index);

      case XHPChildrenExpressionType::SUB_EXPR_SEQUENCE:
        // Specific order -- :fb_thing, :fb_other_thing
        $oindex = $index;
        list($sub_expr_1, $sub_expr_2) = $expr->getSubExpressions();
        list($ret, $index) = $this->validateChildrenExpression(
          $sub_expr_1,
          $index,
        );
        if ($ret) {
          list($ret, $index) = $this->validateChildrenExpression(
            $sub_expr_2,
            $index,
          );
        }
        if ($ret) {
          return tuple(true, $index);
        }
        return tuple(false, $oindex);

      case XHPChildrenExpressionType::SUB_EXPR_DISJUNCTION:
        // Either or -- :fb_thing | :fb_other_thing
        $oindex = $index;
        list($sub_expr_1, $sub_expr_2) = $expr->getSubExpressions();
        list($ret, $index) = $this->validateChildrenExpression(
          $sub_expr_1,
          $index,
        );
        if (!$ret) {
          list($ret, $index) = $this->validateChildrenExpression(
            $sub_expr_2,
            $index,
          );
        }
        if ($ret) {
          return tuple(true, $index);
        }
        return tuple(false, $oindex);
    }
  }