private function validateChildrenRule()

in src/core/Node.hack [705:758]
50 lines of code
14 McCabe index (conditional complexity)

  private function validateChildrenRule(
    ReflectionXHPChildrenExpression $expr,
    int $index,
  ): (bool, int) {
    switch ($expr->getConstraintType()) {
      case XHPChildrenConstraintType::ANY:
        if (C\contains_key($this->children, $index)) {
          return tuple(true, $index + 1);
        }
        return tuple(false, $index);

      case XHPChildrenConstraintType::PCDATA:
        if (
          C\contains_key($this->children, $index) &&
          !($this->children[$index] is node)
        ) {
          return tuple(true, $index + 1);
        }
        return tuple(false, $index);

      case XHPChildrenConstraintType::ELEMENT:
        $class = $expr->getConstraintString();
        if (
          C\contains_key($this->children, $index) &&
          \is_a($this->children[$index], $class, true)
        ) {
          return tuple(true, $index + 1);
        }
        return tuple(false, $index);

      case XHPChildrenConstraintType::CATEGORY:
        if (!C\contains_key($this->children, $index)) {
          return tuple(false, $index);
        }
        $child = $this->children[$index];
        if (!$child is node) {
          return tuple(false, $index);
        }
        $category = $expr->getConstraintString()
          |> Str\replace($$, '__', ':')
          |> Str\replace($$, '_', '-');
        $categories = $child->__xhpCategoryDeclaration();
        if (($categories[$category] ?? 0) === 0) {
          return tuple(false, $index);
        }
        return tuple(true, $index + 1);

      case XHPChildrenConstraintType::SUB_EXPR:
        return $this->validateChildrenExpression(
          $expr->getSubExpression(),
          $index,
        );
    }
  }