class FieldDescriptor

class FieldDescriptor {
    use GetPublicDescriptorTrait;
    
    /** @var  \Google\Protobuf\Internal\FieldDescriptor $internal_desc */
    private $internal_desc;
    
    /**
     * @internal
     */
    public function __construct($internal_desc) {
        $this->internal_desc = $internal_desc;
    }
    
    /**
     * @return string Field name
     */
    public function getName() {
        return $this->internal_desc
            ->getName();
    }
    
    /**
     * @return int Protobuf field number
     */
    public function getNumber() {
        return $this->internal_desc
            ->getNumber();
    }
    
    /**
     * @return int
     */
    public function getLabel() {
        return $this->internal_desc
            ->getLabel();
    }
    
    /**
     * @return int
     */
    public function getType() {
        return $this->internal_desc
            ->getType();
    }
    
    /**
     * @return OneofDescriptor
     */
    public function getContainingOneof() {
        return $this->getPublicDescriptor($this->internal_desc
            ->getContainingOneof());
    }
    
    /**
     * Gets the field's containing oneof, only if non-synthetic.
     *
     * @return null|OneofDescriptor
     */
    public function getRealContainingOneof() {
        return $this->getPublicDescriptor($this->internal_desc
            ->getRealContainingOneof());
    }
    
    /**
     * @return boolean
     */
    public function hasOptionalKeyword() {
        return $this->internal_desc
            ->hasOptionalKeyword();
    }
    
    /**
     * @return Descriptor Returns a descriptor for the field type if the field type is a message, otherwise throws \Exception
     * @throws \Exception
     */
    public function getMessageType() {
        if ($this->getType() == GPBType::MESSAGE) {
            return $this->getPublicDescriptor($this->internal_desc
                ->getMessageType());
        }
        else {
            throw new \Exception("Cannot get message type for non-message field '" . $this->getName() . "'");
        }
    }
    
    /**
     * @return EnumDescriptor Returns an enum descriptor if the field type is an enum, otherwise throws \Exception
     * @throws \Exception
     */
    public function getEnumType() {
        if ($this->getType() == GPBType::ENUM) {
            return $this->getPublicDescriptor($this->internal_desc
                ->getEnumType());
        }
        else {
            throw new \Exception("Cannot get enum type for non-enum field '" . $this->getName() . "'");
        }
    }
    
    /**
     * @return boolean
     */
    public function isMap() {
        return $this->internal_desc
            ->isMap();
    }

}