interface RevisionableInterface

interface RevisionableInterface extends EntityInterface {
    
    /**
     * Determines whether a new revision should be created on save.
     *
     * @return bool
     *   TRUE if a new revision should be created.
     *
     * @see \Drupal\Core\Entity\EntityInterface::setNewRevision()
     */
    public function isNewRevision();
    
    /**
     * Enforces an entity to be saved as a new revision.
     *
     * @param bool $value
     *   (optional) Whether a new revision should be saved.
     *
     * @throws \LogicException
     *   Thrown if the entity does not support revisions.
     *
     * @see \Drupal\Core\Entity\EntityInterface::isNewRevision()
     */
    public function setNewRevision($value = TRUE);
    
    /**
     * Gets the revision identifier of the entity.
     *
     * @return int|null|string
     *   The revision identifier of the entity, or NULL if the entity does not
     *   have a revision identifier.
     */
    public function getRevisionId();
    
    /**
     * Gets the loaded Revision ID of the entity.
     *
     * @return int
     *   The loaded Revision identifier of the entity, or NULL if the entity
     *   does not have a revision identifier.
     */
    public function getLoadedRevisionId();
    
    /**
     * Updates the loaded Revision ID with the revision ID.
     *
     * This method should not be used, it could unintentionally cause the original
     * revision ID property value to be lost.
     *
     * @internal
     *
     * @return $this
     */
    public function updateLoadedRevisionId();
    
    /**
     * Checks if this entity is the default revision.
     *
     * @param bool $new_value
     *   (optional) A Boolean to (re)set the isDefaultRevision flag.
     *
     * @return bool
     *   TRUE if the entity is the default revision, FALSE otherwise. If
     *   $new_value was passed, the previous value is returned.
     */
    public function isDefaultRevision($new_value = NULL);
    
    /**
     * Checks whether the entity object was a default revision when it was saved.
     *
     * @return bool
     *   TRUE if the entity object was a revision, FALSE otherwise.
     */
    public function wasDefaultRevision();
    
    /**
     * Checks if this entity is the latest revision.
     *
     * @return bool
     *   TRUE if the entity is the latest revision, FALSE otherwise.
     */
    public function isLatestRevision();
    
    /**
     * Acts on a revision before it gets saved.
     *
     * @param EntityStorageInterface $storage
     *   The entity storage object.
     * @param object $record
     *   The revision object.
     */
    public function preSaveRevision(EntityStorageInterface $storage, \stdClass $record);

}