class EntityContext

class EntityContext extends Context {
    
    /**
     * Gets a context from an entity type ID.
     *
     * @param string $entity_type_id
     *   Entity type ID from which a definition will be derived.
     * @param string $label
     *   (optional) The label of the context.
     *
     * @return static
     */
    public static function fromEntityTypeId($entity_type_id, $label = NULL) {
        $entity_type = \Drupal::entityTypeManager()->getDefinition($entity_type_id);
        return static::fromEntityType($entity_type, $label);
    }
    
    /**
     * Gets a context from an entity type.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   Entity type from which a definition will be derived.
     * @param string $label
     *   (optional) The label of the context.
     *
     * @return static
     */
    public static function fromEntityType(EntityTypeInterface $entity_type, $label = NULL) {
        $definition = EntityContextDefinition::fromEntityType($entity_type);
        if ($label) {
            $definition->setLabel($label);
        }
        return new static($definition);
    }
    
    /**
     * Gets a context object from an entity.
     *
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   Entity that provides a context.
     * @param string $label
     *   (optional) The label of the context.
     *
     * @return static
     */
    public static function fromEntity(EntityInterface $entity, $label = NULL) {
        $context = static::fromEntityType($entity->getEntityType(), $label);
        $context->setContextValue($entity);
        return $context;
    }

}