interface ContextInterface

interface ContextInterface {
    
    /**
     * Gets the context value.
     *
     * @return mixed
     *   The currently set context value, or NULL if it is not set.
     */
    public function getContextValue();
    
    /**
     * Returns whether the context has a value.
     *
     * @return bool
     *   TRUE if the context has a value, FALSE otherwise.
     */
    public function hasContextValue();
    
    /**
     * Gets the provided definition that the context must conform to.
     *
     * @return \Drupal\Component\Plugin\Context\ContextDefinitionInterface
     *   The defining characteristic representation of the context.
     */
    public function getContextDefinition();
    
    /**
     * Gets a list of validation constraints.
     *
     * @return array
     *   Array of constraints, each being an instance of
     *   \Symfony\Component\Validator\Constraint.
     */
    public function getConstraints();
    
    /**
     * Validates the set context value.
     *
     * @return \Symfony\Component\Validator\ConstraintViolationListInterface
     *   A list of constraint violations. If the list is empty, validation
     *   succeeded.
     */
    public function validate();

}