import { IActionHandler, ICommand } from 'sprotty';
import { Action } from 'sprotty-protocol';
type Handler = () => void;
/**
 * Abstract registry which should be used as a base for registries in the container.
 * A registry is supposed to store extra state that is not the diagram model.
 * Examples for such state include diagram options or preferences.
 *
 * The state should be readonly and can only be changed with an {@link Action}.
 * This is similar to the flux architecture that is utilized by Sprotty, where a
 * view dispatches actions, which can change the state, causing the view to react
 * to the changed state and update. Therefore, every registry implements {@link IActionHandler}.
 *
 * Implementations define how their actions are handled and automatically
 * provide a subscription options for listeners, by extending this base class.
 * A handled action should call `notifyListeners` to inform them about state changes.
 *
 * A registry has to be bound to the actions it is supposed to handle in the DI container.
 * Sprotty provides a `configureActionHandler` function to simplify this process.
 */
export declare abstract class Registry implements IActionHandler {
    private _listeners;
    abstract handle(action: Action): void | Action | ICommand;
    onChange(handler: Handler): void;
    protected notifyListeners(): void;
}
export {};
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