sveltekit-sync/dist/realtime/event-emitter.js

Local-first sync engine for SvelteKit

/**
 * Simple event emitter for realtime events.
 * Used as a foundation for both client and server-side event handling.
 */
export class EventEmitter {
    listeners = new Map();
    /**
     * Subscribe to an event
     * @returns Unsubscribe function
     */
    on(event, handler) {
        if (!this.listeners.has(event)) {
            this.listeners.set(event, new Set());
        }
        this.listeners.get(event).add(handler);
        return () => this.off(event, handler);
    }
    /**
     * Unsubscribe from an event
     */
    off(event, handler) {
        const handlers = this.listeners.get(event);
        if (handlers) {
            handlers.delete(handler);
            if (handlers.size === 0) {
                this.listeners.delete(event);
            }
        }
    }
    /**
     * Emit an event to all subscribers
     */
    emit(event, data) {
        const handlers = this.listeners.get(event);
        if (handlers) {
            handlers.forEach(handler => {
                try {
                    handler(data);
                }
                catch (error) {
                    console.error(`Error in event handler for "${event}":`, error);
                }
            });
        }
    }
    /**
     * Subscribe to an event for one-time execution
     */
    once(event, handler) {
        const wrappedHandler = (data) => {
            this.off(event, wrappedHandler);
            handler(data);
        };
        return this.on(event, wrappedHandler);
    }
    /**
     * Remove all listeners for an event or all events
     */
    removeAllListeners(event) {
        if (event) {
            this.listeners.delete(event);
        }
        else {
            this.listeners.clear();
        }
    }
    /**
     * Get listener count for an event
     */
    listenerCount(event) {
        return this.listeners.get(event)?.size ?? 0;
    }
}