@smui/common/dist/internal/SvelteEventManager.js

Svelte Material UI - Common

import { on } from 'svelte/events';
/**
 * A way to keep track of things you've "on"ed so you can "off" them too.
 *
 * This is needed because Svelte doesn't have an "off" function, it returns
 * unlisten functions from its "on" function.
 */
export class SvelteEventManager {
    constructor() {
        this.elementMap = new Map();
    }
    /**
     * Listen to an event on an element.
     */
    on(element, event, handler, options) {
        if (!this.elementMap.has(element)) {
            this.elementMap.set(element, {});
        }
        const eventMap = this.elementMap.get(element);
        if (eventMap == null) {
            throw new Error("Event map couldn't be created.");
        }
        if (!(event in eventMap)) {
            eventMap[event] = new Map();
        }
        const handlerMap = eventMap[event];
        handlerMap.set(handler, on(element, event, handler, options));
    }
    /**
     * Unlisten to an event on an element.
     */
    off(element, event, handler) {
        const eventMap = this.elementMap.get(element);
        if (eventMap == null || !(event in eventMap)) {
            console.warn("Attempted to off an event that couldn't be found.", element, event);
            return;
        }
        const handlerMap = eventMap[event];
        const unlisten = handlerMap.get(handler);
        if (unlisten != null) {
            unlisten();
            handlerMap.delete(handler);
            if (handlerMap.size === 0) {
                delete eventMap[event];
                if (Object.keys(eventMap).length === 0) {
                    this.elementMap.delete(element);
                }
            }
        }
        else {
            console.warn("Attempted to off an event that couldn't be found.", element, event);
        }
    }
    /**
     * Unlisten to all events managed by this instance.
     */
    clear() {
        this.elementMap.forEach((eventMaps, _element) => {
            for (let [_event, eventMap] of Object.entries(eventMaps)) {
                eventMap.forEach((unlisten, _handler) => {
                    unlisten();
                });
            }
        });
        this.elementMap.clear();
    }
}
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