@aws-amplify/core/dist/esm/Hub/index.mjs

Core category of aws-amplify

import { ConsoleLogger } from '../Logger/ConsoleLogger.mjs';
import { NO_HUBCALLBACK_PROVIDED_EXCEPTION } from '../constants.mjs';
import { AmplifyError } from '../errors/AmplifyError.mjs';
import '../types/errors.mjs';
import '../errors/errorHelpers.mjs';

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
const AMPLIFY_SYMBOL = (typeof Symbol !== 'undefined'
    ? Symbol('amplify_default')
    : '@@amplify_default');
const logger = new ConsoleLogger('Hub');
class HubClass {
    constructor(name) {
        this.listeners = new Map();
        this.protectedChannels = [
            'core',
            'auth',
            'api',
            'analytics',
            'interactions',
            'pubsub',
            'storage',
            'ui',
            'xr',
        ];
        this.name = name;
    }
    /**
     * Used internally to remove a Hub listener.
     *
     * @remarks
     * This private method is for internal use only. Instead of calling Hub.remove, call the result of Hub.listen.
     */
    _remove(channel, listener) {
        const holder = this.listeners.get(channel);
        if (!holder) {
            logger.warn(`No listeners for ${channel}`);
            return;
        }
        this.listeners.set(channel, [
            ...holder.filter(({ callback }) => callback !== listener),
        ]);
    }
    dispatch(channel, payload, source, ampSymbol) {
        if (typeof channel === 'string' &&
            this.protectedChannels.indexOf(channel) > -1) {
            const hasAccess = ampSymbol === AMPLIFY_SYMBOL;
            if (!hasAccess) {
                logger.warn(`WARNING: ${channel} is protected and dispatching on it can have unintended consequences`);
            }
        }
        const capsule = {
            channel,
            payload: { ...payload },
            source,
            patternInfo: [],
        };
        try {
            this._toListeners(capsule);
        }
        catch (e) {
            logger.error(e);
        }
    }
    listen(channel, callback, listenerName = 'noname') {
        let cb;
        if (typeof callback !== 'function') {
            throw new AmplifyError({
                name: NO_HUBCALLBACK_PROVIDED_EXCEPTION,
                message: 'No callback supplied to Hub',
            });
        }
        else {
            // Needs to be casted as a more generic type
            cb = callback;
        }
        let holder = this.listeners.get(channel);
        if (!holder) {
            holder = [];
            this.listeners.set(channel, holder);
        }
        holder.push({
            name: listenerName,
            callback: cb,
        });
        return () => {
            this._remove(channel, cb);
        };
    }
    _toListeners(capsule) {
        const { channel, payload } = capsule;
        const holder = this.listeners.get(channel);
        if (holder) {
            holder.forEach(listener => {
                logger.debug(`Dispatching to ${channel} with `, payload);
                try {
                    listener.callback(capsule);
                }
                catch (e) {
                    logger.error(e);
                }
            });
        }
    }
}
/* We export a __default__ instance of HubClass to use it as a
pseudo Singleton for the main messaging bus, however you can still create
your own instance of HubClass() for a separate "private bus" of events. */
const Hub = new HubClass('__default__');
/**
 * @internal
 *
 * Internal hub used for core Amplify functionality. Not intended for use outside of Amplify.
 *
 */
const HubInternal = new HubClass('internal-hub');

export { AMPLIFY_SYMBOL, Hub, HubClass, HubInternal };
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