mirror of
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66 lines
2.3 KiB
JavaScript
66 lines
2.3 KiB
JavaScript
/*
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Copyright 2019 the JSDoc Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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https://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import EventEmitter from 'node:events';
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import _ from 'lodash';
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import ow from 'ow';
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let cache = {};
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/**
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* An event bus that works the same way as a standard Node.js event emitter, with a few key
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* differences:
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*
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* + When you create an event bus, you must specify its name. Consider using your package's name.
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* + Event buses are cached and shared by default. If module A and module B both create an event bus
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* called `foo`, both modules get the same event bus. This behavior makes it easier to share one
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* event bus among all of the modules in your package.
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*
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* To prevent a new event bus from being cached and shared, set the `opts.cache` property to
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* `false` when you create the event bus. Setting this property to `false` also forces a new
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* event bus to be created, even if there's a cached event bus with the same name.
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*
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* @alias module:@jsdoc/util.EventBus
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* @extends module:events.EventEmitter
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*/
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export default class EventBus extends EventEmitter {
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/**
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* Create a new event bus, or retrieve the cached event bus for the ID you specify.
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*
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* @param {(string|Symbol)} id - The ID for the event bus.
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* @param {Object} opts - Options for the event bus.
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* @param {boolean} [opts.cache=true] - Set to `false` to prevent the event bus from being
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* cached, and to return a new event bus even if there is already an event bus with the same ID.
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*/
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constructor(id, opts = {}) {
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super();
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ow(id, ow.any(ow.string, ow.symbol));
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const shouldCache = _.isBoolean(opts.cache) ? opts.cache : true;
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if (Object.hasOwn(cache, id) && shouldCache) {
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return cache[id];
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}
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this._id = id;
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if (shouldCache) {
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cache[id] = this;
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}
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}
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}
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