39 lines
1.2 KiB
TypeScript
39 lines
1.2 KiB
TypeScript
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import { EventEmitter } from 'events'
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/**
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* Creates a lazy instance of modules that can't be required before the
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* app 'ready' event by returning a proxy object to mitigate side effects
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* on 'require'
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*
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* @param {Function} creator - Function that creates a new module instance
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* @param {Object} holder - the object holding the module prototype
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* @param {Boolean} isEventEmitter - whether or not the module is an EventEmitter
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* @returns {Object} - a proxy object for the
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*/
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export function createLazyInstance (
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creator: Function,
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holder: Object,
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isEventEmitter: Boolean
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) {
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let lazyModule: Object
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const module: any = {}
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for (const method in (holder as any).prototype) {
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module[method] = (...args: any) => {
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// create new instance of module at runtime if none exists
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if (!lazyModule) {
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lazyModule = creator()
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if (isEventEmitter) EventEmitter.call(lazyModule as any)
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}
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// check for properties on the prototype chain that aren't functions
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if (typeof (lazyModule as any)[method] !== 'function') {
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return (lazyModule as any)[method]
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}
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return (lazyModule as any)[method](...args)
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}
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}
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return module
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}
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