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48 lines
1.1 KiB
48 lines
1.1 KiB
/**
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* Responsible for sequentially executing actions on the database
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* @private
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*/
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class Waterfall {
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/**
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* Instantiate a new Waterfall.
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*/
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constructor () {
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/**
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* This is the internal Promise object which resolves when all the tasks of the `Waterfall` are done.
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*
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* It will change any time `this.waterfall` is called.
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*
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* @type {Promise}
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*/
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this.guardian = Promise.resolve()
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}
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/**
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*
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* @param {AsyncFunction} func
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* @return {AsyncFunction}
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*/
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waterfall (func) {
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return (...args) => {
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this.guardian = this.guardian.then(() => {
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return func(...args)
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.then(result => ({ error: false, result }), result => ({ error: true, result }))
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})
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return this.guardian.then(({ error, result }) => {
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if (error) return Promise.reject(result)
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else return Promise.resolve(result)
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})
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}
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}
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/**
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* Shorthand for chaining a promise to the Waterfall
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* @param {Promise} promise
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* @return {Promise}
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*/
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chain (promise) {
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return this.waterfall(() => promise)()
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}
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}
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module.exports = Waterfall
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