gatsby/cache-dir/server-utils/writable-as-promise.js

Blazing fast modern site generator for React

import { Writable } from "stream"

export class WritableAsPromise extends Writable {
  constructor() {
    super()

    this._output = ``
    this._deferred = {
      promise: null,
      resolve: null,
      reject: null,
    }
    this._deferred.promise = new Promise((resolve, reject) => {
      this._deferred.resolve = resolve
      this._deferred.reject = reject
    })
  }

  _write(chunk, _, next) {
    this._output += chunk.toString()
    next()
  }

  _destroy(error, next) {
    if (error instanceof Error) {
      this._deferred.reject(error)
    } else {
      next()
    }
  }

  end() {
    this._deferred.resolve(this._output)
    this.destroy()
  }

  // disguise us as a promise
  then(resolve, reject) {
    return this._deferred.promise.then(resolve, reject)
  }
}