ReadableStreamDefaultReader-impl.js

'use strict';

const { newPromise, resolvePromise, rejectPromise, promiseRejectedWith } = require('./helpers/webidl.js');
const aos = require('./abstract-ops/readable-streams.js');
const { mixin } = require('./helpers/miscellaneous.js');
const ReadableStreamGenericReaderImpl = require('./ReadableStreamGenericReader-impl.js').implementation;

class ReadableStreamDefaultReaderImpl {
  constructor(globalObject, [stream]) {
    aos.SetUpReadableStreamDefaultReader(this, stream);
  }

  read() {
    if (this._stream === undefined) {
      return promiseRejectedWith(readerLockException('read from'));
    }

    const promise = newPromise();
    const readRequest = {
      chunkSteps: chunk => resolvePromise(promise, { value: chunk, done: false }),
      closeSteps: () => resolvePromise(promise, { value: undefined, done: true }),
      errorSteps: e => rejectPromise(promise, e)
    };

    aos.ReadableStreamDefaultReaderRead(this, readRequest);
    return promise;
  }

  releaseLock() {
    if (this._stream === undefined) {
      return;
    }

    aos.ReadableStreamDefaultReaderRelease(this);
  }
}

mixin(ReadableStreamDefaultReaderImpl.prototype, ReadableStreamGenericReaderImpl.prototype);

exports.implementation = ReadableStreamDefaultReaderImpl;

function readerLockException(name) {
  return new TypeError('Cannot ' + name + ' a stream using a released reader');
}