async-iterator-map.js 2.0 KB

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  1. 'use strict';
  2. var call = require('../internals/function-call');
  3. var aCallable = require('../internals/a-callable');
  4. var anObject = require('../internals/an-object');
  5. var isObject = require('../internals/is-object');
  6. var getIteratorDirect = require('../internals/get-iterator-direct');
  7. var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
  8. var createIterResultObject = require('../internals/create-iter-result-object');
  9. var closeAsyncIteration = require('../internals/async-iterator-close');
  10. var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise) {
  11. var state = this;
  12. var iterator = state.iterator;
  13. var mapper = state.mapper;
  14. return new Promise(function (resolve, reject) {
  15. var doneAndReject = function (error) {
  16. state.done = true;
  17. reject(error);
  18. };
  19. var ifAbruptCloseAsyncIterator = function (error) {
  20. closeAsyncIteration(iterator, doneAndReject, error, doneAndReject);
  21. };
  22. try {
  23. Promise.resolve(anObject(call(state.next, iterator))).then(function (step) {
  24. try {
  25. if (anObject(step).done) {
  26. state.done = true;
  27. resolve(createIterResultObject(undefined, true));
  28. } else {
  29. var value = step.value;
  30. try {
  31. var result = mapper(value, state.counter++);
  32. var handler = function (mapped) {
  33. resolve(createIterResultObject(mapped, false));
  34. };
  35. if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
  36. else handler(result);
  37. } catch (error2) { ifAbruptCloseAsyncIterator(error2); }
  38. }
  39. } catch (error) { doneAndReject(error); }
  40. }, doneAndReject);
  41. } catch (error) { doneAndReject(error); }
  42. });
  43. });
  44. // `AsyncIterator.prototype.map` method
  45. // https://github.com/tc39/proposal-async-iterator-helpers
  46. module.exports = function map(mapper) {
  47. anObject(this);
  48. aCallable(mapper);
  49. return new AsyncIteratorProxy(getIteratorDirect(this), {
  50. mapper: mapper
  51. });
  52. };