async-iterator-iteration.js 3.6 KB

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  1. 'use strict';
  2. // https://github.com/tc39/proposal-async-iterator-helpers
  3. // https://github.com/tc39/proposal-array-from-async
  4. var call = require('../internals/function-call');
  5. var aCallable = require('../internals/a-callable');
  6. var anObject = require('../internals/an-object');
  7. var isObject = require('../internals/is-object');
  8. var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
  9. var getBuiltIn = require('../internals/get-built-in');
  10. var createProperty = require('../internals/create-property');
  11. var setArrayLength = require('../internals/array-set-length');
  12. var getIteratorDirect = require('../internals/get-iterator-direct');
  13. var closeAsyncIteration = require('../internals/async-iterator-close');
  14. var createMethod = function (TYPE) {
  15. var IS_TO_ARRAY = TYPE === 0;
  16. var IS_FOR_EACH = TYPE === 1;
  17. var IS_EVERY = TYPE === 2;
  18. var IS_SOME = TYPE === 3;
  19. return function (object, fn, target) {
  20. anObject(object);
  21. var MAPPING = fn !== undefined;
  22. if (MAPPING || !IS_TO_ARRAY) aCallable(fn);
  23. var record = getIteratorDirect(object);
  24. var Promise = getBuiltIn('Promise');
  25. var iterator = record.iterator;
  26. var next = record.next;
  27. var counter = 0;
  28. return new Promise(function (resolve, reject) {
  29. var ifAbruptCloseAsyncIterator = function (error) {
  30. closeAsyncIteration(iterator, reject, error, reject);
  31. };
  32. var loop = function () {
  33. try {
  34. if (MAPPING) try {
  35. doesNotExceedSafeInteger(counter);
  36. } catch (error5) { ifAbruptCloseAsyncIterator(error5); }
  37. Promise.resolve(anObject(call(next, iterator))).then(function (step) {
  38. try {
  39. if (anObject(step).done) {
  40. if (IS_TO_ARRAY) {
  41. setArrayLength(target, counter);
  42. resolve(target);
  43. } else resolve(IS_SOME ? false : IS_EVERY || undefined);
  44. } else {
  45. var value = step.value;
  46. try {
  47. if (MAPPING) {
  48. var result = fn(value, counter);
  49. var handler = function ($result) {
  50. if (IS_FOR_EACH) {
  51. loop();
  52. } else if (IS_EVERY) {
  53. $result ? loop() : closeAsyncIteration(iterator, resolve, false, reject);
  54. } else if (IS_TO_ARRAY) {
  55. try {
  56. createProperty(target, counter++, $result);
  57. loop();
  58. } catch (error4) { ifAbruptCloseAsyncIterator(error4); }
  59. } else {
  60. $result ? closeAsyncIteration(iterator, resolve, IS_SOME || value, reject) : loop();
  61. }
  62. };
  63. if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
  64. else handler(result);
  65. } else {
  66. createProperty(target, counter++, value);
  67. loop();
  68. }
  69. } catch (error3) { ifAbruptCloseAsyncIterator(error3); }
  70. }
  71. } catch (error2) { reject(error2); }
  72. }, reject);
  73. } catch (error) { reject(error); }
  74. };
  75. loop();
  76. });
  77. };
  78. };
  79. module.exports = {
  80. // `AsyncIterator.prototype.toArray` / `Array.fromAsync` methods
  81. toArray: createMethod(0),
  82. // `AsyncIterator.prototype.forEach` method
  83. forEach: createMethod(1),
  84. // `AsyncIterator.prototype.every` method
  85. every: createMethod(2),
  86. // `AsyncIterator.prototype.some` method
  87. some: createMethod(3),
  88. // `AsyncIterator.prototype.find` method
  89. find: createMethod(4)
  90. };