es.iterator.flat-map.js 2.8 KB

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  1. 'use strict';
  2. var $ = require('../internals/export');
  3. var call = require('../internals/function-call');
  4. var aCallable = require('../internals/a-callable');
  5. var anObject = require('../internals/an-object');
  6. var getIteratorDirect = require('../internals/get-iterator-direct');
  7. var getIteratorFlattenable = require('../internals/get-iterator-flattenable');
  8. var createIteratorProxy = require('../internals/iterator-create-proxy');
  9. var iteratorClose = require('../internals/iterator-close');
  10. var IS_PURE = require('../internals/is-pure');
  11. var iteratorHelperThrowsOnInvalidIterator = require('../internals/iterator-helper-throws-on-invalid-iterator');
  12. var iteratorHelperWithoutClosingOnEarlyError = require('../internals/iterator-helper-without-closing-on-early-error');
  13. // Should not throw an error for an iterator without `return` method. Fixed in Safari 26.2
  14. // https://bugs.webkit.org/show_bug.cgi?id=297532
  15. function throwsOnIteratorWithoutReturn() {
  16. try {
  17. // eslint-disable-next-line es/no-map, es/no-iterator, es/no-iterator-prototype-flatmap -- required for testing
  18. var it = Iterator.prototype.flatMap.call(new Map([[4, 5]]).entries(), function (v) { return v; });
  19. it.next();
  20. it['return']();
  21. } catch (error) {
  22. return true;
  23. }
  24. }
  25. var FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR = !IS_PURE
  26. && !iteratorHelperThrowsOnInvalidIterator('flatMap', function () { /* empty */ });
  27. var flatMapWithoutClosingOnEarlyError = !IS_PURE && !FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR
  28. && iteratorHelperWithoutClosingOnEarlyError('flatMap', TypeError);
  29. var FORCED = IS_PURE || FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR || flatMapWithoutClosingOnEarlyError
  30. || throwsOnIteratorWithoutReturn();
  31. var IteratorProxy = createIteratorProxy(function () {
  32. var iterator = this.iterator;
  33. var mapper = this.mapper;
  34. var result, inner;
  35. while (true) {
  36. if (inner = this.inner) try {
  37. result = anObject(call(inner.next, inner.iterator));
  38. if (!result.done) return result.value;
  39. this.inner = null;
  40. } catch (error) { iteratorClose(iterator, 'throw', error); }
  41. result = anObject(call(this.next, iterator));
  42. if (this.done = !!result.done) return;
  43. try {
  44. this.inner = getIteratorFlattenable(mapper(result.value, this.counter++), false);
  45. } catch (error) { iteratorClose(iterator, 'throw', error); }
  46. }
  47. });
  48. // `Iterator.prototype.flatMap` method
  49. // https://tc39.es/ecma262/#sec-iterator.prototype.flatmap
  50. $({ target: 'Iterator', proto: true, real: true, forced: FORCED }, {
  51. flatMap: function flatMap(mapper) {
  52. anObject(this);
  53. try {
  54. aCallable(mapper);
  55. } catch (error) {
  56. iteratorClose(this, 'throw', error);
  57. }
  58. if (flatMapWithoutClosingOnEarlyError) return call(flatMapWithoutClosingOnEarlyError, this, mapper);
  59. return new IteratorProxy(getIteratorDirect(this), {
  60. mapper: mapper,
  61. inner: null
  62. });
  63. }
  64. });