es.iterator.flat-map.js 2.3 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061
  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. var FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR = !IS_PURE
  14. && !iteratorHelperThrowsOnInvalidIterator('flatMap', function () { /* empty */ });
  15. var flatMapWithoutClosingOnEarlyError = !IS_PURE && !FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR
  16. && iteratorHelperWithoutClosingOnEarlyError('flatMap', TypeError);
  17. var FORCED = IS_PURE || FLAT_MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR || flatMapWithoutClosingOnEarlyError;
  18. var IteratorProxy = createIteratorProxy(function () {
  19. var iterator = this.iterator;
  20. var mapper = this.mapper;
  21. var result, inner;
  22. while (true) {
  23. if (inner = this.inner) try {
  24. result = anObject(call(inner.next, inner.iterator));
  25. if (!result.done) return result.value;
  26. this.inner = null;
  27. } catch (error) { iteratorClose(iterator, 'throw', error); }
  28. result = anObject(call(this.next, iterator));
  29. if (this.done = !!result.done) return;
  30. try {
  31. this.inner = getIteratorFlattenable(mapper(result.value, this.counter++), false);
  32. } catch (error) { iteratorClose(iterator, 'throw', error); }
  33. }
  34. });
  35. // `Iterator.prototype.flatMap` method
  36. // https://tc39.es/ecma262/#sec-iterator.prototype.flatmap
  37. $({ target: 'Iterator', proto: true, real: true, forced: FORCED }, {
  38. flatMap: function flatMap(mapper) {
  39. anObject(this);
  40. try {
  41. aCallable(mapper);
  42. } catch (error) {
  43. iteratorClose(this, 'throw', error);
  44. }
  45. if (flatMapWithoutClosingOnEarlyError) return call(flatMapWithoutClosingOnEarlyError, this, mapper);
  46. return new IteratorProxy(getIteratorDirect(this), {
  47. mapper: mapper,
  48. inner: null
  49. });
  50. }
  51. });