GetIterator.js 1.8 KB

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  1. 'use strict';
  2. var GetIntrinsic = require('get-intrinsic');
  3. var $TypeError = require('es-errors/type');
  4. var $asyncIterator = GetIntrinsic('%Symbol.asyncIterator%', true);
  5. var inspect = require('object-inspect');
  6. var hasSymbols = require('has-symbols')();
  7. var AdvanceStringIndex = require('./AdvanceStringIndex');
  8. var CreateAsyncFromSyncIterator = require('./CreateAsyncFromSyncIterator');
  9. var GetIteratorFromMethod = require('./GetIteratorFromMethod');
  10. var GetMethod = require('./GetMethod');
  11. var IsArray = require('./IsArray');
  12. var getIteratorMethod = require('../helpers/getIteratorMethod');
  13. var ES = {
  14. AdvanceStringIndex: AdvanceStringIndex,
  15. GetMethod: GetMethod,
  16. IsArray: IsArray
  17. };
  18. // https://262.ecma-international.org/14.0/#sec-getiterator
  19. module.exports = function GetIterator(obj, kind) {
  20. if (kind !== 'sync' && kind !== 'async') {
  21. throw new $TypeError("Assertion failed: `kind` must be one of 'sync' or 'async', got " + inspect(kind));
  22. }
  23. var method;
  24. if (kind === 'async') { // step 1
  25. if (hasSymbols && $asyncIterator) {
  26. method = GetMethod(obj, $asyncIterator); // step 1.a
  27. }
  28. }
  29. if (typeof method === 'undefined') { // step 1.b
  30. // var syncMethod = GetMethod(obj, $iterator); // step 1.b.i
  31. var syncMethod = getIteratorMethod(ES, obj);
  32. if (kind === 'async') {
  33. if (typeof syncMethod === 'undefined') {
  34. throw new $TypeError('iterator method is `undefined`'); // step 1.b.ii
  35. }
  36. var syncIteratorRecord = GetIteratorFromMethod(obj, syncMethod); // step 1.b.iii
  37. return CreateAsyncFromSyncIterator(syncIteratorRecord); // step 1.b.iv
  38. }
  39. method = syncMethod; // step 2, kind of
  40. }
  41. if (typeof method === 'undefined') {
  42. throw new $TypeError('iterator method is `undefined`'); // step 3
  43. }
  44. return GetIteratorFromMethod(obj, method); // step 4
  45. };