GetIterator.js 1.7 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253
  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 getIteratorMethod = require('../helpers/getIteratorMethod');
  12. var ES = {
  13. AdvanceStringIndex: AdvanceStringIndex,
  14. GetMethod: GetMethod
  15. };
  16. // https://262.ecma-international.org/14.0/#sec-getiterator
  17. module.exports = function GetIterator(obj, kind) {
  18. if (kind !== 'sync' && kind !== 'async') {
  19. throw new $TypeError("Assertion failed: `kind` must be one of 'sync' or 'async', got " + inspect(kind));
  20. }
  21. var method;
  22. if (kind === 'async') { // step 1
  23. if (hasSymbols && $asyncIterator) {
  24. method = GetMethod(obj, $asyncIterator); // step 1.a
  25. }
  26. }
  27. if (typeof method === 'undefined') { // step 1.b
  28. // var syncMethod = GetMethod(obj, $iterator); // step 1.b.i
  29. var syncMethod = getIteratorMethod(ES, obj);
  30. if (kind === 'async') {
  31. if (typeof syncMethod === 'undefined') {
  32. throw new $TypeError('iterator method is `undefined`'); // step 1.b.ii
  33. }
  34. var syncIteratorRecord = GetIteratorFromMethod(obj, syncMethod); // step 1.b.iii
  35. return CreateAsyncFromSyncIterator(syncIteratorRecord); // step 1.b.iv
  36. }
  37. method = syncMethod; // step 2, kind of
  38. }
  39. if (typeof method === 'undefined') {
  40. throw new $TypeError('iterator method is `undefined`'); // step 3
  41. }
  42. return GetIteratorFromMethod(obj, method); // step 4
  43. };