--- /dev/null
+'use strict';
+var path = require('../internals/path');
+var aFunction = require('../internals/a-function');
+var anObject = require('../internals/an-object');
+var create = require('../internals/object-create');
+var createNonEnumerableProperty = require('../internals/create-non-enumerable-property');
+var redefineAll = require('../internals/redefine-all');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+var InternalStateModule = require('../internals/internal-state');
+var getBuiltIn = require('../internals/get-built-in');
+
+var Promise = getBuiltIn('Promise');
+
+var setInternalState = InternalStateModule.set;
+var getInternalState = InternalStateModule.get;
+
+var TO_STRING_TAG = wellKnownSymbol('toStringTag');
+
+var $return = function (value) {
+ var iterator = getInternalState(this).iterator;
+ var $$return = iterator['return'];
+ return $$return === undefined
+ ? Promise.resolve({ done: true, value: value })
+ : anObject($$return.call(iterator, value));
+};
+
+var $throw = function (value) {
+ var iterator = getInternalState(this).iterator;
+ var $$throw = iterator['throw'];
+ return $$throw === undefined
+ ? Promise.reject(value)
+ : $$throw.call(iterator, value);
+};
+
+module.exports = function (nextHandler, IS_ITERATOR) {
+ var AsyncIteratorProxy = function AsyncIterator(state) {
+ state.next = aFunction(state.iterator.next);
+ state.done = false;
+ setInternalState(this, state);
+ };
+
+ AsyncIteratorProxy.prototype = redefineAll(create(path.AsyncIterator.prototype), {
+ next: function next(arg) {
+ var state = getInternalState(this);
+ if (state.done) return Promise.resolve({ done: true, value: undefined });
+ try {
+ return Promise.resolve(anObject(nextHandler.call(state, arg, Promise)));
+ } catch (error) {
+ return Promise.reject(error);
+ }
+ },
+ 'return': $return,
+ 'throw': $throw
+ });
+
+ if (!IS_ITERATOR) {
+ createNonEnumerableProperty(AsyncIteratorProxy.prototype, TO_STRING_TAG, 'Generator');
+ }
+
+ return AsyncIteratorProxy;
+};