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38 lines
1.7 KiB
38 lines
1.7 KiB
3 years ago
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// https://github.com/tc39/proposal-iterator-helpers
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var $ = require('../internals/export');
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var apply = require('../internals/function-apply');
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var anObject = require('../internals/an-object');
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var toObject = require('../internals/to-object');
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var isPrototypeOf = require('../internals/object-is-prototype-of');
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var AsyncIteratorPrototype = require('../internals/async-iterator-prototype');
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var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
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var getAsyncIterator = require('../internals/get-async-iterator');
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var getIterator = require('../internals/get-iterator');
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var getIteratorMethod = require('../internals/get-iterator-method');
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var getMethod = require('../internals/get-method');
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var wellKnownSymbol = require('../internals/well-known-symbol');
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var AsyncFromSyncIterator = require('../internals/async-from-sync-iterator');
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var ASYNC_ITERATOR = wellKnownSymbol('asyncIterator');
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var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise, args) {
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return anObject(apply(this.next, this.iterator, args));
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}, true);
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$({ target: 'AsyncIterator', stat: true, forced: true }, {
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from: function from(O) {
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var object = toObject(O);
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var usingIterator = getMethod(object, ASYNC_ITERATOR);
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var iterator;
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if (usingIterator) {
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iterator = getAsyncIterator(object, usingIterator);
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if (isPrototypeOf(AsyncIteratorPrototype, iterator)) return iterator;
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}
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if (iterator === undefined) {
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usingIterator = getIteratorMethod(object);
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if (usingIterator) return new AsyncFromSyncIterator(getIterator(object, usingIterator));
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}
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return new AsyncIteratorProxy({ iterator: iterator !== undefined ? iterator : object });
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}
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});
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