33 lines
1.5 KiB
JavaScript
33 lines
1.5 KiB
JavaScript
// https://github.com/tc39/proposal-iterator-helpers
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var $ = require('../internals/export');
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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 getAsyncIterator = require('../internals/get-async-iterator');
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var getIterator = require('../internals/get-iterator');
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var getIteratorDirect = require('../internals/get-iterator-direct');
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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 WrapAsyncIterator = require('../internals/async-iterator-wrap');
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var ASYNC_ITERATOR = wellKnownSymbol('asyncIterator');
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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) iterator = new AsyncFromSyncIterator(getIterator(object, usingIterator));
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}
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return new WrapAsyncIterator(getIteratorDirect(iterator !== undefined ? iterator : object));
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}
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});
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