32 lines
1.1 KiB
JavaScript
32 lines
1.1 KiB
JavaScript
// https://github.com/tc39/proposal-iterator-helpers
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var $ = require('../internals/export');
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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 IteratorPrototype = require('../internals/iterators-core').IteratorPrototype;
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var createIteratorProxy = require('../internals/iterator-create-proxy');
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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 isPrototypeOf = {}.isPrototypeOf;
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var IteratorProxy = createIteratorProxy(function (args) {
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var result = anObject(this.next.apply(this.iterator, args));
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var done = this.done = !!result.done;
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if (!done) return result.value;
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}, true);
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$({ target: 'Iterator', stat: true }, {
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from: function from(O) {
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var object = toObject(O);
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var usingIterator = getIteratorMethod(object);
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var iterator;
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if (usingIterator != null) {
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iterator = getIterator(object, usingIterator);
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if (isPrototypeOf.call(IteratorPrototype, iterator)) return iterator;
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} else {
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iterator = object;
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} return new IteratorProxy({
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iterator: iterator
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});
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}
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});
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