41 lines
1.3 KiB
JavaScript
41 lines
1.3 KiB
JavaScript
'use strict';
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// 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 toPositiveInteger = require('../internals/to-positive-integer');
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var createAsyncIteratorProxy = require('../internals/create-async-iterator-proxy');
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var AsyncIteratorProxy = createAsyncIteratorProxy(function (arg, Promise) {
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var state = this;
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return new Promise(function (resolve, reject) {
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var loop = function () {
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try {
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Promise.resolve(
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anObject(state.next.call(state.iterator, state.remaining ? undefined : arg))
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).then(function (step) {
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try {
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if (anObject(step).done) {
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state.done = true;
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resolve({ done: true, value: undefined });
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} else if (state.remaining) {
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state.remaining--;
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loop();
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} else resolve({ done: false, value: step.value });
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} catch (err) { reject(err); }
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}, reject);
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} catch (error) { reject(error); }
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};
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loop();
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});
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});
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$({ target: 'AsyncIterator', proto: true, real: true }, {
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drop: function drop(limit) {
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return new AsyncIteratorProxy({
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iterator: anObject(this),
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remaining: toPositiveInteger(limit)
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});
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}
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});
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