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esnext.async-iterator.filter.js
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esnext.async-iterator.filter.js
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'use strict';
// https://github.com/tc39/proposal-iterator-helpers
var $ = require('../internals/export');
var aFunction = require('../internals/a-function');
var anObject = require('../internals/an-object');
var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
var AsyncIteratorProxy = createAsyncIteratorProxy(function (arg, Promise) {
var state = this;
var filterer = state.filterer;
return new Promise(function (resolve, reject) {
var loop = function () {
try {
Promise.resolve(anObject(state.next.call(state.iterator, arg))).then(function (step) {
try {
if (anObject(step).done) {
state.done = true;
resolve({ done: true, value: undefined });
} else {
var value = step.value;
Promise.resolve(filterer(value)).then(function (selected) {
selected ? resolve({ done: false, value: value }) : loop();
}, reject);
}
} catch (err) { reject(err); }
}, reject);
} catch (error) { reject(error); }
};
loop();
});
});
$({ target: 'AsyncIterator', proto: true, real: true }, {
filter: function filter(filterer) {
return new AsyncIteratorProxy({
iterator: anObject(this),
filterer: aFunction(filterer)
});
}
});