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2 years ago
'use strict';
// https://github.com/tc39/proposal-iterator-helpers
var $ = require('../internals/export');
var call = require('../internals/function-call');
var aCallable = require('../internals/a-callable');
var anObject = require('../internals/an-object');
var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
var getAsyncIterator = require('../internals/get-async-iterator');
var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise) {
var state = this;
var mapper = state.mapper;
var innerIterator;
return new Promise(function (resolve, reject) {
var outerLoop = function () {
try {
Promise.resolve(anObject(call(state.next, state.iterator))).then(function (step) {
try {
if (anObject(step).done) {
state.done = true;
resolve({ done: true, value: undefined });
} else {
Promise.resolve(mapper(step.value)).then(function (mapped) {
try {
state.innerIterator = innerIterator = getAsyncIterator(mapped);
state.innerNext = aCallable(innerIterator.next);
return innerLoop();
} catch (error2) { reject(error2); }
}, reject);
}
} catch (error1) { reject(error1); }
}, reject);
} catch (error) { reject(error); }
};
var innerLoop = function () {
if (innerIterator = state.innerIterator) {
try {
Promise.resolve(anObject(call(state.innerNext, innerIterator))).then(function (result) {
try {
if (anObject(result).done) {
state.innerIterator = state.innerNext = null;
outerLoop();
} else resolve({ done: false, value: result.value });
} catch (error1) { reject(error1); }
}, reject);
} catch (error) { reject(error); }
} else outerLoop();
};
innerLoop();
});
});
$({ target: 'AsyncIterator', proto: true, real: true, forced: true }, {
flatMap: function flatMap(mapper) {
return new AsyncIteratorProxy({
iterator: anObject(this),
mapper: aCallable(mapper),
innerIterator: null,
innerNext: null
});
}
});