67 lines
2.4 KiB
JavaScript
67 lines
2.4 KiB
JavaScript
'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/create-async-iterator-proxy');
|
|
var getAsyncIteratorMethod = require('../internals/get-async-iterator-method');
|
|
|
|
var AsyncIteratorProxy = createAsyncIteratorProxy(function (arg, Promise) {
|
|
var state = this;
|
|
var mapper = state.mapper;
|
|
var innerIterator, iteratorMethod;
|
|
|
|
return new Promise(function (resolve, reject) {
|
|
var outerLoop = 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 {
|
|
Promise.resolve(mapper(step.value)).then(function (mapped) {
|
|
try {
|
|
iteratorMethod = getAsyncIteratorMethod(mapped);
|
|
if (iteratorMethod !== undefined) {
|
|
state.innerIterator = innerIterator = anObject(iteratorMethod.call(mapped));
|
|
state.innerNext = aFunction(innerIterator.next);
|
|
return innerLoop();
|
|
} reject(TypeError('.flatMap callback should return an iterable object'));
|
|
} 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(state.innerNext.call(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 }, {
|
|
flatMap: function flatMap(mapper) {
|
|
return new AsyncIteratorProxy({
|
|
iterator: anObject(this),
|
|
mapper: aFunction(mapper),
|
|
innerIterator: null,
|
|
innerNext: null
|
|
});
|
|
}
|
|
});
|