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esnext.iterator.flat-map.js
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esnext.iterator.flat-map.js
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'use strict';
var $ = require('../internals/export');
var call = require('../internals/function-call');
var aCallable = require('../internals/a-callable');
var anObject = require('../internals/an-object');
var getIteratorDirect = require('../internals/get-iterator-direct');
var getIteratorFlattenable = require('../internals/get-iterator-flattenable');
var createIteratorProxy = require('../internals/iterator-create-proxy');
var iteratorClose = require('../internals/iterator-close');
var IS_PURE = require('../internals/is-pure');
var IteratorProxy = createIteratorProxy(function () {
var iterator = this.iterator;
var mapper = this.mapper;
var result, inner;
while (true) {
if (inner = this.inner) try {
result = anObject(call(inner.next, inner.iterator));
if (!result.done) return result.value;
this.inner = null;
} catch (error) { iteratorClose(iterator, 'throw', error); }
result = anObject(call(this.next, iterator));
if (this.done = !!result.done) return;
try {
this.inner = getIteratorFlattenable(mapper(result.value, this.counter++), false);
} catch (error) { iteratorClose(iterator, 'throw', error); }
}
});
// `Iterator.prototype.flatMap` method
// https://github.com/tc39/proposal-iterator-helpers
$({ target: 'Iterator', proto: true, real: true, forced: IS_PURE }, {
flatMap: function flatMap(mapper) {
anObject(this);
aCallable(mapper);
return new IteratorProxy(getIteratorDirect(this), {
mapper: mapper,
inner: null
});
}
});