优化

MrShi

7 天以前 1ab34d6347171b10acf78fcd3d6678eac0483bae

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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 createIteratorProxy = require('../internals/iterator-create-proxy');
var callWithSafeIterationClosing = require('../internals/call-with-safe-iteration-closing');
var iteratorClose = require('../internals/iterator-close');
var iteratorHelperThrowsOnInvalidIterator = require('../internals/iterator-helper-throws-on-invalid-iterator');
var iteratorHelperWithoutClosingOnEarlyError = require('../internals/iterator-helper-without-closing-on-early-error');
var IS_PURE = require('../internals/is-pure');
 
var MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR = !IS_PURE && !iteratorHelperThrowsOnInvalidIterator('map', function () { /* empty */ });
var mapWithoutClosingOnEarlyError = !IS_PURE && !MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR
  && iteratorHelperWithoutClosingOnEarlyError('map', TypeError);
 
var FORCED = IS_PURE || MAP_WITHOUT_THROWING_ON_INVALID_ITERATOR || mapWithoutClosingOnEarlyError;
 
var IteratorProxy = createIteratorProxy(function () {
  var iterator = this.iterator;
  var result = anObject(call(this.next, iterator));
  var done = this.done = !!result.done;
  if (!done) return callWithSafeIterationClosing(iterator, this.mapper, [result.value, this.counter++], true);
});
 
// `Iterator.prototype.map` method
// https://tc39.es/ecma262/#sec-iterator.prototype.map
$({ target: 'Iterator', proto: true, real: true, forced: FORCED }, {
  map: function map(mapper) {
    anObject(this);
    try {
      aCallable(mapper);
    } catch (error) {
      iteratorClose(this, 'throw', error);
    }
 
    if (mapWithoutClosingOnEarlyError) return call(mapWithoutClosingOnEarlyError, this, mapper);
 
    return new IteratorProxy(getIteratorDirect(this), {
      mapper: mapper
    });
  }
});