1 | var wellKnownSymbol = require('../internals/well-known-symbol');
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2 |
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3 | var ITERATOR = wellKnownSymbol('iterator');
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4 | var SAFE_CLOSING = false;
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5 |
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6 | try {
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7 | var called = 0;
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8 | var iteratorWithReturn = {
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9 | next: function () {
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10 | return { done: !!called++ };
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11 | },
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12 | 'return': function () {
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13 | SAFE_CLOSING = true;
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14 | }
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15 | };
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16 | iteratorWithReturn[ITERATOR] = function () {
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17 | return this;
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18 | };
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19 |
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20 | Array.from(iteratorWithReturn, function () { throw 2; });
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21 | } catch (error) { }
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22 |
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23 | module.exports = function (exec, SKIP_CLOSING) {
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24 | if (!SKIP_CLOSING && !SAFE_CLOSING) return false;
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25 | var ITERATION_SUPPORT = false;
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26 | try {
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27 | var object = {};
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28 | object[ITERATOR] = function () {
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29 | return {
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30 | next: function () {
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31 | return { done: ITERATION_SUPPORT = true };
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32 | }
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33 | };
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34 | };
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35 | exec(object);
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36 | } catch (error) { }
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37 | return ITERATION_SUPPORT;
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38 | };
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