'use strict';
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var regexpFlags = require('./_flags');
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var nativeExec = RegExp.prototype.exec;
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// This always refers to the native implementation, because the
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// String#replace polyfill uses ./fix-regexp-well-known-symbol-logic.js,
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// which loads this file before patching the method.
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var nativeReplace = String.prototype.replace;
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var patchedExec = nativeExec;
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var LAST_INDEX = 'lastIndex';
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var UPDATES_LAST_INDEX_WRONG = (function () {
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var re1 = /a/,
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re2 = /b*/g;
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nativeExec.call(re1, 'a');
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nativeExec.call(re2, 'a');
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return re1[LAST_INDEX] !== 0 || re2[LAST_INDEX] !== 0;
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})();
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// nonparticipating capturing group, copied from es5-shim's String#split patch.
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var NPCG_INCLUDED = /()??/.exec('')[1] !== undefined;
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var PATCH = UPDATES_LAST_INDEX_WRONG || NPCG_INCLUDED;
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if (PATCH) {
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patchedExec = function exec(str) {
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var re = this;
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var lastIndex, reCopy, match, i;
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if (NPCG_INCLUDED) {
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reCopy = new RegExp('^' + re.source + '$(?!\\s)', regexpFlags.call(re));
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}
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if (UPDATES_LAST_INDEX_WRONG) lastIndex = re[LAST_INDEX];
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match = nativeExec.call(re, str);
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if (UPDATES_LAST_INDEX_WRONG && match) {
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re[LAST_INDEX] = re.global ? match.index + match[0].length : lastIndex;
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}
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if (NPCG_INCLUDED && match && match.length > 1) {
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// Fix browsers whose `exec` methods don't consistently return `undefined`
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// for NPCG, like IE8. NOTE: This doesn' work for /(.?)?/
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// eslint-disable-next-line no-loop-func
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nativeReplace.call(match[0], reCopy, function () {
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for (i = 1; i < arguments.length - 2; i++) {
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if (arguments[i] === undefined) match[i] = undefined;
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}
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});
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}
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return match;
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};
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}
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module.exports = patchedExec;
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