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