--- /dev/null
+'use strict';
+var regexpFlags = require('./regexp-flags');
+var stickyHelpers = require('./regexp-sticky-helpers');
+
+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 UPDATES_LAST_INDEX_WRONG = (function () {
+ var re1 = /a/;
+ var re2 = /b*/g;
+ nativeExec.call(re1, 'a');
+ nativeExec.call(re2, 'a');
+ return re1.lastIndex !== 0 || re2.lastIndex !== 0;
+})();
+
+var UNSUPPORTED_Y = stickyHelpers.UNSUPPORTED_Y || stickyHelpers.BROKEN_CARET;
+
+// nonparticipating capturing group, copied from es5-shim's String#split patch.
+// eslint-disable-next-line regexp/no-assertion-capturing-group, regexp/no-empty-group -- required for testing
+var NPCG_INCLUDED = /()??/.exec('')[1] !== undefined;
+
+var PATCH = UPDATES_LAST_INDEX_WRONG || NPCG_INCLUDED || UNSUPPORTED_Y;
+
+if (PATCH) {
+ patchedExec = function exec(str) {
+ var re = this;
+ var lastIndex, reCopy, match, i;
+ var sticky = UNSUPPORTED_Y && re.sticky;
+ var flags = regexpFlags.call(re);
+ var source = re.source;
+ var charsAdded = 0;
+ var strCopy = str;
+
+ if (sticky) {
+ flags = flags.replace('y', '');
+ if (flags.indexOf('g') === -1) {
+ flags += 'g';
+ }
+
+ strCopy = String(str).slice(re.lastIndex);
+ // Support anchored sticky behavior.
+ if (re.lastIndex > 0 && (!re.multiline || re.multiline && str[re.lastIndex - 1] !== '\n')) {
+ source = '(?: ' + source + ')';
+ strCopy = ' ' + strCopy;
+ charsAdded++;
+ }
+ // ^(? + rx + ) is needed, in combination with some str slicing, to
+ // simulate the 'y' flag.
+ reCopy = new RegExp('^(?:' + source + ')', flags);
+ }
+
+ if (NPCG_INCLUDED) {
+ reCopy = new RegExp('^' + source + '$(?!\\s)', flags);
+ }
+ if (UPDATES_LAST_INDEX_WRONG) lastIndex = re.lastIndex;
+
+ match = nativeExec.call(sticky ? reCopy : re, strCopy);
+
+ if (sticky) {
+ if (match) {
+ match.input = match.input.slice(charsAdded);
+ match[0] = match[0].slice(charsAdded);
+ match.index = re.lastIndex;
+ re.lastIndex += match[0].length;
+ } else re.lastIndex = 0;
+ } else if (UPDATES_LAST_INDEX_WRONG && match) {
+ re.lastIndex = 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 /(.?)?/
+ 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;