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'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.
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;