private static function _getCharMap(): array
    {
        // Keep local copy
        static $map = [];

        if (empty($map)) {
            // This will replace accented chars with non-accented chars
            foreach (StringHelper::asciiCharMap() as $asciiChar => $charsArray) {
                foreach ($charsArray as $char) {
                    $map[$char] = $asciiChar;
                }
            }

            // Replace punctuation with a space
            foreach (self::_getPunctuation() as $value) {
                $map[$value] = ' ';
            }
        }

        // Return the char map
        return $map;
    }