Method _

/**
 * Translate function, mimics the php gettext (alias _) function.
 *
 * The function checks if $jsSafe is true, then if $interpretBackslashes is true.
 *
 * @param   string   $string                The string to translate
 * @param   boolean  $jsSafe                Make the result javascript safe
 * @param   boolean  $interpretBackSlashes  Interpret \t and \n
 *
 * @return  string  The translation of the string
 *
 * @since   1.7.0
 */
public function _($string, $jsSafe = false, $interpretBackSlashes = true)
{
    // Detect empty string
    if ($string == '') {
        return '';
    }
    $key = strtoupper($string);
    if (isset($this->strings[$key])) {
        $string = $this->strings[$key];
        // Store debug information
        if ($this->debug) {
            $value = Factory::getApplication()->get('debug_lang_const', true) ? $string : $key;
            $string = '**' . $value . '**';
            $caller = $this->getCallerInfo();
            if (!\array_key_exists($key, $this->used)) {
                $this->used[$key] = array();
            }
            $this->used[$key][] = $caller;
        }
    } else {
        if ($this->debug) {
            $info = [];
            $info['trace'] = $this->getTrace();
            $info['key'] = $key;
            $info['string'] = $string;
            if (!\array_key_exists($key, $this->orphans)) {
                $this->orphans[$key] = array();
            }
            $this->orphans[$key][] = $info;
            $string = '??' . $string . '??';
        }
    }
    if ($jsSafe) {
        // Javascript filter
        $string = addslashes($string);
    } elseif ($interpretBackSlashes) {
        if (strpos($string, '\\') !== false) {
            // Interpret \n and \t characters
            $string = str_replace(array('\\\\', '\\t', '\\n'), array("\\", "\t", "\n"), $string);
        }
    }
    return $string;
}