lessc_parser::argumentDef PHP Method

    protected function argumentDef(&$args, &$isVararg)
    {
        $s = $this->seek();
        if (!$this->literal('(')) {
            return false;
        }
        $values = array();
        $delim = ",";
        $method = "expressionList";
        $isVararg = false;
        while (true) {
            if ($this->literal("...")) {
                $isVararg = true;
                break;
            }
            if ($this->{$method}($value)) {
                if ($value[0] == "variable") {
                    $arg = array("arg", $value[1]);
                    $ss = $this->seek();
                    if ($this->assign() && $this->{$method}($rhs)) {
                        $arg[] = $rhs;
                    } else {
                        $this->seek($ss);
                        if ($this->literal("...")) {
                            $arg[0] = "rest";
                            $isVararg = true;
                        }
                    }
                    $values[] = $arg;
                    if ($isVararg) {
                        break;
                    }
                    continue;
                } else {
                    $values[] = array("lit", $value);
                }
            }
            if (!$this->literal($delim)) {
                if ($delim == "," && $this->literal(";")) {
                    // found new delim, convert existing args
                    $delim = ";";
                    $method = "propertyValue";
                    // transform arg list
                    if (isset($values[1])) {
                        // 2 items
                        $newList = array();
                        foreach ($values as $i => $arg) {
                            switch ($arg[0]) {
                                case "arg":
                                    if ($i) {
                                        $this->throwError("Cannot mix ; and , as delimiter types");
                                    }
                                    $newList[] = $arg[2];
                                    break;
                                case "lit":
                                    $newList[] = $arg[1];
                                    break;
                                case "rest":
                                    $this->throwError("Unexpected rest before semicolon");
                            }
                        }
                        $newList = array("list", ", ", $newList);
                        switch ($values[0][0]) {
                            case "arg":
                                $newArg = array("arg", $values[0][1], $newList);
                                break;
                            case "lit":
                                $newArg = array("lit", $newList);
                                break;
                        }
                    } elseif ($values) {
                        // 1 item
                        $newArg = $values[0];
                    }
                    if ($newArg) {
                        $values = array($newArg);
                    }
                } else {
                    break;
                }
            }
        }
        if (!$this->literal(')')) {
            $this->seek($s);
            return false;
        }
        $args = $values;
        return true;
    }