如何在PHP中将这个复杂的文本块解析为多维数组？

Question

I have a complex text-block; and, its content is:

    line_1(element_1,sub_line_1(sub_element_1,sub_element_2),element_2).
    line_2(sub_line_2(element_3,element_4),sub_line_3(sub_sub_line(element_5,element_6),element_7),element_8).
    ...
    line_n(element_a,element_b,element_c).

And, there is already an simple array, in PHP code:

$my_array = array();

Now, I want to parse into this PHP array, like:

$my_array = array (

    "line_1" => array (
            "element_1",
            "sub_line_1" => array (
                "sub_element_1",
                "sub_element_2" ),
            "element_2"),

    "line_2" => array (
            "sub_line_2" => array (
                "sub_element_3",
                "sub_element_4" ),
            "sub_line_3" => array (
                "sub_sub_line" => array ("element_5","element_6"),
                "sub_element_7" ),
            "element_8" )
    ),
    ...
    "line_n" => array ("element_a", "element_b", "element_c")

);

All data is general; and, the level of array is more. Could you help me to do it, with PHP?