$indexの内容
Array
(
    [ルート] => Array
        (
            [0] => 0
            [1] => 5
        )

    [親] => Array
        (
            [0] => 1
            [1] => 3
            [2] => 4
        )

    [子] => Array
        (
            [0] => 2
        )

)
$valuesの内容
Array
(
    [0] => Array
        (
            [tag] => ルート
            [type] => open
            [level] => 1
        )

    [1] => Array
        (
            [tag] => 親
            [type] => open
            [level] => 2
            [attributes] => Array
                (
                    [属性] => 値
                )

        )

    [2] => Array
        (
            [tag] => 子
            [type] => complete
            [level] => 3
            [value] => 文字列１
        )

    [3] => Array
        (
            [tag] => 親
            [value] => 文字列２
            [type] => cdata
            [level] => 2
        )

    [4] => Array
        (
            [tag] => 親
            [type] => close
            [level] => 2
        )

    [5] => Array
        (
            [tag] => ルート
            [type] => close
            [level] => 1
        )

)