I Want a More Concice Form of Data than an Array

Question

This is pretty abstract and isn't truly WordPress related, except that I'm storing this data in a WordPress installation, so I am limited to PHP/MySQL-esque parameters.

Here's what I want to do. I've got a list of Post ID's that I need to store in specific arrangements, different from their nested order as presented by WordPress. For example:

• ID 101
  • ID 106
    • ID 115
    • ID 116
  • ID 107
    • ID 117
  • ID 108
    • ID 118
    • ID 119
    • ID 120
  • ID 109
• ID 102
  • ID 110
    • ID 121
    • ID 122
  • ID 111
    • ID 123
  • ID 112
• ID 103
  • ID 113
  • ID 114
• ID 104
• ID 105

The idea here is that this is a deep and complex list that could go on recursively forever if needed.

Now I could create a set of nested arrays to house this structure in PHP, but that feels a little sloppy on my end. My question is this: Is there a simpler/cleaner way to store this complex list of nested ID's -- A JSON list, XML list or some other form of data that could be programmatically manipulated as needed?

Answer 1

Instead of going for a complex nested array, I decided that it might be best to keep it to simple two level set of arrays.

    $x = array(
            101 => [ (int $parent_id), (bool $completed)  ], 
            102 => [ (int $parent_id), (bool $completed)  ], 
            103 => [ (int $parent_id), (bool $completed)  ], 
            104 => [ (int $parent_id), (bool $completed)  ], 
            ...
        );

I realized that I was looking for something simpler like what python offers with its "list" data type. I feel like this is about as simple as I could get with storing an unorder list in PHP/MySQL. Anyone got anything better?