How to implement recursive merging of trees?

Question

PHP

How can you recursively merge trees?

Trees look like:

$tree1 = new \ArrayObject(<br>
    array(<br>
        array('category' => \Shop\Model\Category, 'child' => \ArrayObject([*RECURSIVE*]))<br>
    )<br>
);<br>

\ArrayObject([*RECURSIVE*]) - well, here it is clear that there can be, in turn, another \ArrayObject object with elements of a similar structure.

Those. in this case, you need to check when merging that if the categories match, then you need to go further through the descendants.
There's a lot going on here, I just can't figure out where to start.
Maybe there is some kind of algorithm?

Answer 1

php.net/manual/en/function.array-merge-recursive.php

Answer 2

Recursive tree operations are most easily done with a recursive function. Your question is described in such a way that you don’t understand anything, so I’ll give an example of a function that goes through the tree and multiplies each element by 2:
ideone.com/2zVf8C
That is, we make a function that processes one array, and if it has subarrays, we simply call the same function for them. The same approach, it seems to me, will perfectly suit your task.