PHP Manual: Create a RecursiveCallbackFilterIterator from a RecursiveIterator

public RecursiveCallbackFilterIterator::__construct(RecursiveIterator $iterator, callable $callback)

Creates a filtered iterator from a RecursiveIterator using the callback to determine which items are accepted or rejected.

iterator

The recursive iterator to be filtered.

callback

The callback, which should return true to accept the current item or false otherwise. See Examples.

May be any valid callable value.

RecursiveCallbackFilterIterator::__construct