(PHP 5 >= 5.1.0, PHP 7)
This extended FilterIterator allows a recursive iteration using RecursiveIteratorIterator that only shows those elements which have children.
Easy example for understanding:
<?php
$iterator = new ParentIterator(
new RecursiveArrayIterator(
array(array(1, 2, 3), 'A', 'B', 'C')
)
);
foreach ($iterator as $recursive) {
foreach ($recursive as $value) {
echo $value . PHP_EOL;
}
}
?>
1
2
3
ParentIterator is just a RecursiveFilterIterator whos accept() method calls the RecursiveFilterIterator->hasChildren() method to filter itself.
Basically, it filters out leaf nodes. For example
This would yield all files and directories
<?php
$rdi = new RecursiveDirectoryIterator(__DIR__);
$iter = new RecursiveIteratorIterator($rdi, RecursiveIteratorIterator::CHILD_FIRST);
?>
wrapping that in a ParentIterator would filter it down to just directories
<?php
$rdi = new RecursiveDirectoryIterator(__DIR__);
$iter = new RecursiveIteratorIterator($rdi, RecursiveIteratorIterator::CHILD_FIRST);
$dirsOnly = new ParentIterator($iter);
?>