PHP - Recursive Multidimension Array iterator - php

Question

I'm trying to write a recursive array iterator function in which the function will return a result set of all sets that are specified by '$needle'. Where $needle = key
Here is my function:
function recursive($needle, $array, $holder = array()) {
foreach ($array as $key => $value) {
if (gettype($value) == 'array') {
if ($key != $needle) {
recursive($needle, $value);
} elseif ($key == $needle) {
if (!empty($value)) {
array_push($holder, $value);
}
}
}
}
return $holder;
}
But I'm not getting all the results back and instead get a few empty results, if I don't specify the !empty($value), although the input array does not have any empty sets. What am I doing wrong?

Answer 1

You don't need to reinvent the wheel since PHP has standard Recursive Iterator API:
//$array is your multi-dimensional array
$result = [];
$search = 'foo';
$iterator = new RecursiveIteratorIterator(
new RecursiveArrayIterator(
$array,
RecursiveArrayIterator::CHILD_ARRAYS_ONLY
)
);
foreach($iterator as $key=>$value)
{
if($search==$key && $value!=='')
{
$result[] = $value;
}
}
-note, that, since you're searching for value by key - in common case $value will hold entire subsection.
If you want to do this in your own recursive function, here's one:
function recursive($needle, $array, $holder = [])
{
$holder = [];
foreach($array as $key=>$value)
{
if($key===$needle && $value!=='')
{
$holder = array_merge($holder, [$value]);
}
if(is_array($value))
{
$holder = array_merge($holder, recursive($needle, $value, $holder));
}
}
return $holder;
}

Answer 2

More fine-grained control is perhaps possible with true (tm) recursive array traversal via RecursiveIterator interface and some key filters and array conversion functions:
$needle = '0';
$array = [[1]];
$it = new KeyFilter(
new RecursiveIteratorIterator(
new MyRecursiveArrayIterator($array)
, RecursiveIteratorIterator::SELF_FIRST
)
, $needle
);
$result = iterator_to_array($it, FALSE);
var_dump($result);
Providing an exemplary result as:
array(2) {
[0] =>
array(1) {
[0] =>
int(1)
}
[1] =>
int(1)
}
Full code example (Demo):
<?php
/**
* #link http://stackoverflow.com/q/19709410/367456
*/
Class MyRecursiveArrayIterator extends ArrayIterator implements RecursiveIterator
{
public function hasChildren()
{
$current = $this->current();
return is_array($current) && count($current);
}
public function getChildren()
{
return new self($this->current());
}
}
class KeyFilter extends RegexIterator
{
public function __construct(Iterator $iterator, $key)
{
parent::__construct(
$iterator, '/' . preg_quote($key) . '/', NULL, RegexIterator::USE_KEY
);
}
}
$needle = '0';
$array = [[1]];
$it = new KeyFilter(
new RecursiveIteratorIterator(
new MyRecursiveArrayIterator($array)
, RecursiveIteratorIterator::SELF_FIRST
)
, $needle
);
$result = iterator_to_array($it, FALSE);
var_dump($result);

Answer 3

A tiny modification of your construction:
$holder = recursive($needle, $value, $holder);
Ay?