How do I use a recursive array iterator to process a multidimensional array?

Question

I'm trying to get something like this working:

function posts_formatter (&$posts){
    foreach ($posts as $k => $v){

        if (is_array($v)){

            posts_formatter($v);

        }else{

            switch (strtolower($k)){

                # make email addresses lowercase
                case (strpos($k, 'email') !== FALSE):
                    $posts[$k] = strtolower($v);
                    break;

                # make postcodes uppercase
                case (strpos($k, 'postcode') !== FALSE):
                    $posts[$k] = strtoupper($v);
                    break;

                # capitalize certain things
                case (strpos($k, 'line1') !== FALSE):
                case (strpos($k, 'line2') !== FALSE):
                case (strpos($k, 'line3') !== FALSE):
                case (strpos($k, 'forename') !== FALSE):
                case (strpos($k, 'surname') !== FALSE):
                    $posts[$k] = capitalize($v);
                    break;
            }

        }
    }
}

It will correctly go through the array and format the values but I can't get it to return them. I've played around with removing the & from the function declaration and adding a return at the end but it won't do anything.

Additionally, I'm thinking perhaps using a RecursiveArrayIterator might be the way to go. However, despite the presence of a book right in front of me with a chapter on SPL Iterators its examples are useless towards being able to achieve what I'm trying to. How would I go about implementing one?

Edit:

array (
  'user' => 
  array (
    'title' => 'Mr.',
    'forename' => 'lowercase',
    'surname' => 'name',
    'businessName' => 'some dude',
    'telephone' => '07545464646',
    'postcode' => 'wa1 6nj',
    'line1' => 'blergh road',
    'line2' => 'randomLY cApitaLIzed wOrds',
    'line3' => '',
  ),
  'email' => '[email protected]',
  'address' => 
  array (
    'postcode' => 'ab1 1ba',
    'line1' => 'test road',
    'line2' => 'testville',
    'line3' => 'testshire',
  ),
  'date' => '2010-09-30'
)

Solution

Ok, here is a quick something for you to figure out:

$data = array(
    'title'    => 'how to work with iterators',
    'posts' => array(
        array(
        'title'  => 'introduction to iterators',
        'email'  => '[email protected]'
     ), array(
        'title'  => 'extending iterators',
        'email'  => '[email protected]'
     )
));

The main idea is to influence how the Iterator returns the current element. Iterators are stackable, so you should use a RecursiveArrayIterator and wrap it into a RecursiveIteratorIterator. To achieve custom functionality, you can either subclass the RecursiveIteratorIterator (as shown below) or use additional iterators to decorate the RecursiveIteratorIterator:

class PostFormatter extends RecursiveIteratorIterator
{
    public function current()
    {
        $current = parent::current();
        switch($this->key()) {
            case 'email':
                $current = strtolower($current);
                break;
            case 'title':
                $current = ucwords($current);
                break;
            default:
                break;
        }
        return $current;
    }
}

Then you simply foreach over the iterator

$it = new PostFormatter(new RecursiveArrayIterator($data));
foreach($it as $key => $post) {
    echo "$key: $post", PHP_EOL;
}

and get

title: How To Work With Iterators
title: Introduction To Iterators
email: [email protected]
title: Extending Iterators
email: [email protected]

---

You can try to get the array back from the with iterator_to_array or iterator_apply functions. However, to get the values reapplied to the original array structure, you dont need an iterator:

array_walk_recursive($data, function(&$val, $key) {
    switch($key) {
        case 'title': $val = ucwords($val); break;
        case 'email': $val = strtolower($val); break;
        default: break;
    }
});
print_r($data);

Note: exchange Lambda with Function name when using PHP<5.3

Comments

[bcmcfc]

Thanks for your help Gordon. Just one more quick Q- how do I amend it return the processed array with the original array structure intact?

[bcmcfc]

Thanks for the detailed explanation.

[Gordon]

@bcmcfc You're welcome. I had to remove the iterator_to_array code because it wouldnt apply the changes to the inner arrays. I am sure you can do it somehow, but right now I cant fiddle with it (time constraints). Sorry.