PHP – Concatenate / cascade multidimensional array keys

I’ve realized I need to stop banging my head and ask for help…

I have the following array:

$permissionTypes = array(
        'system' => array(
            'view' => 'View system settings.',
            'manage' => 'Manage system settings.'
        ),
        'users' => array(
            'all' => array(
                'view' => 'View all users.',
                'manage' => 'Manage all users.'
            )
        ),
        'associations' => array(
            'generalInformation' => array(
                'all' => array(
                    'view' => 'View general information of all associations.',
                    'manage' => 'Manage general information of all associations.'
                ),
                'own' => array(
                    'view' => 'View general information of the association the user is a member of.',
                    'manage' => 'Manage general information of the association the user is a member of.'
                )
            )
    ));

I’m trying to collapse / cascade the keys into a one-dimension array like so:

array(
    'system_view',
    'system_manage',
    'users_all_view',
    'users_all_manage',
    'associations_generalInformation_all_view',
    'associations_generalInformation_all_manage',
    'associations_generalInformation_own_view',
    'associations_generalInformation_own_manage'
)

I could use nested loops, but the array will be an undefined number of dimensions.

This is the closest I’ve gotten:

public function iterateKeys(array $array, $joiner, $prepend = NULL) {
    if (!isset($formattedArray)) { $formattedArray = array(); }
    foreach ($array as $key => $value) {
        if(is_array($value)) {
            array_push($formattedArray, $joiner . $this->iterateKeys($value, $joiner, $key));
        } else {
            $formattedArray = $prepend . $joiner . $key;
        }

    }
    return $formattedArray;
}

Any ideas?

Answer

I think this should do it:

public function iterateKeys(array $array, $joiner, $prepend = NULL) {
    if (!isset($formattedArray)) {
       $formattedArray = array(); 
    }

    foreach ($array as $key => $value) {
        if(is_array($value)) {
            $formattedArray = array_merge($formattedArray, $this->iterateKeys($value, $joiner, $prepend . $joiner . $key));
        } else {
            $formattedArray[] = $prepend . $joiner . $key;
        }

    }
    return $formattedArray;
}

Since the recursive call returns an array, you need to use array_merge to combine it with what you currently have. And for the non-array case, you need to push the new string onto the array, not replace the array with a string.