A helper function expand_array for PHP

expand_array.php

<?php

/**
 * A helper function expand_array for PHP
 *
 * This is actually developed during the real need to develop JSON api
 * I wanted to have JSON api response spitted properly expanded (with semantic nodes)
 * But didnot want to do it by playing with arrays (looping, merging n' what not) time and again.
 * So, After fetching single dimensional array data from database, with keys having
 * some specific delimeter, this helper would do for me what i want to.
 * PS: This thing here is designed to work in multidimensional (deep nested) array too.
 * PPS: That example here is just simple teaser, what you can do &/or achieve is limitless. 
 *
 * @author Jitendra Adhikari | adhocore <jiten.adhikary@gmail.com>
 *
 * @param array  $source  The source array to expand
 * @param string $delim   The delimeter that is used to expand keys
 * @param bool   $deep    Is the $source array deep nested ? (You better know it)
 *
 * @return array
 */
function expand_array(array $source, $delim = '.', $deep = false)
{    
    $deep and ksort($source); // Without this we would miss something
    $target = array();

    // This closure is based on laravel's array helper; you can say i copied it ;)
    $arraySet = function (&$array, $key, $value) use ($delim) {
        if (is_null($key)) {
            return $array = $value;
        }
        $keys = explode($delim, $key);
        while (count($keys) > 1) {
            $key = array_shift($keys);
            if (! isset($array[$key]) or ! is_array($array[$key])) {
                $array[$key] = [];
            }
            $array = & $array[$key];
        }

        $array[array_shift($keys)] = $value;

        return $array;
    };

    foreach ($source as $key => $value) {
        if (is_array($value)) {
            $value = expand_array($value, $delim, $deep);
        }
        if (strpos($key, $delim) !== false) {
            $arraySet($target, $key, $value);
        } else {
            $target[$key] = $value;
        }
    }

    return $target;
}

// Usage:

// Suppose this is what i fetch from database
$source = array(
    array(
        'id' => 1,
        'username' => 'adhocore',
        'name.first' => 'Jitendra',
        'name.last' => 'Adhikari',
        'address.city' => 'Ktm', 
        'address.state' => 'Bagmati',    
    ),
    array(
        'id' => 2,
        'username' => '_adhocore',
        'name.first' => '_Jitendra',
        'name.last' => '_Adhikari',
        'address.city' => '_Ktm', 
        'address.state' => '_Bagmati',    
    ),
);

// Expand it, Yay !
$target = expand_array($source, '.');

print_r($target);

// Whoa, This is what i want
echo json_encode($target, JSON_PRETTY_PRINT);