array_flatten_keys function

gistfile1.php

/**
 * @param array $array
 * @param string|null $keyPrefix
 * @param string $format 'dot'|'form'
 * @return array
 */
function array_flatten_keys($array, $keyPrefix = null, $format = 'dot')
{
    $newArray = array();

    foreach ($array as $key => $value) {

        if (is_null($keyPrefix)) {
            $fullKey = $key;
        } else {
            $fullKey = $keyPrefix;

            if ($format === 'dot') {
                $fullKey .= '.' . (string)$key;
            } elseif ($format === 'form') {
                $fullKey .= '[' . (string)$key . ']';
            } else {
                new InvalidArgumentException('Unknown format');
            }
        }

        if (is_array($value)) {
            $newArray = array_merge(
                $newArray,
                array_flatten_keys($value, $fullKey, $format)
            );
        } else {
            $newArray[$fullKey] = $value;
        }
    }

    return $newArray;
}