PHP で配列の文字列表現を配列に変換するにはどうすればよいですか?

function text_to_array($str) {

    // Initialize arrays
    $keys = array();
    $values = array();
    $output = array();

    // Check if the input is an array
    if( substr($str, 0, 5) == 'Array' ) {

        // Parse the input
        $array_contents = substr($str, 7, -2);
        $array_contents = str_replace(array('[', ']', '=>'), array('#!#', '#?#', ''), $array_contents);
        $array_fields = explode("#!#", $array_contents);

        // Process each array field
        for($i = 0; $i < count($array_fields); $i++ ) {

            // Skip the first field (it's empty)
            if( $i != 0 ) {

                $bits = explode('#?#', $array_fields[$i]);
                if( $bits[0] != '' ) $output[$bits[0]] = $bits[1];

            }
        }
    }

    return $output;
}

$array_string = print_r($original_array, true);
$new_array = text_to_array($array_string);