<?php
function get_string_between($string, $start, $end){
    $string = " ".$string;
    $ini = strpos($string,$start);
    if ($ini == 0) return "";
    $ini += strlen($start);
    $len = strpos($string,$end,$ini) - $ini;
    return substr($string,$ini,$len);
}

$original = "'foo, bar', ['name' => 'John, Smith' , 'anotherKey' => 'another value']";
$str = get_string_between($original, "'", "'");
$arr = get_string_between($original, "[", "]");
$arr = json_decode(str_replace(' => ',':',str_replace('\'','"','{'.$arr.'}')), true);
var_dump($str);
print_r($arr);
?>