[php] Convert multidimensional array into single array

I had come across the same requirement to flatter multidimensional array into single dimensional array than search value using text in key. here is my code

$data = '{
    "json_data": [{
            "downtime": true,
            "pfix": {
                "max": 100,
                "threshold": 880
            },
            "ints": {
                "int": [{
                    "rle": "pri",
                    "device": "laptop",
                    "int": "Ether3",
                    "ip": "127.0.0.3"
                }],
                "eth": {
                    "lan": 57
                }
            }
        },
        {
            "downtime": false,
            "lsi": "987654",
            "pfix": {
                "min": 10000,
                "threshold": 890
            },
            "mana": {
                "mode": "NONE"
            },
            "ints": {
                "int": [{
                    "rle": "sre",
                    "device": "desk",
                    "int": "Ten",
                    "ip": "1.1.1.1",
                    "UF": true
                }],
                "ethernet": {
                    "lan": 2
                }
            }
        }
    ]
}
';

$data = json_decode($data,true);


$stack = &$data;
$separator = '.';
$toc = array();

while ($stack) {
    list($key, $value) = each($stack);
    unset($stack[$key]);
    if (is_array($value)) {
        $build = array($key => ''); # numbering without a title.
        foreach ($value as $subKey => $node)
            $build[$key . $separator . $subKey] = $node;
        $stack = $build + $stack;
        continue;
    }
    if(!is_numeric($key)){
        $toc[$key] = $value;
    }
}


echo '<pre/>';
print_r($toc);


My output:

Array
(
    [json_data] => 
    [json_data.0] => 
    [json_data.0.downtime] => 1
    [json_data.0.pfix] => 
    [json_data.0.pfix.max] => 100
    [json_data.0.pfix.threshold] => 880
    [json_data.0.ints] => 
    [json_data.0.ints.int] => 
    [json_data.0.ints.int.0] => 
    [json_data.0.ints.int.0.rle] => pri
    [json_data.0.ints.int.0.device] => laptop
    [json_data.0.ints.int.0.int] => Ether3
    [json_data.0.ints.int.0.ip] => 127.0.0.3
    [json_data.0.ints.eth] => 
    [json_data.0.ints.eth.lan] => 57
    [json_data.1] => 
    [json_data.1.downtime] => 
    [json_data.1.lsi] => 987654
    [json_data.1.pfix] => 
    [json_data.1.pfix.min] => 10000
    [json_data.1.pfix.threshold] => 890
    [json_data.1.mana] => 
    [json_data.1.mana.mode] => NONE
    [json_data.1.ints] => 
    [json_data.1.ints.int] => 
    [json_data.1.ints.int.0] => 
    [json_data.1.ints.int.0.rle] => sre
    [json_data.1.ints.int.0.device] => desk
    [json_data.1.ints.int.0.int] => Ten
    [json_data.1.ints.int.0.ip] => 1.1.1.1
    [json_data.1.ints.int.0.UF] => 1
    [json_data.1.ints.ethernet] => 
    [json_data.1.ints.ethernet.lan] => 2
)