PHP: check if object/array is a reference

Question

Sorry to ask, its late and I can\'t figure a way to do it... anyone can help?

$users = array(
    array(
        \"name\" => \"John\",
        \"age\"   =         


        

Answer 1

function var_reference_count(&$xVal) {
    $ao = is_array($xVal)||is_object($xVal);

    if($ao) { $temp= $xVal;    $xVal=array();    }

    ob_start();        
     debug_zval_dump(&$xVal);
    $dump = ob_get_clean();

    if($ao) $xVal=$temp;

    preg_match('/refcount\((\d*)\)/',$dump,$matches);
    return $matches[1] - 3;
}
//-------------------------------------------------------------------------------------------

This works with HUDGE objects and arrays.

Answer 2

You can test for references in a multi-dimensional array by making a copy of the array, and then altering and testing each entry in turn:

$roomCopy = $room;
foreach ($room as $key => $val) {
  $roomCopy[$key]['_test'] = true;
  if (isset($room[$key]['_test'])) {
    // It's a reference
    unset($room[$key]);
  }
}
unset($roomCopy);

With your example data, $room['furniture'] and $roomCopy['furniture'] will be separate arrays (as $roomCopy is a copy of $room), so adding a new key to one won't affect the other. But, $room['users'] and $roomCopy['users'] will be references to the same $users array (as it's the reference that's copied, not the array), so when we add a key to $roomCopy['users'] it is visible in $room['users'].

Answer 3

The best I can manage is a test of two variables to determine if one is a reference to the other:

$x = "something";
$y = &$x;
$z = "something else";

function testReference(&$xVal,&$yVal) {
    $temp = $xVal;
    $xVal = "I am a reference";
    if ($yVal == "I am a reference")  { echo "is reference<br />"; }  else  { echo "is not reference<br />"; }
    $xVal = $temp;
}

testReference($x,$y);
testReference($y,$x);

testReference($x,$z);
testReference($z,$x);

testReference($y,$z);
testReference($z,$y);

but I doubt if it's much help

Really dirty method (not well tested either):

$x = "something";
$y = &$x;
$z = "something else";

function isReference(&$xVal) {
    ob_start();
    debug_zval_dump(&$xVal);
    $dump = ob_get_clean();
    preg_match('/refcount\((\d*)\)/',$dump,$matches);
    if ($matches[1] > 4) { return true; } else { return false; }
}

var_dump(isReference($x));
var_dump(isReference($y));
var_dump(isReference($z));

To use this last method in your code, you'd need to do something like:

foreach($room as $key => $val) {
    if(isReference($room[$key])) unset($room[$key]);
}

because $val is never a reference as it's a copy of the original array element; and using &$val makes it always a reference

Answer 4

something recursive maybe.

function removeReferences($inbound)
{
    foreach($inbound as $key => $context)
    {
        if(is_array($context))
        {
            $inbound[$key] = removeReferences($context)
        }elseif(is_object($context) && is_reference($context))
        {
            unset($inbound[$key]); //Remove the entity from the array.
        }
    }
    return $inbound;
}

Answer 5

if you want to get rid of recursive elements:

<?php
$arr=(object)(NULL); $arr->a=3; $arr->b=&$arr;
//$arr=array('a'=>3, 'b'=>&$arr);
print_r($arr);

$arr_clean=eval('return '.strtr(var_export($arr, true), array('stdClass::__set_state'=>'(object)')).';');
print_r($arr_clean);
?>

output:

stdClass Object ( [a] => 3 [b] => stdClass Object *RECURSION* ) 
stdClass Object ( [a] => 3 [b] => )