[Resolved] Recursion & references

Anarchyh

Ok ... this is quite a tough one i think ... I've been pondering over it for quite a while now.

Basically, what i want to do is allow someone to access an infinitely nested number of arrays by specifying a "path"
(like to access greetings->hello in :
:

array('greetings' => array('hello' => "Hiya"));

you would use the path 'greetings->hello')

... that can be done with recursion easily with code like

function _getTarget($path, &$currentBranch)
	{
		$retVal = null;	
		if(is_array($currentBranch))
		{
			$current = array_shift($path);			
			if(isset($currentBranch[$current]))
				$retVal = $this->_getTarget($path, $currentBranch[$current]);
		}
		else
			$retVal = $currentBranch;

	return $retVal;
}

Simply pass in the root branch on the first calland it works a treat...
HOWEVER, instead of returning the value I want it to return a reference.

Simply changing the $retVal assignments to reference assignments doesn't work because when the function returns from the last level of recursion the reference is invalidated becasue it was in the top level of recursions function scope.

It's quite a mind bender and I'm beginning to think it isn't possiblewithout writing a custom array implementation in PHP which would be intensely slow 🙁

Hope it makes sense because it's qutie hard to explain.

Any comments or theories (or even solutions 😃) are much appreciated.

bad76

Hi,
I've played a lot with your code.
Now I think you can get the value, or the complete last level array:
"Hiya" //this ...
array('hello' => "Hiya", 'see you'=> "bye" , ... ); // or this...

In both case, you can read only, and not modify it,
reference (&) don't allows this for array (in php4...).
(more info)

If you want a short reference to item found, to work with (reading and writing), I think you have to use object instead of the array.

But this is what I've experiancing, maybe i'm wrong.

However i hope this help you...

Anarchyh

Thanks for the reply, however; I've solved it (totally dumb ass mistake i didnt even think of checking) ... I was using "&=" to assign reference and not "=&" and thusly all of my references were turning out as null :rolleyes:

Here's the working code to do it (takes an exploded path)


function &_getTarget($path, &$currentBranch)
{
	$retVal = null;	
	if(is_array($currentBranch))
	{
		$current = array_shift($path);			
		if(isset($currentBranch[$current]))
			$retVal =& _getTarget($path, $currentBranch[$current]);
		else
			$retVal = "";
	}
	else
		$retVal =& $currentBranch;

return $retVal;
}

$test = array("moo"=>array("eeep!"), "hello");
$testResults =& _getTarget(array("moo", 0), $test);
echo $testResults;