Regex with possible empty matches and multi-line match

Question

I\'ve been trying to \"parse\" some data using a regex, and I feel as if I\'m close, but I just can\'t seem to bring it all home.
The data that needs parsing gener

Answer 1

So here's what I came up with using a tricky preg_replace_callback():

$string ='FooID: 123456
Name: Chuck
When: 01/02/2013 01:23:45
InternalID: 789654
User Message: Hello,
this is nillable, but can be quite long. Text can be spread out over many lines
And can start with any number of \n\'s. It can be empty, too
Yellow:cool';

$array = array();
preg_replace_callback('#^(.*?):(.*)|.*$#m', function($m)use(&$array){
    static $last_key = ''; // We are going to use this as a reference
    if(isset($m[1])){// If there is a normal match (key : value)
        $array[$m[1]] = $m[2]; // Then add to array
        $last_key = $m[1]; // define the new last key
    }else{ // else
        $array[$last_key] .= PHP_EOL . $m[0]; // add the whole line to the last entry
    }
}, $string); // Anonymous function used thus PHP 5.3+ is required
print_r($array); // print

Online demo

Downside: I'm using PHP_EOL to add newlines which is OS related.