Description:
------------
preg_split behaves unexpectet with certain pattern (see reproduce code):

It returns tripple offsets with the offsetvalue -1.

It gets even worse when you replace:

 $reg = "~\{(literal)\}(.*?)\{(/literal)\}|\{(.*?)\}~s";
with
 $reg = "~\{\*(literal)\}(.*?)\{(/literal)\}|\{(.*?)\}~s";

it simply returns several off those empty string, offset -1 triples.


P.S.: Hope it is actually a bug and not my ignorance of regex, however i asked in a forum if anybody knew where the mistake is and i got no answer and in addition the offset -1 mykes it look like a bug to me.
If it however should be a mistake in my regex it would be kind if you would let me know how to put it.

Thx in advance

Reproduce code:
---------------
$reg = "~\{(literal)\}(.*?)\{(/literal)\}|\{(.*?)\}~s";
echo $reg.'<br>';
$res = preg_split( $reg, "df{g}s{literal}asd{as}d{/literal}", -1, PREG_SPLIT_DELIM_CAPTURE|PREG_SPLIT_OFFSET_CAPTURE );
echo '<pre>'.print_r($res, 1).'</pre>';

Expected result:
----------------
~\{(literal)\}(.*?)\{(/literal)\}|\{(.*?)\}~s

Array
(
    [0] => Array
        (
            [0] => df
            [1] => 0
        )

    [1] => Array
        (
            [0] => g
            [1] => 3
        )

    [2] => Array
        (
            [0] => s
            [1] => 5
        )

    [3] => Array
        (
            [0] => literal
            [1] => 7
        )

    [4] => Array
        (
            [0] => asd{as}d
            [1] => 15
        )

    [5] => Array
        (
            [0] => /literal
            [1] => 24
        )

    [6] => Array
        (
            [0] => 
            [1] => 33
        )

)


Actual result:
--------------
~\{(literal)\}(.*?)\{(/literal)\}|\{(.*?)\}~s

Array
(
    [0] => Array
        (
            [0] => df
            [1] => 0
        )

    [1] => Array
        (
            [0] => 
            [1] => -1
        )

    [2] => Array
        (
            [0] => 
            [1] => -1
        )

    [3] => Array
        (
            [0] => 
            [1] => -1
        )

    [4] => Array
        (
            [0] => g
            [1] => 3
        )

    [5] => Array
        (
            [0] => s
            [1] => 5
        )

    [6] => Array
        (
            [0] => literal
            [1] => 7
        )

    [7] => Array
        (
            [0] => asd{as}d
            [1] => 15
        )

    [8] => Array
        (
            [0] => /literal
            [1] => 24
        )

    [9] => Array
        (
            [0] => 
            [1] => 33
        )

)