Views argument handler for parent and weight

Problem #1: Getting the SQL to work properly.

I will not go into great detail of this problem as this is related to #1877662: Allow for different sort per user as they are trying to add an argument. In #1877662 case, its the uid.

Problem #2: Parent argument will only work for Native if we fix #1906454: Change Native Handler organization to how Taxonomy does it.

Say you had parent arguments working...currently, after you resave it will break everything.

I will illustrate it for everyone:

Say you have this little, without a weight/parent argument filter.

A 0:0
   B  1:A
   C  2:A
D 3:0
   E 4:D
      F 5:E
   G 6:D

Now let say you have an weight argument D and it produces:

D 3:0
   E 4:D
      F 5:E
   G 6:D

Say you move some things around

D 0:0
   G 1:D
      F 2:G
   E 3:D

It would get save like this

A 0:0
   B  1:A
   C  2:A
D 0:0
   G 1:D
      F 2:G
   E 3:D

It will actually get displayed like

A 0:0
D 0:0
   B 1:A
   G 1:D
   C  2:A
      F 2:G
   E 3:D

See #1906454: Change Native Handler organization to how Taxonomy does it for more illustrations

Problem #3: Do you display the root/parent or not?

Now let say you have an weight argument D and #1906454 is working. It produces:

D 1:0
   E 0:D
      F 0:E
   G 1:D

if you reorder you get

D 0:0
   G 0:D
      F 0:G
   E 1:D

This now doesn't work becaus D now has a weight of 0. If remove D somehow you get
D 1:0

   E 0:D
      F 0:E
   G 1:D

if you reorder you get
D 1:0

   G 0:0
      F 0:G
   E 1:0

Now the parents do not line up, and the view/order is broken.

Yes you probably can do some validation too fix it display with or without the root/parent, but now things are extremely more complicated.

Markup

This issue is pretty old, and comment #1 seems to no longer be relevant as of 7.x-2.x. However, the functionality would still be great to have! Here's a patch.

I've been using this patch for a little while and it works fine (I've been using the parent argument handler mainly, but I don't see why the weight one would be different).

I think some of the comments in #1 might be correct, but I don't think they're necessarily relevant for this issue in the sense that they don't seem like a problem that would be unique to the argument handler introduced here - wouldn't those concerns apply the same to the already-existing parent/weight filters also?