\ B-tree list                                                        vandys
\ Implementation of a B-tree whose leaves are Sets.  Cogbot
\  uses this in a number of places, so we implement this as
\  its own data structure here.
only extensions definitions

Btree -> subclass: BtSet
BtSet -> :method ! { val key self -- }
   key self super-> @ 0= if
      Set -> new   dup key self super-> !   then
   ( set ) val swap -> add method;
: .btl ( 0 set key -- )   . ." ->"   -> .   drop ; scrLocal
BtSet -> :method .elems ( self -- )   0   ['] .btl   rot -> do method;
: (empty!) ( 0 set -- )   nip   -> free ; scrLocal
BtSet -> :method empty! ( self -- )   dup   0   ['] (empty!) rot -> do
   ( self ) super-> empty! method;









\ B-tree list                                                        vandys