ui/src/split/FilterClass.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 by Steve Glassman, Mark Manasse and Greg Nelson           
 Last modified on Tue Mar 10 18:59:59 1992 by steveg   
      modified on Mon Feb 24 13:53:16 PST 1992 by muller   
      modified on Wed Dec 11 23:14:29 PST 1991 by gnelson  
      modified on Wed Sep 11 15:14:27 PDT 1991 by msm      


<*PRAGMA LL*>

 The FilterClass interface reveals the representation
   of a filter.   If you are implementing a subtype of Filter.T,
   you can import FilterClass to gain access to the
   child field. 


INTERFACE FilterClass;

IMPORT Filter, VBT;

REVEAL Filter.T <: Public;

TYPE Public =
  Filter.Public OBJECT <* LL >= {SELF, VBT.mu} *>
    ch: VBT.T
  END;

 A filter f is a split with the single child f.ch, or
   with no children if f.ch=NIL.


   The beChild method initializes ch and calls Split.T.beChild.
   The succ, pred, nth, index, and locate methods use the
   ch field in the obvious way.  The misc, key, read, write,
   reshape, shape, and axisOrder methods forward to the child.
   


END FilterClass.