set/src/SetDef.ig

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
 Last modified on Sat Sep  4 21:50:20 PDT 1993 by detlefs                  
      modified on Tue Feb 11 20:48:45 PST 1992 by muller                   


 SetDef is a generic interface defining sets of Elem.T's,
   implemented via hash tables.



GENERIC INTERFACE SetDef(ElemSet);

 WHERE    ElemSet = Set(Elem), and Elem.T is a type that is not an
   open array type and Elem contains 



      PROCEDURE Equal(e1, e2: Elem.T): BOOLEAN;
      PROCEDURE Hash(k: Key.T): Word.T;


   Equal must be an equivalence relation and Hash must respect
   that equivalence relation, i.e., if Equal(k1, k2), then
   Hash(k1)=Hash(k2).


   Hash and Equal may be declared with a parameter mode of either
   VALUE or READONLY, but not VAR.


TYPE
  Public = ElemSet.T OBJECT METHODS
    init(sizeHint: CARDINAL := 0): T
  END;
  T <: Public;
  Iterator <: ElemSet.Iterator;

 The expression



      NEW(SetDef.T).init(sz)


   creates a new, empty set.  The argument sz is a hint; the set may
   be more efficient if sz accurately predicts the maximum number of
   elements it will ever contain.





END SetDef.