map.sa

 
---------------------------> Sather 1.1 source file <--------------------------
-- $Id: map.sa,v 1.3 1996/04/09 10:05:11 borisv Exp $
-- Author: Holger Klawitter <holger@math.uni-muenster.de>
-- Benedict Gomes: Many changes..
-- Abstract and concrete mappings from K (items) to E (data).
--   $MAP{K,E}     :An abstract map
--   MAP_INCL{K,E} :Partial class for Maps
--   H_MAP{K,E}    :A concrete map based on data buckets
--   TEST_MAP      :Test class for MAP{K,E}



abstract class $RO_MAP{K,E} < $CONTAINER{E}, $STR 
abstract class $RO_MAP{K,E} < $CONTAINER{E}, $STR is
   -- A read-only map abstraction that does not permit modifications.
   -- A mapping abstraction from elements of type K to elements of type E
   -- A map stores an element of type E under a key of type K.
   -- Each key can hold one element. 
   -- 
   -- Design note: It would also be reasonable to have a $RO_MAP be
   -- a subtype of $CONTAINER{TUP{K,E}}. However, since we are using
   -- the array notation, to avoid confusion with the way arrays behave
   -- we view maps as containers of the target elements, with the
   -- keys being a kind of indexing method. Arrays are then a special
   -- kind of map where the keys are integers. Though we don't make
   -- use of this possibility in this library, the use of array
   -- notation is consistent with it.


   -- has(e: E): BOOL;
   -- Inherited: Return true if the map contains the element "e". Could be 
   -- very expensive
   
   has_ind(k:K): BOOL;
   -- Returns 'true' if 'k' is mapped to an element.

   has_elt(e: E): BOOL;
   -- Same as "has"
   
   aget(k:K): E;
   -- Returns the element k is mapped to.
   -- If k is absent:
   --        If E < $IS_NIL return E::nil othewise return void 

   -- size: INT;
   -- Inherited: Returns the number of indices/elements in the mapping

   ind!: K;
   -- Yields the indices (keys) of the mapping
   
   -- elt!: E;
   -- Inherited: Yields the elements of the mapping
   
   pair!: TUP{K,E};
   -- Yields the the elements or a tuple containing both
   -- in arbitrary order.

   
end;


abstract class $MAP{K,E} < $RO_MAP{K,E} 
abstract class $MAP{K,E} < $RO_MAP{K,E} is
   -- A modifiable MAP
   -- Elements are stored in a map using the aset notation.
   -- Further assignments to a key will result in a replacement.

   aset(k:K,e:E);
   -- Maps k to e. If k is already mapped, replace the old
   -- maping with ne new one.

   delete(k:K);
   delete(k:K): E;
   -- Removes the mapping from k. The element k was mapped to
   -- will be returned (or an appropiate non-value).

end;