-- File:	TCollection_Set.cdl
-- Created:	Tue Mar  2 11:06:03 1993
-- Author:	Remi LEQUETTE
--		<rle@phylox>
---Copyright:	 Matra Datavision 1993


generic class Set from TCollection (Item as any)

    	---Purpose:  A set is an  unordered  collection  of items without
    	-- duplications. To test for duplications the operators == and !=
    	-- are used on the items.
    	-- Use a SetIterator to explore a Set.
    	-- Warning
    	-- A set generates the same result as a map. A map is
    	-- more effective; therefore it is advisable to use maps instead of sets.
    	-- Set is a generic class which consists of Items, types of elements in a set.
raises   
    NoSuchObject from Standard
    
    private class SetList instantiates List from TCollection(Item);

    class SetIterator from TCollection 				      
        ---Purpose: Functions used for iterating the contents of a Set.
    	-- Note: an iterator class is automatically instantiated from
    	-- this generic class at the time of instantiation of a Set.
    	-- Warning
    	-- -   A set is a non-ordered data structure. The order in
    	--   which entries of a set are explored by the iterator
    	--   depends on its contents, and changes when the set is edited.
    	-- -   It is not recommended to modify the contents of a set
    	--   during iteration: the result is unpredictable.
  

    raises NoSuchObject from Standard
    is     
    	Create returns SetIterator from TCollection;
	    ---Purpose: Creates an empty iterator for a Set;
    	    -- use the function Initialize to define the set to explore;.
 
     	Create(S : Set from TCollection) returns SetIterator from TCollection;
            ---Purpose: Creates an iterator on the set <S>.
	    
	Initialize(me : in out; S : Set from TCollection)
    	    ---Purpose: Sets or resets the iterator on the set <S>.
	is static;

     	More(me) returns Boolean from Standard
            ---Purpose: Returns True if there are other items.
	    ---C++: inline	    
	is static;

     	Next(me: in out)
	    ---Purpose: Positions the iterator to the next item.
	    ---C++: inline
	is static;
	    	
     	Value(me) returns any Item 
    	raises NoSuchObject from Standard
	    ---Purpose: Returns the item   value corresponding to  the
	    -- current position of the iterator.
	    ---C++: return const &
	    ---C++: inline
	is static;

    fields
    	myIterator : ListIteratorOfSetList;
	
    end SetIterator from TCollection;


is

    Create returns Set from TCollection;
        ---Purpose: Creation of an empty set.
	
    Create(Other : Set from TCollection) 
    returns Set from TCollection 
    is private;
	---Purpose: Creates by copying an existing Set.
	--  Warning: Prints a message when  other is not  empty.  It is
	-- recommanded to use Assign (operator =).
    
    Extent(me) returns Integer from Standard
        ---Level: Public
        ---Purpose: Returns the number of items in the set.
	---C++: inline
    is static;

    IsEmpty(me) returns Boolean from Standard
        ---Level: Public
        ---Purpose: Returns    True   if    the  set  is   empty. i.e.
        -- Extent() == 0.
	---C++: inline
    is static;

    Clear(me : in out)
        ---Level: Public
	---Purpose: Removes all items from the set.
	---C++: inline
    is static;

    Add(me : in out; T : Item) returns Boolean from Standard
        ---Level: Public
	---Purpose: Adds the  item <T>  in   the set if  it does   not
	-- already exist.Returns  False if the item T already exists.
	--  Example:          
        -- before
        --   me = {a,b,c,d}, T = y
        -- after
        --   me = {a,b,c,d,y} returns True
    is static;

    Remove(me : in out; T : Item) returns Boolean from Standard
        ---Level: Public
        ---Purpose: Removes the item <T> from the set. Returns True if
        -- the item was in the set.
        --  Example:         
        -- before
        --   me = {a,b,c,d}, T = a
        -- after
        --   me = {b,c,d} returns True
    is static;
 
    Union(me : in out; B : Set from TCollection)
        ---Level: Public
        ---Purpose: Add to <me> all the items of the set <B> 
        -- which are not in <me>.
        --  Example:
        -- before
        --   me = {a,b,c}, B = {d,a,f}
        -- after
        --   me = {a,b,c,d,f}, B = {d,a,f}
    is static;

    Intersection(me : in out; B : Set from TCollection)
        ---Level: Public
        ---Purpose: Removes from <me> all the items which are not in <B>.
        --  Example:
        -- before
        --   me = {a,b,c}, B = {d,a,f}
        -- after
        --   me = {a}, B = {d,a,f}
    is static;

    Difference(me : in out; B: Set from TCollection)
        ---Level: Public
        ---Purpose: Removes from <me> all the items which are in <B>.
        --  Example:
        -- before
        --   me = {a,b,c}, B = {d,a,f}
        -- after
        --   me = {b,c}, B = {d,a,f}
    is static;

    Contains(me; T : Item) returns Boolean from Standard
        ---Level: Public
        ---Purpose: Returns True if the item <T> is in the set.
    is static;

    IsASubset(me; S : Set from TCollection) returns Boolean from Standard
        ---Level: Public
        ---Purpose: returns True if <S> is a subset  of <me>. i.e. all
        -- elements of <S> are in <me>.
    is static;

    IsAProperSubset(me; S : Set from TCollection) 
    returns Boolean from Standard
        ---Level: Public
        ---Purpose: returns True if <S> is strictly contained in <me>.
        -- i.e <S> is a subset and its extent is not equal to
        -- the extent of <me>.
    is static;

fields
    myItems : SetList;
    
friends
    class SetIterator from TCollection
    
end Set from TCollection;