-- File:	GraphTools_TopologicalSortFromIterator.cdl
-- Created:	Thu Dec 24 14:07:47 1992
-- Author:	Denis PASCAL
--		<dp@bravox>
---Copyright:	 Matra Datavision 1992


generic class TopologicalSortFromIterator from GraphTools
    (Graph     as any;
     Vertex    as any;
     VHasher   as any;
     VIterator as any)

--generic class TopologicalSortFromIterator from GraphTools
--    	         (Graph     as any;
--    	          Vertex    as any;
--    	          VHasher   as MapHasher from TCollection (Vertex);
--	          VIterator as VertexIterator (Graph,Vertex))

	---Purpose: This generic  class defines  an iterator to  visit
	--          each vertex of   the underlying graph,  in such an
	--          order that noone vertex is reach before any vertex
	--          that point to it. In general the order produced by
	--          topological sort  is  not unique. Usefull  for DAG
	--          Topological  Sort.  The   option  <ignoreSelfLoop>
	--          allows the user to ignore (or not) any vertex wich
	--          contains a  self loop.   The option <processCycle>
	--          allows the user to  visit (or not> vertices  which
	--          are in a cycle.


uses SequenceOfInteger from TColStd

raises NoSuchObject from Standard,
       NoMoreObject from Standard,
       DomainError  from Standard

    private class TSMap instantiates IndexedDataMap from TCollection 
                (Vertex,TSNode from GraphTools,VHasher);
    
is

    Create 
	---Purpose: Create an empty algorithm.
    returns TopologicalSortFromIterator from GraphTools;

    FromVertex (me : in out; V : Vertex);
	---Purpose: Add  <V>  as  initial  condition.  This method  is
	--          cumulative.  Use Perform method before visting the
	--          result of the algorithm.  
	---Level: Public

    Reset (me : in out);
	---Purpose: Reset the  algorithm.  It  may be reused  with new
	--          initial conditions.  
	---Level: Public

    Perform (me : in out; G              : Graph;
                          ignoreSelfLoop : Boolean from Standard;
                          processCycle   : Boolean from Standard);
    	---Purpose: Peform the  algorithm  in  <G> from initial setted
    	--          conditions according to  the two following flags.
	--          * <ignoreSelfLoop>  allows the  user to ignore (or
	--          not) any vertex wich contains a self loop.
	--          * <processCycle> allows the user to visit (or not>
	--          vertex which is in a cycle.
       ---Level: Public

    More (me) 
    returns Boolean from Standard;
       ---Level: Public
    
    Next (me : in out) 
    raises NoMoreObject from Standard;
       ---Level: Public
    
    Value (me) 
    returns any Vertex
       ---Level: Public
	---C++: return const &
    raises NoSuchObject from Standard;

    IsInCycle (me) 
    returns Boolean from Standard
	---Purpose: Returns TRUE if the current vertex is in a cycle.
       ---Level: Public
    raises NoSuchObject from Standard;
    
    
fields

-- conditions
   myVertices       : TSMap   from GraphTools; 
   myIgnoreSelfLoop : Boolean from Standard;
   myProcessCycle   : Boolean from Standard;
-- result   
   mySort           : SequenceOfInteger from TColStd;
   myCycles         : Integer from Standard;
   myCurrent        : Integer from Standard;

end TopologicalSortFromIterator;