-- File:	SelectDiff.cdl
-- Created:	Wed Nov 18 16:40:10 1992
-- Author:	Christian CAILLET
--		<cky@topsn2>
---Copyright:	 Matra Datavision 1992


class SelectDiff  from IFSelect  inherits SelectControl

    ---Purpose : A SelectDiff keeps the entities from a Selection, the Main
    --           Input, which are not listed by the Second Input

uses AsciiString from TCollection, EntityIterator, Graph

is

    Create returns mutable SelectDiff;
    ---Purpose : Creates an empty SelectDiff


    RootResult (me; G : Graph) returns EntityIterator;
    ---Purpose : Returns the list of selected entities : they are the Entities
    --           gotten from the Main Input but not from the Diff Input

    HasUniqueResult (me) returns Boolean  is redefined protected;
    ---Purpose : Returns always True, because RootResult gives a Unique list


    Label (me) returns AsciiString from TCollection;
    ---Purpose : Returns a text defining the criterium : "Difference"

end SelectDiff;