-- File:	TDataStd_Relation.cdl
-- Created:	Wed Dec 10 11:05:48 1997
-- Author:	Denis PASCAL
--		<dp@dingox.paris1.matra-dtv.fr>
---Copyright:	 Matra Datavision 1997



class Relation from TDataStd inherits Attribute from TDF
    
    ---Purpose: Relation attribute. 
    --          ==================
    --
    --            *  Data Structure of  the  Expression is stored in a
    --           string and references to variables used by the string
    --
    --  Warning:  To be consistent,  each  Variable  referenced by  the
    --          relation must have its equivalent in the string


uses Attribute       from TDF,
     Label           from TDF,
     GUID            from Standard,
     Real            from Standard,
     DataSet         from TDF,
     RelocationTable from TDF,
     ExtendedString  from TCollection,
     AttributeList   from TDF
     

is

    ---Purpose: class methods
    --          =============

    GetID (myclass)    
    	---C++: return const & 
    returns GUID from Standard;
    

    Set (myclass ; label : Label from TDF)
    ---Purpose: Find, or create, an Relation attribute.
    returns Relation from TDataStd;
    
    ---Purpose: Real methods
    --          ============

    Create
    returns mutable Relation from TDataStd;
    
    Name (me)
    ---Purpose: build and return the relation name
    returns ExtendedString from TCollection;
    
    SetRelation (me : mutable; E : ExtendedString from TCollection);
    
    GetRelation (me)
    returns ExtendedString from TCollection; 
    ---C++: return const &
    
    GetVariables (me : mutable)
    ---C++: return &
    returns AttributeList from TDF;    
    
    ---Category: TDF_Attribute methods
    --           =====================
    
    ID (me) 
    ---C++: return const &  
    returns GUID from Standard;

    Restore (me: mutable; With : Attribute from TDF);

    NewEmpty(me)
    returns mutable Attribute from TDF;

    Paste (me; Into : mutable Attribute from TDF;
	       RT   : mutable RelocationTable from TDF);    

    Dump(me; anOS : in out OStream from Standard)
    returns OStream from Standard
    is redefined;
    ---C++: return &

fields

    myRelation   : ExtendedString from TCollection;
    myVariables  : AttributeList from TDF;  

end Relation;