-- File:	TDocStd_XLink.cdl
--      	--------------
-- Author:	DAUTRY Philippe
--		<fid@fox.paris1.matra-dtv.fr>
---Copyright:	 MATRA DATAVISION 1997

---Version:	0.0
---History:	Version	Date		Purpose
--		0.0	Sep 15 1997	Creation

class XLink from TDocStd inherits Attribute from TDF

	---Purpose: An attribute to store the path and the entry of
    	-- external links.
    	--  These refer from one data structure to a data
    	--  structure in another document.

uses

    GUID            from Standard,
    AsciiString     from TCollection,
    Label           from TDF,
    RelocationTable from TDF,
    AttributeDelta  from TDF,
    Reference       from TDF,
    XLinkPtr         from TDocStd

-- raises

is

    -- Class methods ---------------------------------------------------------

    Set (myclass; atLabel : Label from TDF)
    returns mutable XLink from TDocStd;
	---Purpose: Sets an empty external reference, at the label aLabel.

    -- -----------------------------------------------------------------------

    Create
    returns mutable XLink from TDocStd;
    ---Purpose: Initializes fields.
    
    Update (me : mutable)
    returns Reference from TDF;
    
    ---Purpose:  Updates the data referenced in this external link attribute.
        
    ID(me) returns GUID from Standard
    	is redefined static;
	---Purpose: Returns the ID of the attribute.
	--
	---C++: return const &             	
  
    GetID(myclass) returns GUID from Standard;
	---Purpose: Returns the GUID for external links.
	--          
    	---C++: return const &

    DocumentEntry(me : mutable; aDocEntry : AsciiString from TCollection);
	---Purpose: Sets the name aDocEntry for the external
    	-- document in this external link attribute.
    
    DocumentEntry(me)
    	returns AsciiString from TCollection;
	---Purpose: Returns the contents of the document identified by aDocEntry.
    	-- aDocEntry provides external data to this external link attribute.  
	---C++ : return const &

    LabelEntry(me : mutable; aLabel : Label from TDF);
	---Purpose: Sets the label entry for this external link attribute with the label aLabel. 
    	-- aLabel pilots the importation of data from the document entry.

    LabelEntry(me : mutable; aLabEntry : AsciiString from TCollection);
	---Purpose:  Sets the label entry for this external link attribute
    	-- as a document identified by aLabEntry.

    LabelEntry(me)
    	returns AsciiString from TCollection;
	---Purpose: Returns the contents of the field <myLabelEntry>.
	--          
	---C++ : return const &


    Next (me : mutable; anXLinkPtr : XLinkPtr from TDocStd)
    	is private;
	---Purpose: Sets the field <myNext> with <anXLinkPtr>.
	--          
	---C++: inline

    Next (me)
    	returns XLinkPtr from TDocStd
    	is private;
	---Purpose: Returns the contents of the field <myNext>.
	--          
	---C++: inline


    -- Call back methods.
    -- ------------------

    AfterAddition(me: mutable)
    	is redefined static;
	---Purpose: Updates the XLinkRoot attribute by adding <me>
	--          to its list.

    BeforeRemoval(me: mutable)
    	is redefined static;
	---Purpose: Updates the XLinkRoot attribute by removing <me>
	--          from its list.

    BeforeUndo(me: mutable;
    	       anAttDelta : AttributeDelta from TDF;
    	       forceIt : Boolean from Standard = Standard_False)
    	returns Boolean from Standard
    	is redefined;
	---Purpose: Something to do before applying <anAttDelta>.

    AfterUndo(me: mutable;
    	      anAttDelta : AttributeDelta from TDF;
    	      forceIt : Boolean from Standard = Standard_False)
    	returns Boolean from Standard
    	is redefined;
	---Purpose: Something to do after applying <anAttDelta>.


    -- Modification & Transaction use methods.
    -- --------------------------------------

    BackupCopy(me) returns mutable Attribute from TDF
    	is redefined static;
	---Purpose: Returns a null handle. Raise allways for ,it is
	--          nonsense to use this method.

    Restore(me: mutable;
    	    anAttribute : Attribute from TDF)
    	is redefined static;
	---Purpose: Does nothing.


    -- Copy use methods
    -- ----------------

    NewEmpty(me)
    	returns mutable Attribute from TDF
    	is redefined static;
	---Purpose: Returns a null handle.

    Paste(me;
    	  intoAttribute    : mutable Attribute from TDF;
	  aRelocationTable : mutable RelocationTable from TDF)
    	is redefined static;
	---Purpose: Does nothing.

    -- Miscelleaneous
    -- --------------


    Dump(me; anOS : in out OStream from Standard)
    	returns OStream from Standard
    	is redefined static;
	---Purpose: Dumps the attribute on <aStream>.
    	---C++ : return &



fields

    myDocEntry   : AsciiString from TCollection;
    myLabelEntry : AsciiString from TCollection;
    myNext       : XLinkPtr from TDocStd;

friends

    class XLinkRoot     from TDocStd,
    class XLinkIterator from TDocStd

end XLink from TDocStd;