-- Created on: 1997-12-16
-- Created by: Denis PASCAL
-- Copyright (c) 1997-1999 Matra Datavision
-- Copyright (c) 1999-2012 OPEN CASCADE SAS
--
-- The content of this file is subject to the Open CASCADE Technology Public
-- License Version 6.5 (the "License"). You may not use the content of this file
-- except in compliance with the License. Please obtain a copy of the License
-- at http://www.opencascade.org and read it completely before using this file.
--
-- The Initial Developer of the Original Code is Open CASCADE S.A.S., having its
-- main offices at: 1, place des Freres Montgolfier, 78280 Guyancourt, France.
--
-- The Original Code and all software distributed under the License is
-- distributed on an "AS IS" basis, without warranty of any kind, and the
-- Initial Developer hereby disclaims all such warranties, including without
-- limitation, any warranties of merchantability, fitness for a particular
-- purpose or non-infringement. Please see the License for the specific terms
-- and conditions governing the rights and limitations under the License.



class Expression from TDataStd inherits Attribute from TDF
    
    ---Purpose: Expression 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
    --          expression 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 Expression attribute.
    returns Expression from TDataStd;
    
    ---Purpose: Expressionmethods
    --          ============

    Create
    returns mutable Expression from TDataStd;
    
    Name (me)
    ---Purpose: build and return the expression name
    returns ExtendedString from TCollection;
    
    SetExpression (me : mutable; E : ExtendedString from TCollection);
    
    GetExpression (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

    myExpression : ExtendedString from TCollection;
    myVariables  : AttributeList from TDF;   
    
end Expression;