-- File:	GeneralExpression.cdl
-- Created:	Thu Jan 10 11:57:22 1991
-- Author:	Arnaud BOUZY
--		<adn@topsn3>
---Copyright:	 Matra Datavision 1991

deferred class GeneralExpression from Expr
    
inherits TShared from MMgt

    ---Purpose: Defines the general purposes of any expression.

uses NamedUnknown from Expr,
    Array1OfNamedUnknown from Expr,
    Array1OfReal from TColStd,
    AsciiString from TCollection

raises OutOfRange from Standard, 
    NumericError from Standard,
    NotEvaluable from Expr,
    InvalidOperand from Expr

is

    NbSubExpressions(me)
    ---Purpose: Returns the number of sub-expressions contained
    --          in <me> ( >= 0)
    ---Level: Internal
    returns Integer
    is deferred;

    SubExpression(me; I : Integer)
    ---Purpose: Returns the <I>-th sub-expression of <me>
    --          raises OutOfRange if <I> > NbSubExpressions(me)
    ---C++: return const &
    ---Level: Internal 
    returns any GeneralExpression
    raises OutOfRange
    is deferred;

    Simplified(me) 
    ---Purpose: Returns a GeneralExpression after replacement of
    --          NamedUnknowns by an associated expression and after
    --          values computation.
    ---Level: Advanced 
    returns any GeneralExpression 
    raises NumericError
    is deferred;

    ShallowSimplified(me)
    ---Purpose: Returns a GeneralExpression after a simplification 
    --          of the arguments of <me>.
    ---Level: Internal
    returns any GeneralExpression
    raises NumericError
    is deferred;
    
    Copy(me)
    ---Purpose: Returns a copy of <me> having the same unknowns and 
    --          functions. 
    ---Level: Advanced 
    returns mutable like me
    is deferred;
    
    ContainsUnknowns(me) 
    ---Purpose: Tests if <me> contains NamedUnknowns.
    ---Level: Advanced 
    returns Boolean
    is deferred;
    
    Contains(me; exp : GeneralExpression)
    ---Purpose: Tests if <exp> is contained in <me>.
    ---Level: Advanced 
    returns Boolean
    is deferred;	

    IsLinear(me)
    ---Purpose: Tests if <me> is linear on every NamedUnknown it 
    --          contains. 
    ---Level: Internal
    returns Boolean
    is deferred;

    IsShareable(me)
    ---Purpose: Tests if <me> can be shared by one or more expressions 
    --          or must be copied. This method returns False as a 
    --          default value. To be redefined ( especially for 
    --          NamedUnknown). 
    ---Level: Internal
    returns Boolean is virtual;
    
    IsIdentical(me; Other : GeneralExpression)
    ---Purpose: Tests if <me> and <Other> define the same expression.
    --  Warning: This method does not include any simplification before
    --          testing. It could also be very slow; to be used 
    --          carefully.
    ---Level: Internal 
    returns Boolean
    is deferred;
    
    Derivative(me; X : NamedUnknown)
    ---Purpose: Returns the derivative on <X> unknown of <me> 
    ---Level: Advanced 
    returns any GeneralExpression
    is deferred;

    NDerivative(me; X : NamedUnknown; N : Integer)
    ---Purpose: Returns the <N>-th derivative on <X> unknown of <me>.
    --          Raise OutOfRange if N <= 0
    ---Level: Advanced 
    returns any GeneralExpression
    raises OutOfRange is virtual;

    Replace(me : mutable ; var : NamedUnknown ; with : GeneralExpression)
    ---Purpose: Replaces all occurences of <var> with copies of <with> 
    --          in <me>. Copies of <with> are made with the Copy() method.
    --          Raises InvalidOperand if <with> contains <me>.
    ---Level: Internal
    raises InvalidOperand
    is deferred;
    
    Evaluate(me; vars : Array1OfNamedUnknown; vals : Array1OfReal)
    ---Purpose: Returns the value of <me> (as a Real) by 
    --          replacement of <vars> by <vals>.
    --          Raises NotEvaluable if <me> contains NamedUnknown not 
    --          in <vars> or NumericError if result cannot be computed.
    ---Level: Advanced 
    returns Real
    raises NotEvaluable,NumericError
    is deferred;
    
    EvaluateNumeric(me)
    ---Purpose: Returns the value of <me> (as a Real) by 
    --          replacement of <vars> by <vals>.
    --          Raises NotEvaluable if <me> contains NamedUnknown not 
    --          in <vars> or NumericError if result cannot be computed.
    ---Level: Internal
    returns Real
    raises NotEvaluable,NumericError;

    String(me)
    ---Purpose: returns a string representing <me> in a readable way.
    ---Level: Public 
    returns AsciiString
    is deferred;
    
end GeneralExpression;