-- File:	PolyExpression.cdl
-- Created:	Thu Jan 10 14:28:48 1991
-- Author:	Arnaud BOUZY
--		<adn@topsn3>
---Copyright:	 Matra Datavision 1991

deferred class PolyExpression from Expr

inherits GeneralExpression from Expr

uses SequenceOfGeneralExpression from Expr,
    NamedUnknown from Expr

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

is

    Initialize;
    ---Purpose: initialize an empty list of operands.
    
    NbOperands(me)
    ---Purpose: returns the number of operands contained in <me>
    ---Level : Internal
    returns Integer
    is static;

    Operand(me; index : Integer)
    ---Purpose: Returns the <index>-th operand used in <me>.
    --          An exception is raised if index is out of range
    ---C++: inline
    ---C++: return const &
    ---Level : Internal
    returns any GeneralExpression
    raises OutOfRange
    is static;

    SetOperand(me : mutable; exp : GeneralExpression; index : Integer)
    ---Purpose: Sets the <index>-th operand used in <me>.
    --          An exception is raised if <index> is out of range
    --          Raises InvalidOperand if <exp> contains <me>.
    ---Level : Internal
    raises OutOfRange,InvalidOperand
    is static;

    AddOperand(me : mutable; exp : GeneralExpression)
    ---Purpose: Adds an operand to the list of <me>.
    ---Level : Internal
    is static protected;

    RemoveOperand(me : mutable; index : Integer)
    ---Purpose: Remove the operand denoted by <index> from the list of 
    --          <me>. 
    --          Raises exception if <index> is out of range or if 
    --          removing operand intend to leave only one or no 
    --          operand. 
    ---Level : Internal
    raises OutOfRange
    is static protected;

    NbSubExpressions(me)
    ---Purpose: returns the number of sub-expressions contained
    --          in <me> ( >= 2)
    returns Integer
    is static;

    SubExpression(me; I : Integer)
    ---Purpose: Returns the sub-expression denoted by <I> in <me>
    --          Raises OutOfRange if <I> > NbSubExpressions(me)
    ---C++: return const &
    returns any GeneralExpression
    raises OutOfRange
    is static;

    ContainsUnknowns(me) 
    ---Purpose: Does <me> contains NamedUnknown ?
    returns Boolean
    is static;

    Contains(me; exp : GeneralExpression)
    ---Purpose: Tests if <exp> is contained in <me>.
    returns Boolean
    is static;

    Replace(me : mutable ; var : NamedUnknown ; with : GeneralExpression)
    ---Purpose: Replaces all occurences of <var> with <with> in <me>
    --          Raises InvalidOperand if <with> contains <me>.
    raises InvalidOperand
    is static;
    
    Simplified(me) 
    ---Purpose: Returns a GeneralExpression after replacement of
    --          NamedUnknowns by an associated expression and after
    --          values computation.
    returns any GeneralExpression
    raises NumericError;
    
fields

    myOperands  : SequenceOfGeneralExpression;

end PolyExpression;