/// <summary>
        /// method creates Bindings from the bound constraint and adds them to
        /// the Rule.
        /// </summary>
        /// <param name="cnstr">The CNSTR.</param>
        /// <param name="templ">The templ.</param>
        /// <param name="rule">The rule.</param>
        /// <param name="position">The position.</param>
        /// <returns></returns>
        public virtual BaseAlpha2 compileConstraint(BoundConstraint cnstr, ITemplate templ, Rule.IRule rule, int position)
        {
            BaseAlpha2 current = null;

            if (rule.getBinding(cnstr.VariableName) == null)
            {
                // if the HashMap doesn't already contain the binding, we create
                // a new one
                if (cnstr.IsObjectBinding)
                {
                    Binding bind = new Binding();
                    bind.VarName     = cnstr.VariableName;
                    bind.LeftRow     = position;
                    bind.LeftIndex   = -1;
                    bind.IsObjectVar = true;
                    rule.addBinding(cnstr.VariableName, bind);
                }
                else
                {
                    Binding bind = new Binding();
                    bind.VarName           = cnstr.VariableName;
                    bind.LeftRow           = position;
                    bind.LeftIndex         = templ.getSlot(cnstr.Name).Id;
                    bind.RowDeclared       = position;
                    cnstr.FirstDeclaration = true;
                    rule.addBinding(cnstr.VariableName, bind);
                }
            }
            return(current);
        }
        /// <summary>
        /// Compiles the constraint.
        /// </summary>
        /// <param name="cnstr">The CNSTR.</param>
        /// <param name="templ">The templ.</param>
        /// <param name="rule">The rule.</param>
        /// <param name="position">The position.</param>
        /// <returns></returns>
        public virtual BaseAlpha2 compileConstraint(PredicateConstraint cnstr, ITemplate templ, Rule.IRule rule, int position)
        {
            BaseAlpha2 current = null;

            // for now we expect the user to write the predicate in this
            // way (> ?bind value), where the binding is first. this
            // needs to be updated so that we look at the order of the
            // parameters and set the node appropriately

            // we only create an AlphaNode if the predicate isn't
            // joining 2 bindings.
            if (!cnstr.PredicateJoin)
            {
                if (ConversionUtils.isPredicateOperatorCode(cnstr.FunctionName))
                {
                    int    oprCode = ConversionUtils.getOperatorCode(cnstr.FunctionName);
                    Slot   sl      = (Slot)templ.getSlot(cnstr.Name).Clone();
                    Object sval    = ConversionUtils.convert(sl.ValueType, cnstr.Value);
                    sl.Value = sval;
                    // create the alphaNode
                    if (rule.RememberMatch)
                    {
                        current = new AlphaNode(engine.nextNodeId());
                    }
                    else
                    {
                        current = new NoMemANode(engine.nextNodeId());
                    }
                    current.Slot     = sl;
                    current.Operator = oprCode;
                    current.incrementUseCount();
                    // we increment the node use count when when create a new
                    // AlphaNode for the LiteralConstraint
                    templ.getSlot(sl.Id).incrementNodeCount();
                }
                else
                {
                    // the function isn't a built in predicate function that
                    // returns boolean true/false. We look up the function
                    IFunction f = engine.findFunction(cnstr.FunctionName);
                    if (f != null)
                    {
                        // we create the alphaNode if a function is found and
                        // the return type is either boolean primitive or object
                        if (f.ReturnType == Constants.BOOLEAN_PRIM_TYPE || f.ReturnType != Constants.BOOLEAN_OBJECT)
                        {
                            // TODO - need to implement it
                        }
                        else
                        {
                            // the function doesn't return boolean, so we have to notify
                            // the listeners the condition is not valid
                            CompileMessageEventArgs ce = new CompileMessageEventArgs(this, EventType.FUNCTION_INVALID);
                            ce.Message = INVALID_FUNCTION + " " + f.ReturnType; //$NON-NLS-1$
                            notifyListener(ce);
                        }
                    }
                    else
                    {
                        // we need to notify listeners the function wasn't found
                        CompileMessageEventArgs ce = new CompileMessageEventArgs(this, EventType.FUNCTION_NOT_FOUND);
                        ce.Message = FUNCTION_NOT_FOUND + " " + cnstr.FunctionName;
                        notifyListener(ce);
                    }
                }
            }
            Binding bind = new Binding();

            bind.VarName     = cnstr.VariableName;
            bind.LeftRow     = position;
            bind.LeftIndex   = templ.getSlot(cnstr.Name).Id;
            bind.RowDeclared = position;
            // we only Add the binding to the map if it doesn't already exist
            if (rule.getBinding(cnstr.VariableName) == null)
            {
                rule.addBinding(cnstr.VariableName, bind);
            }
            return(current);
        }