Horizon » Horizon Simulation Framework

//=========================================================================

//  CUSTOMFILTER.H - part of

//                  OMNeT++/OMNEST

//           Discrete System Simulation in C++

//

//  Author: Andras Varga

//

//=========================================================================

/*--------------------------------------------------------------*

  Copyright (C) 1992-2008 Andras Varga

  Copyright (C) 2006-2008 OpenSim Ltd.

  This file is distributed WITHOUT ANY WARRANTY. See the file

  `license' for details on this and other legal matters.

*--------------------------------------------------------------*/

#ifndef _CUSTOMFILTER_H_

#define _CUSTOMFILTER_H_

#include "commonnodes.h"

#include "expression.h"

NAMESPACE_BEGIN

/**

 * Processing node which evaluates an arbitrary expression entered

 * by the user.

 *

 * TODO:

 *  - support parameters: $windowsize or $(windowsize) in the expression

 *    would prompt user to enter a value for windowsize;

 *  - extend the expression syntax into a mini imperative language to allow

 *    for writing more powerful filters: introduce variables and assigment operator

 *    (=, +=, *=, ++, --, etc); allow several expressions separated by semicolon;

 *    implement 'for', 'while', 'if'; filternode to keep a variables table;

 *    "init-expression" attr where user could initialize variables;

 *    possibly implement array variables as well.

 */

class SCAVE_API ExpressionFilterNode : public FilterNode

{

    public:

        /**

         * Implements a variable in the expression. Currently just delegates

         * to ExpressionFilterNode::getVariable().

         */

        class NodeVar : public Expression::Variable

        {

          private:

            ExpressionFilterNode *hostnode;

            std::string varname;

          public:

            NodeVar(ExpressionFilterNode *node, const char *name)

                {hostnode = node; varname = name; hostnode->skipFirstDatum |= (varname=="tprev" || varname=="yprev"); }

            virtual ~NodeVar() {}

            virtual Expression::Functor *dup() const {return new NodeVar(hostnode, varname.c_str());}

            virtual const char *getName() const {return varname.c_str();}

            virtual char getReturnType() const {return Expression::Value::DBL;}

            virtual Expression::Value evaluate(Expression::Value args[], int numargs)

                {return hostnode->getVariable(varname.c_str());}

        };

    private:

        Expression *expr;

        Datum currentDatum, prevDatum;

        bool skipFirstDatum;

    public:

        ExpressionFilterNode(const char *expression);

        virtual ~ExpressionFilterNode();

        virtual bool isReady() const;

        virtual void process();

        double getVariable(const char *varname);

};

class SCAVE_API ExpressionFilterNodeType : public FilterNodeType

{

    public:

        virtual const char *getName() const {return "expression";}

        virtual const char *getDescription() const;

        virtual void getAttributes(StringMap& attrs) const;

        virtual Node *create(DataflowManager *mgr, StringMap& attrs) const;

        virtual void mapVectorAttributes(/*inout*/StringMap &attrs) const;

};

NAMESPACE_END

#endif