Application: gvSIG desktop

/* gvSIG. Sistema de Informaci�n Geogr�fica de la Generalitat Valenciana

 *

 * Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,USA.

 *

 * For more information, contact:

 *

 *  Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib��ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *      +34 963862235

 *   gvsig@gva.es

 *      www.gvsig.gva.es

 *

 *    or

 *

 *   IVER T.I. S.A

 *   Salamanca 50

 *   46005 Valencia

 *   Spain

 *

 *   +34 963163400

 *   dac@iver.es

 */

package org.gvsig.sldsupport.filterencoding.operations;

import java.util.HashMap;

import java.util.Hashtable;

/**

 * Implements methods that allow the user to create new operators to be

 * included in an expression to be parsed

 *

 * @author Pepe Vidal Salvador - jose.vidal.salvador@iver.es

 *

 */

public class OperatorsFactory  {

        private static OperatorsFactory instance = new OperatorsFactory();

    public HashMap<String,Class> functions = new HashMap<String,Class>();

        Class myClass;

    public static OperatorsFactory getInstance()

    {

        return instance;

    }

    private OperatorsFactory()

    {

        // logical functions

        addOperator(OrOperator.class);

        addOperator(AndOperator.class);

        addOperator(NotOperator.class);

        addOperator(EqOperator.class);

        addOperator(NeOperator.class);

        addOperator(LessThanOperator.class);

        addOperator(LessThanOrEqualsOperator.class);

        addOperator(GreaterThanOperator.class);

        addOperator(GreaterThanOrEqualsOperator.class);

        addOperator(AddOperator.class);

        addOperator(MinusOperator.class);

        addOperator(MultOperator.class);

        addOperator(DivOperator.class);

        addOperator(IsBetweenOperator.class);

        addOperator(IsNullOperator.class);

        addOperator(ReplaceOperator.class);

    }

    public void addOperator(Class<? extends Expression> newClass)

    {

        if (!Expression.class.isAssignableFrom(newClass))

            throw new RuntimeException("Tried to register an operator which does not implement the Expression inteface");

        try {

                        functions.put(((Expression) newClass.

                                        getConstructor(new Class[] { Hashtable.class }).newInstance(

                                                        new Hashtable<String, Object>())).getName(), newClass);

                } catch (Exception e) {

                         throw new RuntimeException("Tried to register an operator which does not implement the Expression inteface");

                }

    }

    public Expression getOperator(String name) throws Exception {

        return (Expression)functions.get(name).newInstance();

    }

    public Expression createOperator(String name) throws Exception

    {

            myClass = (Class)functions.get(name);

        if (myClass == null)

            return null;

        return (Expression)myClass.newInstance();

    }

}