Application: gvSIG desktop

package org.gvsig.labeling.lang;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import org.gvsig.tools.evaluator.EvaluatorWithDescriptions;

import org.gvsig.tools.evaluator.sqljep.SQLJEPEvaluator;

/**

 * 

 * Utility class to centralize the creation of an

 * @link {@link EvaluatorWithDescriptions}

 * 

 * TODO Perhaps create a manager in Tools to perform this operation

 * 

 * @author jldominguez

 *

 */

public class EvaluatorCreator {

        private static Map<String, EvaluatorWithDescriptions> evCache =

                        new HashMap<String, EvaluatorWithDescriptions>();

        static {

                for (int i=0; i<200; i++) {

                        String e = "XXX" + i;

                        SQLJEPEvaluator p = new SQLJEPEvaluator(e);

                        evCache.put(e, p);

                }

        }

    /**

     * Create an {@link EvaluatorWithDescriptions} that uses

     * the string expression provided

     * 

     * @param expr

     * @return

     */

    public static EvaluatorWithDescriptions getEvaluator(String expr) {

            EvaluatorWithDescriptions resp = evCache.get(expr);

            if (resp == null) {

                    resp = new SQLJEPEvaluator(expr);

                    if (evCache.size() > 100) {

                            removeOne(evCache);

                    }

                    evCache.put(expr, resp);

            }

        return resp; 

    }

        private static void removeOne(

                        Map<String, EvaluatorWithDescriptions> themap) {

                Iterator<String> iter = themap.keySet().iterator();

                int count = 50;

                String k = null;

                while (iter.hasNext() && count > 0) {

                        k = iter.next();

                        count--;

                }

                themap.remove(k);

        }

}