Application: gvSIG desktop

/* gvSIG. Geographic Information System of the Valencian Government

 *

 * Copyright (C) 2007-2008 Infrastructures and Transports Department

 * of the Valencian Government (CIT)

 *

 * 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., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 */

/*

 * AUTHORS (In addition to CIT):

 * 2008 {{Company}}   {{Task}}

 */

package org.gvsig.fmap.dal.feature.impl;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.feature.FeatureIndex;

import org.gvsig.fmap.dal.feature.FeatureIndexes;

import org.gvsig.fmap.dal.feature.FeatureSet;

import org.gvsig.fmap.dal.feature.exception.FeatureIndexException;

import org.gvsig.fmap.dal.feature.spi.index.FeatureIndexProviderServices;

import org.gvsig.tools.evaluator.Evaluator;

import org.gvsig.tools.evaluator.EvaluatorFieldValue;

import org.gvsig.tools.evaluator.EvaluatorFieldValueMatch;

import org.gvsig.tools.evaluator.EvaluatorFieldValueNearest;

import org.gvsig.tools.evaluator.EvaluatorFieldValueRange;

/**

 * This class provides access to a FeatureStore local indexes and also decides

 * which index to use given an evaluator containing the filter expression.

 *

 * @author jyarza

 */

public class DefaultFeatureIndexes implements FeatureIndexes {

        // Access by index name

        private Map names;

        // Store to which this belongs

        private DefaultFeatureStore store;

        /**

         * Creates an empty DataIndexes for the given FeatureStore

         *

         * @param store

         *            FeatureStore to whom this belongs

         * @throws DataException

         */

        public DefaultFeatureIndexes(DefaultFeatureStore store)

                        throws DataException {

                names = new HashMap();

                this.store = store;

        }

        /*

         * (non-Javadoc)

         *

         * @see org.gvsig.fmap.dal.index.DataIndexes#getDataIndex(java.lang.String)

         */

        public FeatureIndex getFeatureIndex(String name) {

                return (FeatureIndex) names.get(name);

        }

        /*

         * (non-Javadoc)

         *

         * @see org.gvsig.fmap.dal.index.DataIndexes#addIndex(org.gvsig.fmap.dal.feature.FeatureType,

         *      java.lang.String, org.gvsig.fmap.dal.feature.DataIndex)

         */

        public void addIndex(FeatureIndexProviderServices index) {

                // By name

                names.put(index.getName(), index);

        }

        public Iterator iterator() {

                return names.values().iterator();

        }

        /**

         * Using the given evaluator attributes, choose and use an appropriate index

         * to obtain a FeatureSet. If no index can be applied, then this method

         * returns null

         * 

         * @param evaluator

         * @return FeatureSet or null if could not find any appropriate index.

         * @throws FeatureIndexException

         * 

         */

        public FeatureSet getFeatureSet(Evaluator evaluator)

                        throws FeatureIndexException {

                class ApplyIndex {

                        DefaultFeatureIndex index;

                        EvaluatorFieldValue[] data;

                        ApplyIndex(DefaultFeatureIndex index, EvaluatorFieldValue[] data) {

                                this.index = index;

                                this.data = data;

                        }

                        /**

                         * Checks whether the index supports the evaluator request

                         *

                         * @return

                         */

                        boolean isSupported() {

                                switch (data[0].getType()) {

                                case EvaluatorFieldValue.MATCH:

                                        return index.getFeatureIndexProvider().isMatchSupported();

                                case EvaluatorFieldValue.NEAREST:

                                        return index.getFeatureIndexProvider().isNearestSupported();

                                case EvaluatorFieldValue.RANGE:

                                        return index.getFeatureIndexProvider().isRangeSupported();

                                default:

                                        return false;

                                }

                        }

                        /**

                         * Applies the index using the evaluator fields

                         *

                         * @return FeatureSet with the result

                         * @throws FeatureIndexException

                         */

                        IndexFeatureSet apply() throws FeatureIndexException {

                                EvaluatorFieldValueRange rangeField;

                                EvaluatorFieldValueNearest nearestField;

                                // Trick: we know DefaultIndexProvider returns an IndexFeatureSet,

                                // which implements both FeatureSetProvider and FeatureSet.

                                switch (data[0].getType()) {

                                case EvaluatorFieldValue.MATCH:

                                        return (IndexFeatureSet) index.getMatchFeatureSet(

                                                        ((EvaluatorFieldValueMatch) data[0])

                                                                        .getValue());

                                case EvaluatorFieldValue.RANGE:

                                        rangeField = (EvaluatorFieldValueRange) data[0];

                                        return (IndexFeatureSet) index.getRangeFeatureSet(

                                                        rangeField.getValue1(), rangeField.getValue2());

                                case EvaluatorFieldValue.NEAREST:

                                        nearestField = (EvaluatorFieldValueNearest) data[0];

                                        if ((nearestField.getTolerance() == null)

                                                        || (!isSupported())) {

                                                return (IndexFeatureSet) index.getNearestFeatureSet(

                                                                nearestField.getCount(), nearestField

                                                                                .getValue());

                                        } else {

                                                return (IndexFeatureSet) index.getNearestFeatureSet(

                                                                nearestField.getCount(), nearestField

                                                                                .getValue(), nearestField

                                                                                .getTolerance());

                                        }

                                }

                                return null;

                        }

                }

                // Select applicable indexes

                List applyIndexes = new ArrayList();

                Iterator indexes = this.iterator();

                while (indexes.hasNext()) {

                        DefaultFeatureIndex index = (DefaultFeatureIndex) indexes.next();

                        String[] attrs = (String[]) index.getAttributeNames().toArray(

                                        new String[0]);

                        for (int i = 0; i < attrs.length; i++) {

                                String attrname = attrs[i];

                                EvaluatorFieldValue[] values = null;

                                if (evaluator.getFieldsInfo() != null) {

                                        values = evaluator.getFieldsInfo().getFieldValues(attrname);

                                }

                                if (values != null) {

                                        applyIndexes.add(new ApplyIndex(index, values));

                                        break;

                                }

                        }

                }

                // If there's not any applicable index, return null

                if (applyIndexes.size() == 0) {

                        return null;

                }

                // Lookup an index with support for the requested function

                Iterator it = applyIndexes.iterator();

                ApplyIndex index = (ApplyIndex) it.next();

                while (it.hasNext() && (!index.isSupported())) {

                        index = (ApplyIndex) it.next();

                }

                // If there is not any any index supporting the function, use the

                // first one

                if (!index.isSupported()) {

                        this.store

                                        .getLogger()

                                        .info(

                                                        "No index support for the evaluator values. Using default index.");

                        index = (ApplyIndex) applyIndexes.get(0);

                }

                // Apply index

                return index.apply();

        }

}