/**
* Copyright (c) 2010-2013 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.gis.spatial.indexfilter;
import org.geotools.data.neo4j.Neo4jFeatureBuilder;
import org.geotools.filter.text.cql2.CQLException;
import org.geotools.filter.text.ecql.ECQL;
import org.neo4j.gis.spatial.rtree.Envelope;
import org.neo4j.gis.spatial.rtree.SpatialIndexRecordCounter;
import org.neo4j.gis.spatial.rtree.filter.SearchFilter;
import org.neo4j.gis.spatial.rtree.filter.SearchResults;
import org.neo4j.gis.spatial.Layer;
import org.neo4j.gis.spatial.LayerTreeIndexReader;
import org.neo4j.gis.spatial.SpatialDatabaseRecord;
import org.neo4j.gis.spatial.Utilities;
import org.neo4j.gis.spatial.filter.SearchRecords;
import org.neo4j.graphdb.Node;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.filter.Filter;
/**
* This class enables support for CQL based dynamic layers. This means the
* filtering on the result set is based on matches to a CQL query. Some key
* differences between CQL queries and JSON queries are:
* <ul>
* <li>CQL will operate on the geometry itself, performing spatial
* operations, but also requiring the geometry to be created from the graph.
* This makes it slower than the JSON approach, but richer from a GIS
* perspective</li>
* <li>JSON will operate on the graph itself, and so it is more specific to
* the data model, and not at all specific to the GIS meaning of the data.
* This makes it faster, but more complex to develop to. You really need to
* know your graph structure well to write a complex JSON query. For simple
* single-node property matches, this is the easiest solution.</li>
* </ul>
*
* @author dwins
*/
public class CQLIndexReader extends LayerIndexReaderWrapper {
private final Filter filter;
private final Envelope filterEnvelope;
private final Neo4jFeatureBuilder builder;
private final Layer layer;
public CQLIndexReader(LayerTreeIndexReader index, Layer layer, String query) throws CQLException {
super(index);
this.filter = ECQL.toFilter(query);
this.builder = new Neo4jFeatureBuilder(layer);
this.layer = layer;
this.filterEnvelope = Utilities.extractEnvelopeFromFilter(filter);
}
private class Counter extends SpatialIndexRecordCounter {
@Override
public boolean needsToVisit(Envelope indexNodeEnvelope) {
return queryIndexNode(indexNodeEnvelope);
}
@Override
public void onIndexReference(Node geomNode) {
if (queryLeafNode(geomNode)) {
super.onIndexReference(geomNode);
}
}
}
private boolean queryIndexNode(Envelope indexNodeEnvelope) {
return filterEnvelope == null || filterEnvelope.intersects(indexNodeEnvelope);
}
private boolean queryLeafNode(Node indexNode) {
SpatialDatabaseRecord dbRecord = new SpatialDatabaseRecord(layer, indexNode);
SimpleFeature feature = builder.buildFeature(dbRecord);
return filter.evaluate(feature);
}
@Override
public int count() {
Counter counter = new Counter();
index.visit(counter, index.getIndexRoot());
return counter.getResult();
}
private SearchFilter wrapSearchFilter(final SearchFilter filter) {
return new SearchFilter() {
@Override
public boolean needsToVisit(Envelope envelope) {
return queryIndexNode(envelope) &&
filter.needsToVisit(envelope);
}
@Override
public boolean geometryMatches(Node geomNode) {
return queryLeafNode(geomNode) && filter.geometryMatches(geomNode);
}
};
}
@Override
public SearchResults searchIndex(SearchFilter filter) {
return index.searchIndex(wrapSearchFilter(filter));
}
@Override
public SearchRecords search(SearchFilter filter) {
return index.search(wrapSearchFilter(filter));
}
}