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The main module contains the GeoTools public interfaces that are used by other GeoTools modules (and GeoTools applications). Where possible we make use industry standard terms as provided by OGC and ISO standards. The formal GeoTools public api consists of gt-metadata, jts and the gt-main module. The main module contains the default implementations that are available provided to other GeoTools modules using our factory system. Factories are obtained from an appropriate FactoryFinder, giving applications a chance configure the factory used using the Factory Hints facilities. FilterFactory ff = CommonFactoryFinder.getFilterFactory(); Expression expr = ff.add( expression1, expression2 ); If you find yourself using implementation specific classes chances are you doing it wrong: Expression expr = new AddImpl( expression1, expressiom2 );

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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2003-2008, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library 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
 *    Lesser General Public License for more details.
 */
package org.geotools.data;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import org.locationtech.jts.geom.Envelope;
import org.locationtech.jts.geom.Geometry;
import org.opengis.feature.Feature;
import org.opengis.feature.IllegalAttributeException;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.type.FeatureType;
import org.opengis.filter.Filter;
import org.opengis.filter.Id;
import org.opengis.filter.expression.PropertyName;
import org.opengis.filter.identity.Identifier;
import org.opengis.filter.spatial.BBOX;
import org.opengis.filter.spatial.BinarySpatialOperator;
import org.opengis.filter.spatial.Contains;
import org.opengis.filter.spatial.Crosses;
import org.opengis.filter.spatial.Overlaps;
import org.opengis.filter.spatial.Touches;
import org.opengis.filter.spatial.Within;

/**
 * A FeatureReader that considers differences.
 *
 * Used to implement In-Process Transaction support. This implementation will need to peek ahead
 * in order to check for deletetions.
 *
 * @author Jody Garnett, Refractions Research
 */
public class DiffFeatureReader
        implements FeatureReader {
    FeatureReader reader;
    Diff diff;

    /** Next value as peeked by hasNext() */
    F next = null;

    private Filter filter;
    private Set encounteredFids;

    private Iterator addedIterator;
    private Iterator modifiedIterator;
    private Iterator fids;
    private Iterator spatialIndexIterator;

    private boolean indexedGeometryFilter = false;
    private boolean fidFilter = false;

    /**
     * This constructor grabs a "copy" of the current diff.
     *
     * 
This reader is not "live" to changes over the course of the Transaction. (Iterators are
     * not always stable of the course of modifications)
     *
     * @param diff2 Differences of Feature by FID
     */
    public DiffFeatureReader(FeatureReader reader, Diff diff2) {
        this(reader, diff2, Filter.INCLUDE);
    }

    /**
     * This constructor grabs a "copy" of the current diff.
     *
     * This reader is not "live" to changes over the course of the Transaction. (Iterators are
     * not always stable of the course of modifications)
     *
     * @param diff2 Differences of Feature by FID
     */
    public DiffFeatureReader(FeatureReader reader, Diff diff2, Filter filter) {
        this.reader = reader;
        this.diff = diff2;
        this.filter = filter;
        encounteredFids = new HashSet();

        if (filter instanceof Id) {
            fidFilter = true;
        } else if (isSubsetOfBboxFilter(filter)) {
            indexedGeometryFilter = true;
        }

        synchronized (diff) {
            if (indexedGeometryFilter) {
                spatialIndexIterator = getIndexedFeatures().iterator();
            }
            addedIterator = (Iterator) diff.getAdded().values().iterator();
            modifiedIterator = (Iterator) diff.getModified().values().iterator();
        }
    }

    /** @see org.geotools.data.FeatureReader#getFeatureType() */
    public T getFeatureType() {
        return reader.getFeatureType();
    }

    /** @see org.geotools.data.FeatureReader#next() */
    public F next() throws IOException, IllegalAttributeException, NoSuchElementException {
        if (hasNext()) {
            F live = next;
            next = null;

            return live;
        }

        throw new NoSuchElementException("No more Feature exists");
    }

    /** @see org.geotools.data.FeatureReader#hasNext() */
    public boolean hasNext() throws IOException {
        if (next != null) {
            // We found it already
            return true;
        }
        F peek;

        if (filter == Filter.EXCLUDE) return false;

        while ((reader != null) && reader.hasNext()) {

            try {
                peek = reader.next();
            } catch (NoSuchElementException e) {
                throw new DataSourceException("Could not aquire the next Feature", e);
            } catch (IllegalAttributeException e) {
                throw new DataSourceException("Could not aquire the next Feature", e);
            }

            String fid = peek.getIdentifier().getID();
            encounteredFids.add(fid);

            Map modified = diff.getModified();
            if (modified.containsKey(fid)) {
                F changed = (F) modified.get(fid);
                if (changed == Diff.NULL || !filter.evaluate(changed)) {
                    continue;
                } else {
                    next = changed;
                    return true;
                }
            } else {

                next = peek; // found feature
                return true;
            }
        }

        queryDiff();
        return next != null;
    }

    /** @see org.geotools.data.FeatureReader#close() */
    public void close() throws IOException {
        if (reader != null) {
            reader.close();
            reader = null;
        }

        if (diff != null) {
            diff = null;
            addedIterator = null;
        }
    }

    protected void queryDiff() {
        if (fidFilter) {
            queryFidFilter();
        } else if (indexedGeometryFilter) {
            querySpatialIndex();
        } else {
            queryAdded();
            queryModified();
        }
    }

    protected void querySpatialIndex() {
        while (spatialIndexIterator.hasNext() && next == null) {
            F f = (F) spatialIndexIterator.next();
            if (encounteredFids.contains(f.getIdentifier().getID()) || !filter.evaluate(f)) {
                continue;
            }
            next = f;
        }
    }

    protected void queryAdded() {
        while (addedIterator.hasNext() && next == null) {
            next = (F) addedIterator.next();
            if (encounteredFids.contains(next.getIdentifier().getID()) || !filter.evaluate(next)) {
                next = null;
            }
        }
    }

    protected void queryModified() {
        while (modifiedIterator.hasNext() && next == null) {
            next = (F) modifiedIterator.next();
            if (next == Diff.NULL
                    || encounteredFids.contains(next.getIdentifier().getID())
                    || !filter.evaluate(next)) {
                next = null;
            }
        }
    }

    protected void queryFidFilter() {
        Id fidFilter = (Id) filter;
        if (fids == null) {
            fids = fidFilter.getIdentifiers().iterator();
        }
        while (fids.hasNext() && next == null) {
            String fid = fids.next().toString();
            if (!encounteredFids.contains(fid)) {
                next = (F) diff.getModified().get(fid);
                if (next == null) {
                    next = (F) diff.getAdded().get(fid);
                }
            }
        }
    }

    protected List getIndexedFeatures() {
        // TODO: check geom is default geom.
        Envelope env = null;
        env = extractBboxForSpatialIndexQuery((BinarySpatialOperator) filter);
        return diff.queryIndex(env);
    }

    protected Envelope extractBboxForSpatialIndexQuery(BinarySpatialOperator filter) {
        org.opengis.filter.expression.Expression leftGeom = filter.getExpression1();
        org.opengis.filter.expression.Expression rightGeom = filter.getExpression2();

        Object g;
        if (leftGeom instanceof org.opengis.filter.expression.Literal) {
            g = ((org.opengis.filter.expression.Literal) leftGeom).getValue();
        } else {
            g = ((org.opengis.filter.expression.Literal) rightGeom).getValue();
        }

        Envelope envelope = null;
        if (g instanceof Geometry) {
            envelope = ((Geometry) g).getEnvelopeInternal();
        } else if (g instanceof Envelope) {
            envelope = (Envelope) g;
        }
        return envelope;
    }

    protected boolean isDefaultGeometry(PropertyName ae) {
        return reader.getFeatureType()
                .getGeometryDescriptor()
                .getLocalName()
                .equals(ae.getPropertyName());
    }

    protected boolean isSubsetOfBboxFilter(Filter f) {
        return filter instanceof Contains
                || filter instanceof Crosses
                || filter instanceof Overlaps
                || filter instanceof Touches
                || filter instanceof Within
                || filter instanceof BBOX;
    }
}