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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) 2005-2008, 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.feature.collection;

import org.geotools.data.DataUtilities;
import org.geotools.data.Query;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.data.simple.SimpleFeatureSource;
import org.geotools.data.store.EmptyFeatureCollection;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.geometry.jts.ReferencedEnvelope;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory;
import org.opengis.filter.sort.SortBy;

/**
 * Reasonable default implementation for subCollection making use of parent {@link
 * SimpleFeatureCollection#features()} and provided Filter.
 *
 * This is only a reasonable implementation and is not optimal. It is recommended that
 * implementors construct a new {@link Query} and use {@link
 * SimpleFeatureSource#getFeatures(Query)}.
 *
 * @author Jody Garnett, Refractions Research, Inc.
 */
public class SubFeatureCollection extends BaseSimpleFeatureCollection {

    /** Filter */
    protected Filter filter;

    /** Original Collection */
    protected SimpleFeatureCollection collection;

    protected FilterFactory ff = CommonFactoryFinder.getFilterFactory();

    public SubFeatureCollection(SimpleFeatureCollection collection) {
        this(collection, Filter.INCLUDE);
    }
    /** @param collection Collection or AbstractFeatureCollection */
    public SubFeatureCollection(SimpleFeatureCollection collection, Filter subfilter) {
        super(collection.getSchema());

        if (subfilter == null) {
            subfilter = Filter.INCLUDE;
        }
        if (subfilter.equals(Filter.EXCLUDE)) {
            throw new IllegalArgumentException(
                    "A subcollection with Filter.EXCLUDE would be empty");
        }
        if (collection instanceof SubFeatureCollection) {
            SubFeatureCollection filtered = (SubFeatureCollection) collection;
            if (subfilter.equals(Filter.INCLUDE)) {
                this.collection = filtered.collection;
                this.filter = filtered.filter();
            } else {
                this.collection = filtered.collection;
                this.filter = ff.and(filtered.filter(), subfilter);
            }
        } else {
            this.collection = collection;
            this.filter = subfilter;
        }
    }

    public SimpleFeatureIterator features() {
        return new FilteringSimpleFeatureIterator(collection.features(), filter());
    }

    public int size() {
        int count = 0;
        SimpleFeatureIterator i = features();
        try {
            while (i.hasNext()) {
                i.next();
                count++;
            }
        } finally {
            i.close();
        }
        return count;
    }
    /**
     * Generate filter to use for content, makes use of {@link #createFilter()} if needed.
     *
     * @return Filter to use for content
     */
    protected Filter filter() {
        if (filter == null) {
            filter = createFilter();
        }
        return filter;
    }

    /** Override to implement subsetting */
    protected Filter createFilter() {
        return Filter.INCLUDE;
    }

    public SimpleFeatureCollection subCollection(Filter filter) {
        if (filter.equals(Filter.INCLUDE)) {
            return this;
        }
        if (filter.equals(Filter.EXCLUDE)) {
            return new EmptyFeatureCollection(schema);
        }
        return new SubFeatureCollection(this, filter);
    }

    public SimpleFeatureCollection sort(SortBy order) {
        return new SubFeatureList(collection, filter, order);
    }

    public String getID() {
        return collection.getID();
    }

    /** Calculates the bounds of the features without caching. */
    @Override
    public ReferencedEnvelope getBounds() {
        return DataUtilities.bounds(this);
    }
}