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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.NoSuchElementException;
import org.geotools.feature.SchemaException;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
import org.opengis.feature.IllegalAttributeException;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;

/**
 * Experimental FeatureReader that always takes the first column
 * of the attributeReader as the FeatureID. I want to get this working with postgis, but then will
 * consider other options, for those who want featureIDs created automatically. Perhaps a
 * constructor param or a method to say that you would just like to have the
 * FeatureReader increment one for each feature, prepending the
 * typeName. I'm also don't really like the one argument constructor defaulting to the xxx typename.
 * I feel that it should perhaps take a typename. If people deliberately set to null then we could
 * use xxx or something. ch
 *
 * This now feels sorta hacky, I'm not sure that I like it, but I'm going to commit as I need to
 * go now and revisit it in a bit. I think the idea of passing in an FIDAttributeReader might be
 * cleaner, and if none is provided then do an auto-increment one. This might then work as the
 * DefaultFeatureReader.
 *
 * @author Ian Schneider
 * @author Chris Holmes, TOPP
 * @version $Id$
 */
public class FIDFeatureReader implements FeatureReader {
    private final AttributeReader attributeReader;
    private final SimpleFeatureType schema;
    private final FIDReader fidReader;
    protected final Object[] attributes;
    private SimpleFeatureBuilder builder;
    private Boolean hasNextFlag;

    /**
     * Creates a new instance of AbstractFeatureReader
     *
     * @param attributeReader AttributeReader
     * @param fidReader FIDReader used to ID Features
     * @param schema FeatureType to use, may be null
     * @throws SchemaException if we could not determine the correct FeatureType
     */
    public FIDFeatureReader(
            AttributeReader attributeReader, FIDReader fidReader, SimpleFeatureType schema)
            throws SchemaException {
        this.attributeReader = attributeReader;
        this.fidReader = fidReader;

        if (schema == null) {
            schema = createSchema();
        }

        this.schema = schema;
        this.attributes = new Object[attributeReader.getAttributeCount()];
        this.builder = new SimpleFeatureBuilder(schema);
    }

    public FIDFeatureReader(AttributeReader attributeReader, FIDReader fidReader)
            throws SchemaException {
        this(attributeReader, fidReader, null);
    }

    public SimpleFeature next()
            throws IOException, IllegalAttributeException, NoSuchElementException {
        if (hasNext()) {
            hasNextFlag = null;
            attributeReader.next();

            return readFeature(attributeReader);
        } else {
            throw new NoSuchElementException("There are no more Features to be read");
        }
    }

    protected SimpleFeatureType createSchema() throws SchemaException {
        SimpleFeatureTypeBuilder b = new SimpleFeatureTypeBuilder();
        b.setName("xxx");

        for (int i = 0, ii = attributeReader.getAttributeCount(); i < ii; i++) {
            b.add(attributeReader.getAttributeType(i));
        }

        return b.buildFeatureType();
    }

    protected SimpleFeature readFeature(AttributeReader atts)
            throws IllegalAttributeException, IOException {

        // Seems like doing it here could be a bit expensive.
        // The other option from this is to have this constructed with two
        // attributeReaders, the FID one and real attributes one.  Could then
        // have default FIDAttributeReader.
        String fid = fidReader.next();

        for (int i = 0, ii = atts.getAttributeCount(); i < ii; i++) {
            builder.add(atts.read(i));
        }
        return builder.buildFeature(fid);
    }

    public void close() throws IOException {
        fidReader.close();
        attributeReader.close();
    }

    public SimpleFeatureType getFeatureType() {
        return schema;
    }

    public boolean hasNext() throws IOException {
        if (hasNextFlag == null) {
            hasNextFlag = Boolean.valueOf(attributeReader.hasNext());
        }
        return hasNextFlag;
    }
}