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):

* 2009 {}  {{Task}}

*/

package org.gvsig.fmap.dal.spi;

import org.gvsig.fmap.dal.feature.spi.FeatureProvider;

import org.gvsig.fmap.dal.resource.Resource;

import org.gvsig.fmap.dal.resource.ResourceAction;

import org.gvsig.tools.dispose.DisposableIterator;

import org.gvsig.tools.dispose.impl.AbstractDisposable;

/**

 * Abstract base implementation for data iterators.

 * 

 * @author 2009- <a href="cordinyana@gvsig.org">C?sar Ordi?ana</a> - gvSIG team

 */

public abstract class AbstractDataProviderIterator extends AbstractDisposable

                implements DisposableIterator {

        private final DataStoreProvider dataStoreProvider;

        private final ResourceAction nextResourceAction = new ResourceAction() {

                public Object run() throws Exception {

                        dataStoreProvider.open();

                        return internalNext();

                }

        };

        private final ResourceAction hasNextResourceAction = new ResourceAction() {

                public Object run() throws Exception {

                        boolean value = internalHasNext();

                        return value ? Boolean.TRUE : Boolean.FALSE;

                }

        };

        /**

         * Creates a new iterator instance.

         * 

         * @param storeProvider

         *            to load the {@link FeatureProvider}s from

         */

        public AbstractDataProviderIterator(DataStoreProvider dataStoreProvider) {

                this.dataStoreProvider = dataStoreProvider;

        }

    public Object next() {

                return getResource().execute(nextResourceAction);

        }

    public boolean hasNext() {

                Object hasNext = getResource().execute(hasNextResourceAction);

                return ((Boolean) hasNext).booleanValue();

        }

        /**

         * Returns the {@link Resource} from where the data is going to be loaded.

         * 

         * @return the {@link Resource} from where the data is going to be loaded

         */

        protected final Resource getResource() {

                return getDataStoreProvider().getResource();

        }

        /**

         * Returns the {@link DataStoreProvider} to load the Iterator data.

         * 

         * @return the {@link DataStoreProvider}

         */

        protected DataStoreProvider getDataStoreProvider() {

                return dataStoreProvider;

        }

        /**

         * Returns the next iterator element. It is the child classes implementation

         * for the {@link #next()} method.

         * 

         * @return the next element

         */

        protected abstract Object internalNext();

        /**

         * Returns if there are more elements to get from the iterator. It is the

         * child classes implementation for the {@link #hasNext()} method.

         * 

         * @return if there are more elements

         */

        protected abstract boolean internalHasNext();

}