| gvSIG desktop 1

package org.gvsig.fmap.mapcontext.layers;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.NoSuchElementException;

import org.gvsig.fmap.mapcontext.layers.operations.LayerCollection;

/**

 * Interator for iterate in a Layers tree

 * <P>

 * Extend this class to create an expecific layer iterator

 * and override the method <code>evaluate</code> for check

 * if a layer will be in the iteration list.

 * <P> 

 * @author jmvivo

 *

 */

public class LayersIterator implements Iterator {

        ArrayList layersList  =new ArrayList();

        int index = 0;

        public LayersIterator() {

        }

        public LayersIterator(FLayer layer) {

                this.appendLayer(layer);

        }

        protected void appendLayer(FLayer layer) {

                if (this.evaluate(layer)) {

                        layersList.add(layer);

                }

                if (layer instanceof LayerCollection) {

                        appendLayers((LayerCollection)layer);                        

                }

        }

        private void appendLayers(LayerCollection layers) {

                int i;

                for (i=0;i< layers.getLayersCount();i++) {

                        appendLayer(layers.getLayer(i));

                }

        }

        public void remove() {

                throw new UnsupportedOperationException();                

        }

        public boolean hasNext() {

                return  index < layersList.size();

        }

        public Object next() {                

                return nextLayer();

        }

    /**

     * Returns the next layer in the iteration.

     *

     * @return the next layer in the iteration.

     * @exception NoSuchElementException iteration has no more elements.

     * 

     * @see next()

     */

        public FLayer nextLayer() {

                if (!this.hasNext()) {

                        throw new NoSuchElementException();

                }

                FLayer aux = (FLayer)layersList.get(index);

                index++;

                return aux;

        }

        /**

         * Called before add a layer to the iteration

         * list.         

         * @param layer the layer to check

         * @return true if the layer will be in the iteration list

         */

        public boolean evaluate(FLayer layer) {

                return true;

        }

}