JsArrayCollection.java

package org.oscim.tiling.source.geojson;

import java.util.AbstractCollection;
import java.util.Iterator;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * a Java Friendly way of working with Js Arrays using the Java.util.Collection
 * API
 * https://groups.google.com/forum/#!topic/google-web-toolkit/_8X9WPL6qwM
 * 
 * @author sg
 * 
 * @param <T>
 */
public class JsArrayCollection<T> extends AbstractCollection<T> {

	private JsArr<T> _data;

	/**
	 * creates an empty array
	 */
	public JsArrayCollection() {
		_data = JsArr.create().cast();
	}

	/**
	 * creates JsArrayCollection wrapping an existing js array
	 */
	public JsArrayCollection(JavaScriptObject data) {
		this._data = data.cast();
	}

	public static <T> JsArrayCollection<T> create(JavaScriptObject data) {
		return new JsArrayCollection<T>(data);
	}

	@Override
	public Iterator<T> iterator() {
		return new JsArrayIterator<T>(this);
	}

	@Override
	public int size() {
		return _data.size();
	}

	public static class JsArrayIterator<T> implements Iterator<T> {

		private JsArrayCollection<T> arr;
		int currentIndex;

		public JsArrayIterator(JsArrayCollection<T> arr) {
			this.arr = arr;
			currentIndex = 0;
		}

		@Override
		public boolean hasNext() {
			//        System.out.println(currentIndex+" - "+arr.size());
			return currentIndex < arr.size();
		}

		@Override
		public T next() {
			currentIndex++;
			return arr._data.get(currentIndex - 1);
		}

		@Override
		public void remove() {
			arr._data.slice(currentIndex - 1, currentIndex);
		}

	}

	/** untyped array */
	private static class JsArr<T> extends JavaScriptObject {
		protected JsArr() {
		}

		public native final JsArr<T> slice(int start, int end)/*-{
			return this.slice(start, end);
		}-*/;

		public static final native <T> JsArr<T> create() /*-{
			return [];
		}-*/;

		public final native int size() /*-{
			return this.length;
		}-*/;

		public final native T get(int i) /*-{
			return this[i];
		}-*/;
	}

}