ImmutableIterableFrom.java

package net.slightlymagic.braids.util;

import java.util.Iterator;

/**
 * Acts as both immutable Iterator and Iterable; remove method always throws
 * exception.
 */
public class ImmutableIterableFrom<T> implements Iterable<T>, Iterator<T> {
	private Iterator<T> iterator;

	/**
	 * Wrap an iterable so that it cannot be changed via
	 * the remove method.
	 * 
	 * @param iterable  the iterable to wrap
	 */
	public ImmutableIterableFrom(Iterable<T> iterable) {
		this.iterator = iterable.iterator();
	}

	/**
	 * Wrap an iterator so that its container cannot be changed via
	 * the remove method.
	 * 
	 * @param iterator  the iterator to wrap
	 */
	public ImmutableIterableFrom(Iterator<T> iterator) {
		this.iterator = iterator;
	}

	/**
	 * This class acts as both an Iterable and an Iterator.
	 */
	public Iterator<T> iterator() {
		return this;
	}

	/**
	 * Returns hasNext from the wrapped [object's] iterator.
	 */
	public boolean hasNext() {
		return iterator.hasNext();
	}

	/**
	 * Returns next from the wrapped [object's] iterator.
	 */
	public T next() {
		return iterator.next();
	}

	/**
	 * Never succeeeds.
	 * @throws UnsupportedOperationException always.
	 */
	public void remove() {
		throw new UnsupportedOperationException();
	}
}