juneau-core/juneau-marshall/src/main/java/org/apache/juneau/internal/ReverseIterable.java

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package org.apache.juneau.internal;

import java.util.*;

/**
 * Implements a reversed iteration {@link Iterable} without altering the underlying list.
 *
 * @param <T> The entry type.
 */
public class ReverseIterable<T> implements Iterable<T> {
    private final List<T> list;

    /**
     * Constructor
     *
     * @param list The original list.
     */
    public ReverseIterable(List<T> list) {
        this.list = list;
    }

    /**
     * Convenience method for constructing instances.
     *
     * @param list The original list.
     * @return A new {@link ReverseIterable}.
     */
    public static <T> ReverseIterable<T> of(List<T> list) {
        return new ReverseIterable<>(list);
    }

    /**
     * Convenience method for constructing instances.
     *
     * @param list The original list.
     * @return A new {@link ReverseIterable}.
     */
    public static <T> ReverseIterable<T> of(T[] list) {
        return new ReverseIterable<>(Arrays.asList(list));
    }

    @Override
	public Iterator<T> iterator() {
        final ListIterator<T> i = list.listIterator(list.size());

        return new Iterator<T>() {
            @Override
			public boolean hasNext() { return i.hasPrevious(); }
            @Override
			public T next() { return i.previous(); }
            @Override
			public void remove() { i.remove(); }
        };
    }
}