/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.runtime;

import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

/**
 * A reverse iterator over a list. Utilizes the {@link ListIterator}
 * obtained from the provided {@link List} and converts it to an
 * {@link Iterator} that efficiently traverses the <code>List</code> in
 * reverse. The fail-fast semantics of this iterator are the same as the
 * semantics of the underlying <code>ListIterator</code>.
 *
 * @author Mike Dillon
 */
public class ReverseListIterator<T> implements Iterator<T> {
    private ListIterator<T> delegate;

    /**
     * Constructs a new <code>ReverseListIterator</code> for the provided list.
     * @param list the list to iterate over in reverse
     */
    public ReverseListIterator(List<T> list) {
        this.delegate = list.listIterator(list.size());
    }

    /**
     * {@inheritDoc}
     */
    public boolean hasNext() {
        return delegate.hasPrevious();
    }

    /**
     * {@inheritDoc}
     */
    public T next() {
        return delegate.previous();
    }

    /**
     * {@inheritDoc}
     */
    public void remove() {
        delegate.remove();
    }
}