/**
 * Copyright 2010 Google Inc.
 *
 * 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.waveprotocol.wave.client.common.util;

import java.util.Iterator;

/**
 * An iterator over a {@link Sequence}.
 *
 */
public final class SequenceIterator<T> implements Iterator<T> {
  private final Sequence<T> sequence;
  private T next;

  private SequenceIterator(Sequence<T> sequence, T next) {
    this.sequence = sequence;
    this.next = next;
  }

  public static <T> SequenceIterator<T> create(Sequence<T> sequence) {
    return new SequenceIterator<T>(sequence, sequence.getFirst());
  }

  @Override
  public boolean hasNext() {
    return next != null;
  }

  @Override
  public T next() {
    T toReturn = next;
    next = sequence.getNext(next);
    return toReturn;
  }

  @Override
  public void remove() {
    throw new UnsupportedOperationException();
  }
}