/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * 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.spf4j.ds;

import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;
import javax.annotation.Nullable;

/**
 *
 * @author zoly
 */
public final class LinkedHashSetEx<V> extends AbstractSet<V>
        implements LinkedSet<V> {

  private static final Object PRESENT = new Object();

  private final LinkedMap<V, Object> map;

  public LinkedHashSetEx() {
    map = new LinkedHashMapEx<>();
  }

  public LinkedHashSetEx(final int capacity) {
    map = new LinkedHashMapEx<>(capacity);
  }

  @Override
  public Iterator<V> iterator() {
    return map.keySet().iterator();
  }

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

  @Override
  @Nullable
  public V getLastValue() {
    Map.Entry<V, Object> lastEntry = map.getLastEntry();
    if (lastEntry == null) {
      return null;
    } else {
      return lastEntry.getKey();
    }
  }

  @Override
  @Nullable
  public V pollLastValue() {
    Map.Entry<V, Object> lastEntry = map.pollLastEntry();
    if (lastEntry == null) {
      return null;
    } else {
      return lastEntry.getKey();
    }
  }

  @Override
  public boolean add(final V e) {
    return map.put(e, PRESENT) == null;
  }

  @Override
  public boolean contains(final Object o) {
    return map.containsKey(o);
  }

  @Override
  public boolean isEmpty() {
    return map.isEmpty();
  }

}
