package soot.util;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 2004 Ondrej Lhotak
 * %%
 * This program 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 program 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 Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-2.1.html>.
 * #L%
 */

import java.util.AbstractSet;
import java.util.Collection;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.Set;

/**
 * Implements a hashset with comparison over identity.
 *
 * @author Eric Bodden
 * @deprecated can be replaced with
 *             <code>java.util.Collections.newSetFromMap(new java.util.IdentityHashMap<E,Boolean>())</code>
 */
@Deprecated
public class IdentityHashSet<E> extends AbstractSet<E> implements Set<E> {

  protected IdentityHashMap<E, E> delegate;

  /**
   * Creates a new, empty IdentityHashSet.
   */
  public IdentityHashSet() {
    delegate = new IdentityHashMap<E, E>();
  }

  /**
   * Creates a new IdentityHashSet containing the same elements as the given collection.
   *
   * @param original
   *          The original collection whose elements to inherit
   */
  public IdentityHashSet(Collection<E> original) {
    delegate = new IdentityHashMap<E, E>();
    addAll(original);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public int size() {
    return delegate.size();
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean contains(Object o) {
    return delegate.containsKey(o);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Iterator<E> iterator() {
    return delegate.keySet().iterator();
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean add(E o) {
    return delegate.put(o, o) == null;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean remove(Object o) {
    return delegate.remove(o) != null;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void clear() {
    delegate.entrySet().clear();
  }

  /*
   * Equality based on identity.
   */
  @Override
  public int hashCode() {
    final int PRIME = 31;
    int result = 1;
    result = PRIME * result + ((delegate == null) ? 0 : delegate.hashCode());
    return result;
  }

  /*
   * Hash code based on identity.
   */
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (getClass() != obj.getClass()) {
      return false;
    }
    final IdentityHashSet<?> other = (IdentityHashSet<?>) obj;
    if (delegate == null) {
      if (other.delegate != null) {
        return false;
      }
    } else if (!delegate.equals(other.delegate)) {
      return false;
    }
    return true;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public String toString() {
    return delegate.keySet().toString();
  }

}
