/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2022
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package elki.utilities.pairs;

/**
 * Pair storing a native double value and an arbitrary object.
 * 
 * @author Erich Schubert
 * @since 0.4.0
 * 
 * @param <O> Object type
 */
public class DoubleObjPair<O> implements Comparable<DoubleObjPair<O>> {
  /**
   * Double value
   */
  public double first;

  /**
   * Second object value
   */
  public O second;

  /**
   * Constructor.
   * 
   * @param first First value
   * @param second Second value
   */
  public DoubleObjPair(double first, O second) {
    this.first = first;
    this.second = second;
  }

  @Override
  public int compareTo(DoubleObjPair<O> o) {
    return Double.compare(first, o.first);
  }

  @Override
  public boolean equals(Object obj) {
    if(this == obj) {
      return true;
    }
    if(obj == null || this.getClass() != obj.getClass()) {
      return false;
    }
    DoubleObjPair<?> other = (DoubleObjPair<?>) obj;
    return (first == other.first) && //
        (second == other.second || second != null && second.equals(other.second));
  }

  @Override
  public int hashCode() {
    return Double.hashCode(first) * 0x9e3779b1 + (second != null ? second.hashCode() : 0);
  }

  /**
   * Canonical toString operator
   */
  @Override
  public String toString() {
    return "Pair(" + first + ", " + (second != null ? second.toString() : "null") + ")";
  }
}
