content: /*
  * Copyright (c) 1997 - 2016
  * Actelion Pharmaceuticals Ltd.
  * Gewerbestrasse 16
  * CH-4123 Allschwil, Switzerland
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice, this
  *    list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. Neither the name of the the copyright holder nor the
  *    names of its contributors may be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
  
  package com.actelion.research.chem.forcefield.mmff;
  
  /**
   * SortedPair class is used in the Separation table. It holds a pair of
   * integers and ensures that they are sorted such that the first value is
   * larger than the second. The Sorted pair is used to ensure that
   * duplicate values are not stored in the separation table and that the
   * Hashtable can be keyed on both atom indices.
   */
  public class SortedPair implements Comparable<SortedPair> {
      public final int a;
      public final int b;
  
      /**
       * Construct a new SortedPair. Make sure that A > B.
       */
      public SortedPair(int a, int b) {
          this.a = a>b ? a : b;
          this.b = a>b ? b : a;
      }
  
      /**
       * Returns the hash code of this sorted pair object. Defined as the
       * XOR of the hashes of A and B.
       *  @return The hash code.
       */
      @Override
      public int hashCode() {
          return Integer.hashCode(a) ^ Integer.hashCode(b);
      }
  
      /**
       * Returns true if this SortedPair is equal with another object.
       *  @param obj The object to compare with.
       *  @return True if SortedPair and object are equal.
       */
      @Override
      public boolean equals(Object obj) {
          if (obj == this)
              return true;
  
          if (!(obj instanceof SortedPair))
              return false;
  
          SortedPair that = (SortedPair)obj;
  
          return a == that.a && b == that.b;
      }
  
      /**
       * Compares this object with another. This allows collections of
       * SortedPairs to be sorted using the java standard library sorting
       * algorithms.
       */
      @Override
      public int compareTo(SortedPair that) {
          if (a > that.a)
              return 1;
          if (a < that.a)
              return -1;
          if (b > that.b)
              return 1;
          if (b < that.b)
              return -1;
          return 0;
      }
  
      @Override
      public String toString() {
          return a+","+b;
      }
  }
  