package jalview.util;

import java.util.Set;

public class SetUtils
{
  /**
   * Returns the count of things that are in one or other of two sets but not in
   * both. The sets are not modified.
   * 
   * @param set1
   * @param set2
   * @return
   */
  public static int countDisjunction(Set<? extends Object> set1,
          Set<? extends Object> set2)
  {
    if (set1 == null)
    {
      return set2 == null ? 0 : set2.size();
    }
    if (set2 == null)
    {
      return set1.size();
    }

    int size1 = set1.size();
    int size2 = set2.size();
    Set<? extends Object> smallerSet = size1 < size2 ? set1 : set2;
    Set<? extends Object> largerSet = (smallerSet == set1 ? set2 : set1);
    int inCommon = 0;
    for (Object k : smallerSet)
    {
      if (largerSet.contains(k))
      {
        inCommon++;
      }
    }

    int notInCommon = (size1 - inCommon) + (size2 - inCommon);
    return notInCommon;
  }
}