// file:    TitleComparator.java
// author:  Robert Keller
// purpose: Comparator for use in sorting title triples in kwic application

/**
 * Define functio object that compares two triples representing titles.
 * The second element of the triples is a list of words beginning with the
 * keyword.  These elements determine the outcome of the comparison, which
 * is lexicographic ordering of the corresponding lower-case version of
 * the strings in the lists.
 */

class TitleComparator implements java.util.Comparator
{
/**
 * @return -1 if o1 is "less than" o2, +1 if "greater than, and 0 if "equal"
 */

public int compare(Object o1, Object o2)
  {
  OpenList L1 = (OpenList)((OpenList)o1).second();
  OpenList L2 = (OpenList)((OpenList)o2).second();

  while( L1.nonEmpty() && L2.nonEmpty() )
    {
    String Word1 = (String)L1.first();
    String Word2 = (String)L2.first();
    int firstWordComparison = Word1.compareToIgnoreCase(Word2);
    if( firstWordComparison < 0 )
      {
      return -1;
      }
    else if( firstWordComparison > 0 )
      {
      return +1;
      }
    L1 = L1.rest();
    L2 = L2.rest();
    }
  if( L2.nonEmpty() ) return -1;
  if( L1.nonEmpty() ) return +1;
  return 0;
  }
}