package jflex.core.unicode;

import static jflex.base.Build.DEBUG;

import java.util.Comparator;

Comparator of IntCharSet . /** Comparator of {@link IntCharSet} . */
public class IntCharSetComparator implements Comparator<IntCharSet> {

  
Compares two IntCharSets.
Assumption: the IntCharSets are disjoint, e.g. members of a partition.
This method does not implement subset order, but instead compares the smallest elements of the two sets, with the empty set smaller than any other set. This is to make the order total for partitions as in CharClasses. It is unlikely to otherwise be a useful order, and it does probably not implement the contract for Comparable.compareTo correctly if the sets have the same smallest element but are not equal. 
Returns:
0 if the parameter is equal, -1 if its smallest element (if any) is larger than the
    smallest element of this set, and +1 if it is larger./**
   * Compares two IntCharSets.
   *
   * <p>Assumption: the IntCharSets are disjoint, e.g. members of a partition.
   *
   * <p>This method <em>does not</em> implement subset order, but instead compares the smallest
   * elements of the two sets, with the empty set smaller than any other set. This is to make the
   * order total for partitions as in {@link CharClasses}. It is unlikely to otherwise be a useful
   * order, and it does probably not implement the contract for {@link Comparable#compareTo}
   * correctly if the sets have the same smallest element but are not equal.
   *
   * @return 0 if the parameter is equal, -1 if its smallest element (if any) is larger than the
   *     smallest element of this set, and +1 if it is larger.
   */
  @Override
  public int compare(IntCharSet left, IntCharSet right) {
    if (left == null || right == null) {
      throw new NullPointerException();
    }

    if (left.equals(right)) {
      return 0;
    }

    if (DEBUG) {
      assert !left.and(right).containsElements();
    }

    if (!left.containsElements()) {
      return -1;
    }
    if (!right.containsElements()) {
      return 1;
    }

    if (left.getFirstInterval().start < right.getFirstInterval().start) {
      return -1;
    } else {
      return 1;
    }
  }
}