Method intersection

src/main/java/gate/relations/RelationSet.java:390–417

Calculates the intersection of a set of lists containing relation IDs @param indexLists the list to be intersected. @return the list of relations contained in all the supplied index lists.

(BitSet... indexLists)

   *         lists.
   */
  protected Collection<Relation> intersection(BitSet... indexLists) {

    Set<Relation> res = new HashSet<Relation>();

    BitSet relIds = new BitSet(maxID + 1);
    relIds.set(0, maxID + 1);

    boolean found = false;

    for(BitSet aList : indexLists) {
      if(aList != null) {
        found = true;
        relIds.and(aList);

        // if there is no intersection then return the empty list
        if(relIds.isEmpty()) return res;
      }
    }

    if(!found) return res;

    for(int relIdx = 0; relIdx < (maxID + 1); relIdx++) {
      if(relIds.get(relIdx)) {
        res.add(indexById.get(relIdx));
      }
    }
    return res;
  }

  /*
   * (non-Javadoc)