sclass ConceptFieldIndexCI<A extends Concept> implements IConceptIndex, IFieldIndex<A, S>, IConceptCounter {

  Class<A> cc;

  S field;

  new HashMap<A, S> objectToValue;

  MultiMap<S, A> valueToObject = ciMultiMap();

  *() {}

  *(Class<A> cc, S field) { this(db_mainConcepts(), cc, field); }

  *(Concepts concepts, Class<A> *cc, S *field) {

    concepts.addConceptIndex(this);

    for (A c : list(concepts, cc))

      updateImpl(c);

    concepts.addCIFieldIndex(cc, field, this);

  }

  public void update(Concept c) {

    if (!isInstance(cc, c)) ret;

    updateImpl(c);

  }

  synchronized void updateImpl(Concept c) {

    S newValue = cast cget(c, field);

    S oldValue = objectToValue.get(c);

    if (newValue == null || newValue != oldValue) {

      valueToObject.remove(oldValue, (A) c);

      valueToObject.put(newValue, (A) c);

      objectToValue.put((A) c, newValue);

    }

  }

  public synchronized void remove(Concept c) {

    if (!isInstance(cc, c)) ret;

    S value = cast cget(c, field);

    objectToValue.remove(c);

    valueToObject.remove(value, (A) c);

  }

  synchronized A get(S value) {

    ret valueToObject.getFirst(value);

  }

  public synchronized L<A> getAll(S value) {

    ret valueToObject.get(value);

  }

  public Class<? extends Concept> conceptClass() { ret cc; }

  public int countConcepts() { ret l(objectToValue); }

  // Note: NOT SORTED

  public Collection<Concept> allConcepts() { ret (Collection) keys(objectToValue); }

  public synchronized LS allValues() { ret cloneKeys_noSync(valueToObject.data); }

  public synchronized MultiSet<S> allValues_multiSet() {

    ret multiMapToMultiSet(valueToObject);

  }

  // SORTED

  IterableIterator<A> objectIterator() {

    ret navigableMultiMapValuesIterator(valueToObject);

  }

}