Java 类org.apache.commons.collections4.collection.CompositeCollection 实例源码

/**
 * Avoids creating a generic array, which is converted back to list in CompositeCollection.
 */
private <T extends TMObjectIF> CompositeCollection<T> createComposite(Collection<Collection<T>> collections) {
  CompositeCollection<T> result = new CompositeCollection<>();
  for (Collection<T> collection : collections) {
    result.addComposited(collection);
  }
  return result;
}

/**
 * Add the necessary constraints to produce an equal-conflict (EC) Petri net. A Petri net is EC if is
 * homogeneous (all transitions consuming tokens from a place do so with the same weight) and transitions with
 * non-disjoint presets have the same preset.
 * @param utility The region utility.
 * @param backwardWeight Terms representing the backwards weights of transitions.
 * @return The needed terms.
 */
private List<Term> requireEqualConflict(RegionUtility utility, Term[] backwardWeight) {
    if (backwardWeight.length == 0)
        return Collections.emptyList();

    TransitionSystem ts = utility.getTransitionSystem();
    DomainEquivalenceRelation<String> relation = new DomainEquivalenceRelation<>(ts.getAlphabet());

    // Begin with assuming that all events are equivalent
    String someEvent = ts.getAlphabet().iterator().next();
    for (String otherEvent : ts.getAlphabet())
        relation.joinClasses(someEvent, otherEvent);

    // Then refine this so that in the end only events are equivalent which are always enabled together
    for (final State state : ts.getNodes()) {
        relation = relation.refine(new IEquivalenceRelation<String>() {
            @Override
            public boolean isEquivalent(String event1, String event2) {
                Set<State> postset1 = state.getPostsetNodesByLabel(event1);
                Set<State> postset2 = state.getPostsetNodesByLabel(event2);
                return postset1.isEmpty() == postset2.isEmpty();
            }
        });
    }
    debug("Enabling-equivalent transitions: ", relation);

    // The postset of the region must be an equivalence class (or the empty set)
    List<Term> result = new ArrayList<>();
    List<String> eventList = utility.getEventList();
    for (Set<String> equivalenceClass : new CompositeCollection<Set<String>>(relation,
                Collections.singleton(Collections.<String>emptySet()))) {
        Term[] current = new Term[eventList.size()];
        Term pivot = null;
        for (int index = 0; index < backwardWeight.length; index++) {
            if (equivalenceClass.contains(utility.getEventList().get(index))) {
                if (pivot == null) {
                    // The first event in the class must have non-zero backward weight
                    pivot = backwardWeight[index];
                    current[index] = script.term("<", script.numeral(BigInteger.ZERO), pivot);
                } else {
                    // All other events in the class must have the same weight as pivot
                    current[index] = script.term("=", pivot, backwardWeight[index]);
                }
            } else {
                // Events outside the class must have weight zero
                current[index] = script.term("=", script.numeral(BigInteger.ZERO), backwardWeight[index]);
            }
        }
        result.add(collectTerms("and", current, script.term("true")));
    }
    return Arrays.asList(collectTerms("or", result.toArray(new Term[0]), script.term("false")));
}