private static RandomTree randomTreeByBuilder(int minSize, int maxSize) {
    assert minSize > 3;
    ThreadLocalRandom random = ThreadLocalRandom.current();
    BTree.Builder<Integer> builder = BTree.builder(naturalOrder());

    int targetSize = random.nextInt(minSize, maxSize);
    int maxModificationSize = (int) Math.sqrt(targetSize);

    TreeSet<Integer> canonical = new TreeSet<>();

    int curSize = 0;
    TreeSet<Integer> ordered = new TreeSet<>();
    List<Integer> shuffled = new ArrayList<>();
    while (curSize < targetSize) {
      int nextSize = maxModificationSize <= 1 ? 1 : random.nextInt(1, maxModificationSize);

      // leave a random selection of previous values
      (random.nextBoolean() ? ordered.headSet(random.nextInt()) : ordered.tailSet(random.nextInt()))
          .clear();
      shuffled =
          new ArrayList<>(
              shuffled.subList(0, shuffled.size() < 2 ? 0 : random.nextInt(shuffled.size() / 2)));

      for (int i = 0; i < nextSize; i++) {
        Integer next = random.nextInt();
        ordered.add(next);
        shuffled.add(next);
        canonical.add(next);
      }

      switch (random.nextInt(5)) {
        case 0:
          builder.addAll(ordered);
          break;
        case 1:
          builder.addAll(BTreeSet.of(ordered));
          break;
        case 2:
          for (Integer i : ordered) builder.add(i);
        case 3:
          builder.addAll(shuffled);
          break;
        case 4:
          for (Integer i : shuffled) builder.add(i);
      }

      curSize += nextSize;
      maxModificationSize = Math.min(maxModificationSize, targetSize - curSize);
    }

    BTreeSet<Integer> btree = BTreeSet.<Integer>wrap(builder.build(), naturalOrder());
    Assert.assertEquals(canonical.size(), btree.size());
    return new RandomTree(canonical, btree);
  }
示例#2
0
 protected Builder(Comparator<? super V> comparator) {
   builder = BTree.builder(comparator);
 }