@Override
public int hashCode() {
if (hashCode == 0) {
int result = key.hashCode();
result = result * 31 + left.hashCode();
result = result * 31 + right.hashCode();
result = result * 31 + value.hashCode();
hashCode = result;
}
return hashCode;
}
@Test
public void buckets() {
Object k1 = new Key(42, "k1");
Object k2 = new Key(42, "k2");
Object k3 = new Key(42, "k3");
AVLTree<Object, Object> t = AVLTree.create().put(k1, "v1").put(k2, "v2");
assertThat(t.toString()).as("should create bucket").isEqualTo(" k2->v2 k1->v1");
AVLTree<Object, Object> t2 = AVLTree.create().put(k2, "v2").put(k1, "v1");
assertThat(t2.toString())
.as("toString depends on order of operations")
.isEqualTo(" k1->v1 k2->v2");
assertThat(t.equals(t2)).as("should compare buckets").isTrue();
assertThat(t2.equals(t)).as("should compare buckets").isTrue();
assertThat(t.hashCode())
.isEqualTo(
((31 * k1.hashCode()) ^ "v1".hashCode()) + ((31 * k2.hashCode()) ^ "v2".hashCode()));
assertThat(t2.hashCode())
.as("hashCode doesn't depend on order of operations")
.isEqualTo(t.hashCode());
assertThat(t.get(k1)).isEqualTo("v1");
assertThat(t.get(k2)).isEqualTo("v2");
assertThat(t.get(k3)).as("not such key").isNull();
assertThat(t.put(k2, "new v2").toString())
.as("should replace head of bucket")
.isEqualTo(" k2->new v2 k1->v1");
assertThat(t.put(k1, "new v1").toString())
.as("should replace element of bucket")
.isEqualTo(" k1->new v1 k2->v2");
assertThat(t.put(k1, "v1")).as("should not change").isSameAs(t);
assertThat(t.put(k2, "v2")).as("should not change").isSameAs(t);
assertThat(t.put(k3, "v3").toString())
.as("should add to bucket")
.isEqualTo(" k3->v3 k2->v2 k1->v1");
assertThat(t.remove(k2).toString()).as("should remove head of bucket").isEqualTo(" k1->v1");
assertThat(t.remove(k1).toString()).as("should remove element of bucket").isEqualTo(" k2->v2");
assertThat(t.remove(k1).remove(k2).toString()).as("should remove bucket").isEqualTo("");
assertThat(t.remove(k3)).as("should not change").isSameAs(t);
HashMap<Object, Object> biConsumer = new HashMap<>();
t.forEach((k, v) -> assertThat(biConsumer.put(k, v)).as("unique key-value").isNull());
assertThat(biConsumer).isEqualTo(ImmutableMap.of(k1, "v1", k2, "v2"));
HashSet<Object> consumer = new HashSet<>();
t.forEach(k -> assertThat(consumer.add(k)).as("unique key").isTrue());
assertThat(consumer).containsOnly(k1, k2);
}
@Test
public void test_empty() {
AVLTree<String, String> t = AVLTree.create();
assertThat(t).as("singleton").isSameAs(AVLTree.create());
assertThat(t.get("anything")).isNull();
assertThat(t.remove("anything")).isSameAs(t);
assertThat(t.toString()).isEqualTo("");
assertThat(t.hashCode()).isEqualTo(0);
}
@Test
public void hashCode_and_equals_should_not_depend_on_order_of_construction() {
Object o1 = new Key(21, "o1");
Object o2 = new Key(45, "o2");
AVLTree<Object, Object> t1 = AVLTree.create().add(o1).add(o2);
AVLTree<Object, Object> t2 = AVLTree.create().add(o2).add(o1);
assertThat(t1.key()).as("shape is different").isNotEqualTo(t2.key());
assertThat(t1.hashCode()).isEqualTo(t2.hashCode());
assertThat(t1).isEqualTo(t2);
assertThat(t2).isEqualTo(t1);
Object o3 = new Key(0, "o3");
AVLTree<Object, Object> t3 = t1.add(o3);
assertThat(t1.hashCode()).isEqualTo(t3.hashCode());
assertThat(t1).isNotEqualTo(t3);
assertThat(t3).isNotEqualTo(t1);
}