1/*
2 * Copyright (C) 2011 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the
10 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
11 * express or implied. See the License for the specific language governing permissions and
12 * limitations under the License.
13 */
14
15package com.google.common.collect;
16
17import com.google.common.annotations.GwtCompatible;
18
19import javax.annotation.Nullable;
20
21/**
22 * A factory for copying nodes in binary search trees with different children.
23 *
24 * <p>Typically, nodes will carry more information than the fields in the {@link BstNode} class,
25 * often some kind of value or some aggregate data for the subtree. This factory is responsible for
26 * copying this additional data between nodes.
27 *
28 * @author Louis Wasserman
29 * @param <N> The type of the tree nodes constructed with this {@code BstNodeFactory}.
30 */
31@GwtCompatible
32abstract class BstNodeFactory<N extends BstNode<?, N>> {
33  /**
34   * Returns a new {@code N} with the key and value data from {@code source}, with left child
35   * {@code left}, and right child {@code right}. If {@code left} or {@code right} is null, the
36   * returned node will not have a child on the corresponding side.
37   */
38  public abstract N createNode(N source, @Nullable N left, @Nullable N right);
39
40  /**
41   * Returns a new {@code N} with the key and value data from {@code source} that is a leaf.
42   */
43  public final N createLeaf(N source) {
44    return createNode(source, null, null);
45  }
46}
47