/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect;
import com.google.common.annotations.GwtCompatible;
import javax.annotation.Nullable;
/**
* A specification for a local change to an entry in a binary search tree.
*
* @author Louis Wasserman
*/
@GwtCompatible
interface BstModifier<K, N extends BstNode<K, N>> {
/**
* Given a target key and the original entry (if any) with the specified key, returns the entry
* with key {@code key} after this mutation has been performed. The result must either be {@code
* null} or must have a key that compares as equal to {@code key}. A deletion operation, for
* example, would always return {@code null}, or an insertion operation would always return a
* non-null {@code insertedEntry}.
*
* <p>If this method returns a non-null entry of type {@code N}, any children it has will be
* ignored.
*
* <p>This method may return {@code originalEntry} itself to indicate that no change is made.
*
* @param key The key being targeted for modification.
* @param originalEntry The original entry in the binary search tree with the specified key, if
* any. No guarantees are made about the children of this entry when treated as a node; in
* particular, they are not necessarily the children of the corresponding node in the
* binary search tree.
* @return the entry (if any) with the specified key after this modification is performed
*/
BstModificationResult<N> modify(K key, @Nullable N originalEntry);
}
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