code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * 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 net.openhft.chronicle.set;
  
  import org.jetbrains.annotations.NotNull;
  
  /**
   * SPI interface fro customizing "low-level" modification operations on {@link ChronicleSet}
   * entries.
   *
   * @param <K> the set key type
   * @param <R> methods return type, used for communication between lower- and higher-level SPI
   * @see ChronicleSetBuilder#entryOperations(SetEntryOperations)
   */
  public interface SetEntryOperations<K, R> {
  
      /**
       * Removes the given entry from the set.
       *
       * @param entry the entry to remove
       * @return result of operation, understandable by higher-level SPIs
       * @throws IllegalStateException if some locking/state conditions required to perform remove
       *                               operation are not met
       * @throws RuntimeException      if removal was unconditionally unsuccessful due to any reason
       * @implNote default implementation calls {@link SetEntry#doRemove()} on the given entry and
       * returns {@code null}.
       */
      default R remove(@NotNull SetEntry<K> entry) {
          entry.doRemove();
          return null;
      }
  
      /**
       * Inserts the new entry into the set, of {@link SetAbsentEntry#absentKey() the key} from
       * the given insertion context (<code>absentEntry</code>).
       *
       * @return result of operation, understandable by higher-level SPIs
       * @throws IllegalStateException if some locking/state conditions required to perform insertion
       *                               operation are not met
       * @throws RuntimeException      if insertion was unconditionally unsuccessful due to any reason
       * @implNote default implementation calls {@link SetAbsentEntry#doInsert()} and returns
       * {@code null}.
       */
      default R insert(@NotNull SetAbsentEntry<K> absentEntry) {
          absentEntry.doInsert();
          return null;
      }
  }
  