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.map;
  
  import net.openhft.chronicle.hash.Data;
  import org.jetbrains.annotations.NotNull;
  
  /**
   * Default value computation strategy, used
   * in {@link ChronicleMapBuilder#defaultValueProvider(DefaultValueProvider)} configuration.
   *
   * @param <K> map key class
   * @param <V> map value class
   */
  @FunctionalInterface
  public interface DefaultValueProvider<K, V> {
  
      /**
       * Returns the "nil" value, which should be inserted into the map, in the given
       * {@code absentEntry} context. This is primarily used in {@link ChronicleMap#acquireUsing}
       * operation implementation, i. e. {@link MapMethods#acquireUsing}.
       * <p>
       * The default implementation simply delegates to {@link MapAbsentEntry#defaultValue()}.
       */
      Data<V> defaultValue(@NotNull MapAbsentEntry<K, V> absentEntry);
  }
  