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   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you under the Apache License, Version 2.0 (the
   *  "License"); you may not use this file except in compliance
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   *    https://www.apache.org/licenses/LICENSE-2.0
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  package org.apache.cayenne.access.types;
  
  import java.util.Objects;
  
  /**
   * Descriptor and serialization helper for custom value objects that can be safely stored in the DB.
   * Lightweight alternative for the {@link ExtendedType}.
   *
   * @param <V> type of user's custom object.
   * @param <T> type that custom object will be serialized to/from
   *            should be backed by appropriate {@link ExtendedType}.
   *
   * @since 4.0
   */
  public interface ValueObjectType<V, T> {
  
      /**
       * @return base type used to serialize <b>V</b> objects to.
       */
      Class<T> getTargetType();
  
      /**
       * @return type of Objects described by this ValueObjectType.
       */
      Class<V> getValueType();
  
      /**
       * @param value of type T
       * @return java object
       */
      V toJavaObject(T value);
  
      /**
       * @param object java object
       * @return value of type T
       */
      T fromJavaObject(V object);
  
      /**
       * Returned value should be same for objects that is logically equal.
       *
       * @return String representation usable for cache.
       */
      String toCacheKey(V object);
  
      /**
       * Allows to use special logic to compare values for equality
       * as in rare cases it is not suffice to use default equals() method.
       * Default implementation uses {@link Objects#equals(Object, Object)} method.
       *
       * @param value1 to compare
       * @param value2 to compare
       * @return true if given values are equal
       */
      default boolean equals(V value1, V value2) {
          return Objects.equals(value1, value2);
      }
  }
  