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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package javax.jdo.annotations;
    18
    19  import java.lang.annotation.ElementType;
    20  import java.lang.annotation.Retention;
    21  import java.lang.annotation.RetentionPolicy;
    22  import java.lang.annotation.Target;
    23
    24  /**
    25   * Annotation for the discriminator of the class.
    26   * Corresponds to the xml element "discriminator" of the "inheritance" element.
    27   *
    28   * @version 2.1
    29   * @since 2.1
    30   */
    31  @Target(ElementType.TYPE)
    32  @Retention(RetentionPolicy.RUNTIME)
    33  public @interface Discriminator
    34  {
    35      /**
    36       * Strategy to use for the discriminator. The discriminator determines
    37       * the class associated with a row in the datastore.
    38       * @return the strategy to use for the discriminator
    39       */
    40      DiscriminatorStrategy strategy()
    41          default DiscriminatorStrategy.UNSPECIFIED;
    42
    43      /** Custom strategy to use for the discriminator.
    44       * If customStrategy is non-empty, then strategy must be UNSPECIFIED.
    45       * @return the custom strategy
    46       */
    47      String customStrategy() default "";
    48
    49      /**
    50       * Whether the discriminator is indexed.
    51       * @return whether the discriminator is indexed
    52       */
    53      String indexed() default "";
    54
    55      /**
    56       * Name of the column for the discriminator
    57       * @return the name of the column for the discriminator
    58       */
    59      String column() default "";
    60
    61      /**
    62       * The value for the discriminator for objects of this class
    63       * when using "value-map" strategy.
    64       * @return The value for the discriminator for objects of this class
    65       * when using "value-map" strategy
    66       */
    67      String value() default "";
    68
    69      /**
    70       * The column(s) making up the discriminator.
    71       * @return the column(s) making up the discriminator
    72       */
    73      Column[] columns() default {};
    74  }