code: /*
   * Copyright (C) 2008 Google Inc.
   *
   * 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 tools.com.google.gson;
  
  /**
   * A strategy (or policy) definition that is used to decide whether or not a field or top-level
   * class should be serialized or deserialized as part of the JSON output/input. For serialization,
   * if the {@link #shouldSkipClass(Class)} method returns true then that class or field type
   * will not be part of the JSON output.  For deserialization, if {@link #shouldSkipClass(Class)}
   * returns true, then it will not be set as part of the Java object structure.
   *
   * <p>The following are a few examples that shows how you can use this exclusion mechanism.
   *
   * <p><strong>Exclude fields and objects based on a particular class type:</strong>
   * <pre class="code">
   * private static class SpecificClassExclusionStrategy implements ExclusionStrategy {
   *   private final Class&lt;?&gt; excludedThisClass;
   *
   *   public SpecificClassExclusionStrategy(Class&lt;?&gt; excludedThisClass) {
   *     this.excludedThisClass = excludedThisClass;
   *   }
   *
   *   public boolean shouldSkipClass(Class&lt;?&gt; clazz) {
   *     return excludedThisClass.equals(clazz);
   *   }
   *
   *   public boolean shouldSkipField(FieldAttributes f) {
   *     return excludedThisClass.equals(f.getDeclaredClass());
   *   }
   * }
   * </pre>
   *
   * <p><strong>Excludes fields and objects based on a particular annotation:</strong>
   * <pre class="code">
   * public &#64interface FooAnnotation {
   *   // some implementation here
   * }
   *
   * // Excludes any field (or class) that is tagged with an "&#64FooAnnotation"
   * private static class FooAnnotationExclusionStrategy implements ExclusionStrategy {
   *   public boolean shouldSkipClass(Class&lt;?&gt; clazz) {
   *     return clazz.getAnnotation(FooAnnotation.class) != null;
   *   }
   *
   *   public boolean shouldSkipField(FieldAttributes f) {
   *     return f.getAnnotation(FooAnnotation.class) != null;
   *   }
   * }
   * </pre>
   *
   * <p>Now if you want to configure {@code Gson} to use a user defined exclusion strategy, then
   * the {@code GsonBuilder} is required. The following is an example of how you can use the
   * {@code GsonBuilder} to configure Gson to use one of the above sample:
   * <pre class="code">
   * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class);
   * Gson gson = new GsonBuilder()
   *     .setExclusionStrategies(excludeStrings)
   *     .create();
   * </pre>
   *
   * <p>For certain model classes, you may only want to serialize a field, but exclude it for
   * deserialization. To do that, you can write an {@code ExclusionStrategy} as per normal;
   * however, you would register it with the
   * {@link GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy)} method.
   * For example:
   * <pre class="code">
   * ExclusionStrategy excludeStrings = new UserDefinedExclusionStrategy(String.class);
   * Gson gson = new GsonBuilder()
   *     .addDeserializationExclusionStrategy(excludeStrings)
   *     .create();
   * </pre>
   *
   * @author Inderjeet Singh
   * @author Joel Leitch
   *
   * @see GsonBuilder#setExclusionStrategies(ExclusionStrategy...)
   * @see GsonBuilder#addDeserializationExclusionStrategy(ExclusionStrategy)
   * @see GsonBuilder#addSerializationExclusionStrategy(ExclusionStrategy)
   *
   * @since 1.4
   */
  public interface ExclusionStrategy {
  
    /**
     * @param f the field object that is under test
     * @return true if the field should be ignored; otherwise false
     */
    public boolean shouldSkipField(FieldAttributes f);
  
    /**
     * @param clazz the class object that is under test
     * @return true if the class should be ignored; otherwise false
     */
    public boolean shouldSkipClass(Class<?> clazz);
  }
  