text: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * 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
   * 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 org.waveprotocol.wave.model.supplement;
  
  import org.waveprotocol.wave.model.conversation.ConversationThread;
  
  /**
   * A simple {@link PresentationPolicy}.
   *
   * @author kalman@google.com (Benjamin Kalman)
   */
  public final class SimplePresentationPolicy implements PresentationPolicy {
  
    private final ThreadState defaultState;
  
    /**
     * Creates a simple presentation policy with a default thread state to return
     * in {@link #getThreadState} when none is given.
     *
     * @param defaultState the default thread state
     */
    public SimplePresentationPolicy(ThreadState defaultState) {
      this.defaultState = defaultState;
    }
  
    @Override
    public ThreadState expand(ConversationThread thread, ThreadState current) {
      return ThreadState.EXPANDED;
    }
  
    @Override
    public ThreadState collapse(ConversationThread thread, ThreadState current) {
      return ThreadState.COLLAPSED;
    }
  
    @Override
    public ThreadState getThreadState(ConversationThread thread, ThreadState specified) {
      return (specified != null) ? specified : defaultState;
    }
  }
  