content: /*
   *  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.apache.causeway.applib.util;
  
  /**
   * Helper class to create properly concatenated reason string for use in method
   * that return {@link String}s with reasons.
   *
   * <p>
   * If no reasons are specified {@link #getReason()} will return
   * <code>null</code> , otherwise it will return a {@link String} with all the
   * valid reasons concatenated with a semi-colon separating each one.
   * </p>
   *
   * <p>
   * An alternative is to use the (very simple) {@link Reasons} class or the
   * (much more sophisticated) {@link ReasonBuffer2}.
   * </p>
   *
   * @see Reasons
   * @see ReasonBuffer2
   *
   * @since 1.x {@index}
   */
  public class ReasonBuffer {
      StringBuffer reasonBuffer = new StringBuffer();
  
      /**
       * Append a reason to the list of existing reasons.
       */
      public void append(final String reason) {
          if (reason != null) {
              if (reasonBuffer.length() > 0) {
                  reasonBuffer.append("; ");
              }
              reasonBuffer.append(reason);
          }
      }
  
      /**
       * Append a reason to the list of existing reasons if the condition flag is
       * true.
       */
      public void appendOnCondition(final boolean condition, final String reason) {
          if (condition) {
              append(reason);
          }
      }
  
      /**
       * Return the combined set of reasons, or <code>null</code> if there are
       * none.
       */
      public String getReason() {
          return reasonBuffer.length() == 0 ? null : reasonBuffer.toString();
      }
  
  }
  