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
   *
   *      https://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.tools.ant.types.selectors.modifiedselector;
  
  
  import java.io.File;
  
  
  /**
   * The <i>Algorithm</i> defines how a value for a file is computed.
   * It must be sure that multiple calls for the same file results in the
   * same value.
   * The implementing class should implement a useful toString() method.
   *
   * @version 2003-09-13
   * @since  Ant 1.6
   */
  public interface Algorithm {
  
      /**
       * Checks its prerequisites.
       * @return <i>true</i> if all is ok, otherwise <i>false</i>.
       */
      boolean isValid();
  
      /**
       * Get the value for a file.
       * @param file    File object for which the value should be evaluated.
       * @return        The value for that file
       */
      String getValue(File file);
  }
  