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.taskdefs.condition;
  
  import org.apache.tools.ant.BuildException;
  import org.apache.tools.ant.ProjectComponent;
  import org.apache.tools.ant.types.Resource;
  
  /**
   * Condition that checks whether a given resource exists.
   *
   * @since Ant 1.8.0
   */
  public class ResourceExists extends ProjectComponent implements Condition {
      private Resource resource;
  
      /**
       * The resource to test.
       *
       * @param r Resource
       */
      public void add(Resource r) {
          if (resource != null) {
              throw new BuildException("only one resource can be tested");
          }
          resource = r;
      }
  
      /**
       * Argument validation.
       */
      protected void validate() throws BuildException {
          if (resource == null) {
              throw new BuildException("resource is required");
          }
      }
  
      public boolean eval() throws BuildException {
          validate();
          return resource.isExists();
      }
  }
  