/*
    * 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.maven.resolver.internal.ant.types;
  
  import org.apache.tools.ant.PropertyHelper;
  import org.apache.tools.ant.PropertyHelper.PropertyEvaluator;
  import org.apache.tools.ant.property.NullReturn;
  
  /**
   */
  class PomPropertyEvaluator implements PropertyEvaluator {
  
      private final ModelValueExtractor extractor;
  
      public static void register(ModelValueExtractor extractor, PropertyHelper propertyHelper) {
          propertyHelper.add(new PomPropertyEvaluator(extractor));
      }
  
      private PomPropertyEvaluator(ModelValueExtractor extractor) {
          if (extractor == null) {
              throw new IllegalArgumentException("no model value exractor specified");
          }
          this.extractor = extractor;
      }
  
      public Object evaluate(String property, PropertyHelper propertyHelper) {
          Object value = extractor.getValue(property);
          if (value != null) {
              return value;
          } else if (extractor.isApplicable(property)) {
              return NullReturn.NULL;
          }
          return null;
      }
  }