org.onebusaway.collections.FunctionalLibrary Maven / Gradle / Ivy

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/**
 * Copyright (C) 2011 Brian Ferris 
 *
 * Licensed 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.onebusaway.collections;

import java.util.ArrayList;
import java.util.List;

public final class FunctionalLibrary {
  private FunctionalLibrary() {

  }

  public static  List filter(Iterable elements,
      String propertyPathExpression, Object value) {
    List matches = new ArrayList();
    PropertyPathExpression query = new PropertyPathExpression(
        propertyPathExpression);
    for (T element : elements) {
      Object result = query.invoke(element);
      if ((value == null && result == null)
          || (value != null && value.equals(result)))
        matches.add(element);
    }
    return matches;
  }

  public static  T filterFirst(Iterable elements,
      String propertyPathExpression, Object value) {
    List matches = filter(elements, propertyPathExpression, value);
    return matches.isEmpty() ? null : matches.get(0);
  }
}