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 backtype.storm.tuple;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.io.Serializable;
  
  public class Fields implements Iterable<String>, Serializable {
      private List<String> _fields;
      private Map<String, Integer> _index = new HashMap<>();
  
      public Fields(String... fields) {
          this(Arrays.asList(fields));
      }
  
      public Fields(List<String> fields) {
          _fields = new ArrayList<>(fields.size());
          for (String field : fields) {
              if (_fields.contains(field))
                  throw new IllegalArgumentException(String.format("duplicate field '%s'", field));
              _fields.add(field);
          }
          index();
      }
  
      public List<Object> select(Fields selector, List<Object> tuple) {
          List<Object> ret = new ArrayList<>(selector.size());
          for (String s : selector) {
              ret.add(tuple.get(_index.get(s)));
          }
          return ret;
      }
  
      public Object select(String selector, List<Object> tuple) {
          return tuple.get(_index.get(selector));
      }
  
      public List<String> toList() {
          return new ArrayList<>(_fields);
      }
  
      public int size() {
          return _fields.size();
      }
  
      public String get(int index) {
          return _fields.get(index);
      }
  
      public Iterator<String> iterator() {
          return _fields.iterator();
      }
  
      /**
       * Returns the position of the specified field.
       */
      public int fieldIndex(String field) {
          Integer ret = _index.get(field);
          if (ret == null) {
              throw new IllegalArgumentException(field + " does not exist");
          }
          return ret;
      }
  
      /**
       * Returns true if this contains the specified name of the field.
       */
      public boolean contains(String field) {
          return _index.containsKey(field);
      }
  
      private void index() {
          for (int i = 0; i < _fields.size(); i++) {
              _index.put(_fields.get(i), i);
          }
      }
  
      @Override
      public String toString() {
          return _fields.toString();
      }
  }
  