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 org.apache.cassandra.index.sai.iterators;
  
  import java.util.List;
  
  import com.google.common.collect.Iterators;
  import com.google.common.collect.PeekingIterator;
  
  import org.apache.cassandra.index.sai.utils.PrimaryKey;
  
  /**
   * A {@link KeyRangeIterator} that iterates over a list of {@link PrimaryKey}s without modifying the underlying list.
   */
  public class KeyRangeListIterator extends KeyRangeIterator
  {
      private final PeekingIterator<PrimaryKey> keyQueue;
  
      /**
       * Create a new {@link KeyRangeListIterator} that iterates over the provided list of keys.
       *
       * @param minimumKey the minimum key for the provided list of keys
       * @param maximumKey the maximum key for the provided list of keys
       * @param keys the list of keys to iterate over
       */
      public KeyRangeListIterator(PrimaryKey minimumKey, PrimaryKey maximumKey, List<PrimaryKey> keys)
      {
          super(minimumKey, maximumKey, keys.size());
          this.keyQueue = Iterators.peekingIterator(keys.iterator());
      }
  
      @Override
      protected void performSkipTo(PrimaryKey nextKey)
      {
          while (keyQueue.hasNext())
          {
              if (keyQueue.peek().compareTo(nextKey, false) >= 0)
                  break;
              keyQueue.next();
          }
      }
  
      @Override
      public void close() {}
  
      @Override
      protected PrimaryKey computeNext()
      {
          return keyQueue.hasNext() ? keyQueue.next() : endOfData();
      }
  }
  