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 accord.utils.btree;
  
  import java.util.Iterator;
  
  public interface BulkIterator<V> extends AutoCloseable
  {
      void fetch(Object[] into, int offset, int count);
      V next();
      default void close() {};
  
      public static class FromArray<V> implements BulkIterator<V>, AutoCloseable
      {
          private static final TinyThreadLocalPool<FromArray> POOL = new TinyThreadLocalPool<>();
  
          private Object[] from;
          private int i;
          private TinyThreadLocalPool.TinyPool<FromArray> pool;
  
          private void init(Object[] from, int offset)
          {
              this.from = from;
              this.i = offset;
          }
  
          public void close()
          {
              pool.offer(this);
              from = null;
              pool = null;
          }
  
          public void fetch(Object[] into, int offset, int count)
          {
              System.arraycopy(from, i, into, offset, count);
              i += count;
          }
  
          public V next()
          {
              return (V) from[i++];
          }
      }
  
      public static class Adapter<V> implements BulkIterator<V>
      {
          final Iterator<V> adapt;
  
          private Adapter(Iterator<V> adapt)
          {
              this.adapt = adapt;
          }
  
          public void fetch(Object[] into, int offset, int count)
          {
              count += offset;
              while (offset < count && adapt.hasNext())
                  into[offset++] = adapt.next();
          }
  
          public boolean hasNext()
          {
              return adapt.hasNext();
          }
  
          public V next()
          {
              return adapt.next();
          }
      }
  
      public static <V> FromArray<V> of(Object[] from)
      {
          return of(from, 0);
      }
  
      public static <V> FromArray<V> of(Object[] from, int offset)
      {
          TinyThreadLocalPool.TinyPool<FromArray> pool = FromArray.POOL.get();
          FromArray<V> result = pool.poll();
          if (result == null)
              result = new FromArray<>();
          result.init(from, offset);
          result.pool = pool;
          return result;
      }
  
      public static <V> Adapter<V> of(Iterator<V> from)
      {
          return new Adapter<>(from);
      }
  }
  
  