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.db.rows;
  
  import org.apache.cassandra.db.*;
  
  /**
   * An iterator over the rows of a given partition that also includes deletion informations.
   * <p>
   * An {@code UnfilteredRowIterator} contains a few partition top-level informations and is an
   * iterator of {@code Unfiltered}, that is of either {@code Row} or {@code RangeTombstoneMarker}.
   * An implementation of {@code UnfilteredRowIterator} <b>must</b> provide the following
   * guarantees:
   *   1. the returned {@code Unfiltered} must be in clustering order, or in reverse clustering
   *      order iff {@link #isReverseOrder} returns true.
   *   2. the iterator should not shadow its own data. That is, no deletion
   *      (partition level deletion, row deletion, range tombstone, complex
   *      deletion) should delete anything else returned by the iterator (cell, row, ...).
   *   3. every "start" range tombstone marker should have a corresponding "end" marker, and no other
   *      marker should be in-between this start-end pair of marker. Note that due to the
   *      previous rule this means that between a "start" and a corresponding "end" marker there
   *      can only be rows that are not deleted by the markers. Also note that when iterating
   *      in reverse order, "end" markers are returned before their "start" counterpart (i.e.
   *      "start" and "end" are always in the sense of the clustering order).
   *
   * Note further that the objects returned by next() are only valid until the
   * next call to hasNext() or next(). If a consumer wants to keep a reference on
   * the returned objects for longer than the iteration, it must make a copy of
   * it explicitly.
   */
  public interface UnfilteredRowIterator extends BaseRowIterator<Unfiltered>
  {
      /**
       * The partition level deletion for the partition this iterate over.
       */
      public DeletionTime partitionLevelDeletion();
  
      /**
       * Return "statistics" about what is returned by this iterator. Those are used for
       * performance reasons (for delta-encoding for instance) and code should not
       * expect those to be exact.
       */
      public EncodingStats stats();
  
      /**
       * Returns whether this iterator has no data (including no deletion data).
       */
      public default boolean isEmpty()
      {
          return partitionLevelDeletion().isLive()
              && staticRow().isEmpty()
              && !hasNext();
      }
  }
  