/*
 * 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.lucene.document.column;

import org.apache.lucene.search.DocIdSetIterator;

/**
 * A tuple cursor over a {@link DictionaryColumn}. Yields {@code (docID, ordinal)} pairs.
 * Batch-local doc-ids are returned in non-decreasing order; the same doc-id may repeat for
 * multi-valued fields (e.g. {@link org.apache.lucene.index.DocValuesType#SORTED_SET SORTED_SET}).
 *
 * <p>Each ordinal must be in {@code [0, column.dictionary().length)}.
 *
 * @lucene.experimental
 */
public abstract class OrdinalsTupleCursor {

  /**
   * Advances to the next tuple and returns its batch-local doc-id, or {@link
   * DocIdSetIterator#NO_MORE_DOCS} if exhausted.
   *
   * <p>Returned doc-ids are batch-local ({@code 0} to {@code numDocs - 1}) and are emitted in
   * non-decreasing order. The same doc-id may be returned multiple times when a document has
   * multiple values.
   */
  public abstract int nextDoc();

  /**
   * Returns the ordinal at the current cursor position. Only valid after a successful {@link
   * #nextDoc()} call that returned a value other than {@link DocIdSetIterator#NO_MORE_DOCS}.
   *
   * <p>The returned value must be in {@code [0, dictionary.length)} where {@code dictionary} is the
   * enclosing column's dictionary.
   */
  public abstract int ordValue();
}
