/*
 * 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.datasketches.quantilescommon;

/**
 * This is the base API for the iterator hierarchy used for viewing the
 * non-ordered quantiles retained by the classic Quantiles* sketches and KLL sketches, for example.
 *
 * <p>Prototype example of the recommended iteration loop:</p>
 * <pre>{@code
 *   SketchIterator itr = sketch.iterator();
 *   while (itr.next()) {
 *     ...get*();
 *   }
 * }</pre>
 *
 * @author Lee Rhodes
 */

public interface QuantilesSketchIteratorAPI {

  /**
   * Gets the natural weight at the current index.
   *
   * <p>Don't call this before calling next() for the first time
   * or after getting false from next().</p>
   *
   * @return the natural weight at the current index.
   */
  long getWeight();

  /**
   * Advances the index and checks if it is valid.
   * The state of this iterator is undefined before the first call of this method.
   * @return true if the next index is valid.
   */
  boolean next();

}

