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.beam.sdk.extensions.sorter;
  
  import java.io.IOException;
  import org.apache.beam.sdk.values.KV;
  
  /**
   * Interface for classes which can sort {@code <key, value>} pairs by the key.
   *
   * <p>Records must first be added by calling {@link #add(KV)}. Then {@link #sort()} can be called at
   * most once.
   *
   * <p>TODO: Support custom comparison functions.
   */
  interface Sorter {
  
    /**
     * Adds a given record to the sorter.
     *
     * <p>Records can only be added before calling {@link #sort()}.
     */
    void add(KV<byte[], byte[]> record) throws IOException;
  
    /**
     * Sorts the added elements and returns an {@link Iterable} over the sorted elements.
     *
     * <p>Can be called at most once.
     */
    Iterable<KV<byte[], byte[]>> sort() throws IOException;
  }
  