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.causeway.commons.internal.collections;
  
  import java.util.Comparator;
  import java.util.stream.Stream;
  
  import org.jspecify.annotations.Nullable;
  
  /**
   * <h1>- internal use only -</h1>
   * <p>
   * Stream extensions.
   * </p>
   * <p>
   * <b>WARNING</b>: Do <b>NOT</b> use any of the classes provided by this package! <br/>
   * These may be changed or removed without notice!
   * </p>
   *
   * @since 2.0
   */
  public final class _Streams {
  
      private _Streams(){}
  
      // -- CONCATENATION
  
      /**
       * 3 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c) {
          return Stream.concat(Stream.concat(a, b), c);
      }
  
      /**
       * 4 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(
              final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c, final Stream<? extends T> d) {
  
          return Stream.concat(Stream.concat(a, b), Stream.concat(c, d));
      }
  
      /**
       * 5 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(
              final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c, final Stream<? extends T> d,
              final Stream<? extends T> e) {
  
          return Stream.concat(
                  Stream.concat(Stream.concat(a, b), Stream.concat(c, d)),
                  e);
      }
  
      /**
       * 6 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(
              final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c, final Stream<? extends T> d,
              final Stream<? extends T> e, final Stream<? extends T> f) {
  
          return Stream.concat(
                  Stream.concat(Stream.concat(a, b), Stream.concat(c, d)),
                  Stream.concat(e, f));
      }
  
      /**
       * 7 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(
              final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c, final Stream<? extends T> d,
              final Stream<? extends T> e, final Stream<? extends T> f, final Stream<? extends T> g) {
  
          return Stream.concat(
                  Stream.concat(Stream.concat(a, b), Stream.concat(c, d)),
                  Stream.concat(Stream.concat(e, f), g));
      }
  
      /**
       * 8 param variant of {@link Stream#concat(Stream, Stream)}
       */
      public static <T> Stream<T> concat(
              final Stream<? extends T> a, final Stream<? extends T> b, final Stream<? extends T> c, final Stream<? extends T> d,
              final Stream<? extends T> e, final Stream<? extends T> f, final Stream<? extends T> g, final Stream<? extends T> h) {
  
          return Stream.concat(
                  Stream.concat(Stream.concat(a, b), Stream.concat(c, d)),
                  Stream.concat(Stream.concat(e, f), Stream.concat(g, h)));
      }
  
      /**
       * Conditionally sorts the stream based on presence of a comparator.
       * @return null for null
       */
      public static <T> Stream<T> sortConditionally(
          final @Nullable Stream<T> input,
          final @Nullable Comparator<? super T> comparator) {
          if(comparator==null) return input;
          if(input==null) return null;
          return input.sorted(comparator);
      }
  
  }
  