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.lang.reflect.Array;
  import java.util.Collections;
  import java.util.Set;
  import java.util.function.BiConsumer;
  import java.util.function.BinaryOperator;
  import java.util.function.Function;
  import java.util.function.Supplier;
  import java.util.stream.Collector;
  
  import org.apache.causeway.commons.internal.base._Casts;
  
  /**
   * package private helper for utility class {@link _Arrays}
   *
   * Collector for Arrays.
   */
  record _Arrays_Collector<T>(
          Class<T> componentType,
          int size
          ) implements Collector<T, _Arrays_Collector.FastList<T>, T[]> {
  
      @Override
      public Supplier<FastList<T>> supplier() {
          return ()->new FastList<>(componentType, size);
      }
  
      @Override
      public BiConsumer<FastList<T>, T> accumulator() {
          return FastList::add;
      }
  
      @Override
      public BinaryOperator<FastList<T>> combiner() {
          return (a, b)->a.addAll(b);
      }
  
      @Override
      public Function<FastList<T>, T[]> finisher() {
          return list->list.buffer;
      }
  
      @Override
      public Set<Characteristics> characteristics() {
          return Collections.emptySet();
      }
  
      // -- HELPER
  
      static final class FastList<T> {
          private final T[] buffer;
          private int offset=0;
  
          public FastList(final Class<T> componentType, final int size) {
              this.buffer = _Casts.uncheckedCast(Array.newInstance(componentType, size));
          }
          public void add(final T x){
              buffer[offset++]=x;
          }
          public FastList<T> addAll(final FastList<T> x){
              System.arraycopy(x.buffer, 0, buffer, offset, x.offset);
              return this;
          }
      }
  
  }
  