content: /*
   * Copyright 2015, 2024 StreamEx contributors
   *
   * Licensed 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 one.util.streamex;
  
  import java.util.Spliterator;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.function.*;
  
  import static one.util.streamex.Internals.CancelException;
  import static one.util.streamex.Internals.CloneableSpliterator;
  
  /**
   * @author Tagir Valeev
   */
  /* package */class UnorderedCancellableSpliterator<T, A> extends CloneableSpliterator<A, UnorderedCancellableSpliterator<T, A>> {
      private volatile Spliterator<T> source;
      private final BiConsumer<A, ? super T> accumulator;
      private final Predicate<A> cancelPredicate;
      private final Supplier<A> supplier;
      private final ConcurrentLinkedQueue<A> partialResults = new ConcurrentLinkedQueue<>();
      private final AtomicBoolean cancelled = new AtomicBoolean(false);
      private final AtomicInteger nPeers = new AtomicInteger(1);
      private final BinaryOperator<A> combiner;
      private boolean flag;
  
      UnorderedCancellableSpliterator(Spliterator<T> source, Supplier<A> supplier, BiConsumer<A, ? super T> accumulator,
              BinaryOperator<A> combiner, Predicate<A> cancelPredicate) {
          this.source = source;
          this.supplier = supplier;
          this.accumulator = accumulator;
          this.combiner = combiner;
          this.cancelPredicate = cancelPredicate;
      }
  
      private boolean checkCancel(A acc) {
          if (cancelPredicate.test(acc)) {
              if (cancelled.compareAndSet(false, true)) {
                  flag = true;
                  return true;
              }
          }
          if (cancelled.get()) {
              flag = false;
              return true;
          }
          return false;
      }
  
      private boolean handleCancel(Consumer<? super A> action, A acc) {
          source = null;
          if (flag) {
              action.accept(acc);
              return true;
          }
          return false;
      }
  
      @Override
      public boolean tryAdvance(Consumer<? super A> action) {
          Spliterator<T> source = this.source;
          if (source == null || cancelled.get()) {
              this.source = null;
              return false;
          }
          A acc = supplier.get();
          if (checkCancel(acc))
              return handleCancel(action, acc);
          try {
              source.forEachRemaining(t -> {
                  accumulator.accept(acc, t);
                  if (checkCancel(acc))
                      throw new CancelException();
              });
          } catch (CancelException ex) {
              return handleCancel(action, acc);
          }
          A result = acc;
          while (true) {
              A acc2 = partialResults.poll();
              if (acc2 == null)
                  break;
              result = combiner.apply(result, acc2);
              if (checkCancel(result))
                  return handleCancel(action, result);
          }
          partialResults.offer(result);
          this.source = null;
          if (nPeers.decrementAndGet() == 0) {
              result = partialResults.poll();
              // non-cancelled finish
              while (true) {
                  A acc2 = partialResults.poll();
                  if (acc2 == null)
                      break;
                  result = combiner.apply(result, acc2);
                  if (cancelPredicate.test(result))
                      break;
              }
              this.source = null;
              action.accept(result);
              return true;
          }
          return false;
      }
  
      @Override
      public void forEachRemaining(Consumer<? super A> action) {
          tryAdvance(action);
      }
  
      @Override
      public Spliterator<A> trySplit() {
          if (source == null || cancelled.get()) {
              source = null;
              return null;
          }
          Spliterator<T> prefix = source.trySplit();
          if (prefix == null) {
              return null;
          }
          UnorderedCancellableSpliterator<T, A> result = doClone();
          result.source = prefix;
          nPeers.incrementAndGet();
          return result;
      }
  
      @Override
      public long estimateSize() {
          return source == null ? 0 : source.estimateSize();
      }
  
      @Override
      public int characteristics() {
          return source == null ? SIZED : 0;
      }
  }
  