Java Spliterator.trySplit方法代码示例

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T, S extends Spliterator<T>> void testSplitAfterFullTraversal(
        Supplier<S> supplier,
        UnaryOperator<Consumer<T>> boxingAdapter) {
    // Full traversal using tryAdvance
    Spliterator<T> spliterator = supplier.get();
    while (spliterator.tryAdvance(boxingAdapter.apply(e -> { }))) { }
    Spliterator<T> split = spliterator.trySplit();
    assertNull(split);

    // Full traversal using forEach
    spliterator = supplier.get();
    spliterator.forEachRemaining(boxingAdapter.apply(e -> { }));
    split = spliterator.trySplit();
    assertNull(split);

    // Full traversal using tryAdvance then forEach
    spliterator = supplier.get();
    spliterator.tryAdvance(boxingAdapter.apply(e -> { }));
    spliterator.forEachRemaining(boxingAdapter.apply(e -> { }));
    split = spliterator.trySplit();
    assertNull(split);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
static<U> void mixedTraverseAndSplit(Consumer<U> b, Spliterator<U> splTop) {
    Spliterator<U> spl1, spl2, spl3;
    splTop.tryAdvance(b);
    spl2 = splTop.trySplit();
    if (spl2 != null) {
        spl2.tryAdvance(b);
        spl1 = spl2.trySplit();
        if (spl1 != null) {
            spl1.tryAdvance(b);
            spl1.forEachRemaining(b);
        }
        spl2.tryAdvance(b);
        spl2.forEachRemaining(b);
    }
    splTop.tryAdvance(b);
    spl3 = splTop.trySplit();
    if (spl3 != null) {
        spl3.tryAdvance(b);
        spl3.forEachRemaining(b);
    }
    splTop.tryAdvance(b);
    splTop.forEachRemaining(b);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T, S extends Spliterator<T>> void testSplitAfterFullTraversal(
        Supplier<S> supplier,
        UnaryOperator<Consumer<T>> boxingAdapter) {
    // Full traversal using tryAdvance
    Spliterator<T> spliterator = supplier.get();
    while (spliterator.tryAdvance(boxingAdapter.apply(e -> { }))) { }
    Spliterator<T> split = spliterator.trySplit();
    assertNull(split);

    // Full traversal using forEach
    spliterator = supplier.get();
    spliterator.forEachRemaining(boxingAdapter.apply(e -> {
    }));
    split = spliterator.trySplit();
    assertNull(split);

    // Full traversal using tryAdvance then forEach
    spliterator = supplier.get();
    spliterator.tryAdvance(boxingAdapter.apply(e -> { }));
    spliterator.forEachRemaining(boxingAdapter.apply(e -> {
    }));
    split = spliterator.trySplit();
    assertNull(split);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T, S extends Spliterator<T>> void testSplitOnce(
        Collection<T> exp,
        Supplier<S> supplier,
        UnaryOperator<Consumer<T>> boxingAdapter) {
    S spliterator = supplier.get();
    long sizeIfKnown = spliterator.getExactSizeIfKnown();
    boolean isOrdered = spliterator.hasCharacteristics(Spliterator.ORDERED);

    ArrayList<T> fromSplit = new ArrayList<>();
    Spliterator<T> s1 = supplier.get();
    Spliterator<T> s2 = s1.trySplit();
    long s1Size = s1.getExactSizeIfKnown();
    long s2Size = (s2 != null) ? s2.getExactSizeIfKnown() : 0;

    Consumer<T> addToFromSplit = boxingAdapter.apply(fromSplit::add);
    if (s2 != null)
        s2.forEachRemaining(addToFromSplit);
    s1.forEachRemaining(addToFromSplit);

    if (sizeIfKnown >= 0) {
        assertEquals(sizeIfKnown, fromSplit.size());
        if (s1Size >= 0 && s2Size >= 0)
            assertEquals(sizeIfKnown, s1Size + s2Size);
    }
    assertContents(fromSplit, exp, isOrdered);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T, S extends Spliterator<T>> void testSplitOnce(
        Collection<T> exp,
        Supplier<S> supplier,
        UnaryOperator<Consumer<T>> boxingAdapter) {
    S spliterator = supplier.get();
    long sizeIfKnown = spliterator.getExactSizeIfKnown();
    boolean isOrdered = spliterator.hasCharacteristics(Spliterator.ORDERED);

    ArrayList<T> fromSplit = new ArrayList<>();
    Spliterator<T> s1 = supplier.get();
    Spliterator<T> s2 = s1.trySplit();
    long s1Size = s1.getExactSizeIfKnown();
    long s2Size = (s2 != null) ? s2.getExactSizeIfKnown() : 0;
    Consumer<T> addToFromSplit = boxingAdapter.apply(fromSplit::add);
    if (s2 != null)
        s2.forEachRemaining(addToFromSplit);
    s1.forEachRemaining(addToFromSplit);

    if (sizeIfKnown >= 0) {
        assertEquals(sizeIfKnown, fromSplit.size());
        if (s1Size >= 0 && s2Size >= 0)
            assertEquals(sizeIfKnown, s1Size + s2Size);
    }
    assertContents(fromSplit, exp, isOrdered);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
@Nullable
private static <E> Spliterator<E> trySplitTestingSize(Spliterator<E> spliterator) {
  boolean subsized = spliterator.hasCharacteristics(Spliterator.SUBSIZED);
  long originalSize = spliterator.estimateSize();
  Spliterator<E> trySplit = spliterator.trySplit();
  if (spliterator.estimateSize() > originalSize) {
    fail(
        format(
            "estimated size of spliterator after trySplit (%s) is larger than original size (%s)",
            spliterator.estimateSize(),
            originalSize));
  }
  if (trySplit != null) {
    if (trySplit.estimateSize() > originalSize) {
      fail(
          format(
              "estimated size of trySplit result (%s) is larger than original size (%s)",
              trySplit.estimateSize(),
              originalSize));
    }
  }
  if (subsized) {
    if (trySplit != null) {
      assertEquals(
          "sum of estimated sizes of trySplit and original spliterator after trySplit",
          originalSize,
          trySplit.estimateSize() + spliterator.estimateSize());
    } else {
      assertEquals(
          "estimated size of spliterator after failed trySplit",
          originalSize,
          spliterator.estimateSize());
    }
  }
  return trySplit;
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T, S extends Spliterator<T>> void testSplitOnce(
        Collection<T> exp,
        Supplier<S> supplier,
        UnaryOperator<Consumer<T>> boxingAdapter,
        ContentAsserter<T> asserter) {
    S spliterator = supplier.get();
    long sizeIfKnown = spliterator.getExactSizeIfKnown();
    boolean isOrdered = spliterator.hasCharacteristics(Spliterator.ORDERED);

    ArrayList<T> fromSplit = new ArrayList<>();
    Spliterator<T> s1 = supplier.get();
    Spliterator<T> s2 = s1.trySplit();
    long s1Size = s1.getExactSizeIfKnown();
    long s2Size = (s2 != null) ? s2.getExactSizeIfKnown() : 0;
    Consumer<T> addToFromSplit = boxingAdapter.apply(fromSplit::add);
    if (s2 != null)
        s2.forEachRemaining(addToFromSplit);
    s1.forEachRemaining(addToFromSplit);

    if (sizeIfKnown >= 0) {
        assertEquals(sizeIfKnown, fromSplit.size());
        if (s1Size >= 0 && s2Size >= 0)
            assertEquals(sizeIfKnown, s1Size + s2Size);
    }

    asserter.assertContents(fromSplit, exp, isOrdered);
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
void testSpliterator(Supplier<Spliterator<Map.Entry<Integer, Integer>>> ss,
                     // Higher order function that given a spliterator returns a
                     // consumer for that spliterator which traverses elements
                     // using an EntryConsumer
                     Function<Spliterator<Map.Entry<Integer, Integer>>, Consumer<EntryConsumer>> sc) {
    testWithEntryConsumer(sc.apply(ss.get()));

    Spliterator<Map.Entry<Integer, Integer>> s = ss.get();
    Spliterator<Map.Entry<Integer, Integer>> split = s.trySplit();
    if (split != null) {
        testWithEntryConsumer(sc.apply(split));
        testWithEntryConsumer(sc.apply(s));
    }
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
/** Returns a {@code Spliterator} filtered by the specified predicate. */
static <T> Spliterator<T> filter(Spliterator<T> fromSpliterator, Predicate<? super T> predicate) {
  checkNotNull(fromSpliterator);
  checkNotNull(predicate);
  class Splitr implements Spliterator<T>, Consumer<T> {
    T holder = null;

    @Override
    public void accept(T t) {
      this.holder = t;
    }

    @Override
    public boolean tryAdvance(Consumer<? super T> action) {
      while (fromSpliterator.tryAdvance(this)) {
        try {
          if (predicate.test(holder)) {
            action.accept(holder);
            return true;
          }
        } finally {
          holder = null;
        }
      }
      return false;
    }

    @Override
    public Spliterator<T> trySplit() {
      Spliterator<T> fromSplit = fromSpliterator.trySplit();
      return (fromSplit == null) ? null : filter(fromSplit, predicate);
    }

    @Override
    public long estimateSize() {
      return fromSpliterator.estimateSize() / 2;
    }

    @Override
    public Comparator<? super T> getComparator() {
      return fromSpliterator.getComparator();
    }

    @Override
    public int characteristics() {
      return fromSpliterator.characteristics()
          & (Spliterator.DISTINCT
              | Spliterator.NONNULL
              | Spliterator.ORDERED
              | Spliterator.SORTED);
    }
  }
  return new Splitr();
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T> void testSplitUntilNull(SplitNode<T> e) {
    // Use an explicit stack to avoid a StackOverflowException when testing a Spliterator
    // that when repeatedly split produces a right-balanced (and maybe degenerate) tree, or
    // for a spliterator that is badly behaved.
    Deque<SplitNode<T>> stack = new ArrayDeque<>();
    stack.push(e);

    int iteration = 0;
    while (!stack.isEmpty()) {
        assertTrue(iteration++ < MAXIMUM_STACK_CAPACITY, "Exceeded maximum stack modification count of 1 << 18");

        e = stack.pop();
        Spliterator<T> parentAndRightSplit = e.s;

        long parentEstimateSize = parentAndRightSplit.estimateSize();
        assertTrue(parentEstimateSize >= 0,
                   String.format("Split size estimate %d < 0", parentEstimateSize));

        long parentSize = parentAndRightSplit.getExactSizeIfKnown();
        Spliterator<T> leftSplit = parentAndRightSplit.trySplit();
        if (leftSplit == null) {
            parentAndRightSplit.forEachRemaining(e.c);
            continue;
        }

        assertSpliterator(leftSplit, e.rootCharacteristics);
        assertSpliterator(parentAndRightSplit, e.rootCharacteristics);

        if (parentEstimateSize != Long.MAX_VALUE && leftSplit.estimateSize() > 0
            && parentAndRightSplit.estimateSize() > 0) {
            assertTrue(leftSplit.estimateSize() < parentEstimateSize,
                       String.format("Left split size estimate %d >= parent split size estimate %d",
                                     leftSplit.estimateSize(), parentEstimateSize));
            assertTrue(parentAndRightSplit.estimateSize() < parentEstimateSize,
                       String.format("Right split size estimate %d >= parent split size estimate %d",
                                     leftSplit.estimateSize(), parentEstimateSize));
        }
        else {
            assertTrue(leftSplit.estimateSize() <= parentEstimateSize,
                       String.format("Left split size estimate %d > parent split size estimate %d",
                                     leftSplit.estimateSize(), parentEstimateSize));
            assertTrue(parentAndRightSplit.estimateSize() <= parentEstimateSize,
                       String.format("Right split size estimate %d > parent split size estimate %d",
                                     leftSplit.estimateSize(), parentEstimateSize));
        }

        long leftSize = leftSplit.getExactSizeIfKnown();
        long rightSize = parentAndRightSplit.getExactSizeIfKnown();
        if (parentSize >= 0 && leftSize >= 0 && rightSize >= 0)
            assertEquals(parentSize, leftSize + rightSize,
                         String.format("exact left split size %d + exact right split size %d != parent exact split size %d",
                                       leftSize, rightSize, parentSize));

        // Add right side to stack first so left side is popped off first
        stack.push(e.fromSplit(parentAndRightSplit));
        stack.push(e.fromSplit(leftSplit));
    }
}
 

import java.util.Spliterator; //导入方法依赖的package包/类
private static <T> void testSplitUntilNull(SplitNode<T> e) {
    // Use an explicit stack to avoid a StackOverflowException when testing a Spliterator
    // that when repeatedly split produces a right-balanced (and maybe degenerate) tree, or
    // for a spliterator that is badly behaved.
    Deque<SplitNode<T>> stack = new ArrayDeque<>();
    stack.push(e);

    int iteration = 0;
    while (!stack.isEmpty()) {
        assertTrue(iteration++ < MAXIMUM_STACK_CAPACITY, "Exceeded maximum stack modification count of 1 << 18");

        e = stack.pop();
        Spliterator<T> parentAndRightSplit = e.s;

        long parentEstimateSize = parentAndRightSplit.estimateSize();
        assertTrue(parentEstimateSize >= 0,
                   String.format("Split size estimate %d < 0", parentEstimateSize));

        long parentSize = parentAndRightSplit.getExactSizeIfKnown();
        Spliterator<T> leftSplit = parentAndRightSplit.trySplit();
        if (leftSplit == null) {
            parentAndRightSplit.forEachRemaining(e.c);
            continue;
        }

        assertSpliterator(leftSplit, e.rootCharacteristics);
        assertSpliterator(parentAndRightSplit, e.rootCharacteristics);

        if (parentEstimateSize != Long.MAX_VALUE && leftSplit.estimateSize() > 0 && parentAndRightSplit.estimateSize() > 0) {
            assertTrue(leftSplit.estimateSize() < parentEstimateSize,
                       String.format("Left split size estimate %d >= parent split size estimate %d", leftSplit.estimateSize(), parentEstimateSize));
            assertTrue(parentAndRightSplit.estimateSize() < parentEstimateSize,
                       String.format("Right split size estimate %d >= parent split size estimate %d", leftSplit.estimateSize(), parentEstimateSize));
        }
        else {
            assertTrue(leftSplit.estimateSize() <= parentEstimateSize,
                       String.format("Left split size estimate %d > parent split size estimate %d", leftSplit.estimateSize(), parentEstimateSize));
            assertTrue(parentAndRightSplit.estimateSize() <= parentEstimateSize,
                       String.format("Right split size estimate %d > parent split size estimate %d", leftSplit.estimateSize(), parentEstimateSize));
        }

        long leftSize = leftSplit.getExactSizeIfKnown();
        long rightSize = parentAndRightSplit.getExactSizeIfKnown();
        if (parentSize >= 0 && leftSize >= 0 && rightSize >= 0)
            assertEquals(parentSize, leftSize + rightSize,
                         String.format("exact left split size %d + exact right split size %d != parent exact split size %d",
                                       leftSize, rightSize, parentSize));

        // Add right side to stack first so left side is popped off first
        stack.push(e.fromSplit(parentAndRightSplit));
        stack.push(e.fromSplit(leftSplit));
    }
}