Examples with Spliterators java8.util.Spliterators used on opensource projects

Example 1 with Spliterators

use of java8.util.Spliterators in project streamsupport by stefan-zobel.

the class Collection8Test method testLateBindingStyle.

/**
 * Spliterators are either IMMUTABLE or truly late-binding or, if
 * concurrent, use the same "late-binding style" of returning
 * elements added between creation and first use.
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
@Test(dataProvider = "Source")
public void testLateBindingStyle(String description, Supplier<CollectionImplementation> sci) {
    if (!testImplementationDetails)
        return;
    CollectionImplementation impl = sci.get();
    // for jdk8
    if (impl.klazz() == ArrayList.class)
        return;
    // Immutable (snapshot) spliterators are exempt
    if (Spliterators.spliterator(impl.emptyCollection()).hasCharacteristics(Spliterator.IMMUTABLE))
        return;
    final Object one = impl.makeElement(1);
    {
        final Collection c = impl.emptyCollection();
        final Spliterator<?> split = Spliterators.spliterator(c);
        c.add(one);
        assertTrue(split.tryAdvance(e -> {
            assertSame(e, one);
        }));
        assertFalse(split.tryAdvance(e -> {
            throw new AssertionError();
        }));
        assertTrue(c.contains(one));
    }
    {
        final AtomicLong count = new AtomicLong(0);
        final Collection c = impl.emptyCollection();
        final Spliterator<?> split = Spliterators.spliterator(c);
        c.add(one);
        split.forEachRemaining(e -> {
            assertSame(e, one);
            count.getAndIncrement();
        });
        assertEquals(1L, count.get());
        assertFalse(split.tryAdvance(e -> {
            throw new AssertionError();
        }));
        assertTrue(c.contains(one));
    }
}

Example 2 with Spliterators

use of java8.util.Spliterators in project streamsupport by stefan-zobel.

the class Collection8Test method testStickySpliteratorExhaustion.

/**
 * Concurrent Spliterators, once exhausted, stay exhausted.
 */
@SuppressWarnings({ "rawtypes", "unchecked" })
@Test(dataProvider = "Source")
public void testStickySpliteratorExhaustion(String description, Supplier<CollectionImplementation> sci) throws Throwable {
    CollectionImplementation impl = sci.get();
    if (HAS_JAVA8_SPLITERATOR_BUG && PriorityBlockingQueue.class.equals(impl.klazz())) {
        // https://bugs.openjdk.java.net/browse/JDK-8172023
        return;
    }
    if (!impl.isConcurrent())
        return;
    if (!testImplementationDetails)
        return;
    final ThreadLocalRandom rnd = ThreadLocalRandom.current();
    final Consumer<?> alwaysThrows = e -> {
        throw new AssertionError();
    };
    final Collection c = impl.emptyCollection();
    final Spliterator s = Spliterators.spliterator(c);
    if (rnd.nextBoolean()) {
        assertFalse(s.tryAdvance(alwaysThrows));
    } else {
        s.forEachRemaining(alwaysThrows);
    }
    final Object one = impl.makeElement(1);
    // Spliterator should not notice added element
    c.add(one);
    if (rnd.nextBoolean()) {
        assertFalse(s.tryAdvance(alwaysThrows));
    } else {
        s.forEachRemaining(alwaysThrows);
    }
}

Example 3 with Spliterators

use of java8.util.Spliterators in project streamsupport by stefan-zobel.

the class Spliterators method iterator.

// Iterators from Spliterators
/**
 * Creates an {@code Iterator} from a {@code Spliterator}.
 *
 * <p>Traversal of elements should be accomplished through the iterator.
 * The behaviour of traversal is undefined if the spliterator is operated
 * after the iterator is returned.
 *
 * @param <T> Type of elements
 * @param spliterator The spliterator
 * @return An iterator
 * @throws NullPointerException if the given spliterator is {@code null}
 */
public static <T> Iterator<T> iterator(Spliterator<? extends T> spliterator) {
    Objects.requireNonNull(spliterator);
    class Adapter implements Iterator<T>, Consumer<T> {

        boolean valueReady = false;

        T nextElement;

        @Override
        public void accept(T t) {
            valueReady = true;
            nextElement = t;
        }

        @Override
        public boolean hasNext() {
            if (!valueReady)
                spliterator.tryAdvance(this);
            return valueReady;
        }

        @Override
        public T next() {
            if (!valueReady && !hasNext())
                throw new NoSuchElementException();
            else {
                valueReady = false;
                return nextElement;
            }
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException("remove");
        }
    }
    return new Adapter();
}