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Preserve spliterator characteristics in collection views #8182

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27 changes: 27 additions & 0 deletions guava-tests/test/com/google/common/collect/CollectSpliteratorsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
import java.util.Arrays;
import java.util.List;
import java.util.Spliterator;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
Expand Down Expand Up @@ -101,6 +102,32 @@ public void testFlatMapToDouble_nullStream() {
.expect(1.0, 1.0, 2.0, 3.0);
}

@GwtIncompatible // CopyOnWriteArrayList
public void testFilterPreservesImmutableCharacteristic() {
CopyOnWriteArrayList<String> cow = new CopyOnWriteArrayList<>(Arrays.asList("a", "b", "c"));
Spliterator<String> source = cow.spliterator();
assertTrue((source.characteristics() & Spliterator.IMMUTABLE) != 0);

Spliterator<String> filtered =
CollectSpliterators.filter(cow.spliterator(), s -> !s.equals("b"));
assertTrue(
"filter() should preserve IMMUTABLE from source",
(filtered.characteristics() & Spliterator.IMMUTABLE) != 0);
}

@GwtIncompatible
public void testFilterDropsSized() {
Spliterator<String> source =
Arrays.spliterator(new String[] {"a", "b", "c"});
assertTrue((source.characteristics() & Spliterator.SIZED) != 0);

Spliterator<String> filtered =
CollectSpliterators.filter(source, s -> !s.equals("b"));
assertFalse(
"filter() should not preserve SIZED",
(filtered.characteristics() & Spliterator.SIZED) != 0);
}

public void testMultisetsSpliterator() {
Multiset<String> multiset = TreeMultiset.create();
multiset.add("a", 3);
Expand Down
65 changes: 65 additions & 0 deletions guava-tests/test/com/google/common/collect/ListsTest.java
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Expand Up @@ -57,6 +57,7 @@
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.RandomAccess;
import java.util.Spliterator;
import java.util.concurrent.CopyOnWriteArrayList;
import junit.framework.Test;
import junit.framework.TestCase;
Expand Down Expand Up @@ -998,4 +999,68 @@ public void testPartitionSize_1() {
public void testPartitionSize_2() {
assertEquals(2, partition(nCopies(0x40000001, 1), 0x40000000).size());
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testAsListSpliteratorIsImmutable() {
List<String> list = Lists.asList("a", new String[] {"b", "c"});
int characteristics = list.spliterator().characteristics();
assertTrue("asList should report IMMUTABLE", (characteristics & Spliterator.IMMUTABLE) != 0);
assertTrue("asList should report ORDERED", (characteristics & Spliterator.ORDERED) != 0);
assertTrue("asList should report SIZED", (characteristics & Spliterator.SIZED) != 0);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testAsListSpliteratorIteration() {
List<String> list = Lists.asList("a", new String[] {"b", "c"});
List<String> collected = new ArrayList<>();
list.spliterator().forEachRemaining(collected::add);
assertEquals(asList("a", "b", "c"), collected);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testAsListTwoSpliteratorIsImmutable() {
List<String> list = Lists.asList("a", "b", new String[] {"c"});
int characteristics = list.spliterator().characteristics();
assertTrue(
"asList(2+) should report IMMUTABLE", (characteristics & Spliterator.IMMUTABLE) != 0);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testAsListTwoSpliteratorIteration() {
List<String> list = Lists.asList("a", "b", new String[] {"c"});
List<String> collected = new ArrayList<>();
list.spliterator().forEachRemaining(collected::add);
assertEquals(asList("a", "b", "c"), collected);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testCharactersOfSpliteratorCharacteristics() {
List<Character> chars = Lists.charactersOf("hello");
int characteristics = chars.spliterator().characteristics();
assertTrue("charactersOf should report ORDERED", (characteristics & Spliterator.ORDERED) != 0);
assertTrue("charactersOf should report NONNULL", (characteristics & Spliterator.NONNULL) != 0);
assertTrue("charactersOf should report SIZED", (characteristics & Spliterator.SIZED) != 0);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testCharactersOfSpliteratorIteration() {
List<Character> chars = Lists.charactersOf("hello");
List<Character> collected = new ArrayList<>();
chars.spliterator().forEachRemaining(collected::add);
assertEquals(asList('h', 'e', 'l', 'l', 'o'), collected);
}

@GwtIncompatible // CopyOnWriteArrayList
@J2ktIncompatible
public void testAbstractListWrapperSpliteratorDelegates() {
CopyOnWriteArrayList<String> cow = new CopyOnWriteArrayList<>(asList("a", "b", "c"));
int cowCharacteristics = cow.spliterator().characteristics();
assertTrue((cowCharacteristics & Spliterator.IMMUTABLE) != 0);
}
}
28 changes: 28 additions & 0 deletions guava-tests/test/com/google/common/collect/MapsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.Spliterator;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentMap;
import junit.framework.TestCase;
Expand Down Expand Up @@ -1624,4 +1625,31 @@ public void testSubMap_unnaturalOrdering() {
ImmutableSortedMap.of(2, 0, 4, 0, 6, 0, 8, 0, 10, 0),
Maps.subMap(map, Range.<Integer>all()));
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testKeySetSpliteratorIsDistinct() {
HashMap<String, Integer> map = new HashMap<>();
map.put("a", 1);
map.put("b", 2);
int characteristics = map.keySet().spliterator().characteristics();
assertTrue(
"keySet spliterator should report DISTINCT",
(characteristics & Spliterator.DISTINCT) != 0);
}

@GwtIncompatible // Spliterator
@J2ktIncompatible
public void testValuesSpliteratorCharacteristics() {
HashMap<String, Integer> map = new HashMap<>();
map.put("a", 1);
map.put("b", 2);
Spliterator<Integer> valuesSpliterator = map.values().spliterator();
assertTrue(
"values spliterator should report SIZED",
(valuesSpliterator.characteristics() & Spliterator.SIZED) != 0);
assertFalse(
"values spliterator should NOT report DISTINCT",
(valuesSpliterator.characteristics() & Spliterator.DISTINCT) != 0);
}
}
6 changes: 5 additions & 1 deletion guava/src/com/google/common/collect/CollectSpliterators.java
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Expand Up @@ -199,11 +199,15 @@ public long estimateSize() {

@Override
public int characteristics() {
// IMMUTABLE and CONCURRENT describe the source, not the elements, so filtering
// does not invalidate them. This matches JDK Stream.filter(), which only clears SIZED.
return fromSpliterator.characteristics()
& (Spliterator.DISTINCT
| Spliterator.NONNULL
| Spliterator.ORDERED
| Spliterator.SORTED);
| Spliterator.SORTED
| Spliterator.IMMUTABLE
| Spliterator.CONCURRENT);
}
}
return new Splitr();
Expand Down
32 changes: 32 additions & 0 deletions guava/src/com/google/common/collect/Lists.java
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.RandomAccess;
import java.util.Spliterator;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.function.Predicate;
import org.jspecify.annotations.Nullable;
Expand Down Expand Up @@ -356,6 +357,14 @@ public E get(int index) {
return (index == 0) ? first : rest[index - 1];
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<E> spliterator() {
return CollectSpliterators.indexed(
size(), Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.SIZED, this::get);
}

@GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
}

Expand Down Expand Up @@ -394,6 +403,14 @@ public E get(int index) {
}
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<E> spliterator() {
return CollectSpliterators.indexed(
size(), Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.SIZED, this::get);
}

@GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
}

Expand Down Expand Up @@ -829,6 +846,14 @@ public Character get(int index) {
public int size() {
return sequence.length();
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<Character> spliterator() {
return CollectSpliterators.indexed(
size(), Spliterator.ORDERED | Spliterator.NONNULL | Spliterator.SIZED, this::get);
}
}

/**
Expand Down Expand Up @@ -1201,6 +1226,13 @@ public boolean contains(@Nullable Object o) {
public int size() {
return backingList.size();
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<E> spliterator() {
return backingList.spliterator();
}
}

private static class RandomAccessListWrapper<E extends @Nullable Object>
Expand Down
15 changes: 15 additions & 0 deletions guava/src/com/google/common/collect/Maps.java
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Expand Up @@ -3942,6 +3942,14 @@ public boolean remove(@Nullable Object o) {
public void clear() {
map().clear();
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<K> spliterator() {
return CollectSpliterators.map(
map().entrySet().spliterator(), Spliterator.DISTINCT, Entry::getKey);
}
}

static <K extends @Nullable Object> @Nullable K keyOrNull(@Nullable Entry<K, ?> entry) {
Expand Down Expand Up @@ -4171,6 +4179,13 @@ public boolean contains(@Nullable Object o) {
public void clear() {
map().clear();
}

@Override
@GwtIncompatible
@J2ktIncompatible
public Spliterator<V> spliterator() {
return CollectSpliterators.map(map().entrySet().spliterator(), 0, Entry::getValue);
}
}

abstract static class EntrySet<K extends @Nullable Object, V extends @Nullable Object>
Expand Down
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