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src/java.base/share/classes/java/util/ImmutableCollections.java
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rev 48077 : 8193128: Reduce number of implementation classes returned by List/Set/Map.of()
Reviewed-by: smarks
*** 70,265 ****
static UnsupportedOperationException uoe() { return new UnsupportedOperationException(); }
// ---------- List Implementations ----------
! abstract static class AbstractImmutableList<E> extends AbstractList<E>
! implements RandomAccess, Serializable {
@Override public boolean add(E e) { throw uoe(); }
@Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
@Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
@Override public void clear() { throw uoe(); }
@Override public boolean remove(Object o) { throw uoe(); }
@Override public boolean removeAll(Collection<?> c) { throw uoe(); }
@Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
@Override public void replaceAll(UnaryOperator<E> operator) { throw uoe(); }
@Override public boolean retainAll(Collection<?> c) { throw uoe(); }
@Override public void sort(Comparator<? super E> c) { throw uoe(); }
- }
! static final class List0<E> extends AbstractImmutableList<E> {
! private static final List0<?> INSTANCE = new List0<>();
! @SuppressWarnings("unchecked")
! static <T> List0<T> instance() {
! return (List0<T>) INSTANCE;
}
! private List0() { }
@Override
! public int size() {
! return 0;
}
@Override
public E get(int index) {
! Objects.checkIndex(index, 0); // always throws IndexOutOfBoundsException
! return null; // but the compiler doesn't know this
}
- @Override
public Iterator<E> iterator() {
! return Collections.emptyIterator();
}
! private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
! throw new InvalidObjectException("not serial proxy");
}
! private Object writeReplace() {
! return new CollSer(CollSer.IMM_LIST);
}
@Override
! public boolean contains(Object o) {
! Objects.requireNonNull(o);
! return false;
}
@Override
! public boolean containsAll(Collection<?> o) {
! return o.isEmpty(); // implicit nullcheck of o
}
@Override
! public int hashCode() {
! return 1;
}
}
! static final class List1<E> extends AbstractImmutableList<E> {
! @Stable
! private final E e0;
! List1(E e0) {
! this.e0 = Objects.requireNonNull(e0);
}
! @Override
! public int size() {
! return 1;
}
! @Override
! public E get(int index) {
! Objects.checkIndex(index, 1);
! return e0;
}
! private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
! throw new InvalidObjectException("not serial proxy");
}
! private Object writeReplace() {
! return new CollSer(CollSer.IMM_LIST, e0);
}
! @Override
! public boolean contains(Object o) {
! return o.equals(e0); // implicit nullcheck of o
}
@Override
! public int hashCode() {
! return 31 + e0.hashCode();
}
}
! static final class List2<E> extends AbstractImmutableList<E> {
@Stable
private final E e0;
@Stable
private final E e1;
! List2(E e0, E e1) {
this.e0 = Objects.requireNonNull(e0);
this.e1 = Objects.requireNonNull(e1);
}
@Override
public int size() {
! return 2;
}
@Override
public E get(int index) {
- Objects.checkIndex(index, 2);
if (index == 0) {
return e0;
! } else { // index == 1
return e1;
}
}
@Override
public boolean contains(Object o) {
! return o.equals(e0) || o.equals(e1); // implicit nullcheck of o
}
@Override
public int hashCode() {
int hash = 31 + e0.hashCode();
! return 31 * hash + e1.hashCode();
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
private Object writeReplace() {
return new CollSer(CollSer.IMM_LIST, e0, e1);
}
}
static final class ListN<E> extends AbstractImmutableList<E> {
@Stable
private final E[] elements;
@SafeVarargs
ListN(E... input) {
// copy and check manually to avoid TOCTOU
@SuppressWarnings("unchecked")
E[] tmp = (E[])new Object[input.length]; // implicit nullcheck of input
for (int i = 0; i < input.length; i++) {
tmp[i] = Objects.requireNonNull(input[i]);
}
! this.elements = tmp;
}
@Override
public int size() {
return elements.length;
}
@Override
public E get(int index) {
- Objects.checkIndex(index, elements.length);
return elements[index];
}
@Override
public boolean contains(Object o) {
for (E e : elements) {
! if (o.equals(e)) { // implicit nullcheck of o
return true;
}
}
return false;
}
@Override
public int hashCode() {
int hash = 1;
for (E e : elements) {
hash = 31 * hash + e.hashCode();
}
--- 70,504 ----
static UnsupportedOperationException uoe() { return new UnsupportedOperationException(); }
// ---------- List Implementations ----------
! static final List<?> EMPTY_LIST = new ListN<>();
!
! @SuppressWarnings("unchecked")
! static <E> List<E> emptyList() {
! return (List<E>) EMPTY_LIST;
! }
!
! static abstract class AbstractImmutableList<E> extends AbstractCollection<E>
! implements List<E>, RandomAccess, Serializable {
!
! // all mutating methods throw UnsupportedOperationException
@Override public boolean add(E e) { throw uoe(); }
+ @Override public void add(int index, E element) { throw uoe(); }
@Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
@Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
@Override public void clear() { throw uoe(); }
@Override public boolean remove(Object o) { throw uoe(); }
+ @Override public E remove(int index) { throw uoe(); }
@Override public boolean removeAll(Collection<?> c) { throw uoe(); }
@Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
@Override public void replaceAll(UnaryOperator<E> operator) { throw uoe(); }
@Override public boolean retainAll(Collection<?> c) { throw uoe(); }
+ @Override public E set(int index, E element) { throw uoe(); }
@Override public void sort(Comparator<? super E> c) { throw uoe(); }
! @Override
! public int indexOf(Object o) {
! // Input should be checked for null, but this needs a CSR. See JDK-8191418
! if (o == null) {
! return -1;
! }
! // Objects.requireNonNull(o);
! ListIterator<E> it = listIterator();
! while (it.hasNext()) {
! if (o.equals(it.next())) {
! return it.previousIndex();
! }
! }
! return -1;
! }
! @Override
! public int lastIndexOf(Object o) {
! // Input should be checked for null, but this needs a CSR. See JDK-8191418
! if (o == null) {
! return -1;
}
+ // Objects.requireNonNull(o);
! ListIterator<E> it = listIterator();
! while (it.hasNext()) {
! if (o.equals(it.next())) {
! return it.previousIndex();
! }
! }
! return -1;
! }
@Override
! public boolean isEmpty() {
! return size() == 0;
}
@Override
+ public List<E> subList(int fromIndex, int toIndex) {
+ int size = size();
+ Objects.checkFromToIndex(fromIndex, toIndex, size);
+ if (size == 0 || fromIndex == toIndex) {
+ return emptyList();
+ } else if (size == 1) {
+ // checks above deal with corner cases subList(0,0) and subList(1,1)
+ // that would return the empty list
+ assert(fromIndex == 0 && toIndex == 1);
+ return this;
+ } else {
+ return new SubList<E>(this, fromIndex, toIndex);
+ }
+ }
+
+ private static class SubList<E> extends AbstractList<E> implements RandomAccess {
+ private final List<E> root;
+ private final int offset;
+ int size;
+
+ // all mutating methods throw UnsupportedOperationException
+ @Override public boolean add(E e) { throw uoe(); }
+ @Override public void add(int index, E element) { throw uoe(); }
+ @Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
+ @Override public boolean addAll(int index, Collection<? extends E> c) { throw uoe(); }
+ @Override public void clear() { throw uoe(); }
+ @Override public boolean remove(Object o) { throw uoe(); }
+ @Override public E remove(int index) { throw uoe(); }
+ @Override public boolean removeAll(Collection<?> c) { throw uoe(); }
+ @Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
+ @Override public void replaceAll(UnaryOperator<E> operator) { throw uoe(); }
+ @Override public boolean retainAll(Collection<?> c) { throw uoe(); }
+ @Override public E set(int index, E element) { throw uoe(); }
+ @Override public void sort(Comparator<? super E> c) { throw uoe(); }
+
+ /**
+ * Constructs a sublist of an arbitrary AbstractList, which is
+ * not a SubList itself.
+ */
+ public SubList(List<E> root, int fromIndex, int toIndex) {
+ this.root = root;
+ this.offset = fromIndex;
+ this.size = toIndex - fromIndex;
+ }
+
+ /**
+ * Constructs a sublist of another SubList.
+ */
+ protected SubList(SubList<E> parent, int fromIndex, int toIndex) {
+ this.root = parent.root;
+ this.offset = parent.offset + fromIndex;
+ this.size = toIndex - fromIndex;
+ }
+
public E get(int index) {
! Objects.checkIndex(index, size);
! return root.get(offset + index);
! }
!
! public int size() {
! return size;
! }
!
! protected void removeRange(int fromIndex, int toIndex) {
! throw uoe();
}
public Iterator<E> iterator() {
! return listIterator();
}
! public ListIterator<E> listIterator(int index) {
! rangeCheck(index);
!
! return new ListIterator<E>() {
! private final ListIterator<E> i =
! root.listIterator(offset + index);
!
! public boolean hasNext() {
! return nextIndex() < size;
}
! public E next() {
! if (hasNext())
! return i.next();
! else
! throw new NoSuchElementException();
! }
!
! public boolean hasPrevious() {
! return previousIndex() >= 0;
! }
!
! public E previous() {
! if (hasPrevious())
! return i.previous();
! else
! throw new NoSuchElementException();
! }
!
! public int nextIndex() {
! return i.nextIndex() - offset;
! }
!
! public int previousIndex() {
! return i.previousIndex() - offset;
! }
!
! public void remove() { throw uoe(); }
! public void set(E e) { throw uoe(); }
! public void add(E e) { throw uoe(); }
! };
! }
!
! public List<E> subList(int fromIndex, int toIndex) {
! subListRangeCheck(fromIndex, toIndex, size);
! return new SubList<>(this, fromIndex, toIndex);
! }
!
! private void rangeCheck(int index) {
! if (index < 0 || index > size)
! throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
! }
!
! private String outOfBoundsMsg(int index) {
! return "Index: "+index+", Size: "+size;
! }
}
@Override
! public Iterator<E> iterator() {
! return new Itr();
}
@Override
! public ListIterator<E> listIterator() {
! return listIterator(0);
}
@Override
! public ListIterator<E> listIterator(final int index) {
! Objects.checkIndex(index, size());
! return new ListItr(index);
}
+
+ private class Itr implements Iterator<E> {
+ Itr() {
+ size = size();
}
! int cursor = 0;
! private final int size;
!
! public boolean hasNext() {
! return cursor != size;
}
! public E next() {
! try {
! int i = cursor;
! E next = get(i);
! cursor = i + 1;
! return next;
! } catch (IndexOutOfBoundsException e) {
! throw new NoSuchElementException();
! }
}
! public void remove() {
! throw uoe();
! }
}
! private class ListItr extends Itr implements ListIterator<E> {
! ListItr(int index) {
! cursor = index;
}
! public boolean hasPrevious() {
! return cursor != 0;
}
! public E previous() {
! try {
! int i = cursor - 1;
! E previous = get(i);
! cursor = i;
! return previous;
! } catch (IndexOutOfBoundsException e) {
! throw new NoSuchElementException();
! }
}
+ public int nextIndex() {
+ return cursor;
+ }
+
+ public int previousIndex() {
+ return cursor - 1;
+ }
+
+ public void set(E e) {
+ throw uoe();
+ }
+
+ public void add(E e) {
+ throw uoe();
+ }
+ }
+
+
@Override
! public boolean equals(Object o) {
! if (o == this) {
! return true;
! }
!
! if (!(o instanceof List)) {
! return false;
! }
!
! Iterator<E> e1 = iterator();
! Iterator<?> e2 = ((List<?>) o).iterator();
! while (e1.hasNext() && e2.hasNext()) {
! E o1 = e1.next();
! Object o2 = e2.next();
! if (!(o1==null ? o2==null : o1.equals(o2)))
! return false;
}
+ return !(e1.hasNext() || e2.hasNext());
}
! IndexOutOfBoundsException outOfBounds(int index) {
! return new IndexOutOfBoundsException("Index: " + index + " Size: " + size());
! }
!
! }
!
! static final class List12<E> extends AbstractImmutableList<E> {
!
@Stable
private final E e0;
+
@Stable
private final E e1;
! List12(E e0) {
! this.e0 = Objects.requireNonNull(e0);
! this.e1 = null;
! }
!
! List12(E e0, E e1) {
this.e0 = Objects.requireNonNull(e0);
this.e1 = Objects.requireNonNull(e1);
}
@Override
+ @SuppressWarnings("unchecked")
public int size() {
! return e1 != null ? 2 : 1;
}
@Override
+ @SuppressWarnings("unchecked")
public E get(int index) {
if (index == 0) {
return e0;
! } else if (index == 1 && e1 != null) {
return e1;
}
+ throw outOfBounds(index);
}
@Override
+ @SuppressWarnings("unchecked")
public boolean contains(Object o) {
! return o.equals(e0) || o.equals(e1); // implicit null check of o
}
@Override
+ @SuppressWarnings("unchecked")
public int hashCode() {
int hash = 31 + e0.hashCode();
! if (e1 != null) {
! hash = 31 * hash + e1.hashCode();
! }
! return hash;
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
+ @SuppressWarnings("unchecked")
private Object writeReplace() {
+ if (e1 == null) {
+ return new CollSer(CollSer.IMM_LIST, e0);
+ } else {
return new CollSer(CollSer.IMM_LIST, e0, e1);
}
}
+ }
static final class ListN<E> extends AbstractImmutableList<E> {
+
@Stable
private final E[] elements;
+ @SuppressWarnings("unchecked")
+ ListN(E e0) {
+ elements = (E[])new Object[] { e0 };
+ }
+
+ @SuppressWarnings("unchecked")
+ ListN(E e0, E e1) {
+ elements = (E[])new Object[] { e0, e1 };
+ }
+
@SafeVarargs
ListN(E... input) {
// copy and check manually to avoid TOCTOU
@SuppressWarnings("unchecked")
E[] tmp = (E[])new Object[input.length]; // implicit nullcheck of input
for (int i = 0; i < input.length; i++) {
tmp[i] = Objects.requireNonNull(input[i]);
}
! elements = tmp;
}
@Override
+ public boolean isEmpty() {
+ return size() == 0;
+ }
+
+ @Override
+ @SuppressWarnings("unchecked")
public int size() {
return elements.length;
}
@Override
+ @SuppressWarnings("unchecked")
public E get(int index) {
return elements[index];
}
@Override
+ @SuppressWarnings("unchecked")
public boolean contains(Object o) {
+ Objects.requireNonNull(o);
for (E e : elements) {
! if (o.equals(e)) {
return true;
}
}
return false;
}
@Override
+ @SuppressWarnings("unchecked")
public int hashCode() {
int hash = 1;
for (E e : elements) {
hash = 31 * hash + e.hashCode();
}
*** 268,383 ****
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
private Object writeReplace() {
return new CollSer(CollSer.IMM_LIST, elements);
}
}
// ---------- Set Implementations ----------
abstract static class AbstractImmutableSet<E> extends AbstractSet<E> implements Serializable {
@Override public boolean add(E e) { throw uoe(); }
@Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
@Override public void clear() { throw uoe(); }
@Override public boolean remove(Object o) { throw uoe(); }
@Override public boolean removeAll(Collection<?> c) { throw uoe(); }
@Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
@Override public boolean retainAll(Collection<?> c) { throw uoe(); }
}
! static final class Set0<E> extends AbstractImmutableSet<E> {
! private static final Set0<?> INSTANCE = new Set0<>();
!
! @SuppressWarnings("unchecked")
! static <T> Set0<T> instance() {
! return (Set0<T>) INSTANCE;
! }
!
! private Set0() { }
!
! @Override
! public int size() {
! return 0;
! }
!
! @Override
! public boolean contains(Object o) {
! Objects.requireNonNull(o);
! return false;
! }
!
! @Override
! public boolean containsAll(Collection<?> o) {
! return o.isEmpty(); // implicit nullcheck of o
! }
!
! @Override
! public Iterator<E> iterator() {
! return Collections.emptyIterator();
! }
!
! private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
! throw new InvalidObjectException("not serial proxy");
! }
!
! private Object writeReplace() {
! return new CollSer(CollSer.IMM_SET);
! }
!
! @Override
! public int hashCode() {
! return 0;
! }
! }
!
! static final class Set1<E> extends AbstractImmutableSet<E> {
! @Stable
! private final E e0;
!
! Set1(E e0) {
! this.e0 = Objects.requireNonNull(e0);
! }
!
! @Override
! public int size() {
! return 1;
! }
!
! @Override
! public boolean contains(Object o) {
! return o.equals(e0); // implicit nullcheck of o
! }
!
! @Override
! public Iterator<E> iterator() {
! return Collections.singletonIterator(e0);
! }
!
! private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
! throw new InvalidObjectException("not serial proxy");
! }
!
! private Object writeReplace() {
! return new CollSer(CollSer.IMM_SET, e0);
! }
!
! @Override
! public int hashCode() {
! return e0.hashCode();
! }
! }
!
! static final class Set2<E> extends AbstractImmutableSet<E> {
@Stable
final E e0;
@Stable
final E e1;
! Set2(E e0, E e1) {
if (e0.equals(Objects.requireNonNull(e1))) { // implicit nullcheck of e0
throw new IllegalArgumentException("duplicate element: " + e0);
}
if (SALT >= 0) {
--- 507,553 ----
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
+ @SuppressWarnings("unchecked")
private Object writeReplace() {
return new CollSer(CollSer.IMM_LIST, elements);
}
}
// ---------- Set Implementations ----------
+ static final Set<?> EMPTY_SET = new SetN<>();
+
+ @SuppressWarnings("unchecked")
+ static <E> Set<E> emptySet() {
+ return (Set<E>) EMPTY_SET;
+ }
+
abstract static class AbstractImmutableSet<E> extends AbstractSet<E> implements Serializable {
@Override public boolean add(E e) { throw uoe(); }
@Override public boolean addAll(Collection<? extends E> c) { throw uoe(); }
@Override public void clear() { throw uoe(); }
@Override public boolean remove(Object o) { throw uoe(); }
@Override public boolean removeAll(Collection<?> c) { throw uoe(); }
@Override public boolean removeIf(Predicate<? super E> filter) { throw uoe(); }
@Override public boolean retainAll(Collection<?> c) { throw uoe(); }
}
! static final class Set12<E> extends AbstractImmutableSet<E> {
@Stable
final E e0;
@Stable
final E e1;
! Set12(E e0) {
! this.e0 = Objects.requireNonNull(e0);
! this.e1 = null;
! }
!
! Set12(E e0, E e1) {
if (e0.equals(Objects.requireNonNull(e1))) { // implicit nullcheck of e0
throw new IllegalArgumentException("duplicate element: " + e0);
}
if (SALT >= 0) {
*** 389,428 ****
}
}
@Override
public int size() {
! return 2;
}
@Override
public boolean contains(Object o) {
return o.equals(e0) || o.equals(e1); // implicit nullcheck of o
}
@Override
public int hashCode() {
! return e0.hashCode() + e1.hashCode();
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
! private int idx = 0;
@Override
public boolean hasNext() {
! return idx < 2;
}
@Override
public E next() {
! if (idx == 0) {
! idx = 1;
return e0;
! } else if (idx == 1) {
! idx = 2;
return e1;
} else {
throw new NoSuchElementException();
}
}
--- 559,598 ----
}
}
@Override
public int size() {
! return (e1 == null) ? 1 : 2;
}
@Override
public boolean contains(Object o) {
return o.equals(e0) || o.equals(e1); // implicit nullcheck of o
}
@Override
public int hashCode() {
! return e0.hashCode() + (e1 == null ? 0 : e1.hashCode());
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
! private int idx = size();
@Override
public boolean hasNext() {
! return idx > 0;
}
@Override
public E next() {
! if (idx == 1) {
! idx = 0;
return e0;
! } else if (idx == 2) {
! idx = 1;
return e1;
} else {
throw new NoSuchElementException();
}
}
*** 432,444 ****
--- 602,618 ----
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
private Object writeReplace() {
+ if (e1 == null) {
+ return new CollSer(CollSer.IMM_SET, e0);
+ } else {
return new CollSer(CollSer.IMM_SET, e0, e1);
}
}
+ }
/**
* An array-based Set implementation. The element array must be strictly
* larger than the size (the number of contained elements) so that at
* least one null is always present.
*** 472,482 ****
return size;
}
@Override
public boolean contains(Object o) {
! return probe(o) >= 0; // implicit nullcheck of o
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
--- 646,657 ----
return size;
}
@Override
public boolean contains(Object o) {
! Objects.requireNonNull(0);
! return size > 0 && probe(o) >= 0; // implicit nullcheck of o
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
*** 547,556 ****
--- 722,738 ----
}
}
// ---------- Map Implementations ----------
+ static final Map<?,?> EMPTY_MAP = new MapN<>();
+
+ @SuppressWarnings("unchecked")
+ static <K,V> Map<K,V> emptyMap() {
+ return (Map<K,V>) EMPTY_MAP;
+ }
+
abstract static class AbstractImmutableMap<K,V> extends AbstractMap<K,V> implements Serializable {
@Override public void clear() { throw uoe(); }
@Override public V compute(K key, BiFunction<? super K,? super V,? extends V> rf) { throw uoe(); }
@Override public V computeIfAbsent(K key, Function<? super K,? extends V> mf) { throw uoe(); }
@Override public V computeIfPresent(K key, BiFunction<? super K,? super V,? extends V> rf) { throw uoe(); }
*** 563,613 ****
@Override public V replace(K key, V value) { throw uoe(); }
@Override public boolean replace(K key, V oldValue, V newValue) { throw uoe(); }
@Override public void replaceAll(BiFunction<? super K,? super V,? extends V> f) { throw uoe(); }
}
- static final class Map0<K,V> extends AbstractImmutableMap<K,V> {
- private static final Map0<?,?> INSTANCE = new Map0<>();
-
- @SuppressWarnings("unchecked")
- static <K,V> Map0<K,V> instance() {
- return (Map0<K,V>) INSTANCE;
- }
-
- private Map0() { }
-
- @Override
- public Set<Map.Entry<K,V>> entrySet() {
- return Set.of();
- }
-
- @Override
- public boolean containsKey(Object o) {
- Objects.requireNonNull(o);
- return false;
- }
-
- @Override
- public boolean containsValue(Object o) {
- Objects.requireNonNull(o);
- return false;
- }
-
- private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
- throw new InvalidObjectException("not serial proxy");
- }
-
- private Object writeReplace() {
- return new CollSer(CollSer.IMM_MAP);
- }
-
- @Override
- public int hashCode() {
- return 0;
- }
- }
-
static final class Map1<K,V> extends AbstractImmutableMap<K,V> {
@Stable
private final K k0;
@Stable
private final V v0;
--- 745,754 ----
*** 656,668 ****
* @param <V> the value type
*/
static final class MapN<K,V> extends AbstractImmutableMap<K,V> {
@Stable
final Object[] table; // pairs of key, value
- @Stable
final int size; // number of pairs
MapN(Object... input) {
if ((input.length & 1) != 0) { // implicit nullcheck of input
throw new InternalError("length is odd");
}
size = input.length >> 1;
--- 797,815 ----
* @param <V> the value type
*/
static final class MapN<K,V> extends AbstractImmutableMap<K,V> {
@Stable
final Object[] table; // pairs of key, value
final int size; // number of pairs
+ MapN(K key, V value) {
+ table = new Object[2];
+ table[0] = key;
+ table[1] = value;
+ size = 1;
+ }
+
MapN(Object... input) {
if ((input.length & 1) != 0) { // implicit nullcheck of input
throw new InternalError("length is odd");
}
size = input.length >> 1;
*** 687,697 ****
}
}
@Override
public boolean containsKey(Object o) {
! return probe(o) >= 0; // implicit nullcheck of o
}
@Override
public boolean containsValue(Object o) {
for (int i = 1; i < table.length; i += 2) {
--- 834,845 ----
}
}
@Override
public boolean containsKey(Object o) {
! Objects.requireNonNull(0);
! return size > 0 && probe(o) >= 0;
}
@Override
public boolean containsValue(Object o) {
for (int i = 1; i < table.length; i += 2) {
*** 716,725 ****
--- 864,876 ----
}
@Override
@SuppressWarnings("unchecked")
public V get(Object o) {
+ if (size == 0) {
+ return null;
+ }
int i = probe(o);
if (i >= 0) {
return (V)table[i+1];
} else {
return null;
*** 946,956 ****
return List.of(array);
case IMM_SET:
return Set.of(array);
case IMM_MAP:
if (array.length == 0) {
! return ImmutableCollections.Map0.instance();
} else if (array.length == 2) {
return new ImmutableCollections.Map1<>(array[0], array[1]);
} else {
return new ImmutableCollections.MapN<>(array);
}
--- 1097,1107 ----
return List.of(array);
case IMM_SET:
return Set.of(array);
case IMM_MAP:
if (array.length == 0) {
! return ImmutableCollections.emptyMap();
} else if (array.length == 2) {
return new ImmutableCollections.Map1<>(array[0], array[1]);
} else {
return new ImmutableCollections.MapN<>(array);
}
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