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/*
* Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.util;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import jdk.internal.access.JavaUtilCollectionAccess;
import jdk.internal.access.SharedSecrets;
import jdk.internal.misc.CDS;
import jdk.internal.vm.annotation.Stable;
/**
* Container class for immutable collections. Not part of the public API.
* Mainly for namespace management and shared infrastructure.
*
* Serial warnings are suppressed throughout because all implementation
* classes use a serial proxy and thus have no need to declare serialVersionUID.
*/
@SuppressWarnings("serial")
class ImmutableCollections {
/**
* A "salt" value used for randomizing iteration order. This is initialized once
* and stays constant for the lifetime of the JVM. It need not be truly random, but
* it needs to vary sufficiently from one run to the next so that iteration order
* will vary between JVM runs.
*/
private static final long SALT32L;
/**
* For set and map iteration, we will iterate in "reverse" stochastically,
* decided at bootstrap time.
*/
private static final boolean REVERSE;
static {
// to generate a reasonably random and well-mixed SALT, use an arbitrary
// value (a slice of pi), multiply with a random seed, then pick
// the mid 32-bits from the product. By picking a SALT value in the
// [0 ... 0xFFFF_FFFFL == 2^32-1] range, we ensure that for any positive
// int N, (SALT32L * N) >> 32 is a number in the [0 ... N-1] range. This
// property will be used to avoid more expensive modulo-based
// calculations.
long color = 0x243F_6A88_85A3_08D3L; // slice of pi
// When running with -Xshare:dump, the VM will supply a "random" seed that's
// derived from the JVM build/version, so can we generate the exact same
// CDS archive for the same JDK build. This makes it possible to verify the
// consistency of the JDK build.
long seed = CDS.getRandomSeedForDumping();
if (seed == 0) {
seed = System.nanoTime();
}
SALT32L = (int)((color * seed) >> 16) & 0xFFFF_FFFFL;
// use the lowest bit to determine if we should reverse iteration
REVERSE = (SALT32L & 1) == 0;
}
/**
* Constants following this might be initialized from the CDS archive via
* this array.
*/
private static Object[] archivedObjects;
private static final Object EMPTY;
static final ListN EMPTY_LIST;
static final ListN EMPTY_LIST_NULLS;
static final SetN EMPTY_SET;
static final MapN EMPTY_MAP;
static {
CDS.initializeFromArchive(ImmutableCollections.class);
if (archivedObjects == null) {
EMPTY = new Object();
EMPTY_LIST = new ListN<>(new Object[0], false);
EMPTY_LIST_NULLS = new ListN<>(new Object[0], true);
EMPTY_SET = new SetN<>();
EMPTY_MAP = new MapN<>();
archivedObjects =
new Object[] { EMPTY, EMPTY_LIST, EMPTY_LIST_NULLS, EMPTY_SET, EMPTY_MAP };
} else {
EMPTY = archivedObjects[0];
EMPTY_LIST = (ListN)archivedObjects[1];
EMPTY_LIST_NULLS = (ListN)archivedObjects[2];
EMPTY_SET = (SetN)archivedObjects[3];
EMPTY_MAP = (MapN)archivedObjects[4];
}
}
static class Access {
static {
SharedSecrets.setJavaUtilCollectionAccess(new JavaUtilCollectionAccess() {
public List listFromTrustedArray(Object[] array) {
return ImmutableCollections.listFromTrustedArray(array);
}
public List listFromTrustedArrayNullsAllowed(Object[] array) {
return ImmutableCollections.listFromTrustedArrayNullsAllowed(array);
}
});
}
}
/** No instances. */
private ImmutableCollections() { }
/**
* The reciprocal of load factor. Given a number of elements
* to store, multiply by this factor to get the table size.
*/
static final int EXPAND_FACTOR = 2;
static UnsupportedOperationException uoe() { return new UnsupportedOperationException(); }
@jdk.internal.ValueBased
static abstract class AbstractImmutableCollection extends AbstractCollection {
// all mutating methods throw UnsupportedOperationException
@Override public boolean add(E e) { throw uoe(); }
@Override public boolean addAll(Collection 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 filter) { throw uoe(); }
@Override public boolean retainAll(Collection c) { throw uoe(); }
}
// ---------- List Static Factory Methods ----------
/**
* Copies a collection into a new List, unless the arg is already a safe,
* null-prohibiting unmodifiable list, in which case the arg itself is returned.
* Null argument or null elements in the argument will result in NPE.
*
* @param the List's element type
* @param input the input array
* @return the new list
*/
@SuppressWarnings("unchecked")
static List listCopy(Collection coll) {
if (coll instanceof List12 || (coll instanceof ListN && ! ((ListN)coll).allowNulls)) {
return (List)coll;
} else {
return (List)List.of(coll.toArray()); // implicit nullcheck of coll
}
}
/**
* Creates a new List from an untrusted array, creating a new array for internal
* storage, and checking for and rejecting null elements.
*
* @param the List's element type
* @param input the input array
* @return the new list
*/
@SafeVarargs
static List listFromArray(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]);
}
return new ListN<>(tmp, false);
}
/**
* Creates a new List from a trusted array, checking for and rejecting null
* elements.
*
* A trusted array has no references retained by the caller. It can therefore be
* safely reused as the List's internal storage, avoiding a defensive copy. The array's
* class must be Object[].class. This method is declared with a parameter type of
* Object... instead of E... so that a varargs call doesn't accidentally create an array
* of some class other than Object[].class.
*
* @param the List's element type
* @param input the input array
* @return the new list
*/
@SuppressWarnings("unchecked")
static List listFromTrustedArray(Object... input) {
assert input.getClass() == Object[].class;
for (Object o : input) { // implicit null check of 'input' array
Objects.requireNonNull(o);
}
return switch (input.length) {
case 0 -> (List) ImmutableCollections.EMPTY_LIST;
case 1 -> (List) new List12<>(input[0]);
case 2 -> (List) new List12<>(input[0], input[1]);
default -> (List) new ListN<>(input, false);
};
}
/**
* Creates a new List from a trusted array, allowing null elements.
*
* A trusted array has no references retained by the caller. It can therefore be
* safely reused as the List's internal storage, avoiding a defensive copy. The array's
* class must be Object[].class. This method is declared with a parameter type of
* Object... instead of E... so that a varargs call doesn't accidentally create an array
* of some class other than Object[].class.
*
*
Avoids creating a List12 instance, as it cannot accommodate null elements.
*
* @param the List's element type
* @param input the input array
* @return the new list
*/
@SuppressWarnings("unchecked")
static List listFromTrustedArrayNullsAllowed(Object... input) {
assert input.getClass() == Object[].class;
if (input.length == 0) {
return (List) EMPTY_LIST_NULLS;
} else {
return new ListN<>((E[])input, true);
}
}
// ---------- List Implementations ----------
@jdk.internal.ValueBased
static abstract class AbstractImmutableList extends AbstractImmutableCollection
implements List, RandomAccess {
// all mutating methods throw UnsupportedOperationException
@Override public void add(int index, E element) { throw uoe(); }
@Override public boolean addAll(int index, Collection c) { throw uoe(); }
@Override public E remove(int index) { throw uoe(); }
@Override public void replaceAll(UnaryOperator operator) { throw uoe(); }
@Override public E set(int index, E element) { throw uoe(); }
@Override public void sort(Comparator c) { throw uoe(); }
@Override
public List subList(int fromIndex, int toIndex) {
int size = size();
subListRangeCheck(fromIndex, toIndex, size);
return SubList.fromList(this, fromIndex, toIndex);
}
static void subListRangeCheck(int fromIndex, int toIndex, int size) {
if (fromIndex < 0)
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
if (toIndex > size)
throw new IndexOutOfBoundsException("toIndex = " + toIndex);
if (fromIndex > toIndex)
throw new IllegalArgumentException("fromIndex(" + fromIndex +
") > toIndex(" + toIndex + ")");
}
@Override
public Iterator iterator() {
return new ListItr(this, size());
}
@Override
public ListIterator listIterator() {
return listIterator(0);
}
@Override
public ListIterator listIterator(final int index) {
int size = size();
if (index < 0 || index > size) {
throw outOfBounds(index);
}
return new ListItr(this, size, index);
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof List)) {
return false;
}
Iterator oit = ((List) o).iterator();
for (int i = 0, s = size(); i < s; i++) {
if (!oit.hasNext() || !Objects.equals(get(i), oit.next())) {
return false;
}
}
return !oit.hasNext();
}
@Override
public int hashCode() {
int hash = 1;
for (int i = 0, s = size(); i < s; i++) {
hash = 31 * hash + Objects.hashCode(get(i));
}
return hash;
}
@Override
public boolean contains(Object o) {
return indexOf(o) >= 0;
}
IndexOutOfBoundsException outOfBounds(int index) {
return new IndexOutOfBoundsException("Index: " + index + " Size: " + size());
}
}
static final class ListItr implements ListIterator {
@Stable
private final List list;
@Stable
private final int size;
@Stable
private final boolean isListIterator;
private int cursor;
ListItr(List list, int size) {
this.list = list;
this.size = size;
this.cursor = 0;
isListIterator = false;
}
ListItr(List list, int size, int index) {
this.list = list;
this.size = size;
this.cursor = index;
isListIterator = true;
}
public boolean hasNext() {
return cursor != size;
}
public E next() {
try {
int i = cursor;
E next = list.get(i);
cursor = i + 1;
return next;
} catch (IndexOutOfBoundsException e) {
throw new NoSuchElementException();
}
}
public void remove() {
throw uoe();
}
public boolean hasPrevious() {
if (!isListIterator) {
throw uoe();
}
return cursor != 0;
}
public E previous() {
if (!isListIterator) {
throw uoe();
}
try {
int i = cursor - 1;
E previous = list.get(i);
cursor = i;
return previous;
} catch (IndexOutOfBoundsException e) {
throw new NoSuchElementException();
}
}
public int nextIndex() {
if (!isListIterator) {
throw uoe();
}
return cursor;
}
public int previousIndex() {
if (!isListIterator) {
throw uoe();
}
return cursor - 1;
}
public void set(E e) {
throw uoe();
}
public void add(E e) {
throw uoe();
}
}
static final class SubList extends AbstractImmutableList
implements RandomAccess {
@Stable
private final AbstractImmutableList root;
@Stable
private final int offset;
@Stable
private final int size;
private SubList(AbstractImmutableList root, int offset, int size) {
assert root instanceof List12 || root instanceof ListN;
this.root = root;
this.offset = offset;
this.size = size;
}
/**
* Constructs a sublist of another SubList.
*/
static SubList fromSubList(SubList parent, int fromIndex, int toIndex) {
return new SubList<>(parent.root, parent.offset + fromIndex, toIndex - fromIndex);
}
/**
* Constructs a sublist of an arbitrary AbstractImmutableList, which is
* not a SubList itself.
*/
static SubList fromList(AbstractImmutableList list, int fromIndex, int toIndex) {
return new SubList<>(list, fromIndex, toIndex - fromIndex);
}
public E get(int index) {
Objects.checkIndex(index, size);
return root.get(offset + index);
}
public int size() {
return size;
}
public Iterator iterator() {
return new ListItr<>(this, size());
}
public ListIterator listIterator(int index) {
rangeCheck(index);
return new ListItr<>(this, size(), index);
}
public List subList(int fromIndex, int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
return SubList.fromSubList(this, fromIndex, toIndex);
}
private void rangeCheck(int index) {
if (index < 0 || index > size) {
throw outOfBounds(index);
}
}
private boolean allowNulls() {
return root instanceof ListN && ((ListN)root).allowNulls;
}
@Override
public int indexOf(Object o) {
if (!allowNulls() && o == null) {
throw new NullPointerException();
}
for (int i = 0, s = size(); i < s; i++) {
if (Objects.equals(o, get(i))) {
return i;
}
}
return -1;
}
@Override
public int lastIndexOf(Object o) {
if (!allowNulls() && o == null) {
throw new NullPointerException();
}
for (int i = size() - 1; i >= 0; i--) {
if (Objects.equals(o, get(i))) {
return i;
}
}
return -1;
}
@Override
public Object[] toArray() {
Object[] array = new Object[size];
for (int i = 0; i < size; i++) {
array[i] = get(i);
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
T[] array = a.length >= size ? a :
(T[])java.lang.reflect.Array
.newInstance(a.getClass().getComponentType(), size);
for (int i = 0; i < size; i++) {
array[i] = (T)get(i);
}
if (array.length > size) {
array[size] = null; // null-terminate
}
return array;
}
}
@jdk.internal.ValueBased
static final class List12 extends AbstractImmutableList
implements Serializable {
@Stable
private final E e0;
@Stable
private final Object e1;
List12(E e0) {
this.e0 = Objects.requireNonNull(e0);
// Use EMPTY as a sentinel for an unused element: not using null
// enables constant folding optimizations over single-element lists
this.e1 = EMPTY;
}
List12(E e0, E e1) {
this.e0 = Objects.requireNonNull(e0);
this.e1 = Objects.requireNonNull(e1);
}
@Override
public int size() {
return e1 != EMPTY ? 2 : 1;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
@SuppressWarnings("unchecked")
public E get(int index) {
if (index == 0) {
return e0;
} else if (index == 1 && e1 != EMPTY) {
return (E)e1;
}
throw outOfBounds(index);
}
@Override
public int indexOf(Object o) {
Objects.requireNonNull(o);
if (o.equals(e0)) {
return 0;
} else if (e1 != EMPTY && o.equals(e1)) {
return 1;
} else {
return -1;
}
}
@Override
public int lastIndexOf(Object o) {
Objects.requireNonNull(o);
if (e1 != EMPTY && o.equals(e1)) {
return 1;
} else if (o.equals(e0)) {
return 0;
} else {
return -1;
}
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
if (e1 == EMPTY) {
return new CollSer(CollSer.IMM_LIST, e0);
} else {
return new CollSer(CollSer.IMM_LIST, e0, e1);
}
}
@Override
public Object[] toArray() {
if (e1 == EMPTY) {
return new Object[] { e0 };
} else {
return new Object[] { e0, e1 };
}
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
int size = size();
T[] array = a.length >= size ? a :
(T[])Array.newInstance(a.getClass().getComponentType(), size);
array[0] = (T)e0;
if (size == 2) {
array[1] = (T)e1;
}
if (array.length > size) {
array[size] = null; // null-terminate
}
return array;
}
}
@jdk.internal.ValueBased
static final class ListN extends AbstractImmutableList
implements Serializable {
@Stable
private final E[] elements;
@Stable
private final boolean allowNulls;
// caller must ensure that elements has no nulls if allowNulls is false
private ListN(E[] elements, boolean allowNulls) {
this.elements = elements;
this.allowNulls = allowNulls;
}
@Override
public boolean isEmpty() {
return elements.length == 0;
}
@Override
public int size() {
return elements.length;
}
@Override
public E get(int index) {
return elements[index];
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
return new CollSer(allowNulls ? CollSer.IMM_LIST_NULLS : CollSer.IMM_LIST, elements);
}
@Override
public Object[] toArray() {
return Arrays.copyOf(elements, elements.length);
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
int size = elements.length;
if (a.length < size) {
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(elements, size, a.getClass());
}
System.arraycopy(elements, 0, a, 0, size);
if (a.length > size) {
a[size] = null; // null-terminate
}
return a;
}
@Override
public int indexOf(Object o) {
if (!allowNulls && o == null) {
throw new NullPointerException();
}
Object[] es = elements;
for (int i = 0; i < es.length; i++) {
if (Objects.equals(o, es[i])) {
return i;
}
}
return -1;
}
@Override
public int lastIndexOf(Object o) {
if (!allowNulls && o == null) {
throw new NullPointerException();
}
Object[] es = elements;
for (int i = es.length - 1; i >= 0; i--) {
if (Objects.equals(o, es[i])) {
return i;
}
}
return -1;
}
}
// ---------- Set Implementations ----------
@jdk.internal.ValueBased
static abstract class AbstractImmutableSet extends AbstractImmutableCollection
implements Set {
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
} else if (!(o instanceof Set)) {
return false;
}
Collection c = (Collection) o;
if (c.size() != size()) {
return false;
}
for (Object e : c) {
if (e == null || !contains(e)) {
return false;
}
}
return true;
}
@Override
public abstract int hashCode();
}
@jdk.internal.ValueBased
static final class Set12 extends AbstractImmutableSet
implements Serializable {
@Stable
private final E e0;
@Stable
private final Object e1;
Set12(E e0) {
this.e0 = Objects.requireNonNull(e0);
// Use EMPTY as a sentinel for an unused element: not using null
// enable constant folding optimizations over single-element sets
this.e1 = EMPTY;
}
Set12(E e0, E e1) {
if (e0.equals(Objects.requireNonNull(e1))) { // implicit nullcheck of e0
throw new IllegalArgumentException("duplicate element: " + e0);
}
this.e0 = e0;
this.e1 = e1;
}
@Override
public int size() {
return (e1 == EMPTY) ? 1 : 2;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public boolean contains(Object o) {
return o.equals(e0) || e1.equals(o); // implicit nullcheck of o
}
@Override
public int hashCode() {
return e0.hashCode() + (e1 == EMPTY ? 0 : e1.hashCode());
}
@Override
public Iterator iterator() {
return new Iterator<>() {
private int idx = (e1 == EMPTY) ? 1 : 2;
@Override
public boolean hasNext() {
return idx > 0;
}
@Override
@SuppressWarnings("unchecked")
public E next() {
if (idx == 1) {
idx = 0;
return (REVERSE || e1 == EMPTY) ? e0 : (E)e1;
} else if (idx == 2) {
idx = 1;
return REVERSE ? (E)e1 : e0;
} else {
throw new NoSuchElementException();
}
}
};
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
if (e1 == EMPTY) {
return new CollSer(CollSer.IMM_SET, e0);
} else {
return new CollSer(CollSer.IMM_SET, e0, e1);
}
}
@Override
public Object[] toArray() {
if (e1 == EMPTY) {
return new Object[] { e0 };
} else if (REVERSE) {
return new Object[] { e1, e0 };
} else {
return new Object[] { e0, e1 };
}
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
int size = size();
T[] array = a.length >= size ? a :
(T[])Array.newInstance(a.getClass().getComponentType(), size);
if (size == 1) {
array[0] = (T)e0;
} else if (REVERSE) {
array[0] = (T)e1;
array[1] = (T)e0;
} else {
array[0] = (T)e0;
array[1] = (T)e1;
}
if (array.length > size) {
array[size] = null; // null-terminate
}
return array;
}
}
/**
* 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.
* @param the element type
*/
@jdk.internal.ValueBased
static final class SetN extends AbstractImmutableSet
implements Serializable {
@Stable
final E[] elements;
@Stable
final int size;
@SafeVarargs
@SuppressWarnings("unchecked")
SetN(E... input) {
size = input.length; // implicit nullcheck of input
elements = (E[])new Object[EXPAND_FACTOR * input.length];
for (int i = 0; i < input.length; i++) {
E e = input[i];
int idx = probe(e); // implicit nullcheck of e
if (idx >= 0) {
throw new IllegalArgumentException("duplicate element: " + e);
} else {
elements[-(idx + 1)] = e;
}
}
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
public boolean contains(Object o) {
Objects.requireNonNull(o);
return size > 0 && probe(o) >= 0;
}
private final class SetNIterator implements Iterator {
private int remaining;
private int idx;
SetNIterator() {
remaining = size;
// pick a starting index in the [0 .. element.length-1] range
// randomly based on SALT32L
idx = (int) ((SALT32L * elements.length) >>> 32);
}
@Override
public boolean hasNext() {
return remaining > 0;
}
@Override
public E next() {
if (remaining > 0) {
E element;
int idx = this.idx;
int len = elements.length;
// step to the next element; skip null elements
do {
if (REVERSE) {
if (++idx >= len) {
idx = 0;
}
} else {
if (--idx < 0) {
idx = len - 1;
}
}
} while ((element = elements[idx]) == null);
this.idx = idx;
remaining--;
return element;
} else {
throw new NoSuchElementException();
}
}
}
@Override
public Iterator iterator() {
return new SetNIterator();
}
@Override
public int hashCode() {
int h = 0;
for (E e : elements) {
if (e != null) {
h += e.hashCode();
}
}
return h;
}
// returns index at which element is present; or if absent,
// (-i - 1) where i is location where element should be inserted.
// Callers are relying on this method to perform an implicit nullcheck
// of pe
private int probe(Object pe) {
int idx = Math.floorMod(pe.hashCode(), elements.length);
while (true) {
E ee = elements[idx];
if (ee == null) {
return -idx - 1;
} else if (pe.equals(ee)) {
return idx;
} else if (++idx == elements.length) {
idx = 0;
}
}
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
Object[] array = new Object[size];
int dest = 0;
for (Object o : elements) {
if (o != null) {
array[dest++] = o;
}
}
return new CollSer(CollSer.IMM_SET, array);
}
@Override
public Object[] toArray() {
Object[] array = new Object[size];
Iterator it = iterator();
for (int i = 0; i < size; i++) {
array[i] = it.next();
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
T[] array = a.length >= size ? a :
(T[])Array.newInstance(a.getClass().getComponentType(), size);
Iterator it = iterator();
for (int i = 0; i < size; i++) {
array[i] = (T)it.next();
}
if (array.length > size) {
array[size] = null; // null-terminate
}
return array;
}
}
// ---------- Map Implementations ----------
@jdk.internal.ValueBased
abstract static class AbstractImmutableMap extends AbstractMap implements Serializable {
@Override public void clear() { throw uoe(); }
@Override public V compute(K key, BiFunction rf) { throw uoe(); }
@Override public V computeIfAbsent(K key, Function mf) { throw uoe(); }
@Override public V computeIfPresent(K key, BiFunction rf) { throw uoe(); }
@Override public V merge(K key, V value, BiFunction rf) { throw uoe(); }
@Override public V put(K key, V value) { throw uoe(); }
@Override public void putAll(Map m) { throw uoe(); }
@Override public V putIfAbsent(K key, V value) { throw uoe(); }
@Override public V remove(Object key) { throw uoe(); }
@Override public boolean remove(Object key, Object value) { throw uoe(); }
@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 f) { throw uoe(); }
/**
* @implNote {@code null} values are disallowed in these immutable maps,
* so we can improve upon the default implementation since a
* {@code null} return from {@code get(key)} always means the default
* value should be returned.
*/
@Override
public V getOrDefault(Object key, V defaultValue) {
V v;
return ((v = get(key)) != null)
? v
: defaultValue;
}
}
@jdk.internal.ValueBased
static final class Map1 extends AbstractImmutableMap {
@Stable
private final K k0;
@Stable
private final V v0;
Map1(K k0, V v0) {
this.k0 = Objects.requireNonNull(k0);
this.v0 = Objects.requireNonNull(v0);
}
@Override
public Set> entrySet() {
return Set.of(new KeyValueHolder<>(k0, v0));
}
@Override
public V get(Object o) {
return o.equals(k0) ? v0 : null; // implicit nullcheck of o
}
@Override
public boolean containsKey(Object o) {
return o.equals(k0); // implicit nullcheck of o
}
@Override
public boolean containsValue(Object o) {
return o.equals(v0); // implicit nullcheck of o
}
@Override
public int size() {
return 1;
}
@Override
public boolean isEmpty() {
return false;
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
return new CollSer(CollSer.IMM_MAP, k0, v0);
}
@Override
public int hashCode() {
return k0.hashCode() ^ v0.hashCode();
}
}
/**
* An array-based Map implementation. There is a single array "table" that
* contains keys and values interleaved: table[0] is kA, table[1] is vA,
* table[2] is kB, table[3] is vB, etc. The table size must be even. It must
* also be strictly larger than the size (the number of key-value pairs contained
* in the map) so that at least one null key is always present.
* @param the key type
* @param the value type
*/
@jdk.internal.ValueBased
static final class MapN extends AbstractImmutableMap {
@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;
int len = EXPAND_FACTOR * input.length;
len = (len + 1) & ~1; // ensure table is even length
table = new Object[len];
for (int i = 0; i < input.length; i += 2) {
@SuppressWarnings("unchecked")
K k = Objects.requireNonNull((K)input[i]);
@SuppressWarnings("unchecked")
V v = Objects.requireNonNull((V)input[i+1]);
int idx = probe(k);
if (idx >= 0) {
throw new IllegalArgumentException("duplicate key: " + k);
} else {
int dest = -(idx + 1);
table[dest] = k;
table[dest+1] = v;
}
}
}
@Override
public boolean containsKey(Object o) {
Objects.requireNonNull(o);
return size > 0 && probe(o) >= 0;
}
@Override
public boolean containsValue(Object o) {
Objects.requireNonNull(o);
for (int i = 1; i < table.length; i += 2) {
Object v = table[i];
if (v != null && o.equals(v)) {
return true;
}
}
return false;
}
@Override
public int hashCode() {
int hash = 0;
for (int i = 0; i < table.length; i += 2) {
Object k = table[i];
if (k != null) {
hash += k.hashCode() ^ table[i + 1].hashCode();
}
}
return hash;
}
@Override
@SuppressWarnings("unchecked")
public V get(Object o) {
if (size == 0) {
Objects.requireNonNull(o);
return null;
}
int i = probe(o);
if (i >= 0) {
return (V)table[i+1];
} else {
return null;
}
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
class MapNIterator implements Iterator> {
private int remaining;
private int idx;
MapNIterator() {
remaining = size;
// pick an even starting index in the [0 .. table.length-1]
// range randomly based on SALT32L
idx = (int) ((SALT32L * (table.length >> 1)) >>> 32) << 1;
}
@Override
public boolean hasNext() {
return remaining > 0;
}
private int nextIndex() {
int idx = this.idx;
if (REVERSE) {
if ((idx += 2) >= table.length) {
idx = 0;
}
} else {
if ((idx -= 2) < 0) {
idx = table.length - 2;
}
}
return this.idx = idx;
}
@Override
public Map.Entry next() {
if (remaining > 0) {
int idx;
while (table[idx = nextIndex()] == null) {}
@SuppressWarnings("unchecked")
Map.Entry e =
new KeyValueHolder<>((K)table[idx], (V)table[idx+1]);
remaining--;
return e;
} else {
throw new NoSuchElementException();
}
}
}
@Override
public Set> entrySet() {
return new AbstractSet<>() {
@Override
public int size() {
return MapN.this.size;
}
@Override
public Iterator> iterator() {
return new MapNIterator();
}
};
}
// returns index at which the probe key is present; or if absent,
// (-i - 1) where i is location where element should be inserted.
// Callers are relying on this method to perform an implicit nullcheck
// of pk.
private int probe(Object pk) {
int idx = Math.floorMod(pk.hashCode(), table.length >> 1) << 1;
while (true) {
@SuppressWarnings("unchecked")
K ek = (K)table[idx];
if (ek == null) {
return -idx - 1;
} else if (pk.equals(ek)) {
return idx;
} else if ((idx += 2) == table.length) {
idx = 0;
}
}
}
@java.io.Serial
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
throw new InvalidObjectException("not serial proxy");
}
@java.io.Serial
private Object writeReplace() {
Object[] array = new Object[2 * size];
int len = table.length;
int dest = 0;
for (int i = 0; i < len; i += 2) {
if (table[i] != null) {
array[dest++] = table[i];
array[dest++] = table[i+1];
}
}
return new CollSer(CollSer.IMM_MAP, array);
}
}
}
// ---------- Serialization Proxy ----------
/**
* A unified serialization proxy class for the immutable collections.
*
* @serial
* @since 9
*/
final class CollSer implements Serializable {
@java.io.Serial
private static final long serialVersionUID = 6309168927139932177L;
static final int IMM_LIST = 1;
static final int IMM_SET = 2;
static final int IMM_MAP = 3;
static final int IMM_LIST_NULLS = 4;
/**
* Indicates the type of collection that is serialized.
* The low order 8 bits have the value 1 for an immutable
* {@code List}, 2 for an immutable {@code Set}, 3 for
* an immutable {@code Map}, and 4 for an immutable
* {@code List} that allows null elements.
*
* Any other value causes an
* {@link InvalidObjectException} to be thrown. The high
* order 24 bits are zero when an instance is serialized,
* and they are ignored when an instance is deserialized.
* They can thus be used by future implementations without
* causing compatibility issues.
*
* The tag value also determines the interpretation of the
* transient {@code Object[] array} field.
* For {@code List} and {@code Set}, the array's length is the size
* of the collection, and the array contains the elements of the collection.
* Null elements are not allowed. For {@code Set}, duplicate elements
* are not allowed.
*
*
For {@code Map}, the array's length is twice the number of mappings
* present in the map. The array length is necessarily even.
* The array contains a succession of key and value pairs:
* {@code k1, v1, k2, v2, ..., kN, vN.} Nulls are not allowed,
* and duplicate keys are not allowed.
*
* @serial
* @since 9
*/
private final int tag;
/**
* @serial
* @since 9
*/
private transient Object[] array;
CollSer(int t, Object... a) {
tag = t;
array = a;
}
/**
* Reads objects from the stream and stores them
* in the transient {@code Object[] array} field.
*
* @serialData
* A nonnegative int, indicating the count of objects,
* followed by that many objects.
*
* @param ois the ObjectInputStream from which data is read
* @throws IOException if an I/O error occurs
* @throws ClassNotFoundException if a serialized class cannot be loaded
* @throws InvalidObjectException if the count is negative
* @since 9
*/
@java.io.Serial
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
ois.defaultReadObject();
int len = ois.readInt();
if (len < 0) {
throw new InvalidObjectException("negative length " + len);
}
SharedSecrets.getJavaObjectInputStreamAccess().checkArray(ois, Object[].class, len);
Object[] a = new Object[len];
for (int i = 0; i < len; i++) {
a[i] = ois.readObject();
}
array = a;
}
/**
* Writes objects to the stream from
* the transient {@code Object[] array} field.
*
* @serialData
* A nonnegative int, indicating the count of objects,
* followed by that many objects.
*
* @param oos the ObjectOutputStream to which data is written
* @throws IOException if an I/O error occurs
* @since 9
*/
@java.io.Serial
private void writeObject(ObjectOutputStream oos) throws IOException {
oos.defaultWriteObject();
oos.writeInt(array.length);
for (int i = 0; i < array.length; i++) {
oos.writeObject(array[i]);
}
}
/**
* Creates and returns an immutable collection from this proxy class.
* The instance returned is created as if by calling one of the
* static factory methods for
* List,
* Map, or
* Set.
* This proxy class is the serial form for all immutable collection instances,
* regardless of implementation type. This is necessary to ensure that the
* existence of any particular implementation type is kept out of the
* serialized form.
*
* @return a collection created from this proxy object
* @throws InvalidObjectException if the tag value is illegal or if an exception
* is thrown during creation of the collection
* @throws ObjectStreamException if another serialization error has occurred
* @since 9
*/
@java.io.Serial
private Object readResolve() throws ObjectStreamException {
try {
if (array == null) {
throw new InvalidObjectException("null array");
}
// use low order 8 bits to indicate "kind"
// ignore high order 24 bits
switch (tag & 0xff) {
case IMM_LIST:
return List.of(array);
case IMM_LIST_NULLS:
return ImmutableCollections.listFromTrustedArrayNullsAllowed(
Arrays.copyOf(array, array.length, Object[].class));
case IMM_SET:
return Set.of(array);
case IMM_MAP:
if (array.length == 0) {
return ImmutableCollections.EMPTY_MAP;
} else if (array.length == 2) {
return new ImmutableCollections.Map1<>(array[0], array[1]);
} else {
return new ImmutableCollections.MapN<>(array);
}
default:
throw new InvalidObjectException(String.format("invalid flags 0x%x", tag));
}
} catch (NullPointerException|IllegalArgumentException ex) {
InvalidObjectException ioe = new InvalidObjectException("invalid object");
ioe.initCause(ex);
throw ioe;
}
}
}