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/*
* Copyright (C) 2002-2020 Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package it.unimi.dsi.fastutil.objects;
import java.util.List;
import java.util.Collection;
import java.util.Random;
import java.util.RandomAccess;
/**
* A class providing static methods and objects that do useful things with
* type-specific lists.
*
* @see java.util.Collections
*/
public final class ObjectLists {
private ObjectLists() {
}
/**
* Shuffles the specified list using the specified pseudorandom number
* generator.
*
* @param l
* the list to be shuffled.
* @param random
* a pseudorandom number generator.
* @return {@code l}.
*/
public static ObjectList shuffle(final ObjectList l, final Random random) {
for (int i = l.size(); i-- != 0;) {
final int p = random.nextInt(i + 1);
final K t = l.get(i);
l.set(i, l.get(p));
l.set(p, t);
}
return l;
}
/**
* An immutable class representing an empty type-specific list.
*
*
* This class may be useful to implement your own in case you subclass a
* type-specific list.
*/
public static class EmptyList extends ObjectCollections.EmptyCollection
implements
ObjectList,
RandomAccess,
java.io.Serializable,
Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptyList() {
}
@Override
public K get(int i) {
throw new IndexOutOfBoundsException();
}
@Override
public boolean remove(Object k) {
throw new UnsupportedOperationException();
}
@Override
public K remove(int i) {
throw new UnsupportedOperationException();
}
@Override
public void add(final int index, final K k) {
throw new UnsupportedOperationException();
}
@Override
public K set(final int index, final K k) {
throw new UnsupportedOperationException();
}
@Override
public int indexOf(Object k) {
return -1;
}
@Override
public int lastIndexOf(Object k) {
return -1;
}
@Override
public boolean addAll(int i, Collection c) {
throw new UnsupportedOperationException();
}
// Empty lists are trivially always sorted
@Override
public void sort(final java.util.Comparator comparator) {
}
@Override
public void unstableSort(final java.util.Comparator comparator) {
}
@SuppressWarnings("unchecked")
@Override
public ObjectListIterator listIterator() {
return ObjectIterators.EMPTY_ITERATOR;
}
@SuppressWarnings("unchecked")
@Override
public ObjectListIterator iterator() {
return ObjectIterators.EMPTY_ITERATOR;
}
@SuppressWarnings("unchecked")
@Override
public ObjectListIterator listIterator(int i) {
if (i == 0)
return ObjectIterators.EMPTY_ITERATOR;
throw new IndexOutOfBoundsException(String.valueOf(i));
}
@Override
public ObjectList subList(int from, int to) {
if (from == 0 && to == 0)
return this;
throw new IndexOutOfBoundsException();
}
@Override
public void getElements(int from, Object[] a, int offset, int length) {
if (from == 0 && length == 0 && offset >= 0 && offset <= a.length)
return;
throw new IndexOutOfBoundsException();
}
@Override
public void removeElements(int from, int to) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, final K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public void size(int s) {
throw new UnsupportedOperationException();
}
@Override
public int compareTo(final List o) {
if (o == this)
return 0;
return ((List) o).isEmpty() ? 0 : -1;
}
@Override
public Object clone() {
return EMPTY_LIST;
}
@Override
public int hashCode() {
return 1;
}
@Override
@SuppressWarnings("rawtypes")
public boolean equals(Object o) {
return o instanceof List && ((List) o).isEmpty();
}
@Override
public String toString() {
return "[]";
}
private Object readResolve() {
return EMPTY_LIST;
}
}
/**
* An empty list (immutable). It is serializable and cloneable.
*/
@SuppressWarnings("rawtypes")
public static final EmptyList EMPTY_LIST = new EmptyList();
/**
* Returns an empty list (immutable). It is serializable and cloneable.
*
*
* This method provides a typesafe access to {@link #EMPTY_LIST}.
*
* @return an empty list (immutable).
*/
@SuppressWarnings("unchecked")
public static ObjectList emptyList() {
return EMPTY_LIST;
}
/**
* An immutable class representing a type-specific singleton list.
*
*
* This class may be useful to implement your own in case you subclass a
* type-specific list.
*/
public static class Singleton extends AbstractObjectList
implements
RandomAccess,
java.io.Serializable,
Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
private final K element;
protected Singleton(final K element) {
this.element = element;
}
@Override
public K get(final int i) {
if (i == 0)
return element;
throw new IndexOutOfBoundsException();
}
@Override
public boolean remove(Object k) {
throw new UnsupportedOperationException();
}
@Override
public K remove(final int i) {
throw new UnsupportedOperationException();
}
@Override
public boolean contains(final Object k) {
return java.util.Objects.equals(k, element);
}
/* Slightly optimized w.r.t. the one in ABSTRACT_SET. */
@Override
public Object[] toArray() {
Object a[] = new Object[1];
a[0] = element;
return a;
}
@Override
public ObjectListIterator listIterator() {
return ObjectIterators.singleton(element);
}
@Override
public ObjectListIterator iterator() {
return listIterator();
}
@Override
public ObjectListIterator listIterator(final int i) {
if (i > 1 || i < 0)
throw new IndexOutOfBoundsException();
final ObjectListIterator l = listIterator();
if (i == 1)
l.next();
return l;
}
@Override
@SuppressWarnings("unchecked")
public ObjectList subList(final int from, final int to) {
ensureIndex(from);
ensureIndex(to);
if (from > to)
throw new IndexOutOfBoundsException(
"Start index (" + from + ") is greater than end index (" + to + ")");
if (from != 0 || to != 1)
return EMPTY_LIST;
return this;
}
@Override
public boolean addAll(int i, Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(final Collection c) {
throw new UnsupportedOperationException();
}
// Lists of size 1 are trivially always sorted
@Override
public void sort(final java.util.Comparator comparator) {
}
@Override
public void unstableSort(final java.util.Comparator comparator) {
}
@Override
public void removeElements(int from, int to) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public int size() {
return 1;
}
@Override
public void size(final int size) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
@Override
public Object clone() {
return this;
}
}
/**
* Returns a type-specific immutable list containing only the specified element.
* The returned list is serializable and cloneable.
*
* @param element
* the only element of the returned list.
* @return a type-specific immutable list containing just {@code element}.
*/
public static ObjectList singleton(final K element) {
return new Singleton<>(element);
}
/** A synchronized wrapper class for lists. */
public static class SynchronizedList extends ObjectCollections.SynchronizedCollection
implements
ObjectList,
java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ObjectList list; // Due to the large number of methods that are not in COLLECTION, this is
// worth caching.
protected SynchronizedList(final ObjectList l, final Object sync) {
super(l, sync);
this.list = l;
}
protected SynchronizedList(final ObjectList l) {
super(l);
this.list = l;
}
@Override
public K get(final int i) {
synchronized (sync) {
return list.get(i);
}
}
@Override
public K set(final int i, final K k) {
synchronized (sync) {
return list.set(i, k);
}
}
@Override
public void add(final int i, final K k) {
synchronized (sync) {
list.add(i, k);
}
}
@Override
public K remove(final int i) {
synchronized (sync) {
return list.remove(i);
}
}
@Override
public int indexOf(final Object k) {
synchronized (sync) {
return list.indexOf(k);
}
}
@Override
public int lastIndexOf(final Object k) {
synchronized (sync) {
return list.lastIndexOf(k);
}
}
@Override
public boolean addAll(final int index, final Collection c) {
synchronized (sync) {
return list.addAll(index, c);
}
}
@Override
public void getElements(final int from, final Object a[], final int offset, final int length) {
synchronized (sync) {
list.getElements(from, a, offset, length);
}
}
@Override
public void removeElements(final int from, final int to) {
synchronized (sync) {
list.removeElements(from, to);
}
}
@Override
public void addElements(int index, final K a[], int offset, int length) {
synchronized (sync) {
list.addElements(index, a, offset, length);
}
}
@Override
public void addElements(int index, final K a[]) {
synchronized (sync) {
list.addElements(index, a);
}
}
@Override
public void setElements(final K a[]) {
synchronized (sync) {
list.setElements(a);
}
}
@Override
public void setElements(int index, final K a[]) {
synchronized (sync) {
list.setElements(index, a);
}
}
@Override
public void setElements(int index, final K a[], int offset, int length) {
synchronized (sync) {
list.setElements(index, a, offset, length);
}
}
@Override
public void size(final int size) {
synchronized (sync) {
list.size(size);
}
}
@Override
public ObjectListIterator listIterator() {
return list.listIterator();
}
@Override
public ObjectListIterator iterator() {
return listIterator();
}
@Override
public ObjectListIterator listIterator(final int i) {
return list.listIterator(i);
}
@Override
public ObjectList subList(final int from, final int to) {
synchronized (sync) {
return new SynchronizedList<>(list.subList(from, to), sync);
}
}
@Override
public boolean equals(final Object o) {
if (o == this)
return true;
synchronized (sync) {
return collection.equals(o);
}
}
@Override
public int hashCode() {
synchronized (sync) {
return collection.hashCode();
}
}
@Override
public int compareTo(final List o) {
synchronized (sync) {
return list.compareTo(o);
}
}
@Override
public void sort(final java.util.Comparator comparator) {
synchronized (sync) {
list.sort(comparator);
}
}
@Override
public void unstableSort(final java.util.Comparator comparator) {
synchronized (sync) {
list.unstableSort(comparator);
}
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
synchronized (sync) {
s.defaultWriteObject();
}
}
}
/** A synchronized wrapper class for random-access lists. */
public static class SynchronizedRandomAccessList extends SynchronizedList
implements
RandomAccess,
java.io.Serializable {
private static final long serialVersionUID = 0L;
protected SynchronizedRandomAccessList(final ObjectList l, final Object sync) {
super(l, sync);
}
protected SynchronizedRandomAccessList(final ObjectList l) {
super(l);
}
@Override
public ObjectList subList(final int from, final int to) {
synchronized (sync) {
return new SynchronizedRandomAccessList<>(list.subList(from, to), sync);
}
}
}
/**
* Returns a synchronized type-specific list backed by the given type-specific
* list.
*
* @param l
* the list to be wrapped in a synchronized list.
* @return a synchronized view of the specified list.
* @see java.util.Collections#synchronizedList(List)
*/
public static ObjectList synchronize(final ObjectList l) {
return l instanceof RandomAccess ? new SynchronizedRandomAccessList<>(l) : new SynchronizedList<>(l);
}
/**
* Returns a synchronized type-specific list backed by the given type-specific
* list, using an assigned object to synchronize.
*
* @param l
* the list to be wrapped in a synchronized list.
* @param sync
* an object that will be used to synchronize the access to the list.
* @return a synchronized view of the specified list.
* @see java.util.Collections#synchronizedList(List)
*/
public static ObjectList synchronize(final ObjectList l, final Object sync) {
return l instanceof RandomAccess
? new SynchronizedRandomAccessList<>(l, sync)
: new SynchronizedList<>(l, sync);
}
/** An unmodifiable wrapper class for lists. */
public static class UnmodifiableList extends ObjectCollections.UnmodifiableCollection
implements
ObjectList,
java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ObjectList list; // Due to the large number of methods that are not in COLLECTION, this is
// worth caching.
protected UnmodifiableList(final ObjectList l) {
super(l);
this.list = l;
}
@Override
public K get(final int i) {
return list.get(i);
}
@Override
public K set(final int i, final K k) {
throw new UnsupportedOperationException();
}
@Override
public void add(final int i, final K k) {
throw new UnsupportedOperationException();
}
@Override
public K remove(final int i) {
throw new UnsupportedOperationException();
}
@Override
public int indexOf(final Object k) {
return list.indexOf(k);
}
@Override
public int lastIndexOf(final Object k) {
return list.lastIndexOf(k);
}
@Override
public boolean addAll(final int index, final Collection c) {
throw new UnsupportedOperationException();
}
@Override
public void getElements(final int from, final Object a[], final int offset, final int length) {
list.getElements(from, a, offset, length);
}
@Override
public void removeElements(final int from, final int to) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, final K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public void addElements(int index, final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[]) {
throw new UnsupportedOperationException();
}
@Override
public void setElements(int index, final K a[], int offset, int length) {
throw new UnsupportedOperationException();
}
@Override
public void size(final int size) {
list.size(size);
}
@Override
public ObjectListIterator listIterator() {
return ObjectIterators.unmodifiable(list.listIterator());
}
@Override
public ObjectListIterator iterator() {
return listIterator();
}
@Override
public ObjectListIterator listIterator(final int i) {
return ObjectIterators.unmodifiable(list.listIterator(i));
}
@Override
public ObjectList subList(final int from, final int to) {
return new UnmodifiableList<>(list.subList(from, to));
}
@Override
public boolean equals(final Object o) {
if (o == this)
return true;
return collection.equals(o);
}
@Override
public int hashCode() {
return collection.hashCode();
}
@Override
public int compareTo(final List o) {
return list.compareTo(o);
}
@Override
public void sort(final java.util.Comparator comparator) {
throw new UnsupportedOperationException();
}
@Override
public void unstableSort(final java.util.Comparator comparator) {
throw new UnsupportedOperationException();
}
}
/** An unmodifiable wrapper class for random-access lists. */
public static class UnmodifiableRandomAccessList extends UnmodifiableList
implements
RandomAccess,
java.io.Serializable {
private static final long serialVersionUID = 0L;
protected UnmodifiableRandomAccessList(final ObjectList l) {
super(l);
}
@Override
public ObjectList subList(final int from, final int to) {
return new UnmodifiableRandomAccessList<>(list.subList(from, to));
}
}
/**
* Returns an unmodifiable type-specific list backed by the given type-specific
* list.
*
* @param l
* the list to be wrapped in an unmodifiable list.
* @return an unmodifiable view of the specified list.
* @see java.util.Collections#unmodifiableList(List)
*/
public static ObjectList unmodifiable(final ObjectList l) {
return l instanceof RandomAccess ? new UnmodifiableRandomAccessList<>(l) : new UnmodifiableList<>(l);
}
}