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/*
* Copyright (C) 2002-2021 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.Collection;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.Predicate;
/**
* A class providing static methods and objects that do useful things with
* type-specific collections.
*
* @see java.util.Collections
*/
public final class ReferenceCollections {
private ReferenceCollections() {
}
/**
* An immutable class representing an empty type-specific collection.
*
*
* This class may be useful to implement your own in case you subclass a
* type-specific collection.
*/
public abstract static class EmptyCollection extends AbstractReferenceCollection {
protected EmptyCollection() {
}
@Override
public boolean contains(Object k) {
return false;
}
@Override
public Object[] toArray() {
return ObjectArrays.EMPTY_ARRAY;
}
@Override
public T[] toArray(T[] array) {
if (array.length > 0)
array[0] = null;
return array;
}
@Override
@SuppressWarnings("unchecked")
public ObjectBidirectionalIterator iterator() {
return ObjectIterators.EMPTY_ITERATOR;
}
@Override
@SuppressWarnings("unchecked")
public ObjectSpliterator spliterator() {
return ObjectSpliterators.EMPTY_SPLITERATOR;
}
@Override
public int size() {
return 0;
}
@Override
public void clear() {
}
@Override
public int hashCode() {
return 0;
}
@Override
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof Collection))
return false;
return ((Collection) o).isEmpty();
}
@Override
public void forEach(final Consumer action) {
}
@Override
public boolean containsAll(final Collection c) {
return c.isEmpty();
}
@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();
}
@Override
public boolean removeIf(final java.util.function.Predicate filter) {
Objects.requireNonNull(filter);
return false;
}
}
/** A synchronized wrapper class for collections. */
static class SynchronizedCollection implements ReferenceCollection, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ReferenceCollection collection;
protected final Object sync;
protected SynchronizedCollection(final ReferenceCollection c, final Object sync) {
this.collection = Objects.requireNonNull(c);
this.sync = sync;
}
protected SynchronizedCollection(final ReferenceCollection c) {
this.collection = Objects.requireNonNull(c);
this.sync = this;
}
@Override
public boolean add(final K k) {
synchronized (sync) {
return collection.add(k);
}
}
@Override
public boolean contains(final Object k) {
synchronized (sync) {
return collection.contains(k);
}
}
@Override
public boolean remove(final Object k) {
synchronized (sync) {
return collection.remove(k);
}
}
@Override
public int size() {
synchronized (sync) {
return collection.size();
}
}
@Override
public boolean isEmpty() {
synchronized (sync) {
return collection.isEmpty();
}
}
@Override
public Object[] toArray() {
synchronized (sync) {
return collection.toArray();
}
}
@Override
public T[] toArray(final T[] a) {
synchronized (sync) {
return collection.toArray(a);
}
}
@Override
public ObjectIterator iterator() {
return collection.iterator();
}
@Override
public ObjectSpliterator spliterator() {
return collection.spliterator();
}
@Override
public java.util.stream.Stream stream() {
return collection.stream();
}
@Override
public java.util.stream.Stream parallelStream() {
return collection.parallelStream();
}
@Override
public void forEach(final Consumer action) {
synchronized (sync) {
collection.forEach(action);
}
}
@Override
public boolean addAll(final Collection c) {
synchronized (sync) {
return collection.addAll(c);
}
}
@Override
public boolean containsAll(final Collection c) {
synchronized (sync) {
return collection.containsAll(c);
}
}
@Override
public boolean removeAll(final Collection c) {
synchronized (sync) {
return collection.removeAll(c);
}
}
@Override
public boolean retainAll(final Collection c) {
synchronized (sync) {
return collection.retainAll(c);
}
}
@Override
public boolean removeIf(final Predicate filter) {
synchronized (sync) {
return collection.removeIf(filter);
}
}
@Override
public void clear() {
synchronized (sync) {
collection.clear();
}
}
@Override
public String toString() {
synchronized (sync) {
return collection.toString();
}
}
@Override
public int hashCode() {
synchronized (sync) {
return collection.hashCode();
}
}
@Override
public boolean equals(final Object o) {
if (o == this)
return true;
synchronized (sync) {
return collection.equals(o);
}
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
synchronized (sync) {
s.defaultWriteObject();
}
}
}
/**
* Returns a synchronized collection backed by the specified collection.
*
* @param c
* the collection to be wrapped in a synchronized collection.
* @return a synchronized view of the specified collection.
* @see java.util.Collections#synchronizedCollection(Collection)
*/
public static ReferenceCollection synchronize(final ReferenceCollection c) {
return new SynchronizedCollection<>(c);
}
/**
* Returns a synchronized collection backed by the specified collection, using
* an assigned object to synchronize.
*
* @param c
* the collection to be wrapped in a synchronized collection.
* @param sync
* an object that will be used to synchronize the list access.
* @return a synchronized view of the specified collection.
* @see java.util.Collections#synchronizedCollection(Collection)
*/
public static ReferenceCollection synchronize(final ReferenceCollection c, final Object sync) {
return new SynchronizedCollection<>(c, sync);
}
/** An unmodifiable wrapper class for collections. */
static class UnmodifiableCollection implements ReferenceCollection, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ReferenceCollection collection;
protected UnmodifiableCollection(final ReferenceCollection c) {
this.collection = Objects.requireNonNull(c);
}
@Override
public boolean add(final K k) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(final Object k) {
throw new UnsupportedOperationException();
}
@Override
public int size() {
return collection.size();
}
@Override
public boolean isEmpty() {
return collection.isEmpty();
}
@Override
public boolean contains(final Object o) {
return collection.contains(o);
}
@Override
public ObjectIterator iterator() {
return ObjectIterators.unmodifiable(collection.iterator());
}
@Override
public ObjectSpliterator spliterator() {
return collection.spliterator();
}
@Override
public java.util.stream.Stream stream() {
return collection.stream();
}
@Override
public java.util.stream.Stream parallelStream() {
return collection.parallelStream();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
@Override
public T[] toArray(final T[] a) {
return collection.toArray(a);
}
@Override
public Object[] toArray() {
return collection.toArray();
}
@Override
public void forEach(final Consumer action) {
collection.forEach(action);
}
@Override
public boolean containsAll(Collection c) {
return collection.containsAll(c);
}
@Override
public boolean addAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeIf(final Predicate filter) {
throw new UnsupportedOperationException();
}
@Override
public String toString() {
return collection.toString();
}
@Override
public int hashCode() {
return collection.hashCode();
}
@Override
public boolean equals(final Object o) {
if (o == this)
return true;
return collection.equals(o);
}
}
/**
* Returns an unmodifiable collection backed by the specified collection.
*
* @param c
* the collection to be wrapped in an unmodifiable collection.
* @return an unmodifiable view of the specified collection.
* @see java.util.Collections#unmodifiableCollection(Collection)
*/
public static ReferenceCollection unmodifiable(final ReferenceCollection c) {
return new UnmodifiableCollection<>(c);
}
/** A collection wrapper class for iterables. */
public static class IterableCollection extends AbstractReferenceCollection implements java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ObjectIterable iterable;
protected IterableCollection(final ObjectIterable iterable) {
this.iterable = Objects.requireNonNull(iterable);
}
@Override
public int size() {
long size = iterable.spliterator().getExactSizeIfKnown();
if (size >= 0)
return (int) Math.min(Integer.MAX_VALUE, size);
int c = 0;
final ObjectIterator iterator = iterator();
while (iterator.hasNext()) {
iterator.next();
c++;
}
return c;
}
@Override
public boolean isEmpty() {
return !iterable.iterator().hasNext();
}
@Override
public ObjectIterator iterator() {
return iterable.iterator();
}
@Override
public ObjectSpliterator spliterator() {
return iterable.spliterator();
}
}
/**
* Returns an unmodifiable collection backed by the specified iterable.
*
* @param iterable
* the iterable object to be wrapped in an unmodifiable collection.
* @return an unmodifiable collection view of the specified iterable.
*/
public static ReferenceCollection asCollection(final ObjectIterable iterable) {
if (iterable instanceof ReferenceCollection)
return (ReferenceCollection) iterable;
// TODO test for Collection but not our collection, and make a wrapper for it.
return new IterableCollection<>(iterable);
}
}