it.unimi.dsi.fastutil.objects.ReferenceSortedSets Maven / Gradle / Ivy
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/*
* Copyright (C) 2002-2022 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.SortedSet;
import java.util.NoSuchElementException;
import java.util.Comparator;
/**
* A class providing static methods and objects that do useful things with type-specific sorted
* sets.
*
* @see java.util.Collections
*/
public final class ReferenceSortedSets {
private ReferenceSortedSets() {
}
/**
* An immutable class representing the empty sorted set and implementing a type-specific set
* interface.
*
*
* This class may be useful to implement your own in case you subclass a type-specific sorted set.
*/
public static class EmptySet extends ReferenceSets.EmptySet implements ReferenceSortedSet, java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptySet() {
}
@Override
@SuppressWarnings("unchecked")
public ObjectBidirectionalIterator iterator(K from) {
return ObjectIterators.EMPTY_ITERATOR;
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet subSet(K from, K to) {
return EMPTY_SET;
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet headSet(K from) {
return EMPTY_SET;
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet tailSet(K to) {
return EMPTY_SET;
}
@Override
public K first() {
throw new NoSuchElementException();
}
@Override
public K last() {
throw new NoSuchElementException();
}
@Override
public Comparator comparator() {
return null;
}
@Override
public Object clone() {
return EMPTY_SET;
}
private Object readResolve() {
return EMPTY_SET;
}
}
/**
* An empty sorted set (immutable). It is serializable and cloneable.
*
*/
@SuppressWarnings("rawtypes")
public static final EmptySet EMPTY_SET = new EmptySet();
/**
* Returns an empty sorted set (immutable). It is serializable and cloneable.
*
*
* This method provides a typesafe access to {@link #EMPTY_SET}.
*
* @return an empty sorted set (immutable).
*/
@SuppressWarnings("unchecked")
public static ReferenceSet emptySet() {
return EMPTY_SET;
}
/**
* A class representing a singleton sorted set.
*
*
* This class may be useful to implement your own in case you subclass a type-specific sorted set.
*
*/
public static class Singleton extends ReferenceSets.Singleton implements ReferenceSortedSet, java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
final Comparator comparator;
protected Singleton(final K element, final Comparator comparator) {
super(element);
this.comparator = comparator;
}
Singleton(final K element) {
this(element, null);
}
@SuppressWarnings("unchecked")
final int compare(final K k1, final K k2) {
return comparator == null ? (((Comparable)(k1)).compareTo(k2)) : comparator.compare(k1, k2);
}
@Override
public ObjectBidirectionalIterator iterator(K from) {
ObjectBidirectionalIterator i = iterator();
if (compare(element, from) <= 0) i.next();
return i;
}
@Override
public Comparator comparator() {
return comparator;
}
@Override
public ObjectSpliterator spliterator() {
return ObjectSpliterators.singleton(element, comparator);
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet subSet(final K from, final K to) {
if (compare(from, element) <= 0 && compare(element, to) < 0) return this;
return EMPTY_SET;
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet headSet(final K to) {
if (compare(element, to) < 0) return this;
return EMPTY_SET;
}
@Override
@SuppressWarnings("unchecked")
public ReferenceSortedSet tailSet(final K from) {
if (compare(from, element) <= 0) return this;
return EMPTY_SET;
}
@Override
public K first() {
return element;
}
@Override
public K last() {
return element;
}
}
/**
* Returns a type-specific immutable sorted set containing only the specified element. The returned
* sorted set is serializable and cloneable.
*
* @param element the only element of the returned sorted set.
* @return a type-specific immutable sorted set containing just {@code element}.
*/
public static ReferenceSortedSet singleton(final K element) {
return new Singleton<>(element);
}
/**
* Returns a type-specific immutable sorted set containing only the specified element, and using a
* specified comparator. The returned sorted set is serializable and cloneable.
*
* @param element the only element of the returned sorted set.
* @param comparator the comparator to use in the returned sorted set.
* @return a type-specific immutable sorted set containing just {@code element}.
*/
public static ReferenceSortedSet singleton(final K element, final Comparator comparator) {
return new Singleton<>(element, comparator);
}
/** A synchronized wrapper class for sorted sets. */
public static class SynchronizedSortedSet extends ReferenceSets.SynchronizedSet implements ReferenceSortedSet, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ReferenceSortedSet sortedSet;
protected SynchronizedSortedSet(final ReferenceSortedSet s, final Object sync) {
super(s, sync);
sortedSet = s;
}
protected SynchronizedSortedSet(final ReferenceSortedSet s) {
super(s);
sortedSet = s;
}
@Override
public Comparator comparator() {
synchronized (sync) {
return sortedSet.comparator();
}
}
@Override
public ReferenceSortedSet subSet(final K from, final K to) {
return new SynchronizedSortedSet<>(sortedSet.subSet(from, to), sync);
}
@Override
public ReferenceSortedSet headSet(final K to) {
return new SynchronizedSortedSet<>(sortedSet.headSet(to), sync);
}
@Override
public ReferenceSortedSet tailSet(final K from) {
return new SynchronizedSortedSet<>(sortedSet.tailSet(from), sync);
}
@Override
public ObjectBidirectionalIterator iterator() {
return sortedSet.iterator();
}
@Override
public ObjectBidirectionalIterator iterator(final K from) {
return sortedSet.iterator(from);
}
@Override
public K first() {
synchronized (sync) {
return sortedSet.first();
}
}
@Override
public K last() {
synchronized (sync) {
return sortedSet.last();
}
}
}
/**
* Returns a synchronized type-specific sorted set backed by the given type-specific sorted set.
*
* @param s the sorted set to be wrapped in a synchronized sorted set.
* @return a synchronized view of the specified sorted set.
* @see java.util.Collections#synchronizedSortedSet(SortedSet)
*/
public static ReferenceSortedSet synchronize(final ReferenceSortedSet s) {
return new SynchronizedSortedSet<>(s);
}
/**
* Returns a synchronized type-specific sorted set backed by the given type-specific sorted set,
* using an assigned object to synchronize.
*
* @param s the sorted set to be wrapped in a synchronized sorted set.
* @param sync an object that will be used to synchronize the access to the sorted set.
* @return a synchronized view of the specified sorted set.
* @see java.util.Collections#synchronizedSortedSet(SortedSet)
*/
public static ReferenceSortedSet synchronize(final ReferenceSortedSet s, final Object sync) {
return new SynchronizedSortedSet<>(s, sync);
}
/** An unmodifiable wrapper class for sorted sets. */
public static class UnmodifiableSortedSet extends ReferenceSets.UnmodifiableSet implements ReferenceSortedSet, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected final ReferenceSortedSet sortedSet;
protected UnmodifiableSortedSet(final ReferenceSortedSet s) {
super(s);
sortedSet = s;
}
@Override
public Comparator comparator() {
return sortedSet.comparator();
}
@Override
public ReferenceSortedSet subSet(final K from, final K to) {
return new UnmodifiableSortedSet<>(sortedSet.subSet(from, to));
}
@Override
public ReferenceSortedSet headSet(final K to) {
return new UnmodifiableSortedSet<>(sortedSet.headSet(to));
}
@Override
public ReferenceSortedSet tailSet(final K from) {
return new UnmodifiableSortedSet<>(sortedSet.tailSet(from));
}
@Override
public ObjectBidirectionalIterator iterator() {
return ObjectIterators.unmodifiable(sortedSet.iterator());
}
@Override
public ObjectBidirectionalIterator iterator(final K from) {
return ObjectIterators.unmodifiable(sortedSet.iterator(from));
}
@Override
public K first() {
return sortedSet.first();
}
@Override
public K last() {
return sortedSet.last();
}
}
/**
* Returns an unmodifiable type-specific sorted set backed by the given type-specific sorted set.
*
* @param s the sorted set to be wrapped in an unmodifiable sorted set.
* @return an unmodifiable view of the specified sorted set.
* @see java.util.Collections#unmodifiableSortedSet(SortedSet)
*/
public static ReferenceSortedSet unmodifiable(final ReferenceSortedSet s) {
return new UnmodifiableSortedSet<>(s);
}
}