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/*
* Copyright (C) 2002-2023 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.ints;
import java.util.Collection;
import java.util.Set;
import java.util.function.Consumer;
/**
* A class providing static methods and objects that do useful things with type-specific sets.
*
* @see java.util.Collections
*/
public final class IntSets {
private IntSets() {
}
/** The maximum size to choose ArraySet over OpenHashSet for utilites that automatically choose. */
static final int ARRAY_SET_CUTOFF = 4;
/**
* An immutable class representing the empty set and implementing a type-specific set interface.
*
*
* This class may be useful to implement your own in case you subclass a type-specific set.
*/
public static class EmptySet extends IntCollections.EmptyCollection implements IntSet, java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptySet() {
}
@Override
public boolean remove(int ok) {
throw new UnsupportedOperationException();
}
@Override
public Object clone() {
return EMPTY_SET;
}
@Override
@SuppressWarnings("rawtypes")
public boolean equals(final Object o) {
return o instanceof Set && ((Set)o).isEmpty();
}
@Deprecated
@Override
public boolean rem(final int k) {
return super.rem(k);
}
private Object readResolve() {
return EMPTY_SET;
}
}
/**
* An empty set (immutable). It is serializable and cloneable.
*/
public static final EmptySet EMPTY_SET = new EmptySet();
// Used by Sets.of() instead of SETS.EMPTY_SET to make a dimorphic call site.
// See https://github.com/vigna/fastutil/issues/183
static final IntSet UNMODIFIABLE_EMPTY_SET = IntSets.unmodifiable(new IntArraySet(IntArrays.EMPTY_ARRAY));
/**
* Returns an empty set (immutable). It is serializable and cloneable.
*
*
* This method provides a typesafe access to {@link #EMPTY_SET}.
*
* @return an empty set (immutable).
*/
@SuppressWarnings("unchecked")
public static IntSet emptySet() {
return EMPTY_SET;
}
/**
* An immutable class representing a type-specific singleton set.
*
*
* This class may be useful to implement your own in case you subclass a type-specific set.
*/
public static class Singleton extends AbstractIntSet implements java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected final int element;
protected Singleton(final int element) {
this.element = element;
}
@Override
public boolean contains(final int k) {
return ((k) == (element));
}
@Override
public boolean remove(final int k) {
throw new UnsupportedOperationException();
}
@Override
public IntListIterator iterator() {
return IntIterators.singleton(element);
}
@Override
public IntSpliterator spliterator() {
return IntSpliterators.singleton(element);
}
@Override
public int size() {
return 1;
}
@Override
public int[] toIntArray() {
return new int[] { element };
}
@Deprecated
@Override
public void forEach(final Consumer action) {
action.accept(Integer.valueOf(element));
}
@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();
}
@Deprecated
@Override
public boolean removeIf(final java.util.function.Predicate filter) {
throw new UnsupportedOperationException();
}
@Override
public void forEach(final java.util.function.IntConsumer action) {
action.accept(element);
}
@Override
public boolean addAll(final IntCollection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(final IntCollection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(final IntCollection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeIf(final java.util.function.IntPredicate filter) {
throw new UnsupportedOperationException();
}
@Deprecated
@Override
public Object[] toArray() {
return new Object[] { Integer.valueOf(element) };
}
@Override
public Object clone() {
return this;
}
}
/**
* Returns a type-specific immutable set containing only the specified element. The returned set is
* serializable and cloneable.
*
* @param element the only element of the returned set.
* @return a type-specific immutable set containing just {@code element}.
*/
public static IntSet singleton(final int element) {
return new Singleton(element);
}
/**
* Returns a type-specific immutable set containing only the specified element. The returned set is
* serializable and cloneable.
*
* @param element the only element of the returned set.
* @return a type-specific immutable set containing just {@code element}.
*/
public static IntSet singleton(final Integer element) {
return new Singleton((element).intValue());
}
/** A synchronized wrapper class for sets. */
public static class SynchronizedSet extends IntCollections.SynchronizedCollection implements IntSet, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected SynchronizedSet(final IntSet s, final Object sync) {
super(s, sync);
}
protected SynchronizedSet(final IntSet s) {
super(s);
}
@Override
public boolean remove(final int k) {
synchronized (sync) {
return collection.rem(k);
}
}
@Deprecated
@Override
public boolean rem(final int k) {
return super.rem(k);
}
}
/**
* Returns a synchronized type-specific set backed by the given type-specific set.
*
* @param s the set to be wrapped in a synchronized set.
* @return a synchronized view of the specified set.
* @see java.util.Collections#synchronizedSet(Set)
*/
public static IntSet synchronize(final IntSet s) {
return new SynchronizedSet(s);
}
/**
* Returns a synchronized type-specific set backed by the given type-specific set, using an assigned
* object to synchronize.
*
* @param s the set to be wrapped in a synchronized set.
* @param sync an object that will be used to synchronize the access to the set.
* @return a synchronized view of the specified set.
* @see java.util.Collections#synchronizedSet(Set)
*/
public static IntSet synchronize(final IntSet s, final Object sync) {
return new SynchronizedSet(s, sync);
}
/** An unmodifiable wrapper class for sets. */
public static class UnmodifiableSet extends IntCollections.UnmodifiableCollection implements IntSet, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
protected UnmodifiableSet(final IntSet s) {
super(s);
}
@Override
public boolean remove(final int k) {
throw new UnsupportedOperationException();
}
@Override
public boolean equals(final Object o) {
if (o == this) return true;
return collection.equals(o);
}
@Override
public int hashCode() {
return collection.hashCode();
}
@Deprecated
@Override
public boolean rem(final int k) {
return super.rem(k);
}
}
/**
* Returns an unmodifiable type-specific set backed by the given type-specific set.
*
* @param s the set to be wrapped in an unmodifiable set.
* @return an unmodifiable view of the specified set.
* @see java.util.Collections#unmodifiableSet(Set)
*/
public static IntSet unmodifiable(final IntSet s) {
return new UnmodifiableSet(s);
}
/**
* Returns an unmodifiable type-specific set containing elements in the given range.
*
* @param from the starting element (lower bound) of the set (inclusive).
* @param to the ending element (upper bound) of the set (exclusive).
* @return an unmodifiable set containing the elements in the given range.
*/
public static IntSet fromTo(final int from, final int to) {
return new AbstractIntSet() {
@Override
public boolean contains(final int x) {
return x >= from && x < to;
}
@Override
public IntIterator iterator() {
return IntIterators.fromTo(from, to);
}
@Override
public int size() {
final long size = (long)to - (long)from;
return size >= 0 && size <= Integer.MAX_VALUE ? (int)size : Integer.MAX_VALUE;
}
};
}
/**
* Returns an unmodifiable type-specific set containing elements greater than or equal to a given
* element.
*
* @param from the starting element (lower bound) of the set (inclusive).
* @return an unmodifiable set containing the elements greater than or equal to {@code from}.
*/
public static IntSet from(final int from) {
return new AbstractIntSet() {
@Override
public boolean contains(final int x) {
return x >= from;
}
@Override
public IntIterator iterator() {
return IntIterators.concat(new IntIterator[] { IntIterators.fromTo(from, Integer.MAX_VALUE),
IntSets.singleton(Integer.MAX_VALUE).iterator() });
}
@Override
public int size() {
final long size = Integer.MAX_VALUE - (long)from + 1;
return size >= 0 && size <= Integer.MAX_VALUE ? (int)size : Integer.MAX_VALUE;
}
};
}
/**
* Returns an unmodifiable type-specific set containing elements smaller than a given element.
*
* @param to the ending element (upper bound) of the set (exclusive).
* @return an unmodifiable set containing the elements smaller than {@code to}.
*/
public static IntSet to(final int to) {
return new AbstractIntSet() {
@Override
public boolean contains(final int x) {
return x < to;
}
@Override
public IntIterator iterator() {
return IntIterators.fromTo(Integer.MIN_VALUE, to);
}
@Override
public int size() {
final long size = (long)to - Integer.MIN_VALUE;
return size >= 0 && size <= Integer.MAX_VALUE ? (int)size : Integer.MAX_VALUE;
}
};
}
}