All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.facebook.presto.jdbc.internal.guava.collect.Sets Maven / Gradle / Ivy

The newest version!
/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 com.facebook.presto.jdbc.internal.guava.collect;

import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkArgument;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkNotNull;
import static com.facebook.presto.jdbc.internal.guava.collect.CollectPreconditions.checkNonnegative;

import com.facebook.presto.jdbc.internal.guava.annotations.GwtCompatible;
import com.facebook.presto.jdbc.internal.guava.annotations.GwtIncompatible;
import com.facebook.presto.jdbc.internal.guava.annotations.J2ktIncompatible;
import com.facebook.presto.jdbc.internal.guava.base.Predicate;
import com.facebook.presto.jdbc.internal.guava.base.Predicates;
import com.facebook.presto.jdbc.internal.guava.collect.Collections2.FilteredCollection;
import com.facebook.presto.jdbc.internal.guava.math.IntMath;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.DoNotCall;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.function.Consumer;
import java.util.stream.Collector;
import java.util.stream.Stream;
import com.facebook.presto.jdbc.internal.javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static utility methods pertaining to {@link Set} instances. Also see this class's counterparts
 * {@link Lists}, {@link Maps} and {@link Queues}.
 *
 * 

See the Guava User Guide article on {@code Sets}. * * @author Kevin Bourrillion * @author Jared Levy * @author Chris Povirk * @since 2.0 */ @GwtCompatible(emulated = true) @ElementTypesAreNonnullByDefault public final class Sets { private Sets() {} /** * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll} * implementation. */ abstract static class ImprovedAbstractSet extends AbstractSet { @Override public boolean removeAll(Collection c) { return removeAllImpl(this, c); } @Override public boolean retainAll(Collection c) { return super.retainAll(checkNotNull(c)); // GWT compatibility } } /** * Returns an immutable set instance containing the given enum elements. Internally, the returned * set will be backed by an {@link EnumSet}. * *

The iteration order of the returned set follows the enum's iteration order, not the order in * which the elements are provided to the method. * * @param anElement one of the elements the set should contain * @param otherElements the rest of the elements the set should contain * @return an immutable set containing those elements, minus duplicates */ // http://code.google.com/p/google-web-toolkit/issues/detail?id=3028 @GwtCompatible(serializable = true) public static > ImmutableSet immutableEnumSet( E anElement, E... otherElements) { return ImmutableEnumSet.asImmutable(EnumSet.of(anElement, otherElements)); } /** * Returns an immutable set instance containing the given enum elements. Internally, the returned * set will be backed by an {@link EnumSet}. * *

The iteration order of the returned set follows the enum's iteration order, not the order in * which the elements appear in the given collection. * * @param elements the elements, all of the same {@code enum} type, that the set should contain * @return an immutable set containing those elements, minus duplicates */ // http://code.google.com/p/google-web-toolkit/issues/detail?id=3028 @GwtCompatible(serializable = true) public static > ImmutableSet immutableEnumSet(Iterable elements) { if (elements instanceof ImmutableEnumSet) { return (ImmutableEnumSet) elements; } else if (elements instanceof Collection) { Collection collection = (Collection) elements; if (collection.isEmpty()) { return ImmutableSet.of(); } else { return ImmutableEnumSet.asImmutable(EnumSet.copyOf(collection)); } } else { Iterator itr = elements.iterator(); if (itr.hasNext()) { EnumSet enumSet = EnumSet.of(itr.next()); Iterators.addAll(enumSet, itr); return ImmutableEnumSet.asImmutable(enumSet); } else { return ImmutableSet.of(); } } } /** * Returns a {@code Collector} that accumulates the input elements into a new {@code ImmutableSet} * with an implementation specialized for enums. Unlike {@link ImmutableSet#toImmutableSet}, the * resulting set will iterate over elements in their enum definition order, not encounter order. * * @since 21.0 */ public static > Collector> toImmutableEnumSet() { return CollectCollectors.toImmutableEnumSet(); } /** * Returns a new, mutable {@code EnumSet} instance containing the given elements in their * natural order. This method behaves identically to {@link EnumSet#copyOf(Collection)}, but also * accepts non-{@code Collection} iterables and empty iterables. */ public static > EnumSet newEnumSet( Iterable iterable, Class elementType) { EnumSet set = EnumSet.noneOf(elementType); Iterables.addAll(set, iterable); return set; } // HashSet /** * Creates a mutable, initially empty {@code HashSet} instance. * *

Note: if mutability is not required, use {@link ImmutableSet#of()} instead. If {@code * E} is an {@link Enum} type, use {@link EnumSet#noneOf} instead. Otherwise, strongly consider * using a {@code LinkedHashSet} instead, at the cost of increased memory footprint, to get * deterministic iteration behavior. * *

Note: this method is now unnecessary and should be treated as deprecated. Instead, * use the {@code HashSet} constructor directly, taking advantage of "diamond" syntax. */ public static HashSet newHashSet() { return new HashSet(); } /** * Creates a mutable {@code HashSet} instance initially containing the given elements. * *

Note: if elements are non-null and won't be added or removed after this point, use * {@link ImmutableSet#of()} or {@link ImmutableSet#copyOf(Object[])} instead. If {@code E} is an * {@link Enum} type, use {@link EnumSet#of(Enum, Enum[])} instead. Otherwise, strongly consider * using a {@code LinkedHashSet} instead, at the cost of increased memory footprint, to get * deterministic iteration behavior. * *

This method is just a small convenience, either for {@code newHashSet(}{@link Arrays#asList * asList}{@code (...))}, or for creating an empty set then calling {@link Collections#addAll}. * This method is not actually very useful and will likely be deprecated in the future. */ public static HashSet newHashSet(E... elements) { HashSet set = newHashSetWithExpectedSize(elements.length); Collections.addAll(set, elements); return set; } /** * Creates a mutable {@code HashSet} instance containing the given elements. A very thin * convenience for creating an empty set then calling {@link Collection#addAll} or {@link * Iterables#addAll}. * *

Note: if mutability is not required and the elements are non-null, use {@link * ImmutableSet#copyOf(Iterable)} instead. (Or, change {@code elements} to be a {@link * FluentIterable} and call {@code elements.toSet()}.) * *

Note: if {@code E} is an {@link Enum} type, use {@link #newEnumSet(Iterable, Class)} * instead. * *

Note: if {@code elements} is a {@link Collection}, you don't need this method. * Instead, use the {@code HashSet} constructor directly, taking advantage of "diamond" syntax. * *

Overall, this method is not very useful and will likely be deprecated in the future. */ public static HashSet newHashSet(Iterable elements) { return (elements instanceof Collection) ? new HashSet((Collection) elements) : newHashSet(elements.iterator()); } /** * Creates a mutable {@code HashSet} instance containing the given elements. A very thin * convenience for creating an empty set and then calling {@link Iterators#addAll}. * *

Note: if mutability is not required and the elements are non-null, use {@link * ImmutableSet#copyOf(Iterator)} instead. * *

Note: if {@code E} is an {@link Enum} type, you should create an {@link EnumSet} * instead. * *

Overall, this method is not very useful and will likely be deprecated in the future. */ public static HashSet newHashSet(Iterator elements) { HashSet set = newHashSet(); Iterators.addAll(set, elements); return set; } /** * Returns a new hash set using the smallest initial table size that can hold {@code expectedSize} * elements without resizing. Note that this is not what {@link HashSet#HashSet(int)} does, but it * is what most users want and expect it to do. * *

This behavior can't be broadly guaranteed, but has been tested with OpenJDK 1.7 and 1.8. * * @param expectedSize the number of elements you expect to add to the returned set * @return a new, empty hash set with enough capacity to hold {@code expectedSize} elements * without resizing * @throws IllegalArgumentException if {@code expectedSize} is negative */ public static HashSet newHashSetWithExpectedSize( int expectedSize) { return new HashSet(Maps.capacity(expectedSize)); } /** * Creates a thread-safe set backed by a hash map. The set is backed by a {@link * ConcurrentHashMap} instance, and thus carries the same concurrency guarantees. * *

Unlike {@code HashSet}, this class does NOT allow {@code null} to be used as an element. The * set is serializable. * * @return a new, empty thread-safe {@code Set} * @since 15.0 */ public static Set newConcurrentHashSet() { return Platform.newConcurrentHashSet(); } /** * Creates a thread-safe set backed by a hash map and containing the given elements. The set is * backed by a {@link ConcurrentHashMap} instance, and thus carries the same concurrency * guarantees. * *

Unlike {@code HashSet}, this class does NOT allow {@code null} to be used as an element. The * set is serializable. * * @param elements the elements that the set should contain * @return a new thread-safe set containing those elements (minus duplicates) * @throws NullPointerException if {@code elements} or any of its contents is null * @since 15.0 */ public static Set newConcurrentHashSet(Iterable elements) { Set set = newConcurrentHashSet(); Iterables.addAll(set, elements); return set; } // LinkedHashSet /** * Creates a mutable, empty {@code LinkedHashSet} instance. * *

Note: if mutability is not required, use {@link ImmutableSet#of()} instead. * *

Note: this method is now unnecessary and should be treated as deprecated. Instead, * use the {@code LinkedHashSet} constructor directly, taking advantage of "diamond" syntax. * * @return a new, empty {@code LinkedHashSet} */ public static LinkedHashSet newLinkedHashSet() { return new LinkedHashSet(); } /** * Creates a mutable {@code LinkedHashSet} instance containing the given elements in order. * *

Note: if mutability is not required and the elements are non-null, use {@link * ImmutableSet#copyOf(Iterable)} instead. * *

Note: if {@code elements} is a {@link Collection}, you don't need this method. * Instead, use the {@code LinkedHashSet} constructor directly, taking advantage of "diamond" syntax. * *

Overall, this method is not very useful and will likely be deprecated in the future. * * @param elements the elements that the set should contain, in order * @return a new {@code LinkedHashSet} containing those elements (minus duplicates) */ public static LinkedHashSet newLinkedHashSet( Iterable elements) { if (elements instanceof Collection) { return new LinkedHashSet((Collection) elements); } LinkedHashSet set = newLinkedHashSet(); Iterables.addAll(set, elements); return set; } /** * Creates a {@code LinkedHashSet} instance, with a high enough "initial capacity" that it * should hold {@code expectedSize} elements without growth. This behavior cannot be * broadly guaranteed, but it is observed to be true for OpenJDK 1.7. It also can't be guaranteed * that the method isn't inadvertently oversizing the returned set. * * @param expectedSize the number of elements you expect to add to the returned set * @return a new, empty {@code LinkedHashSet} with enough capacity to hold {@code expectedSize} * elements without resizing * @throws IllegalArgumentException if {@code expectedSize} is negative * @since 11.0 */ public static LinkedHashSet newLinkedHashSetWithExpectedSize( int expectedSize) { return new LinkedHashSet(Maps.capacity(expectedSize)); } // TreeSet /** * Creates a mutable, empty {@code TreeSet} instance sorted by the natural sort ordering of * its elements. * *

Note: if mutability is not required, use {@link ImmutableSortedSet#of()} instead. * *

Note: this method is now unnecessary and should be treated as deprecated. Instead, * use the {@code TreeSet} constructor directly, taking advantage of "diamond" syntax. * * @return a new, empty {@code TreeSet} */ public static TreeSet newTreeSet() { return new TreeSet(); } /** * Creates a mutable {@code TreeSet} instance containing the given elements sorted by their * natural ordering. * *

Note: if mutability is not required, use {@link ImmutableSortedSet#copyOf(Iterable)} * instead. * *

Note: If {@code elements} is a {@code SortedSet} with an explicit comparator, this * method has different behavior than {@link TreeSet#TreeSet(SortedSet)}, which returns a {@code * TreeSet} with that comparator. * *

Note: this method is now unnecessary and should be treated as deprecated. Instead, * use the {@code TreeSet} constructor directly, taking advantage of "diamond" syntax. * *

This method is just a small convenience for creating an empty set and then calling {@link * Iterables#addAll}. This method is not very useful and will likely be deprecated in the future. * * @param elements the elements that the set should contain * @return a new {@code TreeSet} containing those elements (minus duplicates) */ public static TreeSet newTreeSet(Iterable elements) { TreeSet set = newTreeSet(); Iterables.addAll(set, elements); return set; } /** * Creates a mutable, empty {@code TreeSet} instance with the given comparator. * *

Note: if mutability is not required, use {@code * ImmutableSortedSet.orderedBy(comparator).build()} instead. * *

Note: this method is now unnecessary and should be treated as deprecated. Instead, * use the {@code TreeSet} constructor directly, taking advantage of "diamond" syntax. One caveat to this is that the {@code TreeSet} * constructor uses a null {@code Comparator} to mean "natural ordering," whereas this factory * rejects null. Clean your code accordingly. * * @param comparator the comparator to use to sort the set * @return a new, empty {@code TreeSet} * @throws NullPointerException if {@code comparator} is null */ public static TreeSet newTreeSet( Comparator comparator) { return new TreeSet(checkNotNull(comparator)); } /** * Creates an empty {@code Set} that uses identity to determine equality. It compares object * references, instead of calling {@code equals}, to determine whether a provided object matches * an element in the set. For example, {@code contains} returns {@code false} when passed an * object that equals a set member, but isn't the same instance. This behavior is similar to the * way {@code IdentityHashMap} handles key lookups. * * @since 8.0 */ public static Set newIdentityHashSet() { return Collections.newSetFromMap(Maps.newIdentityHashMap()); } /** * Creates an empty {@code CopyOnWriteArraySet} instance. * *

Note: if you need an immutable empty {@link Set}, use {@link Collections#emptySet} * instead. * * @return a new, empty {@code CopyOnWriteArraySet} * @since 12.0 */ @J2ktIncompatible @GwtIncompatible // CopyOnWriteArraySet public static CopyOnWriteArraySet newCopyOnWriteArraySet() { return new CopyOnWriteArraySet(); } /** * Creates a {@code CopyOnWriteArraySet} instance containing the given elements. * * @param elements the elements that the set should contain, in order * @return a new {@code CopyOnWriteArraySet} containing those elements * @since 12.0 */ @J2ktIncompatible @GwtIncompatible // CopyOnWriteArraySet public static CopyOnWriteArraySet newCopyOnWriteArraySet( Iterable elements) { // We copy elements to an ArrayList first, rather than incurring the // quadratic cost of adding them to the COWAS directly. Collection elementsCollection = (elements instanceof Collection) ? (Collection) elements : Lists.newArrayList(elements); return new CopyOnWriteArraySet(elementsCollection); } /** * Creates an {@code EnumSet} consisting of all enum values that are not in the specified * collection. If the collection is an {@link EnumSet}, this method has the same behavior as * {@link EnumSet#complementOf}. Otherwise, the specified collection must contain at least one * element, in order to determine the element type. If the collection could be empty, use {@link * #complementOf(Collection, Class)} instead of this method. * * @param collection the collection whose complement should be stored in the enum set * @return a new, modifiable {@code EnumSet} containing all values of the enum that aren't present * in the given collection * @throws IllegalArgumentException if {@code collection} is not an {@code EnumSet} instance and * contains no elements */ @J2ktIncompatible @GwtIncompatible public static > EnumSet complementOf(Collection collection) { if (collection instanceof EnumSet) { return EnumSet.complementOf((EnumSet) collection); } checkArgument( !collection.isEmpty(), "collection is empty; use the other version of this method"); Class type = collection.iterator().next().getDeclaringClass(); return makeComplementByHand(collection, type); } /** * Creates an {@code EnumSet} consisting of all enum values that are not in the specified * collection. This is equivalent to {@link EnumSet#complementOf}, but can act on any input * collection, as long as the elements are of enum type. * * @param collection the collection whose complement should be stored in the {@code EnumSet} * @param type the type of the elements in the set * @return a new, modifiable {@code EnumSet} initially containing all the values of the enum not * present in the given collection */ @GwtIncompatible public static > EnumSet complementOf( Collection collection, Class type) { checkNotNull(collection); return (collection instanceof EnumSet) ? EnumSet.complementOf((EnumSet) collection) : makeComplementByHand(collection, type); } @GwtIncompatible private static > EnumSet makeComplementByHand( Collection collection, Class type) { EnumSet result = EnumSet.allOf(type); result.removeAll(collection); return result; } /** * Returns a set backed by the specified map. The resulting set displays the same ordering, * concurrency, and performance characteristics as the backing map. In essence, this factory * method provides a {@link Set} implementation corresponding to any {@link Map} implementation. * There is no need to use this method on a {@link Map} implementation that already has a * corresponding {@link Set} implementation (such as {@link java.util.HashMap} or {@link * java.util.TreeMap}). * *

Each method invocation on the set returned by this method results in exactly one method * invocation on the backing map or its {@code keySet} view, with one exception. The {@code * addAll} method is implemented as a sequence of {@code put} invocations on the backing map. * *

The specified map must be empty at the time this method is invoked, and should not be * accessed directly after this method returns. These conditions are ensured if the map is created * empty, passed directly to this method, and no reference to the map is retained, as illustrated * in the following code fragment: * *

{@code
   * Set identityHashSet = Sets.newSetFromMap(
   *     new IdentityHashMap());
   * }
   *
   * 

The returned set is serializable if the backing map is. * * @param map the backing map * @return the set backed by the map * @throws IllegalArgumentException if {@code map} is not empty * @deprecated Use {@link Collections#newSetFromMap} instead. */ @Deprecated public static Set newSetFromMap( Map map) { return Collections.newSetFromMap(map); } /** * An unmodifiable view of a set which may be backed by other sets; this view will change as the * backing sets do. Contains methods to copy the data into a new set which will then remain * stable. There is usually no reason to retain a reference of type {@code SetView}; typically, * you either use it as a plain {@link Set}, or immediately invoke {@link #immutableCopy} or * {@link #copyInto} and forget the {@code SetView} itself. * * @since 2.0 */ public abstract static class SetView extends AbstractSet { private SetView() {} // no subclasses but our own /** * Returns an immutable copy of the current contents of this set view. Does not support null * elements. * *

Warning: this may have unexpected results if a backing set of this view uses a * nonstandard notion of equivalence, for example if it is a {@link TreeSet} using a comparator * that is inconsistent with {@link Object#equals(Object)}. */ @SuppressWarnings("nullness") // Unsafe, but we can't fix it now. public ImmutableSet<@NonNull E> immutableCopy() { return ImmutableSet.copyOf((SetView<@NonNull E>) this); } /** * Copies the current contents of this set view into an existing set. This method has equivalent * behavior to {@code set.addAll(this)}, assuming that all the sets involved are based on the * same notion of equivalence. * * @return a reference to {@code set}, for convenience */ // Note: S should logically extend Set but can't due to either // some javac bug or some weirdness in the spec, not sure which. @CanIgnoreReturnValue public > S copyInto(S set) { set.addAll(this); return set; } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean add(@ParametricNullness E e) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean remove(@CheckForNull Object object) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean addAll(Collection newElements) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean removeAll(Collection oldElements) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean removeIf(java.util.function.Predicate filter) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @CanIgnoreReturnValue @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final boolean retainAll(Collection elementsToKeep) { throw new UnsupportedOperationException(); } /** * Guaranteed to throw an exception and leave the collection unmodified. * * @throws UnsupportedOperationException always * @deprecated Unsupported operation. */ @Deprecated @Override @DoNotCall("Always throws UnsupportedOperationException") public final void clear() { throw new UnsupportedOperationException(); } /** * Scope the return type to {@link UnmodifiableIterator} to ensure this is an unmodifiable view. * * @since 20.0 (present with return type {@link Iterator} since 2.0) */ @Override public abstract UnmodifiableIterator iterator(); } /** * Returns an unmodifiable view of the union of two sets. The returned set contains all * elements that are contained in either backing set. Iterating over the returned set iterates * first over all the elements of {@code set1}, then over each element of {@code set2}, in order, * that is not contained in {@code set1}. * *

Results are undefined if {@code set1} and {@code set2} are sets based on different * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}. */ public static SetView union( final Set set1, final Set set2) { checkNotNull(set1, "set1"); checkNotNull(set2, "set2"); return new SetView() { @Override public int size() { int size = set1.size(); for (E e : set2) { if (!set1.contains(e)) { size++; } } return size; } @Override public boolean isEmpty() { return set1.isEmpty() && set2.isEmpty(); } @Override public UnmodifiableIterator iterator() { return new AbstractIterator() { final Iterator itr1 = set1.iterator(); final Iterator itr2 = set2.iterator(); @Override @CheckForNull protected E computeNext() { if (itr1.hasNext()) { return itr1.next(); } while (itr2.hasNext()) { E e = itr2.next(); if (!set1.contains(e)) { return e; } } return endOfData(); } }; } @Override public Stream stream() { return Stream.concat(set1.stream(), set2.stream().filter((E e) -> !set1.contains(e))); } @Override public Stream parallelStream() { return stream().parallel(); } @Override public boolean contains(@CheckForNull Object object) { return set1.contains(object) || set2.contains(object); } @Override public > S copyInto(S set) { set.addAll(set1); set.addAll(set2); return set; } @Override @SuppressWarnings({"nullness", "unchecked"}) // see supertype public ImmutableSet<@NonNull E> immutableCopy() { ImmutableSet.Builder<@NonNull E> builder = new ImmutableSet.Builder<@NonNull E>() .addAll((Iterable<@NonNull E>) set1) .addAll((Iterable<@NonNull E>) set2); return (ImmutableSet<@NonNull E>) builder.build(); } }; } /** * Returns an unmodifiable view of the intersection of two sets. The returned set contains * all elements that are contained by both backing sets. The iteration order of the returned set * matches that of {@code set1}. * *

Results are undefined if {@code set1} and {@code set2} are sets based on different * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}. * *

Note: The returned view performs slightly better when {@code set1} is the smaller of * the two sets. If you have reason to believe one of your sets will generally be smaller than the * other, pass it first. Unfortunately, since this method sets the generic type of the returned * set based on the type of the first set passed, this could in rare cases force you to make a * cast, for example: * *

{@code
   * Set aFewBadObjects = ...
   * Set manyBadStrings = ...
   *
   * // impossible for a non-String to be in the intersection
   * SuppressWarnings("unchecked")
   * Set badStrings = (Set) Sets.intersection(
   *     aFewBadObjects, manyBadStrings);
   * }
   *
   * 

This is unfortunate, but should come up only very rarely. */ public static SetView intersection( final Set set1, final Set set2) { checkNotNull(set1, "set1"); checkNotNull(set2, "set2"); return new SetView() { @Override public UnmodifiableIterator iterator() { return new AbstractIterator() { final Iterator itr = set1.iterator(); @Override @CheckForNull protected E computeNext() { while (itr.hasNext()) { E e = itr.next(); if (set2.contains(e)) { return e; } } return endOfData(); } }; } @Override public Stream stream() { return set1.stream().filter(set2::contains); } @Override public Stream parallelStream() { return set1.parallelStream().filter(set2::contains); } @Override public int size() { int size = 0; for (E e : set1) { if (set2.contains(e)) { size++; } } return size; } @Override public boolean isEmpty() { return Collections.disjoint(set2, set1); } @Override public boolean contains(@CheckForNull Object object) { return set1.contains(object) && set2.contains(object); } @Override public boolean containsAll(Collection collection) { return set1.containsAll(collection) && set2.containsAll(collection); } }; } /** * Returns an unmodifiable view of the difference of two sets. The returned set contains * all elements that are contained by {@code set1} and not contained by {@code set2}. {@code set2} * may also contain elements not present in {@code set1}; these are simply ignored. The iteration * order of the returned set matches that of {@code set1}. * *

Results are undefined if {@code set1} and {@code set2} are sets based on different * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}. */ public static SetView difference( final Set set1, final Set set2) { checkNotNull(set1, "set1"); checkNotNull(set2, "set2"); return new SetView() { @Override public UnmodifiableIterator iterator() { return new AbstractIterator() { final Iterator itr = set1.iterator(); @Override @CheckForNull protected E computeNext() { while (itr.hasNext()) { E e = itr.next(); if (!set2.contains(e)) { return e; } } return endOfData(); } }; } @Override public Stream stream() { return set1.stream().filter(e -> !set2.contains(e)); } @Override public Stream parallelStream() { return set1.parallelStream().filter(e -> !set2.contains(e)); } @Override public int size() { int size = 0; for (E e : set1) { if (!set2.contains(e)) { size++; } } return size; } @Override public boolean isEmpty() { return set2.containsAll(set1); } @Override public boolean contains(@CheckForNull Object element) { return set1.contains(element) && !set2.contains(element); } }; } /** * Returns an unmodifiable view of the symmetric difference of two sets. The returned set * contains all elements that are contained in either {@code set1} or {@code set2} but not in * both. The iteration order of the returned set is undefined. * *

Results are undefined if {@code set1} and {@code set2} are sets based on different * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}. * * @since 3.0 */ public static SetView symmetricDifference( final Set set1, final Set set2) { checkNotNull(set1, "set1"); checkNotNull(set2, "set2"); return new SetView() { @Override public UnmodifiableIterator iterator() { final Iterator itr1 = set1.iterator(); final Iterator itr2 = set2.iterator(); return new AbstractIterator() { @Override @CheckForNull public E computeNext() { while (itr1.hasNext()) { E elem1 = itr1.next(); if (!set2.contains(elem1)) { return elem1; } } while (itr2.hasNext()) { E elem2 = itr2.next(); if (!set1.contains(elem2)) { return elem2; } } return endOfData(); } }; } @Override public int size() { int size = 0; for (E e : set1) { if (!set2.contains(e)) { size++; } } for (E e : set2) { if (!set1.contains(e)) { size++; } } return size; } @Override public boolean isEmpty() { return set1.equals(set2); } @Override public boolean contains(@CheckForNull Object element) { return set1.contains(element) ^ set2.contains(element); } }; } /** * Returns the elements of {@code unfiltered} that satisfy a predicate. The returned set is a live * view of {@code unfiltered}; changes to one affect the other. * *

The resulting set's iterator does not support {@code remove()}, but all other set methods * are supported. When given an element that doesn't satisfy the predicate, the set's {@code * add()} and {@code addAll()} methods throw an {@link IllegalArgumentException}. When methods * such as {@code removeAll()} and {@code clear()} are called on the filtered set, only elements * that satisfy the filter will be removed from the underlying set. * *

The returned set isn't threadsafe or serializable, even if {@code unfiltered} is. * *

Many of the filtered set's methods, such as {@code size()}, iterate across every element in * the underlying set and determine which elements satisfy the filter. When a live view is * not needed, it may be faster to copy {@code Iterables.filter(unfiltered, predicate)} and * use the copy. * *

Warning: {@code predicate} must be consistent with equals, as documented at * {@link Predicate#apply}. Do not provide a predicate such as {@code * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals. (See {@link * Iterables#filter(Iterable, Class)} for related functionality.) * *

Java 8 users: many use cases for this method are better addressed by {@link * java.util.stream.Stream#filter}. This method is not being deprecated, but we gently encourage * you to migrate to streams. */ // TODO(kevinb): how to omit that last sentence when building GWT javadoc? public static Set filter( Set unfiltered, Predicate predicate) { if (unfiltered instanceof SortedSet) { return filter((SortedSet) unfiltered, predicate); } if (unfiltered instanceof FilteredSet) { // Support clear(), removeAll(), and retainAll() when filtering a filtered // collection. FilteredSet filtered = (FilteredSet) unfiltered; Predicate combinedPredicate = Predicates.and(filtered.predicate, predicate); return new FilteredSet((Set) filtered.unfiltered, combinedPredicate); } return new FilteredSet(checkNotNull(unfiltered), checkNotNull(predicate)); } /** * Returns the elements of a {@code SortedSet}, {@code unfiltered}, that satisfy a predicate. The * returned set is a live view of {@code unfiltered}; changes to one affect the other. * *

The resulting set's iterator does not support {@code remove()}, but all other set methods * are supported. When given an element that doesn't satisfy the predicate, the set's {@code * add()} and {@code addAll()} methods throw an {@link IllegalArgumentException}. When methods * such as {@code removeAll()} and {@code clear()} are called on the filtered set, only elements * that satisfy the filter will be removed from the underlying set. * *

The returned set isn't threadsafe or serializable, even if {@code unfiltered} is. * *

Many of the filtered set's methods, such as {@code size()}, iterate across every element in * the underlying set and determine which elements satisfy the filter. When a live view is * not needed, it may be faster to copy {@code Iterables.filter(unfiltered, predicate)} and * use the copy. * *

Warning: {@code predicate} must be consistent with equals, as documented at * {@link Predicate#apply}. Do not provide a predicate such as {@code * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals. (See {@link * Iterables#filter(Iterable, Class)} for related functionality.) * * @since 11.0 */ public static SortedSet filter( SortedSet unfiltered, Predicate predicate) { if (unfiltered instanceof FilteredSet) { // Support clear(), removeAll(), and retainAll() when filtering a filtered // collection. FilteredSet filtered = (FilteredSet) unfiltered; Predicate combinedPredicate = Predicates.and(filtered.predicate, predicate); return new FilteredSortedSet((SortedSet) filtered.unfiltered, combinedPredicate); } return new FilteredSortedSet(checkNotNull(unfiltered), checkNotNull(predicate)); } /** * Returns the elements of a {@code NavigableSet}, {@code unfiltered}, that satisfy a predicate. * The returned set is a live view of {@code unfiltered}; changes to one affect the other. * *

The resulting set's iterator does not support {@code remove()}, but all other set methods * are supported. When given an element that doesn't satisfy the predicate, the set's {@code * add()} and {@code addAll()} methods throw an {@link IllegalArgumentException}. When methods * such as {@code removeAll()} and {@code clear()} are called on the filtered set, only elements * that satisfy the filter will be removed from the underlying set. * *

The returned set isn't threadsafe or serializable, even if {@code unfiltered} is. * *

Many of the filtered set's methods, such as {@code size()}, iterate across every element in * the underlying set and determine which elements satisfy the filter. When a live view is * not needed, it may be faster to copy {@code Iterables.filter(unfiltered, predicate)} and * use the copy. * *

Warning: {@code predicate} must be consistent with equals, as documented at * {@link Predicate#apply}. Do not provide a predicate such as {@code * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals. (See {@link * Iterables#filter(Iterable, Class)} for related functionality.) * * @since 14.0 */ @GwtIncompatible // NavigableSet @SuppressWarnings("unchecked") public static NavigableSet filter( NavigableSet unfiltered, Predicate predicate) { if (unfiltered instanceof FilteredSet) { // Support clear(), removeAll(), and retainAll() when filtering a filtered // collection. FilteredSet filtered = (FilteredSet) unfiltered; Predicate combinedPredicate = Predicates.and(filtered.predicate, predicate); return new FilteredNavigableSet((NavigableSet) filtered.unfiltered, combinedPredicate); } return new FilteredNavigableSet(checkNotNull(unfiltered), checkNotNull(predicate)); } private static class FilteredSet extends FilteredCollection implements Set { FilteredSet(Set unfiltered, Predicate predicate) { super(unfiltered, predicate); } @Override public boolean equals(@CheckForNull Object object) { return equalsImpl(this, object); } @Override public int hashCode() { return hashCodeImpl(this); } } private static class FilteredSortedSet extends FilteredSet implements SortedSet { FilteredSortedSet(SortedSet unfiltered, Predicate predicate) { super(unfiltered, predicate); } @Override @CheckForNull public Comparator comparator() { return ((SortedSet) unfiltered).comparator(); } @Override public SortedSet subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) { return new FilteredSortedSet( ((SortedSet) unfiltered).subSet(fromElement, toElement), predicate); } @Override public SortedSet headSet(@ParametricNullness E toElement) { return new FilteredSortedSet(((SortedSet) unfiltered).headSet(toElement), predicate); } @Override public SortedSet tailSet(@ParametricNullness E fromElement) { return new FilteredSortedSet(((SortedSet) unfiltered).tailSet(fromElement), predicate); } @Override @ParametricNullness public E first() { return Iterators.find(unfiltered.iterator(), predicate); } @Override @ParametricNullness public E last() { SortedSet sortedUnfiltered = (SortedSet) unfiltered; while (true) { E element = sortedUnfiltered.last(); if (predicate.apply(element)) { return element; } sortedUnfiltered = sortedUnfiltered.headSet(element); } } } @GwtIncompatible // NavigableSet private static class FilteredNavigableSet extends FilteredSortedSet implements NavigableSet { FilteredNavigableSet(NavigableSet unfiltered, Predicate predicate) { super(unfiltered, predicate); } NavigableSet unfiltered() { return (NavigableSet) unfiltered; } @Override @CheckForNull public E lower(@ParametricNullness E e) { return Iterators.find(unfiltered().headSet(e, false).descendingIterator(), predicate, null); } @Override @CheckForNull public E floor(@ParametricNullness E e) { return Iterators.find(unfiltered().headSet(e, true).descendingIterator(), predicate, null); } @Override @CheckForNull public E ceiling(@ParametricNullness E e) { return Iterables.find(unfiltered().tailSet(e, true), predicate, null); } @Override @CheckForNull public E higher(@ParametricNullness E e) { return Iterables.find(unfiltered().tailSet(e, false), predicate, null); } @Override @CheckForNull public E pollFirst() { return Iterables.removeFirstMatching(unfiltered(), predicate); } @Override @CheckForNull public E pollLast() { return Iterables.removeFirstMatching(unfiltered().descendingSet(), predicate); } @Override public NavigableSet descendingSet() { return Sets.filter(unfiltered().descendingSet(), predicate); } @Override public Iterator descendingIterator() { return Iterators.filter(unfiltered().descendingIterator(), predicate); } @Override @ParametricNullness public E last() { return Iterators.find(unfiltered().descendingIterator(), predicate); } @Override public NavigableSet subSet( @ParametricNullness E fromElement, boolean fromInclusive, @ParametricNullness E toElement, boolean toInclusive) { return filter( unfiltered().subSet(fromElement, fromInclusive, toElement, toInclusive), predicate); } @Override public NavigableSet headSet(@ParametricNullness E toElement, boolean inclusive) { return filter(unfiltered().headSet(toElement, inclusive), predicate); } @Override public NavigableSet tailSet(@ParametricNullness E fromElement, boolean inclusive) { return filter(unfiltered().tailSet(fromElement, inclusive), predicate); } } /** * Returns every possible list that can be formed by choosing one element from each of the given * sets in order; the "n-ary Cartesian * product" of the sets. For example: * *

{@code
   * Sets.cartesianProduct(ImmutableList.of(
   *     ImmutableSet.of(1, 2),
   *     ImmutableSet.of("A", "B", "C")))
   * }
* *

returns a set containing six lists: * *

    *
  • {@code ImmutableList.of(1, "A")} *
  • {@code ImmutableList.of(1, "B")} *
  • {@code ImmutableList.of(1, "C")} *
  • {@code ImmutableList.of(2, "A")} *
  • {@code ImmutableList.of(2, "B")} *
  • {@code ImmutableList.of(2, "C")} *
* *

The result is guaranteed to be in the "traditional", lexicographical order for Cartesian * products that you would get from nesting for loops: * *

{@code
   * for (B b0 : sets.get(0)) {
   *   for (B b1 : sets.get(1)) {
   *     ...
   *     ImmutableList tuple = ImmutableList.of(b0, b1, ...);
   *     // operate on tuple
   *   }
   * }
   * }
* *

Note that if any input set is empty, the Cartesian product will also be empty. If no sets at * all are provided (an empty list), the resulting Cartesian product has one element, an empty * list (counter-intuitive, but mathematically consistent). * *

Performance notes: while the cartesian product of sets of size {@code m, n, p} is a * set of size {@code m x n x p}, its actual memory consumption is much smaller. When the * cartesian set is constructed, the input sets are merely copied. Only as the resulting set is * iterated are the individual lists created, and these are not retained after iteration. * * @param sets the sets to choose elements from, in the order that the elements chosen from those * sets should appear in the resulting lists * @param any common base class shared by all axes (often just {@link Object}) * @return the Cartesian product, as an immutable set containing immutable lists * @throws NullPointerException if {@code sets}, any one of the {@code sets}, or any element of a * provided set is null * @throws IllegalArgumentException if the cartesian product size exceeds the {@code int} range * @since 2.0 */ public static Set> cartesianProduct(List> sets) { return CartesianSet.create(sets); } /** * Returns every possible list that can be formed by choosing one element from each of the given * sets in order; the "n-ary Cartesian * product" of the sets. For example: * *

{@code
   * Sets.cartesianProduct(
   *     ImmutableSet.of(1, 2),
   *     ImmutableSet.of("A", "B", "C"))
   * }
* *

returns a set containing six lists: * *

    *
  • {@code ImmutableList.of(1, "A")} *
  • {@code ImmutableList.of(1, "B")} *
  • {@code ImmutableList.of(1, "C")} *
  • {@code ImmutableList.of(2, "A")} *
  • {@code ImmutableList.of(2, "B")} *
  • {@code ImmutableList.of(2, "C")} *
* *

The result is guaranteed to be in the "traditional", lexicographical order for Cartesian * products that you would get from nesting for loops: * *

{@code
   * for (B b0 : sets.get(0)) {
   *   for (B b1 : sets.get(1)) {
   *     ...
   *     ImmutableList tuple = ImmutableList.of(b0, b1, ...);
   *     // operate on tuple
   *   }
   * }
   * }
* *

Note that if any input set is empty, the Cartesian product will also be empty. If no sets at * all are provided (an empty list), the resulting Cartesian product has one element, an empty * list (counter-intuitive, but mathematically consistent). * *

Performance notes: while the cartesian product of sets of size {@code m, n, p} is a * set of size {@code m x n x p}, its actual memory consumption is much smaller. When the * cartesian set is constructed, the input sets are merely copied. Only as the resulting set is * iterated are the individual lists created, and these are not retained after iteration. * * @param sets the sets to choose elements from, in the order that the elements chosen from those * sets should appear in the resulting lists * @param any common base class shared by all axes (often just {@link Object}) * @return the Cartesian product, as an immutable set containing immutable lists * @throws NullPointerException if {@code sets}, any one of the {@code sets}, or any element of a * provided set is null * @throws IllegalArgumentException if the cartesian product size exceeds the {@code int} range * @since 2.0 */ @SafeVarargs public static Set> cartesianProduct(Set... sets) { return cartesianProduct(Arrays.asList(sets)); } private static final class CartesianSet extends ForwardingCollection> implements Set> { private final transient ImmutableList> axes; private final transient CartesianList delegate; static Set> create(List> sets) { ImmutableList.Builder> axesBuilder = new ImmutableList.Builder<>(sets.size()); for (Set set : sets) { ImmutableSet copy = ImmutableSet.copyOf(set); if (copy.isEmpty()) { return ImmutableSet.of(); } axesBuilder.add(copy); } final ImmutableList> axes = axesBuilder.build(); ImmutableList> listAxes = new ImmutableList>() { @Override public int size() { return axes.size(); } @Override public List get(int index) { return axes.get(index).asList(); } @Override boolean isPartialView() { return true; } }; return new CartesianSet(axes, new CartesianList(listAxes)); } private CartesianSet(ImmutableList> axes, CartesianList delegate) { this.axes = axes; this.delegate = delegate; } @Override protected Collection> delegate() { return delegate; } @Override public boolean contains(@CheckForNull Object object) { if (!(object instanceof List)) { return false; } List list = (List) object; if (list.size() != axes.size()) { return false; } int i = 0; for (Object o : list) { if (!axes.get(i).contains(o)) { return false; } i++; } return true; } @Override public boolean equals(@CheckForNull Object object) { // Warning: this is broken if size() == 0, so it is critical that we // substitute an empty ImmutableSet to the user in place of this if (object instanceof CartesianSet) { CartesianSet that = (CartesianSet) object; return this.axes.equals(that.axes); } return super.equals(object); } @Override public int hashCode() { // Warning: this is broken if size() == 0, so it is critical that we // substitute an empty ImmutableSet to the user in place of this // It's a weird formula, but tests prove it works. int adjust = size() - 1; for (int i = 0; i < axes.size(); i++) { adjust *= 31; adjust = ~~adjust; // in GWT, we have to deal with integer overflow carefully } int hash = 1; for (Set axis : axes) { hash = 31 * hash + (size() / axis.size() * axis.hashCode()); hash = ~~hash; } hash += adjust; return ~~hash; } } /** * Returns the set of all possible subsets of {@code set}. For example, {@code * powerSet(ImmutableSet.of(1, 2))} returns the set {@code {{}, {1}, {2}, {1, 2}}}. * *

Elements appear in these subsets in the same iteration order as they appeared in the input * set. The order in which these subsets appear in the outer set is undefined. Note that the power * set of the empty set is not the empty set, but a one-element set containing the empty set. * *

The returned set and its constituent sets use {@code equals} to decide whether two elements * are identical, even if the input set uses a different concept of equivalence. * *

Performance notes: while the power set of a set with size {@code n} is of size {@code * 2^n}, its memory usage is only {@code O(n)}. When the power set is constructed, the input set * is merely copied. Only as the power set is iterated are the individual subsets created, and * these subsets themselves occupy only a small constant amount of memory. * * @param set the set of elements to construct a power set from * @return the power set, as an immutable set of immutable sets * @throws IllegalArgumentException if {@code set} has more than 30 unique elements (causing the * power set size to exceed the {@code int} range) * @throws NullPointerException if {@code set} is or contains {@code null} * @see Power set article at Wikipedia * @since 4.0 */ @GwtCompatible(serializable = false) public static Set> powerSet(Set set) { return new PowerSet(set); } private static final class SubSet extends AbstractSet { private final ImmutableMap inputSet; private final int mask; SubSet(ImmutableMap inputSet, int mask) { this.inputSet = inputSet; this.mask = mask; } @Override public Iterator iterator() { return new UnmodifiableIterator() { final ImmutableList elements = inputSet.keySet().asList(); int remainingSetBits = mask; @Override public boolean hasNext() { return remainingSetBits != 0; } @Override public E next() { int index = Integer.numberOfTrailingZeros(remainingSetBits); if (index == 32) { throw new NoSuchElementException(); } remainingSetBits &= ~(1 << index); return elements.get(index); } }; } @Override public int size() { return Integer.bitCount(mask); } @Override public boolean contains(@CheckForNull Object o) { Integer index = inputSet.get(o); return index != null && (mask & (1 << index)) != 0; } } private static final class PowerSet extends AbstractSet> { final ImmutableMap inputSet; PowerSet(Set input) { checkArgument( input.size() <= 30, "Too many elements to create power set: %s > 30", input.size()); this.inputSet = Maps.indexMap(input); } @Override public int size() { return 1 << inputSet.size(); } @Override public boolean isEmpty() { return false; } @Override public Iterator> iterator() { return new AbstractIndexedListIterator>(size()) { @Override protected Set get(final int setBits) { return new SubSet(inputSet, setBits); } }; } @Override public boolean contains(@CheckForNull Object obj) { if (obj instanceof Set) { Set set = (Set) obj; return inputSet.keySet().containsAll(set); } return false; } @Override public boolean equals(@CheckForNull Object obj) { if (obj instanceof PowerSet) { PowerSet that = (PowerSet) obj; return inputSet.keySet().equals(that.inputSet.keySet()); } return super.equals(obj); } @Override public int hashCode() { /* * The sum of the sums of the hash codes in each subset is just the sum of * each input element's hash code times the number of sets that element * appears in. Each element appears in exactly half of the 2^n sets, so: */ return inputSet.keySet().hashCode() << (inputSet.size() - 1); } @Override public String toString() { return "powerSet(" + inputSet + ")"; } } /** * Returns the set of all subsets of {@code set} of size {@code size}. For example, {@code * combinations(ImmutableSet.of(1, 2, 3), 2)} returns the set {@code {{1, 2}, {1, 3}, {2, 3}}}. * *

Elements appear in these subsets in the same iteration order as they appeared in the input * set. The order in which these subsets appear in the outer set is undefined. * *

The returned set and its constituent sets use {@code equals} to decide whether two elements * are identical, even if the input set uses a different concept of equivalence. * *

Performance notes: the memory usage of the returned set is only {@code O(n)}. When * the result set is constructed, the input set is merely copied. Only as the result set is * iterated are the individual subsets created. Each of these subsets occupies an additional O(n) * memory but only for as long as the user retains a reference to it. That is, the set returned by * {@code combinations} does not retain the individual subsets. * * @param set the set of elements to take combinations of * @param size the number of elements per combination * @return the set of all combinations of {@code size} elements from {@code set} * @throws IllegalArgumentException if {@code size} is not between 0 and {@code set.size()} * inclusive * @throws NullPointerException if {@code set} is or contains {@code null} * @since 23.0 */ public static Set> combinations(Set set, final int size) { final ImmutableMap index = Maps.indexMap(set); checkNonnegative(size, "size"); checkArgument(size <= index.size(), "size (%s) must be <= set.size() (%s)", size, index.size()); if (size == 0) { return ImmutableSet.>of(ImmutableSet.of()); } else if (size == index.size()) { return ImmutableSet.>of(index.keySet()); } return new AbstractSet>() { @Override public boolean contains(@CheckForNull Object o) { if (o instanceof Set) { Set s = (Set) o; return s.size() == size && index.keySet().containsAll(s); } return false; } @Override public Iterator> iterator() { return new AbstractIterator>() { final BitSet bits = new BitSet(index.size()); @Override @CheckForNull protected Set computeNext() { if (bits.isEmpty()) { bits.set(0, size); } else { int firstSetBit = bits.nextSetBit(0); int bitToFlip = bits.nextClearBit(firstSetBit); if (bitToFlip == index.size()) { return endOfData(); } /* * The current set in sorted order looks like * {firstSetBit, firstSetBit + 1, ..., bitToFlip - 1, ...} * where it does *not* contain bitToFlip. * * The next combination is * * {0, 1, ..., bitToFlip - firstSetBit - 2, bitToFlip, ...} * * This is lexicographically next if you look at the combinations in descending order * e.g. {2, 1, 0}, {3, 1, 0}, {3, 2, 0}, {3, 2, 1}, {4, 1, 0}... */ bits.set(0, bitToFlip - firstSetBit - 1); bits.clear(bitToFlip - firstSetBit - 1, bitToFlip); bits.set(bitToFlip); } final BitSet copy = (BitSet) bits.clone(); return new AbstractSet() { @Override public boolean contains(@CheckForNull Object o) { Integer i = index.get(o); return i != null && copy.get(i); } @Override public Iterator iterator() { return new AbstractIterator() { int i = -1; @Override @CheckForNull protected E computeNext() { i = copy.nextSetBit(i + 1); if (i == -1) { return endOfData(); } return index.keySet().asList().get(i); } }; } @Override public int size() { return size; } }; } }; } @Override public int size() { return IntMath.binomial(index.size(), size); } @Override public String toString() { return "Sets.combinations(" + index.keySet() + ", " + size + ")"; } }; } /** An implementation for {@link Set#hashCode()}. */ static int hashCodeImpl(Set s) { int hashCode = 0; for (Object o : s) { hashCode += o != null ? o.hashCode() : 0; hashCode = ~~hashCode; // Needed to deal with unusual integer overflow in GWT. } return hashCode; } /** An implementation for {@link Set#equals(Object)}. */ static boolean equalsImpl(Set s, @CheckForNull Object object) { if (s == object) { return true; } if (object instanceof Set) { Set o = (Set) object; try { return s.size() == o.size() && s.containsAll(o); } catch (NullPointerException | ClassCastException ignored) { return false; } } return false; } /** * Returns an unmodifiable view of the specified navigable set. This method allows modules to * provide users with "read-only" access to internal navigable sets. Query operations on the * returned set "read through" to the specified set, and attempts to modify the returned set, * whether direct or via its collection views, result in an {@code UnsupportedOperationException}. * *

The returned navigable set will be serializable if the specified navigable set is * serializable. * *

Java 8 users and later: Prefer {@link Collections#unmodifiableNavigableSet}. * * @param set the navigable set for which an unmodifiable view is to be returned * @return an unmodifiable view of the specified navigable set * @since 12.0 */ public static NavigableSet unmodifiableNavigableSet( NavigableSet set) { if (set instanceof ImmutableCollection || set instanceof UnmodifiableNavigableSet) { return set; } return new UnmodifiableNavigableSet(set); } static final class UnmodifiableNavigableSet extends ForwardingSortedSet implements NavigableSet, Serializable { private final NavigableSet delegate; private final SortedSet unmodifiableDelegate; UnmodifiableNavigableSet(NavigableSet delegate) { this.delegate = checkNotNull(delegate); this.unmodifiableDelegate = Collections.unmodifiableSortedSet(delegate); } @Override protected SortedSet delegate() { return unmodifiableDelegate; } // default methods not forwarded by ForwardingSortedSet @Override public boolean removeIf(java.util.function.Predicate filter) { throw new UnsupportedOperationException(); } @Override public Stream stream() { return delegate.stream(); } @Override public Stream parallelStream() { return delegate.parallelStream(); } @Override public void forEach(Consumer action) { delegate.forEach(action); } @Override @CheckForNull public E lower(@ParametricNullness E e) { return delegate.lower(e); } @Override @CheckForNull public E floor(@ParametricNullness E e) { return delegate.floor(e); } @Override @CheckForNull public E ceiling(@ParametricNullness E e) { return delegate.ceiling(e); } @Override @CheckForNull public E higher(@ParametricNullness E e) { return delegate.higher(e); } @Override @CheckForNull public E pollFirst() { throw new UnsupportedOperationException(); } @Override @CheckForNull public E pollLast() { throw new UnsupportedOperationException(); } @LazyInit @CheckForNull private transient UnmodifiableNavigableSet descendingSet; @Override public NavigableSet descendingSet() { UnmodifiableNavigableSet result = descendingSet; if (result == null) { result = descendingSet = new UnmodifiableNavigableSet(delegate.descendingSet()); result.descendingSet = this; } return result; } @Override public Iterator descendingIterator() { return Iterators.unmodifiableIterator(delegate.descendingIterator()); } @Override public NavigableSet subSet( @ParametricNullness E fromElement, boolean fromInclusive, @ParametricNullness E toElement, boolean toInclusive) { return unmodifiableNavigableSet( delegate.subSet(fromElement, fromInclusive, toElement, toInclusive)); } @Override public NavigableSet headSet(@ParametricNullness E toElement, boolean inclusive) { return unmodifiableNavigableSet(delegate.headSet(toElement, inclusive)); } @Override public NavigableSet tailSet(@ParametricNullness E fromElement, boolean inclusive) { return unmodifiableNavigableSet(delegate.tailSet(fromElement, inclusive)); } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) navigable set backed by the specified navigable set. In * order to guarantee serial access, it is critical that all access to the backing * navigable set is accomplished through the returned navigable set (or its views). * *

It is imperative that the user manually synchronize on the returned sorted set when * iterating over it or any of its {@code descendingSet}, {@code subSet}, {@code headSet}, or * {@code tailSet} views. * *

{@code
   * NavigableSet set = synchronizedNavigableSet(new TreeSet());
   *  ...
   * synchronized (set) {
   *   // Must be in the synchronized block
   *   Iterator it = set.iterator();
   *   while (it.hasNext()) {
   *     foo(it.next());
   *   }
   * }
   * }
* *

or: * *

{@code
   * NavigableSet set = synchronizedNavigableSet(new TreeSet());
   * NavigableSet set2 = set.descendingSet().headSet(foo);
   *  ...
   * synchronized (set) { // Note: set, not set2!!!
   *   // Must be in the synchronized block
   *   Iterator it = set2.descendingIterator();
   *   while (it.hasNext())
   *     foo(it.next());
   *   }
   * }
   * }
* *

Failure to follow this advice may result in non-deterministic behavior. * *

The returned navigable set will be serializable if the specified navigable set is * serializable. * *

Java 8 users and later: Prefer {@link Collections#synchronizedNavigableSet}. * * @param navigableSet the navigable set to be "wrapped" in a synchronized navigable set. * @return a synchronized view of the specified navigable set. * @since 13.0 */ @GwtIncompatible // NavigableSet public static NavigableSet synchronizedNavigableSet( NavigableSet navigableSet) { return Synchronized.navigableSet(navigableSet); } /** Remove each element in an iterable from a set. */ static boolean removeAllImpl(Set set, Iterator iterator) { boolean changed = false; while (iterator.hasNext()) { changed |= set.remove(iterator.next()); } return changed; } static boolean removeAllImpl(Set set, Collection collection) { checkNotNull(collection); // for GWT if (collection instanceof Multiset) { collection = ((Multiset) collection).elementSet(); } /* * AbstractSet.removeAll(List) has quadratic behavior if the list size * is just more than the set's size. We augment the test by * assuming that sets have fast contains() performance, and other * collections don't. See * http://code.google.com/p/guava-libraries/issues/detail?id=1013 */ if (collection instanceof Set && collection.size() > set.size()) { return Iterators.removeAll(set.iterator(), collection); } else { return removeAllImpl(set, collection.iterator()); } } @GwtIncompatible // NavigableSet static class DescendingSet extends ForwardingNavigableSet { private final NavigableSet forward; DescendingSet(NavigableSet forward) { this.forward = forward; } @Override protected NavigableSet delegate() { return forward; } @Override @CheckForNull public E lower(@ParametricNullness E e) { return forward.higher(e); } @Override @CheckForNull public E floor(@ParametricNullness E e) { return forward.ceiling(e); } @Override @CheckForNull public E ceiling(@ParametricNullness E e) { return forward.floor(e); } @Override @CheckForNull public E higher(@ParametricNullness E e) { return forward.lower(e); } @Override @CheckForNull public E pollFirst() { return forward.pollLast(); } @Override @CheckForNull public E pollLast() { return forward.pollFirst(); } @Override public NavigableSet descendingSet() { return forward; } @Override public Iterator descendingIterator() { return forward.iterator(); } @Override public NavigableSet subSet( @ParametricNullness E fromElement, boolean fromInclusive, @ParametricNullness E toElement, boolean toInclusive) { return forward.subSet(toElement, toInclusive, fromElement, fromInclusive).descendingSet(); } @Override public SortedSet subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) { return standardSubSet(fromElement, toElement); } @Override public NavigableSet headSet(@ParametricNullness E toElement, boolean inclusive) { return forward.tailSet(toElement, inclusive).descendingSet(); } @Override public SortedSet headSet(@ParametricNullness E toElement) { return standardHeadSet(toElement); } @Override public NavigableSet tailSet(@ParametricNullness E fromElement, boolean inclusive) { return forward.headSet(fromElement, inclusive).descendingSet(); } @Override public SortedSet tailSet(@ParametricNullness E fromElement) { return standardTailSet(fromElement); } @SuppressWarnings("unchecked") @Override public Comparator comparator() { Comparator forwardComparator = forward.comparator(); if (forwardComparator == null) { return (Comparator) Ordering.natural().reverse(); } else { return reverse(forwardComparator); } } // If we inline this, we get a javac error. private static Ordering reverse(Comparator forward) { return Ordering.from(forward).reverse(); } @Override @ParametricNullness public E first() { return forward.last(); } @Override @ParametricNullness public E last() { return forward.first(); } @Override public Iterator iterator() { return forward.descendingIterator(); } @Override public @Nullable Object[] toArray() { return standardToArray(); } @Override @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations public T[] toArray(T[] array) { return standardToArray(array); } @Override public String toString() { return standardToString(); } } /** * Returns a view of the portion of {@code set} whose elements are contained by {@code range}. * *

This method delegates to the appropriate methods of {@link NavigableSet} (namely {@link * NavigableSet#subSet(Object, boolean, Object, boolean) subSet()}, {@link * NavigableSet#tailSet(Object, boolean) tailSet()}, and {@link NavigableSet#headSet(Object, * boolean) headSet()}) to actually construct the view. Consult these methods for a full * description of the returned view's behavior. * *

Warning: {@code Range}s always represent a range of values using the values' natural * ordering. {@code NavigableSet} on the other hand can specify a custom ordering via a {@link * Comparator}, which can violate the natural ordering. Using this method (or in general using * {@code Range}) with unnaturally-ordered sets can lead to unexpected and undefined behavior. * * @since 20.0 */ @GwtIncompatible // NavigableSet public static > NavigableSet subSet( NavigableSet set, Range range) { if (set.comparator() != null && set.comparator() != Ordering.natural() && range.hasLowerBound() && range.hasUpperBound()) { checkArgument( set.comparator().compare(range.lowerEndpoint(), range.upperEndpoint()) <= 0, "set is using a custom comparator which is inconsistent with the natural ordering."); } if (range.hasLowerBound() && range.hasUpperBound()) { return set.subSet( range.lowerEndpoint(), range.lowerBoundType() == BoundType.CLOSED, range.upperEndpoint(), range.upperBoundType() == BoundType.CLOSED); } else if (range.hasLowerBound()) { return set.tailSet(range.lowerEndpoint(), range.lowerBoundType() == BoundType.CLOSED); } else if (range.hasUpperBound()) { return set.headSet(range.upperEndpoint(), range.upperBoundType() == BoundType.CLOSED); } return checkNotNull(set); } }