com.google.common.collect.ImmutableSortedSet Maven / Gradle / Ivy
/*
* Copyright (C) 2008 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.google.common.collect;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.ObjectArrays.checkElementsNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.SortedSet;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;
/**
* A {@link NavigableSet} whose contents will never change, with many other important properties
* detailed at {@link ImmutableCollection}.
*
* Warning: as with any sorted collection, you are strongly advised not to use a {@link
* Comparator} or {@link Comparable} type whose comparison behavior is inconsistent with
* equals. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
* if and only if {@code a.equals(b)}. If this advice is not followed, the resulting
* collection will not correctly obey its specification.
*
*
See the Guava User Guide article on immutable collections.
*
* @author Jared Levy
* @author Louis Wasserman
* @since 2.0 (implements {@code NavigableSet} since 12.0)
*/
// TODO(benyu): benchmark and optimize all creation paths, which are a mess now
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableSortedSet extends ImmutableSortedSetFauxverideShim
implements NavigableSet, SortedIterable {
static RegularImmutableSortedSet emptySet(Comparator comparator) {
if (Ordering.natural().equals(comparator)) {
return (RegularImmutableSortedSet) RegularImmutableSortedSet.NATURAL_EMPTY_SET;
} else {
return new RegularImmutableSortedSet(ImmutableList.of(), comparator);
}
}
/** Returns the empty immutable sorted set. */
public static ImmutableSortedSet of() {
return (ImmutableSortedSet) RegularImmutableSortedSet.NATURAL_EMPTY_SET;
}
/** Returns an immutable sorted set containing a single element. */
public static > ImmutableSortedSet of(E element) {
return new RegularImmutableSortedSet(ImmutableList.of(element), Ordering.natural());
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any element is null
*/
@SuppressWarnings("unchecked")
public static > ImmutableSortedSet of(E e1, E e2) {
return construct(Ordering.natural(), 2, e1, e2);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any element is null
*/
@SuppressWarnings("unchecked")
public static > ImmutableSortedSet of(E e1, E e2, E e3) {
return construct(Ordering.natural(), 3, e1, e2, e3);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any element is null
*/
@SuppressWarnings("unchecked")
public static > ImmutableSortedSet of(E e1, E e2, E e3, E e4) {
return construct(Ordering.natural(), 4, e1, e2, e3, e4);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any element is null
*/
@SuppressWarnings("unchecked")
public static > ImmutableSortedSet of(
E e1, E e2, E e3, E e4, E e5) {
return construct(Ordering.natural(), 5, e1, e2, e3, e4, e5);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any element is null
* @since 3.0 (source-compatible since 2.0)
*/
@SuppressWarnings("unchecked")
public static > ImmutableSortedSet of(
E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
Comparable[] contents = new Comparable[6 + remaining.length];
contents[0] = e1;
contents[1] = e2;
contents[2] = e3;
contents[3] = e4;
contents[4] = e5;
contents[5] = e6;
System.arraycopy(remaining, 0, contents, 6, remaining.length);
return construct(Ordering.natural(), contents.length, (E[]) contents);
}
// TODO(kevinb): Consider factory methods that reject duplicates
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
* one specified is included.
*
* @throws NullPointerException if any of {@code elements} is null
* @since 3.0
*/
public static > ImmutableSortedSet copyOf(E[] elements) {
return construct(Ordering.natural(), elements.length, elements.clone());
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@code compareTo()}, only the first one
* specified is included. To create a copy of a {@code SortedSet} that preserves the comparator,
* call {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once.
*
* Note that if {@code s} is a {@code Set}, then {@code ImmutableSortedSet.copyOf(s)}
* returns an {@code ImmutableSortedSet} containing each of the strings in {@code s},
* while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet>}
* containing one element (the given set itself).
*
* Despite the method name, this method attempts to avoid actually copying the data when it is
* safe to do so. The exact circumstances under which a copy will or will not be performed are
* undocumented and subject to change.
*
*
This method is not type-safe, as it may be called on elements that are not mutually
* comparable.
*
* @throws ClassCastException if the elements are not mutually comparable
* @throws NullPointerException if any of {@code elements} is null
*/
public static ImmutableSortedSet copyOf(Iterable elements) {
// Hack around E not being a subtype of Comparable.
// Unsafe, see ImmutableSortedSetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOf(naturalOrder, elements);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@code compareTo()}, only the first one
* specified is included. To create a copy of a {@code SortedSet} that preserves the comparator,
* call {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once.
*
* Note that if {@code s} is a {@code Set}, then {@code ImmutableSortedSet.copyOf(s)}
* returns an {@code ImmutableSortedSet} containing each of the strings in {@code s},
* while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet>}
* containing one element (the given set itself).
*
* Note: Despite what the method name suggests, if {@code elements} is an {@code
* ImmutableSortedSet}, it may be returned instead of a copy.
*
*
This method is not type-safe, as it may be called on elements that are not mutually
* comparable.
*
*
This method is safe to use even when {@code elements} is a synchronized or concurrent
* collection that is currently being modified by another thread.
*
* @throws ClassCastException if the elements are not mutually comparable
* @throws NullPointerException if any of {@code elements} is null
* @since 7.0 (source-compatible since 2.0)
*/
public static ImmutableSortedSet copyOf(Collection elements) {
// Hack around E not being a subtype of Comparable.
// Unsafe, see ImmutableSortedSetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOf(naturalOrder, elements);
}
/**
* Returns an immutable sorted set containing the given elements sorted by their natural ordering.
* When multiple elements are equivalent according to {@code compareTo()}, only the first one
* specified is included.
*
* This method is not type-safe, as it may be called on elements that are not mutually
* comparable.
*
* @throws ClassCastException if the elements are not mutually comparable
* @throws NullPointerException if any of {@code elements} is null
*/
public static ImmutableSortedSet copyOf(Iterator elements) {
// Hack around E not being a subtype of Comparable.
// Unsafe, see ImmutableSortedSetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOf(naturalOrder, elements);
}
/**
* Returns an immutable sorted set containing the given elements sorted by the given {@code
* Comparator}. When multiple elements are equivalent according to {@code compareTo()}, only the
* first one specified is included.
*
* @throws NullPointerException if {@code comparator} or any of {@code elements} is null
*/
public static ImmutableSortedSet copyOf(
Comparator comparator, Iterator elements) {
return new Builder(comparator).addAll(elements).build();
}
/**
* Returns an immutable sorted set containing the given elements sorted by the given {@code
* Comparator}. When multiple elements are equivalent according to {@code compare()}, only the
* first one specified is included. This method iterates over {@code elements} at most once.
*
* Despite the method name, this method attempts to avoid actually copying the data when it is
* safe to do so. The exact circumstances under which a copy will or will not be performed are
* undocumented and subject to change.
*
* @throws NullPointerException if {@code comparator} or any of {@code elements} is null
*/
public static ImmutableSortedSet copyOf(
Comparator comparator, Iterable elements) {
checkNotNull(comparator);
boolean hasSameComparator = SortedIterables.hasSameComparator(comparator, elements);
if (hasSameComparator && (elements instanceof ImmutableSortedSet)) {
@SuppressWarnings("unchecked")
ImmutableSortedSet original = (ImmutableSortedSet) elements;
if (!original.isPartialView()) {
return original;
}
}
@SuppressWarnings("unchecked") // elements only contains E's; it's safe.
E[] array = (E[]) Iterables.toArray(elements);
return construct(comparator, array.length, array);
}
/**
* Returns an immutable sorted set containing the given elements sorted by the given {@code
* Comparator}. When multiple elements are equivalent according to {@code compareTo()}, only the
* first one specified is included.
*
* Despite the method name, this method attempts to avoid actually copying the data when it is
* safe to do so. The exact circumstances under which a copy will or will not be performed are
* undocumented and subject to change.
*
*
This method is safe to use even when {@code elements} is a synchronized or concurrent
* collection that is currently being modified by another thread.
*
* @throws NullPointerException if {@code comparator} or any of {@code elements} is null
* @since 7.0 (source-compatible since 2.0)
*/
public static ImmutableSortedSet copyOf(
Comparator comparator, Collection elements) {
return copyOf(comparator, (Iterable) elements);
}
/**
* Returns an immutable sorted set containing the elements of a sorted set, sorted by the same
* {@code Comparator}. That behavior differs from {@link #copyOf(Iterable)}, which always uses the
* natural ordering of the elements.
*
* Despite the method name, this method attempts to avoid actually copying the data when it is
* safe to do so. The exact circumstances under which a copy will or will not be performed are
* undocumented and subject to change.
*
*
This method is safe to use even when {@code sortedSet} is a synchronized or concurrent
* collection that is currently being modified by another thread.
*
* @throws NullPointerException if {@code sortedSet} or any of its elements is null
*/
public static ImmutableSortedSet copyOfSorted(SortedSet sortedSet) {
Comparator comparator = SortedIterables.comparator(sortedSet);
ImmutableList list = ImmutableList.copyOf(sortedSet);
if (list.isEmpty()) {
return emptySet(comparator);
} else {
return new RegularImmutableSortedSet(list, comparator);
}
}
/**
* Constructs an {@code ImmutableSortedSet} from the first {@code n} elements of {@code contents}.
* If {@code k} is the size of the returned {@code ImmutableSortedSet}, then the sorted unique
* elements are in the first {@code k} positions of {@code contents}, and {@code contents[i] ==
* null} for {@code k <= i < n}.
*
* This method takes ownership of {@code contents}; do not modify {@code contents} after this
* returns.
*
* @throws NullPointerException if any of the first {@code n} elements of {@code contents} is null
*/
static ImmutableSortedSet construct(
Comparator comparator, int n, E... contents) {
if (n == 0) {
return emptySet(comparator);
}
checkElementsNotNull(contents, n);
Arrays.sort(contents, 0, n, comparator);
int uniques = 1;
for (int i = 1; i < n; i++) {
E cur = contents[i];
E prev = contents[uniques - 1];
if (comparator.compare(cur, prev) != 0) {
contents[uniques++] = cur;
}
}
Arrays.fill(contents, uniques, n, null);
if (uniques < contents.length / 2) {
// Deduplication eliminated many of the elements. We don't want to retain an arbitrarily
// large array relative to the number of elements, so we cap the ratio.
contents = Arrays.copyOf(contents, uniques);
}
return new RegularImmutableSortedSet(
ImmutableList.asImmutableList(contents, uniques), comparator);
}
/**
* Returns a builder that creates immutable sorted sets with an explicit comparator. If the
* comparator has a more general type than the set being generated, such as creating a {@code
* SortedSet} with a {@code Comparator}, use the {@link Builder} constructor
* instead.
*
* @throws NullPointerException if {@code comparator} is null
*/
public static Builder orderedBy(Comparator comparator) {
return new Builder(comparator);
}
/**
* Returns a builder that creates immutable sorted sets whose elements are ordered by the reverse
* of their natural ordering.
*/
public static > Builder reverseOrder() {
return new Builder(Collections.reverseOrder());
}
/**
* Returns a builder that creates immutable sorted sets whose elements are ordered by their
* natural ordering. The sorted sets use {@link Ordering#natural()} as the comparator. This method
* provides more type-safety than {@link #builder}, as it can be called only for classes that
* implement {@link Comparable}.
*/
public static > Builder naturalOrder() {
return new Builder(Ordering.natural());
}
/**
* A builder for creating immutable sorted set instances, especially {@code public static final}
* sets ("constant sets"), with a given comparator. Example:
*
* {@code
* public static final ImmutableSortedSet LUCKY_NUMBERS =
* new ImmutableSortedSet.Builder(ODDS_FIRST_COMPARATOR)
* .addAll(SINGLE_DIGIT_PRIMES)
* .add(42)
* .build();
* }
*
* Builder instances can be reused; it is safe to call {@link #build} multiple times to build
* multiple sets in series. Each set is a superset of the set created before it.
*
* @since 2.0
*/
public static final class Builder extends ImmutableSet.Builder {
private final Comparator comparator;
/**
* Creates a new builder. The returned builder is equivalent to the builder generated by {@link
* ImmutableSortedSet#orderedBy}.
*/
public Builder(Comparator comparator) {
this.comparator = checkNotNull(comparator);
}
/**
* Adds {@code element} to the {@code ImmutableSortedSet}. If the {@code ImmutableSortedSet}
* already contains {@code element}, then {@code add} has no effect. (only the previously added
* element is retained).
*
* @param element the element to add
* @return this {@code Builder} object
* @throws NullPointerException if {@code element} is null
*/
@CanIgnoreReturnValue
@Override
public Builder add(E element) {
super.add(element);
return this;
}
/**
* Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate
* elements (only the first duplicate element is added).
*
* @param elements the elements to add
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} contains a null element
*/
@CanIgnoreReturnValue
@Override
public Builder add(E... elements) {
super.add(elements);
return this;
}
/**
* Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate
* elements (only the first duplicate element is added).
*
* @param elements the elements to add to the {@code ImmutableSortedSet}
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} contains a null element
*/
@CanIgnoreReturnValue
@Override
public Builder addAll(Iterable elements) {
super.addAll(elements);
return this;
}
/**
* Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate
* elements (only the first duplicate element is added).
*
* @param elements the elements to add to the {@code ImmutableSortedSet}
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} contains a null element
*/
@CanIgnoreReturnValue
@Override
public Builder addAll(Iterator elements) {
super.addAll(elements);
return this;
}
/**
* Returns a newly-created {@code ImmutableSortedSet} based on the contents of the {@code
* Builder} and its comparator.
*/
@Override
public ImmutableSortedSet build() {
@SuppressWarnings("unchecked") // we're careful to put only E's in here
E[] contentsArray = (E[]) contents;
ImmutableSortedSet result = construct(comparator, size, contentsArray);
this.size = result.size(); // we eliminated duplicates in-place in contentsArray
this.forceCopy = true;
return result;
}
}
int unsafeCompare(Object a, Object b) {
return unsafeCompare(comparator, a, b);
}
static int unsafeCompare(Comparator comparator, Object a, Object b) {
// Pretend the comparator can compare anything. If it turns out it can't
// compare a and b, we should get a CCE on the subsequent line. Only methods
// that are spec'd to throw CCE should call this.
@SuppressWarnings("unchecked")
Comparator