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 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 javax.annotation.Nullable;
/**
* An immutable {@code SortedSet} that stores its elements in a sorted array.
* Some instances are ordered by an explicit comparator, while others follow the
* natural sort ordering of their elements. Either way, null elements are not
* supported.
*
* Unlike {@link Collections#unmodifiableSortedSet}, which is a view
* of a separate collection that can still change, an instance of {@code
* ImmutableSortedSet} contains its own private data and will never
* change. This class is convenient for {@code public static final} sets
* ("constant sets") and also lets you easily make a "defensive copy" of a set
* provided to your class by a caller.
*
*
The sets returned by the {@link #headSet}, {@link #tailSet}, and
* {@link #subSet} methods share the same array as the original set, preventing
* that array from being garbage collected. If this is a concern, the data may
* be copied into a correctly-sized array by calling {@link #copyOfSorted}.
*
*
Note on element equivalence: The {@link #contains(Object)},
* {@link #containsAll(Collection)}, and {@link #equals(Object)}
* implementations must check whether a provided object is equivalent to an
* element in the collection. Unlike most collections, an
* {@code ImmutableSortedSet} doesn't use {@link Object#equals} to determine if
* two elements are equivalent. Instead, with an explicit comparator, the
* following relation determines whether elements {@code x} and {@code y} are
* equivalent:
{@code
*
* {(x, y) | comparator.compare(x, y) == 0}}
*
* With natural ordering of elements, the following relation determines whether
* two elements are equivalent:
{@code
*
* {(x, y) | x.compareTo(y) == 0}}
*
* Warning: Like most sets, an {@code ImmutableSortedSet} will not
* function correctly if an element is modified after being placed in the set.
* For this reason, and to avoid general confusion, it is strongly recommended
* to place only immutable objects into this collection.
*
* Note: Although this class is not final, it cannot be subclassed as
* it has no public or protected constructors. Thus, instances of this type are
* guaranteed to be immutable.
*
*
See the Guava User Guide article on
* immutable collections.
*
* @see ImmutableSet
* @author Jared Levy
* @author Louis Wasserman
* @since 2.0 (imported from Google Collections Library; 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 {
private static final Comparator NATURAL_ORDER =
Ordering.natural();
private static final ImmutableSortedSet NATURAL_EMPTY_SET =
new EmptyImmutableSortedSet(NATURAL_ORDER);
@SuppressWarnings("unchecked")
private static ImmutableSortedSet emptySet() {
return (ImmutableSortedSet) NATURAL_EMPTY_SET;
}
static ImmutableSortedSet emptySet(
Comparator comparator) {
if (NATURAL_ORDER.equals(comparator)) {
return emptySet();
} else {
return new EmptyImmutableSortedSet(comparator);
}
}
/**
* Returns the empty immutable sorted set.
*/
public static ImmutableSortedSet of() {
return emptySet();
}
/**
* 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}.
*
* If {@code k == contents.length}, then {@code contents} may no longer be safe for
* modification.
*
* @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);
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(Ordering.natural().reverse());
}
/**
* 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 (imported from Google Collections Library)
*/
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
*/
@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
*/
@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
*/
@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
*/
@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
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