com.google.common.collect.ImmutableSortedMultiset Maven / Gradle / Ivy
/*
* Copyright (C) 2011 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 com.google.common.annotations.GwtIncompatible;
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.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.function.Function;
import java.util.function.ToIntFunction;
import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A {@link SortedMultiset} 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 Louis Wasserman
* @since 12.0
*/
@GwtIncompatible // hasn't been tested yet
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedMultiset extends ImmutableSortedMultisetFauxverideShim
implements SortedMultiset {
// TODO(lowasser): GWT compatibility
/**
* Returns a {@code Collector} that accumulates the input elements into a new {@code
* ImmutableMultiset}. Elements are sorted by the specified comparator.
*
* Warning: {@code comparator} should be consistent with {@code equals} as
* explained in the {@link Comparator} documentation.
*
* @since 21.0
*/
public static Collector> toImmutableSortedMultiset(
Comparator comparator) {
return toImmutableSortedMultiset(comparator, Function.identity(), e -> 1);
}
/**
* Returns a {@code Collector} that accumulates elements into an {@code ImmutableSortedMultiset}
* whose elements are the result of applying {@code elementFunction} to the inputs, with counts
* equal to the result of applying {@code countFunction} to the inputs.
*
* If the mapped elements contain duplicates (according to {@code comparator}), the first
* occurrence in encounter order appears in the resulting multiset, with count equal to the sum of
* the outputs of {@code countFunction.applyAsInt(t)} for each {@code t} mapped to that element.
*
* @since 22.0
*/
public static
Collector> toImmutableSortedMultiset(
Comparator comparator,
Function elementFunction,
ToIntFunction countFunction) {
checkNotNull(comparator);
checkNotNull(elementFunction);
checkNotNull(countFunction);
return Collector.of(
() -> TreeMultiset.create(comparator),
(multiset, t) ->
multiset.add(checkNotNull(elementFunction.apply(t)), countFunction.applyAsInt(t)),
(multiset1, multiset2) -> {
multiset1.addAll(multiset2);
return multiset1;
},
(Multiset multiset) -> copyOfSortedEntries(comparator, multiset.entrySet()));
}
/**
* Returns the empty immutable sorted multiset.
*
* Performance note: the instance returned is a singleton.
*/
@SuppressWarnings("unchecked")
public static ImmutableSortedMultiset of() {
return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
}
/** Returns an immutable sorted multiset containing a single element. */
public static > ImmutableSortedMultiset of(E element) {
RegularImmutableSortedSet elementSet =
(RegularImmutableSortedSet) ImmutableSortedSet.of(element);
long[] cumulativeCounts = {0, 1};
return new RegularImmutableSortedMultiset(elementSet, cumulativeCounts, 0, 1);
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any element is null
*/
public static > ImmutableSortedMultiset of(E e1, E e2) {
return copyOf(Ordering.natural(), Arrays.asList(e1, e2));
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any element is null
*/
public static > ImmutableSortedMultiset of(E e1, E e2, E e3) {
return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any element is null
*/
public static > ImmutableSortedMultiset of(
E e1, E e2, E e3, E e4) {
return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any element is null
*/
public static > ImmutableSortedMultiset of(
E e1, E e2, E e3, E e4, E e5) {
return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4, e5));
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any element is null
*/
public static > ImmutableSortedMultiset of(
E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
int size = remaining.length + 6;
List all = Lists.newArrayListWithCapacity(size);
Collections.addAll(all, e1, e2, e3, e4, e5, e6);
Collections.addAll(all, remaining);
return copyOf(Ordering.natural(), all);
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* @throws NullPointerException if any of {@code elements} is null
*/
public static > ImmutableSortedMultiset copyOf(E[] elements) {
return copyOf(Ordering.natural(), Arrays.asList(elements));
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering. To create a copy of a {@code SortedMultiset} 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 Multiset}, then {@code
* ImmutableSortedMultiset.copyOf(s)} returns an {@code ImmutableSortedMultiset}
* containing each of the strings in {@code s}, while {@code ImmutableSortedMultiset.of(s)}
* returns an {@code ImmutableSortedMultiset>} containing one element (the given
* multiset 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 ImmutableSortedMultiset copyOf(Iterable elements) {
// Hack around E not being a subtype of Comparable.
// Unsafe, see ImmutableSortedMultisetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOf(naturalOrder, elements);
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by their natural
* ordering.
*
* 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 ImmutableSortedMultiset copyOf(Iterator elements) {
// Hack around E not being a subtype of Comparable.
// Unsafe, see ImmutableSortedMultisetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOf(naturalOrder, elements);
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by the given {@code
* Comparator}.
*
* @throws NullPointerException if {@code comparator} or any of {@code elements} is null
*/
public static ImmutableSortedMultiset copyOf(
Comparator comparator, Iterator elements) {
checkNotNull(comparator);
return new Builder(comparator).addAll(elements).build();
}
/**
* Returns an immutable sorted multiset containing the given elements sorted by the given {@code
* Comparator}. 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 ImmutableSortedMultiset copyOf(
Comparator comparator, Iterable elements) {
if (elements instanceof ImmutableSortedMultiset) {
@SuppressWarnings("unchecked") // immutable collections are always safe for covariant casts
ImmutableSortedMultiset multiset = (ImmutableSortedMultiset) elements;
if (comparator.equals(multiset.comparator())) {
if (multiset.isPartialView()) {
return copyOfSortedEntries(comparator, multiset.entrySet().asList());
} else {
return multiset;
}
}
}
elements = Lists.newArrayList(elements); // defensive copy
TreeMultiset sortedCopy = TreeMultiset.create(checkNotNull(comparator));
Iterables.addAll(sortedCopy, elements);
return copyOfSortedEntries(comparator, sortedCopy.entrySet());
}
/**
* Returns an immutable sorted multiset containing the elements of a sorted multiset, 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 sortedMultiset} is a synchronized or concurrent
* collection that is currently being modified by another thread.
*
* @throws NullPointerException if {@code sortedMultiset} or any of its elements is null
*/
public static ImmutableSortedMultiset copyOfSorted(SortedMultiset sortedMultiset) {
return copyOfSortedEntries(
sortedMultiset.comparator(), Lists.newArrayList(sortedMultiset.entrySet()));
}
private static ImmutableSortedMultiset copyOfSortedEntries(
Comparator comparator, Collection> entries) {
if (entries.isEmpty()) {
return emptyMultiset(comparator);
}
ImmutableList.Builder elementsBuilder = new ImmutableList.Builder(entries.size());
long[] cumulativeCounts = new long[entries.size() + 1];
int i = 0;
for (Entry entry : entries) {
elementsBuilder.add(entry.getElement());
cumulativeCounts[i + 1] = cumulativeCounts[i] + entry.getCount();
i++;
}
return new RegularImmutableSortedMultiset(
new RegularImmutableSortedSet(elementsBuilder.build(), comparator),
cumulativeCounts,
0,
entries.size());
}
@SuppressWarnings("unchecked")
static ImmutableSortedMultiset emptyMultiset(Comparator comparator) {
if (Ordering.natural().equals(comparator)) {
return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
} else {
return new RegularImmutableSortedMultiset(comparator);
}
}
ImmutableSortedMultiset() {}
@Override
public final Comparator comparator() {
return elementSet().comparator();
}
@Override
public abstract ImmutableSortedSet elementSet();
@LazyInit @CheckForNull transient ImmutableSortedMultiset descendingMultiset;
@Override
public ImmutableSortedMultiset descendingMultiset() {
ImmutableSortedMultiset result = descendingMultiset;
if (result == null) {
return descendingMultiset =
this.isEmpty()
? emptyMultiset(Ordering.from(comparator()).reverse())
: new DescendingImmutableSortedMultiset(this);
}
return result;
}
/**
* {@inheritDoc}
*
* This implementation is guaranteed to throw an {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@CanIgnoreReturnValue
@Deprecated
@Override
@DoNotCall("Always throws UnsupportedOperationException")
@CheckForNull
public final Entry pollFirstEntry() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*
* This implementation is guaranteed to throw an {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException always
* @deprecated Unsupported operation.
*/
@CanIgnoreReturnValue
@Deprecated
@Override
@DoNotCall("Always throws UnsupportedOperationException")
@CheckForNull
public final Entry pollLastEntry() {
throw new UnsupportedOperationException();
}
@Override
public abstract ImmutableSortedMultiset headMultiset(E upperBound, BoundType boundType);
@Override
public ImmutableSortedMultiset subMultiset(
E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
checkArgument(
comparator().compare(lowerBound, upperBound) <= 0,
"Expected lowerBound <= upperBound but %s > %s",
lowerBound,
upperBound);
return tailMultiset(lowerBound, lowerBoundType).headMultiset(upperBound, upperBoundType);
}
@Override
public abstract ImmutableSortedMultiset tailMultiset(E lowerBound, BoundType boundType);
/**
* Returns a builder that creates immutable sorted multisets with an explicit comparator. If the
* comparator has a more general type than the set being generated, such as creating a {@code
* SortedMultiset} 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 multisets whose elements are ordered by the
* reverse of their natural ordering.
*
* Note: the type parameter {@code E} extends {@code Comparable} rather than {@code
* Comparable} as a workaround for javac bug 6468354.
*/
public static > Builder reverseOrder() {
return new Builder(Ordering.natural().reverse());
}
/**
* Returns a builder that creates immutable sorted multisets whose elements are ordered by their
* natural ordering. The sorted multisets 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}.
*
* Note: the type parameter {@code E} extends {@code Comparable} rather than {@code
* Comparable} as a workaround for javac bug 6468354.
*/
public static > Builder naturalOrder() {
return new Builder(Ordering.natural());
}
/**
* A builder for creating immutable multiset instances, especially {@code public static final}
* multisets ("constant multisets"). Example:
*
* {@code
* public static final ImmutableSortedMultiset BEANS =
* new ImmutableSortedMultiset.Builder(colorComparator())
* .addCopies(Bean.COCOA, 4)
* .addCopies(Bean.GARDEN, 6)
* .addCopies(Bean.RED, 8)
* .addCopies(Bean.BLACK_EYED, 10)
* .build();
* }
*
* Builder instances can be reused; it is safe to call {@link #build} multiple times to build
* multiple multisets in series.
*
* @since 12.0
*/
public static class Builder extends ImmutableMultiset.Builder {
/**
* Creates a new builder. The returned builder is equivalent to the builder generated by {@link
* ImmutableSortedMultiset#orderedBy(Comparator)}.
*/
public Builder(Comparator comparator) {
super(TreeMultiset.create(checkNotNull(comparator)));
}
/**
* Adds {@code element} to the {@code ImmutableSortedMultiset}.
*
* @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 ImmutableSortedMultiset}.
*
* @param elements the elements to add
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} is null or contains a null element
*/
@CanIgnoreReturnValue
@Override
public Builder add(E... elements) {
super.add(elements);
return this;
}
/**
* Adds a number of occurrences of an element to this {@code ImmutableSortedMultiset}.
*
* @param element the element to add
* @param occurrences the number of occurrences of the element to add. May be zero, in which
* case no change will be made.
* @return this {@code Builder} object
* @throws NullPointerException if {@code element} is null
* @throws IllegalArgumentException if {@code occurrences} is negative, or if this operation
* would result in more than {@link Integer#MAX_VALUE} occurrences of the element
*/
@CanIgnoreReturnValue
@Override
public Builder addCopies(E element, int occurrences) {
super.addCopies(element, occurrences);
return this;
}
/**
* Adds or removes the necessary occurrences of an element such that the element attains the
* desired count.
*
* @param element the element to add or remove occurrences of
* @param count the desired count of the element in this multiset
* @return this {@code Builder} object
* @throws NullPointerException if {@code element} is null
* @throws IllegalArgumentException if {@code count} is negative
*/
@CanIgnoreReturnValue
@Override
public Builder setCount(E element, int count) {
super.setCount(element, count);
return this;
}
/**
* Adds each element of {@code elements} to the {@code ImmutableSortedMultiset}.
*
* @param elements the {@code Iterable} to add to the {@code ImmutableSortedMultiset}
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} is null or 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 ImmutableSortedMultiset}.
*
* @param elements the elements to add to the {@code ImmutableSortedMultiset}
* @return this {@code Builder} object
* @throws NullPointerException if {@code elements} is null or contains a null element
*/
@CanIgnoreReturnValue
@Override
public Builder addAll(Iterator elements) {
super.addAll(elements);
return this;
}
/**
* Returns a newly-created {@code ImmutableSortedMultiset} based on the contents of the {@code
* Builder}.
*/
@Override
public ImmutableSortedMultiset build() {
return copyOfSorted((SortedMultiset) contents);
}
}
private static final class SerializedForm implements Serializable {
final Comparator comparator;
final E[] elements;
final int[] counts;
@SuppressWarnings("unchecked")
SerializedForm(SortedMultiset multiset) {
this.comparator = multiset.comparator();
int n = multiset.entrySet().size();
elements = (E[]) new Object[n];
counts = new int[n];
int i = 0;
for (Entry entry : multiset.entrySet()) {
elements[i] = entry.getElement();
counts[i] = entry.getCount();
i++;
}
}
Object readResolve() {
int n = elements.length;
Builder builder = new Builder<>(comparator);
for (int i = 0; i < n; i++) {
builder.addCopies(elements[i], counts[i]);
}
return builder.build();
}
}
@Override
Object writeReplace() {
return new SerializedForm(this);
}
}