Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $
You can buy this project and download/modify it how often you want.
com.google.common.collect.ImmutableMultiset Maven / Gradle / Ivy
Google Collections Library is a suite of new collections and collection-related goodness for Java 5.0
/*
* Copyright (C) 2008 Google Inc.
*
* 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 com.google.common.base.Nullable;
import com.google.common.collect.Serialization.FieldSetter;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
* An immutable hash-based multiset. Does not permit null elements.
*
* Its iterator orders elements according to the first appearance of the
* element among the items passed to the factory method. When the multiset
* contains multiple instances of an element, those instances are consecutive in
* the iteration order.
*
* @author Jared Levy
*/
public class ImmutableMultiset extends ImmutableCollection
implements Multiset {
private static final ImmutableMultiset EMPTY_MULTISET
= new EmptyMultiset();
private static class EmptyMultiset extends ImmutableMultiset {
EmptyMultiset() {
super(ImmutableMap.of(), 0);
}
Object readResolve() {
return EMPTY_MULTISET; // preserve singleton property
}
private static final long serialVersionUID = 0;
}
/**
* Returns the empty immutable multiset.
*/
@SuppressWarnings("unchecked") // all supported methods are covariant
public static ImmutableMultiset of() {
return (ImmutableMultiset) EMPTY_MULTISET;
}
/**
* Returns an immutable multiset containing the given elements.
*
* The multiset is ordered by the first occurrence of each element. For
* example, {@code ImmutableMultiset.of(2, 3, 1, 3)} yields a multiset with
* elements in the order {@code 2, 3, 3, 1}.
*
* @throws NullPointerException if any of {@code elements} is null
*/
public static ImmutableMultiset of(E... elements) {
return copyOf(Arrays.asList(elements));
}
/**
* Returns an immutable multiset containing the given elements.
*
* The multiset is ordered by the first occurrence of each element. For
* example, {@code ImmutableMultiset.copyOf(Arrays.asList(2, 3, 1, 3))} yields
* a multiset with elements in the order {@code 2, 3, 3, 1}.
*
*
Note that if {@code c} is a {@code Collection}, then {@code
* ImmutableMultiset.copyOf(c)} returns an {@code ImmutableMultiset}
* containing each of the strings in {@code c}, while
* {@code ImmutableMultiset.of(c)} returns an
* {@code ImmutableMultiset>} containing one element (the
* given collection itself).
*
* Note: Despite what the method name suggests, if {@code elements}
* is an {@code ImmutableMultiset}, no copy will actually be performed, and
* the given multiset itself will be returned.
*
* @throws NullPointerException if any of {@code elements} is null
*/
public static ImmutableMultiset copyOf(
Iterable elements) {
if (elements instanceof ImmutableMultiset) {
@SuppressWarnings("unchecked") // all supported methods are covariant
ImmutableMultiset result = (ImmutableMultiset) elements;
return result;
}
@SuppressWarnings("unchecked") // the cast causes a warning
Multiset multiset = (elements instanceof Multiset)
? (Multiset) elements
: LinkedHashMultiset.create(elements);
return copyOfInternal(multiset);
}
private static ImmutableMultiset copyOfInternal(
Multiset multiset) {
long size = 0;
ImmutableMap.Builder builder = ImmutableMap.builder();
for (Entry entry : multiset.entrySet()) {
int count = entry.getCount();
if (count > 0) {
// Since ImmutableMap.Builder throws an NPE if an element is null, no
// other null checks are needed.
builder.put(entry.getElement(), count);
size += count;
}
}
return new ImmutableMultiset(
builder.build(), (int) Math.min(size, Integer.MAX_VALUE));
}
/**
* Returns an immutable multiset containing the given elements.
*
* The multiset is ordered by the first occurrence of each element. For
* example,
* {@code ImmutableMultiset.copyOf(Arrays.asList(2, 3, 1, 3).iterator())}
* yields a multiset with elements in the order {@code 2, 3, 3, 1}.
*
* @throws NullPointerException if any of {@code elements} is null
*/
public static ImmutableMultiset copyOf(
Iterator elements) {
Multiset multiset = LinkedHashMultiset.create();
Iterators.addAll(multiset, elements);
return copyOfInternal(multiset);
}
private final transient ImmutableMap map;
private final transient int size;
// These constants allow the deserialization code to set final fields. This
// holder class makes sure they are not initialized unless an instance is
// deserialized.
private static class FieldSettersHolder {
@SuppressWarnings("unchecked") // raw ImmutableMultiset type
static final FieldSetter MAP_FIELD_SETTER
= Serialization.getFieldSetter(ImmutableMultiset.class, "map");
@SuppressWarnings("unchecked") // raw ImmutableMultiset type
static final FieldSetter SIZE_FIELD_SETTER
= Serialization.getFieldSetter(ImmutableMultiset.class, "size");
}
ImmutableMultiset(ImmutableMap map, int size) {
this.map = map;
this.size = size;
}
public int count(@Nullable Object element) {
Integer value = map.get(element);
return (value == null) ? 0 : value;
}
@Override public UnmodifiableIterator iterator() {
final Iterator> mapIterator
= map.entrySet().iterator();
return new UnmodifiableIterator() {
int remaining;
E element;
public boolean hasNext() {
return (remaining > 0) || mapIterator.hasNext();
}
public E next() {
if (remaining <= 0) {
Map.Entry entry = mapIterator.next();
element = entry.getKey();
remaining = entry.getValue();
}
remaining--;
return element;
}
};
}
public int size() {
return size;
}
@Override public boolean contains(@Nullable Object element) {
return map.containsKey(element);
}
/**
* Guaranteed to throw an exception and leave the collection unmodified.
*
* @throws UnsupportedOperationException always
*/
public boolean add(E element, int occurrences) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the collection unmodified.
*
* @throws UnsupportedOperationException always
*/
public int remove(Object element, int occurrences) {
throw new UnsupportedOperationException();
}
/**
* Guaranteed to throw an exception and leave the collection unmodified.
*
* @throws UnsupportedOperationException always
*/
public int removeAllOccurrences(Object element) {
throw new UnsupportedOperationException();
}
@Override public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
if (object instanceof Multiset) {
Multiset that = (Multiset) object;
if (this.size() != that.size()) {
return false;
}
for (Entry entry : that.entrySet()) {
if (count(entry.getElement()) != entry.getCount()) {
return false;
}
}
return true;
}
return false;
}
@Override public int hashCode() {
// could cache this, but not considered worthwhile to do so
return map.hashCode();
}
@Override public String toString() {
return entrySet().toString();
}
// TODO: Serialization of the element set should serialize the multiset, and
// deserialization should call multiset.elementSet(). Then
// reserialized(multiset).elementSet() == reserialized(multiset.elementSet())
// Currently, those object references differ.
public Set elementSet() {
return map.keySet();
}
private transient ImmutableSet> entrySet;
public Set> entrySet() {
ImmutableSet> es = entrySet;
return (es == null) ? (entrySet = new EntrySet(this)) : es;
}
private static class EntrySet extends ImmutableSet> {
final ImmutableMultiset multiset;
public EntrySet(ImmutableMultiset multiset) {
this.multiset = multiset;
}
@Override public UnmodifiableIterator> iterator() {
final Iterator> mapIterator
= multiset.map.entrySet().iterator();
return new UnmodifiableIterator>() {
public boolean hasNext() {
return mapIterator.hasNext();
}
public Entry next() {
Map.Entry mapEntry = mapIterator.next();
return
Multisets.immutableEntry(mapEntry.getKey(), mapEntry.getValue());
}
};
}
public int size() {
return multiset.map.size();
}
@Override public boolean contains(Object o) {
if (o instanceof Entry) {
Entry entry = (Entry) o;
if (entry.getCount() <= 0) {
return false;
}
int count = multiset.count(entry.getElement());
return count == entry.getCount();
}
return false;
}
@Override public int hashCode() {
return multiset.map.hashCode();
}
@Override Object writeReplace() {
return this;
}
private static final long serialVersionUID = 0;
}
/**
* @serialData the number of distinct elements, the first element, its count,
* the second element, its count, and so on
*/
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
Serialization.writeMultiset(this, stream);
}
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
int entryCount = stream.readInt();
ImmutableMap.Builder builder = ImmutableMap.builder();
long tmpSize = 0;
for (int i = 0; i < entryCount; i++) {
@SuppressWarnings("unchecked") // reading data stored by writeMultiset
E element = (E) stream.readObject();
int count = stream.readInt();
if (count <= 0) {
throw new InvalidObjectException("Invalid count " + count);
}
builder.put(element, count);
tmpSize += count;
}
FieldSettersHolder.MAP_FIELD_SETTER.set(this, builder.build());
FieldSettersHolder.SIZE_FIELD_SETTER.set(
this, (int) Math.min(tmpSize, Integer.MAX_VALUE));
}
@Override Object writeReplace() {
return this;
}
private static final long serialVersionUID = 0;
}
