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/*
* Copyright (C) 2009 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 static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import java.util.TreeMap;
import javax.annotation.Nullable;
/**
* An immutable {@link SortedMap}. Does not permit null keys or values.
*
* Unlike {@link Collections#unmodifiableSortedMap}, which is a view
* of a separate map which can still change, an instance of {@code
* ImmutableSortedMap} contains its own data and will never change.
* {@code ImmutableSortedMap} is convenient for {@code public static final} maps
* ("constant maps") and also lets you easily make a "defensive copy" of a map
* provided to your class by a caller.
*
*
Note: Although this class is not final, it cannot be subclassed as
* it has no public or protected constructors. Thus, instances of this class are
* guaranteed to be immutable.
*
* @author Jared Levy
*/
@GwtCompatible(serializable = true)
public class ImmutableSortedMap
extends ImmutableSortedMapFauxverideShim implements SortedMap {
// TODO: Confirm that ImmutableSortedMap is faster to construct and uses less
// memory than TreeMap; then say so in the class Javadoc.
// TODO: Create separate subclasses for empty, single-entry, and
// multiple-entry instances.
@SuppressWarnings("unchecked")
private static final Comparator NATURAL_ORDER = Ordering.natural();
private static final Entry[] EMPTY_ARRAY = new Entry[0];
@SuppressWarnings("unchecked")
private static final ImmutableMap NATURAL_EMPTY_MAP
= new ImmutableSortedMap(EMPTY_ARRAY, NATURAL_ORDER);
/**
* Returns the empty sorted map.
*/
// Casting to any type is safe because the set will never hold any elements.
@SuppressWarnings("unchecked")
public static ImmutableSortedMap of() {
return (ImmutableSortedMap) NATURAL_EMPTY_MAP;
}
private static ImmutableSortedMap emptyMap(
Comparator comparator) {
if (NATURAL_ORDER.equals(comparator)) {
return ImmutableSortedMap.of();
} else {
return new ImmutableSortedMap(EMPTY_ARRAY, comparator);
}
}
/**
* Returns an immutable map containing a single entry.
*/
public static , V> ImmutableSortedMap
of(K k1, V v1) {
Entry[] entries = { entryOf(k1, v1) };
return new ImmutableSortedMap(entries, Ordering.natural());
}
/**
* Returns an immutable sorted map containing the given entries, sorted by the
* natural ordering of their keys.
*
* @throws IllegalArgumentException if the two keys are equal according to
* their natural ordering
*/
public static , V> ImmutableSortedMap
of(K k1, V v1, K k2, V v2) {
return new Builder(Ordering.natural())
.put(k1, v1).put(k2, v2).build();
}
/**
* Returns an immutable sorted map containing the given entries, sorted by the
* natural ordering of their keys.
*
* @throws IllegalArgumentException if any two keys are equal according to
* their natural ordering
*/
public static , V> ImmutableSortedMap
of(K k1, V v1, K k2, V v2, K k3, V v3) {
return new Builder(Ordering.natural())
.put(k1, v1).put(k2, v2).put(k3, v3).build();
}
/**
* Returns an immutable sorted map containing the given entries, sorted by the
* natural ordering of their keys.
*
* @throws IllegalArgumentException if any two keys are equal according to
* their natural ordering
*/
public static , V> ImmutableSortedMap
of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
return new Builder(Ordering.natural())
.put(k1, v1).put(k2, v2).put(k3, v3).put(k4, v4).build();
}
/**
* Returns an immutable sorted map containing the given entries, sorted by the
* natural ordering of their keys.
*
* @throws IllegalArgumentException if any two keys are equal according to
* their natural ordering
*/
public static , V> ImmutableSortedMap
of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
return new Builder(Ordering.natural())
.put(k1, v1).put(k2, v2).put(k3, v3).put(k4, v4).put(k5, v5).build();
}
/**
* Returns an immutable map containing the same entries as {@code map}, sorted
* by the natural ordering of the keys.
*
* Note: Despite what the method name suggests, if {@code map} is an
* {@code ImmutableSortedMap}, it may be returned instead of a copy.
*
*
This method is not type-safe, as it may be called on a map with keys
* that are not mutually comparable.
*
* @throws ClassCastException if the keys in {@code map} are not mutually
* comparable
* @throws NullPointerException if any key or value in {@code map} is null
* @throws IllegalArgumentException if any two keys are equal according to
* their natural ordering
*/
public static ImmutableSortedMap copyOf(
Map map) {
// Hack around K not being a subtype of Comparable.
// Unsafe, see ImmutableSortedSetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering naturalOrder = (Ordering) Ordering.natural();
return copyOfInternal(map, naturalOrder);
}
/**
* Returns an immutable map containing the same entries as {@code map}, with
* keys sorted by the provided comparator.
*
* Note: Despite what the method name suggests, if {@code map} is an
* {@code ImmutableSortedMap}, it may be returned instead of a copy.
*
* @throws NullPointerException if any key or value in {@code map} is null
* @throws IllegalArgumentException if any two keys are equal according to
* the comparator
*/
public static ImmutableSortedMap copyOf(
Map map, Comparator comparator) {
return copyOfInternal(map, checkNotNull(comparator));
}
/**
* Returns an immutable map containing the same entries as the provided sorted
* map, with the same ordering.
*
* Note: Despite what the method name suggests, if {@code map} is an
* {@code ImmutableSortedMap}, it may be returned instead of a copy.
*
* @throws NullPointerException if any key or value in {@code map} is null
*/
public static ImmutableSortedMap copyOfSorted(
SortedMap map) {
// If map has a null comparator, the keys should have a natural ordering,
// even though K doesn't explicitly implement Comparable.
@SuppressWarnings("unchecked")
Comparator comparator =
(map.comparator() == null) ? NATURAL_ORDER : map.comparator();
return copyOfInternal(map, comparator);
}
private static ImmutableSortedMap copyOfInternal(
Map map, Comparator comparator) {
boolean sameComparator = false;
if (map instanceof SortedMap) {
SortedMap sortedMap = (SortedMap) map;
Comparator comparator2 = sortedMap.comparator();
sameComparator = (comparator2 == null)
? comparator == NATURAL_ORDER
: comparator.equals(comparator2);
}
if (sameComparator && (map instanceof ImmutableSortedMap)) {
// TODO: Prove that this cast is safe, even though
// Collections.unmodifiableSortedMap requires the same key type.
@SuppressWarnings("unchecked")
ImmutableSortedMap kvMap = (ImmutableSortedMap) map;
return kvMap;
}
// Using List to support concurrent map whose size changes
List> list = Lists.newArrayListWithCapacity(map.size());
for (Entry entry : map.entrySet()) {
list.add(entryOf(entry.getKey(), entry.getValue()));
}
Entry[] entryArray = list.toArray(new Entry[list.size()]);
if (!sameComparator) {
sortEntries(entryArray, comparator);
validateEntries(entryArray, comparator);
}
return new ImmutableSortedMap(entryArray, comparator);
}
private static void sortEntries(Entry[] entryArray,
final Comparator comparator) {
Comparator> entryComparator = new Comparator>() {
public int compare(Entry entry1, Entry entry2) {
return ImmutableSortedSet.unsafeCompare(
comparator, entry1.getKey(), entry2.getKey());
}
};
Arrays.sort(entryArray, entryComparator);
}
private static void validateEntries(Entry[] entryArray,
Comparator comparator) {
for (int i = 1; i < entryArray.length; i++) {
if (ImmutableSortedSet.unsafeCompare(comparator,
entryArray[i - 1].getKey(), entryArray[i].getKey()) == 0) {
throw new IllegalArgumentException(
"Duplicate keys in mappings "
+ entryArray[i - 1] + " and " + entryArray[i]);
}
}
}
/**
* Returns a builder that creates immutable sorted maps whose keys are
* ordered by their natural ordering. The sorted maps use {@link
* Ordering#natural()} as the comparator.
*
* Note: the type parameter {@code K} extends {@code Comparable} rather
* than {@code Comparable} as a workaround for javac bug
* 6468354.
*/
public static , V> Builder naturalOrder() {
return new Builder(Ordering.natural());
}
/**
* Returns a builder that creates immutable sorted maps with an explicit
* comparator. If the comparator has a more general type than the map's keys,
* such as creating a {@code SortedMap} 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 maps whose keys are
* ordered by the reverse of their natural ordering.
*
* Note: the type parameter {@code K} extends {@code Comparable} rather
* than {@code Comparable} as a workaround for javac bug
* 6468354.
*/
public static , V> Builder reverseOrder() {
return new Builder(Ordering.natural().reverse());
}
/**
* A builder for creating immutable sorted map instances, especially {@code
* public static final} maps ("constant maps"). Example: {@code
*
* static final ImmutableSortedMap INT_TO_WORD =
* new ImmutableSortedMap.Builder(Ordering.natural())
* .put(1, "one")
* .put(2, "two")
* .put(3, "three")
* .build();}
*
* For small immutable sorted maps, the {@code ImmutableSortedMap.of()}
* methods are even more convenient.
*
* Builder instances can be reused - it is safe to call {@link #build}
* multiple times to build multiple maps in series. Each map is a superset of
* the maps created before it.
*/
public static final class Builder extends ImmutableMap.Builder {
private final Comparator comparator;
/**
* Creates a new builder. The returned builder is equivalent to the builder
* generated by {@link ImmutableSortedMap#orderedBy}.
*/
public Builder(Comparator comparator) {
this.comparator = checkNotNull(comparator);
}
/**
* Associates {@code key} with {@code value} in the built map. Duplicate
* keys, according to the comparator (which might be the keys' natural
* order), are not allowed, and will cause {@link #build} to fail.
*/
@Override public Builder put(K key, V value) {
entries.add(entryOf(key, value));
return this;
}
/**
* Associates all of the given map's keys and values in the built map.
* Duplicate keys, according to the comparator (which might be the keys'
* natural order), are not allowed, and will cause {@link #build} to fail.
*
* @throws NullPointerException if any key or value in {@code map} is null
*/
@Override public Builder putAll(Map map) {
for (Entry entry : map.entrySet()) {
put(entry.getKey(), entry.getValue());
}
return this;
}
/**
* Returns a newly-created immutable sorted map.
*
* @throws IllegalArgumentException if any two keys are equal according to
* the comparator (which might be the keys' natural order)
*/
@Override public ImmutableSortedMap build() {
Entry[] entryArray
= entries.toArray(new Entry[entries.size()]);
sortEntries(entryArray, comparator);
validateEntries(entryArray, comparator);
return new ImmutableSortedMap(entryArray, comparator);
}
}
private final transient Entry[] entries;
private final transient Comparator comparator;
private final transient int fromIndex;
private final transient int toIndex;
private ImmutableSortedMap(Entry[] entries,
Comparator comparator, int fromIndex, int toIndex) {
// each of the callers carefully put only Entrys into the array!
@SuppressWarnings("unchecked")
Entry[] tmp = (Entry[]) entries;
this.entries = tmp;
this.comparator = comparator;
this.fromIndex = fromIndex;
this.toIndex = toIndex;
}
ImmutableSortedMap(Entry[] entries,
Comparator comparator) {
this(entries, comparator, 0, entries.length);
}
public int size() {
return toIndex - fromIndex;
}
@Override public V get(@Nullable Object key) {
if (key == null) {
return null;
}
int i;
try {
i = binarySearch(key);
} catch (ClassCastException e) {
return null;
}
return (i >= 0) ? entries[i].getValue() : null;
}
private int binarySearch(Object key) {
int lower = fromIndex;
int upper = toIndex - 1;
while (lower <= upper) {
int middle = lower + (upper - lower) / 2;
int c = ImmutableSortedSet.unsafeCompare(
comparator, key, entries[middle].getKey());
if (c < 0) {
upper = middle - 1;
} else if (c > 0) {
lower = middle + 1;
} else {
return middle;
}
}
return -lower - 1;
}
@Override public boolean containsValue(@Nullable Object value) {
if (value == null) {
return false;
}
for (int i = fromIndex; i < toIndex; i++) {
if (entries[i].getValue().equals(value)) {
return true;
}
}
return false;
}
private transient ImmutableSet> entrySet;
/**
* Returns an immutable set of the mappings in this map, sorted by the key
* ordering.
*/
@Override public ImmutableSet> entrySet() {
ImmutableSet> es = entrySet;
return (es == null) ? (entrySet = createEntrySet()) : es;
}
private ImmutableSet> createEntrySet() {
return isEmpty() ? ImmutableSet.>of()
: new EntrySet(this);
}
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
private static class EntrySet extends ImmutableSet> {
final transient ImmutableSortedMap map;
EntrySet(ImmutableSortedMap map) {
this.map = map;
}
public int size() {
return map.size();
}
@Override public UnmodifiableIterator> iterator() {
return Iterators.forArray(map.entries, map.fromIndex, size());
}
@Override public boolean contains(Object target) {
if (target instanceof Entry) {
Entry entry = (Entry) target;
V mappedValue = map.get(entry.getKey());
return mappedValue != null && mappedValue.equals(entry.getValue());
}
return false;
}
@Override Object writeReplace() {
return new EntrySetSerializedForm(map);
}
}
private static class EntrySetSerializedForm implements Serializable {
final ImmutableSortedMap map;
EntrySetSerializedForm(ImmutableSortedMap map) {
this.map = map;
}
Object readResolve() {
return map.entrySet();
}
private static final long serialVersionUID = 0;
}
private transient ImmutableSortedSet keySet;
/**
* Returns an immutable sorted set of the keys in this map.
*/
@Override public ImmutableSortedSet keySet() {
ImmutableSortedSet ks = keySet;
return (ks == null) ? (keySet = createKeySet()) : ks;
}
private ImmutableSortedSet createKeySet() {
if (isEmpty()) {
return ImmutableSortedSet.emptySet(comparator);
}
// TODO: For better performance, don't create a separate array.
Object[] array = new Object[size()];
for (int i = fromIndex; i < toIndex; i++) {
array[i - fromIndex] = entries[i].getKey();
}
return new RegularImmutableSortedSet(array, comparator);
}
private transient ImmutableCollection values;
/**
* Returns an immutable collection of the values in this map, sorted by the
* ordering of the corresponding keys.
*/
@Override public ImmutableCollection values() {
ImmutableCollection v = values;
return (v == null) ? (values = new Values(this)) : v;
}
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
private static class Values extends ImmutableCollection {
private final ImmutableSortedMap map;
Values(ImmutableSortedMap map) {
this.map = map;
}
public int size() {
return map.size();
}
@Override public UnmodifiableIterator iterator() {
return new AbstractIterator() {
int index = map.fromIndex;
@Override protected V computeNext() {
return (index < map.toIndex)
? map.entries[index++].getValue()
: endOfData();
}
};
}
@Override public boolean contains(Object target) {
return map.containsValue(target);
}
@Override Object writeReplace() {
return new ValuesSerializedForm(map);
}
}
private static class ValuesSerializedForm implements Serializable {
final ImmutableSortedMap map;
ValuesSerializedForm(ImmutableSortedMap map) {
this.map = map;
}
Object readResolve() {
return map.values();
}
private static final long serialVersionUID = 0;
}
/**
* Returns the comparator that orders the keys, which is
* {@link Ordering#natural()} when the natural ordering of the keys is used.
* Note that its behavior is not consistent with {@link TreeMap#comparator()},
* which returns {@code null} to indicate natural ordering.
*/
public Comparator comparator() {
return comparator;
}
public K firstKey() {
if (isEmpty()) {
throw new NoSuchElementException();
}
return entries[fromIndex].getKey();
}
public K lastKey() {
if (isEmpty()) {
throw new NoSuchElementException();
}
return entries[toIndex - 1].getKey();
}
/**
* This method returns a {@code ImmutableSortedMap}, consisting of the entries
* whose keys are less than {@code toKey}.
*
* The {@link SortedMap#headMap} documentation states that a submap of a
* submap throws an {@link IllegalArgumentException} if passed a {@code toKey}
* greater than an earlier {@code toKey}. However, this method doesn't throw
* an exception in that situation, but instead keeps the original {@code
* toKey}.
*/
public ImmutableSortedMap headMap(K toKey) {
int newToIndex = findSubmapIndex(checkNotNull(toKey));
return createSubmap(fromIndex, newToIndex);
}
/**
* This method returns a {@code ImmutableSortedMap}, consisting of the entries
* whose keys ranges from {@code fromKey}, inclusive, to {@code toKey},
* exclusive.
*
* The {@link SortedMap#subMap} documentation states that a submap of a
* submap throws an {@link IllegalArgumentException} if passed a {@code
* fromKey} less than an earlier {@code fromKey}. However, this method doesn't
* throw an exception in that situation, but instead keeps the original {@code
* fromKey}. Similarly, this method keeps the original {@code toKey}, instead
* of throwing an exception, if passed a {@code toKey} greater than an earlier
* {@code toKey}.
*/
public ImmutableSortedMap subMap(K fromKey, K toKey) {
checkNotNull(fromKey);
checkNotNull(toKey);
checkArgument(comparator.compare(fromKey, toKey) <= 0);
int newFromIndex = findSubmapIndex(fromKey);
int newToIndex = findSubmapIndex(toKey);
return createSubmap(newFromIndex, newToIndex);
}
/**
* This method returns a {@code ImmutableSortedMap}, consisting of the entries
* whose keys are greater than or equals to {@code fromKey}.
*
* The {@link SortedMap#tailMap} documentation states that a submap of a
* submap throws an {@link IllegalArgumentException} if passed a {@code
* fromKey} less than an earlier {@code fromKey}. However, this method doesn't
* throw an exception in that situation, but instead keeps the original {@code
* fromKey}.
*/
public ImmutableSortedMap tailMap(K fromKey) {
int newFromIndex = findSubmapIndex(checkNotNull(fromKey));
return createSubmap(newFromIndex, toIndex);
}
private int findSubmapIndex(K key) {
int index = binarySearch(key);
return (index >= 0) ? index : (-index - 1);
}
private ImmutableSortedMap createSubmap(
int newFromIndex, int newToIndex) {
if (newFromIndex < newToIndex) {
return new ImmutableSortedMap(entries, comparator,
newFromIndex, newToIndex);
} else {
return emptyMap(comparator);
}
}
/**
* Serialized type for all ImmutableSortedMap instances. It captures the
* logical contents and they are reconstructed using public factory methods.
* This ensures that the implementation types remain as implementation
* details.
*/
private static class SerializedForm extends ImmutableMap.SerializedForm {
private final Comparator