/*
* 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.
*
* <p>Unlike {@link Collections#unmodifiableSortedMap}, which is a <i>view</i>
* of a separate map which can still change, an instance of {@code
* ImmutableSortedMap} contains its own data and will <i>never</i> 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.
*
* <p><b>Note</b>: 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
* @since 2010.01.04 <b>stable</b> (imported from Google Collections Library)
*/
@GwtCompatible(serializable = true)
public class ImmutableSortedMap<K, V>
extends ImmutableSortedMapFauxverideShim<K, V> implements SortedMap<K, V> {
// 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<Object, Object> NATURAL_EMPTY_MAP
= new ImmutableSortedMap<Object, Object>(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 <K, V> ImmutableSortedMap<K, V> of() {
return (ImmutableSortedMap) NATURAL_EMPTY_MAP;
}
private static <K, V> ImmutableSortedMap<K, V> emptyMap(
Comparator<? super K> comparator) {
if (NATURAL_ORDER.equals(comparator)) {
return ImmutableSortedMap.of();
} else {
return new ImmutableSortedMap<K, V>(EMPTY_ARRAY, comparator);
}
}
/**
* Returns an immutable map containing a single entry.
*/
public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1) {
Entry<?, ?>[] entries = { entryOf(k1, v1) };
return new ImmutableSortedMap<K, V>(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 <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1, K k2, V v2) {
return new Builder<K, V>(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 <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1, K k2, V v2, K k3, V v3) {
return new Builder<K, V>(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 <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
return new Builder<K, V>(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 <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
return new Builder<K, V>(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.
*
* <p><b>Note:</b> Despite what the method name suggests, if {@code map} is an
* {@code ImmutableSortedMap}, it may be returned instead of a copy.
*
* <p>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 <K, V> ImmutableSortedMap<K, V> copyOf(
Map<? extends K, ? extends V> map) {
// Hack around K not being a subtype of Comparable.
// Unsafe, see ImmutableSortedSetFauxverideShim.
@SuppressWarnings("unchecked")
Ordering<K> naturalOrder = (Ordering) Ordering.<Comparable>natural();
return copyOfInternal(map, naturalOrder);
}
/**
* Returns an immutable map containing the same entries as {@code map}, with
* keys sorted by the provided comparator.
*
* <p><b>Note:</b> 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 <K, V> ImmutableSortedMap<K, V> copyOf(
Map<? extends K, ? extends V> map, Comparator<? super K> comparator) {
return copyOfInternal(map, checkNotNull(comparator));
}
/**
* Returns an immutable map containing the same entries as the provided sorted
* map, with the same ordering.
*
* <p><b>Note:</b> 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 <K, V> ImmutableSortedMap<K, V> copyOfSorted(
SortedMap<K, ? extends V> 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<? super K> comparator =
(map.comparator() == null) ? NATURAL_ORDER : map.comparator();
return copyOfInternal(map, comparator);
}
private static <K, V> ImmutableSortedMap<K, V> copyOfInternal(
Map<? extends K, ? extends V> map, Comparator<? super K> 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<K, V> kvMap = (ImmutableSortedMap<K, V>) map;
return kvMap;
}
// Using List to support concurrent map whose size changes
List<Entry<?, ?>> list = Lists.newArrayListWithCapacity(map.size());
for (Entry<? extends K, ? extends V> 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<K, V>(entryArray, comparator);
}
private static void sortEntries(Entry<?, ?>[] entryArray,
final Comparator<?> comparator) {
Comparator<Entry<?, ?>> entryComparator = new Comparator<Entry<?, ?>>() {
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.
*
* <p>Note: the type parameter {@code K} extends {@code Comparable<K>} rather
* than {@code Comparable<? super K>} as a workaround for javac <a
* href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
* 6468354</a>.
*/
public static <K extends Comparable<K>, V> Builder<K, V> naturalOrder() {
return new Builder<K, V>(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<Integer, String>} with a {@code
* Comparator<Number>}, use the {@link Builder} constructor instead.
*
* @throws NullPointerException if {@code comparator} is null
*/
public static <K, V> Builder<K, V> orderedBy(Comparator<K> comparator) {
return new Builder<K, V>(comparator);
}
/**
* Returns a builder that creates immutable sorted maps whose keys are
* ordered by the reverse of their natural ordering.
*
* <p>Note: the type parameter {@code K} extends {@code Comparable<K>} rather
* than {@code Comparable<? super K>} as a workaround for javac <a
* href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6468354">bug
* 6468354</a>.
*/
public static <K extends Comparable<K>, V> Builder<K, V> reverseOrder() {
return new Builder<K, V>(Ordering.natural().reverse());
}
/**
* A builder for creating immutable sorted map instances, especially {@code
* public static final} maps ("constant maps"). Example: <pre> {@code
*
* static final ImmutableSortedMap<Integer, String> INT_TO_WORD =
* new ImmutableSortedMap.Builder<Integer, String>(Ordering.natural())
* .put(1, "one")
* .put(2, "two")
* .put(3, "three")
* .build();}</pre>
*
* For <i>small</i> immutable sorted maps, the {@code ImmutableSortedMap.of()}
* methods are even more convenient.
*
* <p>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<K, V> extends ImmutableMap.Builder<K, V> {
private final Comparator<? super K> comparator;
/**
* Creates a new builder. The returned builder is equivalent to the builder
* generated by {@link ImmutableSortedMap#orderedBy}.
*/
public Builder(Comparator<? super K> 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<K, V> 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<K, V> putAll(Map<? extends K, ? extends V> map) {
for (Entry<? extends K, ? extends V> 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<K, V> build() {
Entry<?, ?>[] entryArray
= entries.toArray(new Entry<?, ?>[entries.size()]);
sortEntries(entryArray, comparator);
validateEntries(entryArray, comparator);
return new ImmutableSortedMap<K, V>(entryArray, comparator);
}
}
private final transient Entry<K, V>[] entries;
private final transient Comparator<? super K> comparator;
private final transient int fromIndex;
private final transient int toIndex;
private ImmutableSortedMap(Entry<?, ?>[] entries,
Comparator<? super K> comparator, int fromIndex, int toIndex) {
// each of the callers carefully put only Entry<K, V>s into the array!
@SuppressWarnings("unchecked")
Entry<K, V>[] tmp = (Entry<K, V>[]) entries;
this.entries = tmp;
this.comparator = comparator;
this.fromIndex = fromIndex;
this.toIndex = toIndex;
}
ImmutableSortedMap(Entry<?, ?>[] entries,
Comparator<? super K> 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<Entry<K, V>> entrySet;
/**
* Returns an immutable set of the mappings in this map, sorted by the key
* ordering.
*/
@Override public ImmutableSet<Entry<K, V>> entrySet() {
ImmutableSet<Entry<K, V>> es = entrySet;
return (es == null) ? (entrySet = createEntrySet()) : es;
}
private ImmutableSet<Entry<K, V>> createEntrySet() {
return isEmpty() ? ImmutableSet.<Entry<K, V>>of()
: new EntrySet<K, V>(this);
}
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
private static class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
final transient ImmutableSortedMap<K, V> map;
EntrySet(ImmutableSortedMap<K, V> map) {
this.map = map;
}
public int size() {
return map.size();
}
@Override public UnmodifiableIterator<Entry<K, V>> 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<K, V>(map);
}
}
private static class EntrySetSerializedForm<K, V> implements Serializable {
final ImmutableSortedMap<K, V> map;
EntrySetSerializedForm(ImmutableSortedMap<K, V> map) {
this.map = map;
}
Object readResolve() {
return map.entrySet();
}
private static final long serialVersionUID = 0;
}
private transient ImmutableSortedSet<K> keySet;
/**
* Returns an immutable sorted set of the keys in this map.
*/
@Override public ImmutableSortedSet<K> keySet() {
ImmutableSortedSet<K> ks = keySet;
return (ks == null) ? (keySet = createKeySet()) : ks;
}
private ImmutableSortedSet<K> 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<K>(array, comparator);
}
private transient ImmutableCollection<V> values;
/**
* Returns an immutable collection of the values in this map, sorted by the
* ordering of the corresponding keys.
*/
@Override public ImmutableCollection<V> values() {
ImmutableCollection<V> v = values;
return (v == null) ? (values = new Values<V>(this)) : v;
}
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
private static class Values<V> extends ImmutableCollection<V> {
private final ImmutableSortedMap<?, V> map;
Values(ImmutableSortedMap<?, V> map) {
this.map = map;
}
public int size() {
return map.size();
}
@Override public UnmodifiableIterator<V> iterator() {
return new AbstractIterator<V>() {
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<V>(map);
}
}
private static class ValuesSerializedForm<V> implements Serializable {
final ImmutableSortedMap<?, V> map;
ValuesSerializedForm(ImmutableSortedMap<?, V> 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<? super K> 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}.
*
* <p>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<K, V> 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.
*
* <p>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<K, V> 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}.
*
* <p>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<K, V> 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<K, V> createSubmap(
int newFromIndex, int newToIndex) {
if (newFromIndex < newToIndex) {
return new ImmutableSortedMap<K, V>(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<Object> comparator;
@SuppressWarnings("unchecked")
SerializedForm(ImmutableSortedMap<?, ?> sortedMap) {
super(sortedMap);
comparator = (Comparator<Object>) sortedMap.comparator();
}
@Override Object readResolve() {
Builder<Object, Object> builder = new Builder<Object, Object>(comparator);
return createMap(builder);
}
private static final long serialVersionUID = 0;
}
@Override Object writeReplace() {
return new SerializedForm(this);
}
// This class is never actually serialized directly, but we have to make the
// warning go away (and suppressing would suppress for all nested classes too)
private static final long serialVersionUID = 0;
}