/*
* Copyright (C) 2009 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.Maps.newTreeMap;
import static java.util.Collections.unmodifiableSortedMap;
import com.google.common.collect.ImmutableSortedSet;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
/**
* GWT emulated version of {@link ImmutableSortedMap}. It's a thin wrapper
* around a {@link java.util.TreeMap}.
*
* @author Hayward Chan
*/
public abstract class ImmutableSortedMap<K, V>
extends ForwardingImmutableMap<K, V> implements SortedMap<K, V> {
@SuppressWarnings("unchecked")
static final Comparator NATURAL_ORDER = Ordering.natural();
// This reference is only used by GWT compiler to infer the keys and values
// of the map that needs to be serialized.
private Comparator<? super K> unusedComparatorForSerialization;
private K unusedKeyForSerialization;
private V unusedValueForSerialization;
private final transient SortedMap<K, V> sortedDelegate;
// The comparator used by this map. It's the same as that of sortedDelegate,
// except that when sortedDelegate's comparator is null, it points to a
// non-null instance of Ordering.natural().
// (cpovirk: Is sortedDelegate's comparator really ever null?)
// The comparator will likely also differ because of our nullAccepting hack.
// See the bottom of the file for more information about it.
private final transient Comparator<? super K> comparator;
ImmutableSortedMap(SortedMap<K, V> delegate, Comparator<? super K> comparator) {
super(delegate);
this.comparator = comparator;
this.sortedDelegate = delegate;
}
private static <K, V> ImmutableSortedMap<K, V> create(
Comparator<? super K> comparator,
Entry<? extends K, ? extends V>... entries) {
checkNotNull(comparator);
SortedMap<K, V> delegate = newModifiableDelegate(comparator);
for (Entry<? extends K, ? extends V> entry : entries) {
delegate.put(entry.getKey(), entry.getValue());
}
return newView(unmodifiableSortedMap(delegate), comparator);
}
// 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 EmptyImmutableSortedMap.forComparator(NATURAL_ORDER);
}
public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
of(K k1, V v1) {
return create(Ordering.natural(), entryOf(k1, v1));
}
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();
}
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();
}
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();
}
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();
}
public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V>
copyOf(Map<? extends K, ? extends V> map) {
return copyOfInternal(map, Ordering.natural());
}
public static <K, V> ImmutableSortedMap<K, V> copyOf(
Map<? extends K, ? extends V> map, Comparator<? super K> comparator) {
return copyOfInternal(map, checkNotNull(comparator));
}
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) {
if (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;
Comparator<?> comparator2 = kvMap.comparator();
boolean sameComparator = (comparator2 == null)
? comparator == NATURAL_ORDER
: comparator.equals(comparator2);
if (sameComparator) {
return kvMap;
}
}
SortedMap<K, V> delegate = newModifiableDelegate(comparator);
for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
putEntryWithChecks(delegate, entry);
}
return newView(unmodifiableSortedMap(delegate), comparator);
}
private static <K, V> void putEntryWithChecks(
SortedMap<K, V> map, Entry<? extends K, ? extends V> entry) {
K key = checkNotNull(entry.getKey());
V value = checkNotNull(entry.getValue());
if (map.containsKey(key)) {
// When a collision happens, the colliding entry is the first entry
// of the tail map.
Entry<K, V> previousEntry
= map.tailMap(key).entrySet().iterator().next();
throw new IllegalArgumentException(
"Duplicate keys in mappings " + previousEntry.getKey() +
"=" + previousEntry.getValue() + " and " + key +
"=" + value);
}
map.put(key, value);
}
public static <K extends Comparable<K>, V> Builder<K, V> naturalOrder() {
return new Builder<K, V>(Ordering.natural());
}
public static <K, V> Builder<K, V> orderedBy(Comparator<K> comparator) {
return new Builder<K, V>(comparator);
}
public static <K extends Comparable<K>, V> Builder<K, V> reverseOrder() {
return new Builder<K, V>(Ordering.natural().reverse());
}
public static final class Builder<K, V> extends ImmutableMap.Builder<K, V> {
private final Comparator<? super K> comparator;
public Builder(Comparator<? super K> comparator) {
this.comparator = checkNotNull(comparator);
}
@Override public Builder<K, V> put(K key, V value) {
entries.add(entryOf(key, value));
return this;
}
@Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
super.put(entry);
return this;
}
@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;
}
@Override public ImmutableSortedMap<K, V> build() {
SortedMap<K, V> delegate = newModifiableDelegate(comparator);
for (Entry<? extends K, ? extends V> entry : entries) {
putEntryWithChecks(delegate, entry);
}
return newView(unmodifiableSortedMap(delegate), comparator);
}
}
private transient ImmutableSortedSet<K> keySet;
@Override public ImmutableSortedSet<K> keySet() {
ImmutableSortedSet<K> ks = keySet;
return (ks == null) ? (keySet = createKeySet()) : ks;
}
@Override ImmutableSortedSet<K> createKeySet() {
// the keySet() of the delegate is only a Set and TreeMap.navigatableKeySet
// is not available in GWT yet. To keep the code simple and code size more,
// we make a copy here, instead of creating a view of it.
//
// TODO: revisit if it's unbearably slow or when GWT supports
// TreeMap.navigatbleKeySet().
return ImmutableSortedSet.copyOf(comparator, sortedDelegate.keySet());
}
public Comparator<? super K> comparator() {
return comparator;
}
public K firstKey() {
return sortedDelegate.firstKey();
}
public K lastKey() {
return sortedDelegate.lastKey();
}
K higher(K k) {
Iterator<K> iterator = keySet().tailSet(k).iterator();
while (iterator.hasNext()) {
K tmp = iterator.next();
if (comparator().compare(k, tmp) < 0) {
return tmp;
}
}
return null;
}
public ImmutableSortedMap<K, V> headMap(K toKey) {
checkNotNull(toKey);
return newView(sortedDelegate.headMap(toKey));
}
ImmutableSortedMap<K, V> headMap(K toKey, boolean inclusive) {
checkNotNull(toKey);
if (inclusive) {
K tmp = higher(toKey);
if (tmp == null) {
return this;
}
toKey = tmp;
}
return headMap(toKey);
}
public ImmutableSortedMap<K, V> subMap(K fromKey, K toKey) {
checkNotNull(fromKey);
checkNotNull(toKey);
checkArgument(comparator.compare(fromKey, toKey) <= 0);
return newView(sortedDelegate.subMap(fromKey, toKey));
}
ImmutableSortedMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive){
checkNotNull(fromKey);
checkNotNull(toKey);
checkArgument(comparator.compare(fromKey, toKey) <= 0);
return tailMap(fromKey, fromInclusive).headMap(toKey, toInclusive);
}
public ImmutableSortedMap<K, V> tailMap(K fromKey) {
checkNotNull(fromKey);
return newView(sortedDelegate.tailMap(fromKey));
}
public ImmutableSortedMap<K, V> tailMap(K fromKey, boolean inclusive) {
checkNotNull(fromKey);
if (!inclusive) {
fromKey = higher(fromKey);
if (fromKey == null) {
return EmptyImmutableSortedMap.forComparator(comparator());
}
}
return tailMap(fromKey);
}
private ImmutableSortedMap<K, V> newView(SortedMap<K, V> delegate) {
return newView(delegate, comparator);
}
private static <K, V> ImmutableSortedMap<K, V> newView(
SortedMap<K, V> delegate, Comparator<? super K> comparator) {
if (delegate.isEmpty()) {
return EmptyImmutableSortedMap.forComparator(comparator);
}
return new RegularImmutableSortedMap<K, V>(delegate, comparator);
}
/*
* We don't permit nulls, but we wrap every comparator with nullsFirst().
* Why? We want for queries like containsKey(null) to return false, but the
* GWT SortedMap implementation that we delegate to throws
* NullPointerException if the comparator does. Since our construction
* methods ensure that null is never present in the map, it's OK for the
* comparator to look for it wherever it wants.
*
* Note that we do NOT touch the comparator returned by comparator(), which
* should be identical to the one the user passed in. We touch only the
* "secret" comparator used by the delegate implementation.
*/
private static <K, V> SortedMap<K, V> newModifiableDelegate(Comparator<? super K> comparator) {
return newTreeMap(nullAccepting(comparator));
}
private static <E> Comparator<E> nullAccepting(Comparator<E> comparator) {
return Ordering.from(comparator).nullsFirst();
}
}