com.google.common.collect.Maps Maven / Gradle / Ivy
/*
* Copyright (C) 2007 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.base.Predicates.compose;
import static com.google.common.base.Predicates.equalTo;
import static com.google.common.base.Predicates.in;
import static com.google.common.base.Predicates.not;
import static com.google.common.collect.CollectPreconditions.checkNonnegative;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Converter;
import com.google.common.base.Equivalence;
import com.google.common.base.Function;
import com.google.common.base.Joiner.MapJoiner;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.MapDifference.ValueDifference;
import com.google.common.primitives.Ints;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumMap;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Properties;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentMap;
import javax.annotation.Nullable;
/**
* Static utility methods pertaining to {@link Map} instances (including instances of
* {@link SortedMap}, {@link BiMap}, etc.). Also see this class's counterparts
* {@link Lists}, {@link Sets} and {@link Queues}.
*
* See the Guava User Guide article on
* {@code Maps}.
*
* @author Kevin Bourrillion
* @author Mike Bostock
* @author Isaac Shum
* @author Louis Wasserman
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(emulated = true)
public final class Maps {
private Maps() {}
private enum EntryFunction implements Function, Object> {
KEY {
@Override
@Nullable
public Object apply(Entry entry) {
return entry.getKey();
}
},
VALUE {
@Override
@Nullable
public Object apply(Entry entry) {
return entry.getValue();
}
};
}
@SuppressWarnings("unchecked")
static Function, K> keyFunction() {
return (Function) EntryFunction.KEY;
}
@SuppressWarnings("unchecked")
static Function, V> valueFunction() {
return (Function) EntryFunction.VALUE;
}
static Iterator keyIterator(Iterator> entryIterator) {
return Iterators.transform(entryIterator, Maps.keyFunction());
}
static Iterator valueIterator(Iterator> entryIterator) {
return Iterators.transform(entryIterator, Maps.valueFunction());
}
static UnmodifiableIterator valueIterator(
final UnmodifiableIterator> entryIterator) {
return new UnmodifiableIterator() {
@Override
public boolean hasNext() {
return entryIterator.hasNext();
}
@Override
public V next() {
return entryIterator.next().getValue();
}
};
}
/**
* Returns an immutable map instance containing the given entries.
* Internally, the returned map will be backed by an {@link EnumMap}.
*
* The iteration order of the returned map follows the enum's iteration
* order, not the order in which the elements appear in the given map.
*
* @param map the map to make an immutable copy of
* @return an immutable map containing those entries
* @since 14.0
*/
@GwtCompatible(serializable = true)
@Beta
public static , V> ImmutableMap immutableEnumMap(
Map map) {
if (map instanceof ImmutableEnumMap) {
@SuppressWarnings("unchecked") // safe covariant cast
ImmutableEnumMap result = (ImmutableEnumMap) map;
return result;
} else if (map.isEmpty()) {
return ImmutableMap.of();
} else {
for (Map.Entry entry : map.entrySet()) {
checkNotNull(entry.getKey());
checkNotNull(entry.getValue());
}
return ImmutableEnumMap.asImmutable(new EnumMap(map));
}
}
/**
* Creates a mutable, empty {@code HashMap} instance.
*
* Note: if mutability is not required, use {@link
* ImmutableMap#of()} instead.
*
*
Note: if {@code K} is an {@code enum} type, use {@link
* #newEnumMap} instead.
*
* @return a new, empty {@code HashMap}
*/
public static HashMap newHashMap() {
return new HashMap();
}
/**
* Creates a {@code HashMap} instance, with a high enough "initial capacity"
* that it should hold {@code expectedSize} elements without growth.
* This behavior cannot be broadly guaranteed, but it is observed to be true
* for OpenJDK 1.6. It also can't be guaranteed that the method isn't
* inadvertently oversizing the returned map.
*
* @param expectedSize the number of elements you expect to add to the
* returned map
* @return a new, empty {@code HashMap} with enough capacity to hold {@code
* expectedSize} elements without resizing
* @throws IllegalArgumentException if {@code expectedSize} is negative
*/
public static HashMap newHashMapWithExpectedSize(
int expectedSize) {
return new HashMap(capacity(expectedSize));
}
/**
* Returns a capacity that is sufficient to keep the map from being resized as
* long as it grows no larger than expectedSize and the load factor is >= its
* default (0.75).
*/
static int capacity(int expectedSize) {
if (expectedSize < 3) {
checkNonnegative(expectedSize, "expectedSize");
return expectedSize + 1;
}
if (expectedSize < Ints.MAX_POWER_OF_TWO) {
return expectedSize + expectedSize / 3;
}
return Integer.MAX_VALUE; // any large value
}
/**
* Creates a mutable {@code HashMap} instance with the same mappings as
* the specified map.
*
* Note: if mutability is not required, use {@link
* ImmutableMap#copyOf(Map)} instead.
*
*
Note: if {@code K} is an {@link Enum} type, use {@link
* #newEnumMap} instead.
*
* @param map the mappings to be placed in the new map
* @return a new {@code HashMap} initialized with the mappings from {@code
* map}
*/
public static HashMap newHashMap(
Map map) {
return new HashMap(map);
}
/**
* Creates a mutable, empty, insertion-ordered {@code LinkedHashMap}
* instance.
*
* Note: if mutability is not required, use {@link
* ImmutableMap#of()} instead.
*
* @return a new, empty {@code LinkedHashMap}
*/
public static LinkedHashMap newLinkedHashMap() {
return new LinkedHashMap();
}
/**
* Creates a mutable, insertion-ordered {@code LinkedHashMap} instance
* with the same mappings as the specified map.
*
* Note: if mutability is not required, use {@link
* ImmutableMap#copyOf(Map)} instead.
*
* @param map the mappings to be placed in the new map
* @return a new, {@code LinkedHashMap} initialized with the mappings from
* {@code map}
*/
public static LinkedHashMap newLinkedHashMap(
Map map) {
return new LinkedHashMap(map);
}
/**
* Returns a general-purpose instance of {@code ConcurrentMap}, which supports
* all optional operations of the ConcurrentMap interface. It does not permit
* null keys or values. It is serializable.
*
* This is currently accomplished by calling {@link MapMaker#makeMap()}.
*
*
It is preferable to use {@code MapMaker} directly (rather than through
* this method), as it presents numerous useful configuration options,
* such as the concurrency level, load factor, key/value reference types,
* and value computation.
*
* @return a new, empty {@code ConcurrentMap}
* @since 3.0
*/
public static ConcurrentMap newConcurrentMap() {
return new MapMaker().makeMap();
}
/**
* Creates a mutable, empty {@code TreeMap} instance using the natural
* ordering of its elements.
*
* Note: if mutability is not required, use {@link
* ImmutableSortedMap#of()} instead.
*
* @return a new, empty {@code TreeMap}
*/
public static TreeMap newTreeMap() {
return new TreeMap();
}
/**
* Creates a mutable {@code TreeMap} instance with the same mappings as
* the specified map and using the same ordering as the specified map.
*
* Note: if mutability is not required, use {@link
* ImmutableSortedMap#copyOfSorted(SortedMap)} instead.
*
* @param map the sorted map whose mappings are to be placed in the new map
* and whose comparator is to be used to sort the new map
* @return a new {@code TreeMap} initialized with the mappings from {@code
* map} and using the comparator of {@code map}
*/
public static TreeMap newTreeMap(SortedMap map) {
return new TreeMap(map);
}
/**
* Creates a mutable, empty {@code TreeMap} instance using the given
* comparator.
*
* Note: if mutability is not required, use {@code
* ImmutableSortedMap.orderedBy(comparator).build()} instead.
*
* @param comparator the comparator to sort the keys with
* @return a new, empty {@code TreeMap}
*/
public static TreeMap newTreeMap(
@Nullable Comparator comparator) {
// Ideally, the extra type parameter "C" shouldn't be necessary. It is a
// work-around of a compiler type inference quirk that prevents the
// following code from being compiled:
// Comparator> comparator = null;
// Map, String> map = newTreeMap(comparator);
return new TreeMap(comparator);
}
/**
* Creates an {@code EnumMap} instance.
*
* @param type the key type for this map
* @return a new, empty {@code EnumMap}
*/
public static , V> EnumMap newEnumMap(Class type) {
return new EnumMap(checkNotNull(type));
}
/**
* Creates an {@code EnumMap} with the same mappings as the specified map.
*
* @param map the map from which to initialize this {@code EnumMap}
* @return a new {@code EnumMap} initialized with the mappings from {@code
* map}
* @throws IllegalArgumentException if {@code m} is not an {@code EnumMap}
* instance and contains no mappings
*/
public static , V> EnumMap newEnumMap(
Map map) {
return new EnumMap(map);
}
/**
* Creates an {@code IdentityHashMap} instance.
*
* @return a new, empty {@code IdentityHashMap}
*/
public static IdentityHashMap newIdentityHashMap() {
return new IdentityHashMap();
}
/**
* Computes the difference between two maps. This difference is an immutable
* snapshot of the state of the maps at the time this method is called. It
* will never change, even if the maps change at a later time.
*
* Since this method uses {@code HashMap} instances internally, the keys of
* the supplied maps must be well-behaved with respect to
* {@link Object#equals} and {@link Object#hashCode}.
*
*
Note:If you only need to know whether two maps have the same
* mappings, call {@code left.equals(right)} instead of this method.
*
* @param left the map to treat as the "left" map for purposes of comparison
* @param right the map to treat as the "right" map for purposes of comparison
* @return the difference between the two maps
*/
@SuppressWarnings("unchecked")
public static MapDifference difference(
Map left, Map right) {
if (left instanceof SortedMap) {
SortedMap sortedLeft = (SortedMap) left;
SortedMapDifference result = difference(sortedLeft, right);
return result;
}
return difference(left, right, Equivalence.equals());
}
/**
* Computes the difference between two maps. This difference is an immutable
* snapshot of the state of the maps at the time this method is called. It
* will never change, even if the maps change at a later time.
*
* Values are compared using a provided equivalence, in the case of
* equality, the value on the 'left' is returned in the difference.
*
*
Since this method uses {@code HashMap} instances internally, the keys of
* the supplied maps must be well-behaved with respect to
* {@link Object#equals} and {@link Object#hashCode}.
*
* @param left the map to treat as the "left" map for purposes of comparison
* @param right the map to treat as the "right" map for purposes of comparison
* @param valueEquivalence the equivalence relationship to use to compare
* values
* @return the difference between the two maps
* @since 10.0
*/
@Beta
public static MapDifference difference(
Map left, Map right,
Equivalence valueEquivalence) {
Preconditions.checkNotNull(valueEquivalence);
Map onlyOnLeft = newHashMap();
Map onlyOnRight = new HashMap(right); // will whittle it down
Map onBoth = newHashMap();
Map> differences = newHashMap();
doDifference(left, right, valueEquivalence, onlyOnLeft, onlyOnRight, onBoth, differences);
return new MapDifferenceImpl(onlyOnLeft, onlyOnRight, onBoth, differences);
}
private static void doDifference(
Map left, Map right,
Equivalence valueEquivalence,
Map onlyOnLeft, Map onlyOnRight, Map onBoth,
Map> differences) {
for (Entry entry : left.entrySet()) {
K leftKey = entry.getKey();
V leftValue = entry.getValue();
if (right.containsKey(leftKey)) {
V rightValue = onlyOnRight.remove(leftKey);
if (valueEquivalence.equivalent(leftValue, rightValue)) {
onBoth.put(leftKey, leftValue);
} else {
differences.put(
leftKey, ValueDifferenceImpl.create(leftValue, rightValue));
}
} else {
onlyOnLeft.put(leftKey, leftValue);
}
}
}
private static Map unmodifiableMap(Map map) {
if (map instanceof SortedMap) {
return Collections.unmodifiableSortedMap((SortedMap) map);
} else {
return Collections.unmodifiableMap(map);
}
}
static class MapDifferenceImpl implements MapDifference {
final Map onlyOnLeft;
final Map onlyOnRight;
final Map onBoth;
final Map> differences;
MapDifferenceImpl(Map onlyOnLeft,
Map onlyOnRight, Map onBoth,
Map> differences) {
this.onlyOnLeft = unmodifiableMap(onlyOnLeft);
this.onlyOnRight = unmodifiableMap(onlyOnRight);
this.onBoth = unmodifiableMap(onBoth);
this.differences = unmodifiableMap(differences);
}
@Override
public boolean areEqual() {
return onlyOnLeft.isEmpty() && onlyOnRight.isEmpty() && differences.isEmpty();
}
@Override
public Map entriesOnlyOnLeft() {
return onlyOnLeft;
}
@Override
public Map entriesOnlyOnRight() {
return onlyOnRight;
}
@Override
public Map entriesInCommon() {
return onBoth;
}
@Override
public Map> entriesDiffering() {
return differences;
}
@Override public boolean equals(Object object) {
if (object == this) {
return true;
}
if (object instanceof MapDifference) {
MapDifference other = (MapDifference) object;
return entriesOnlyOnLeft().equals(other.entriesOnlyOnLeft())
&& entriesOnlyOnRight().equals(other.entriesOnlyOnRight())
&& entriesInCommon().equals(other.entriesInCommon())
&& entriesDiffering().equals(other.entriesDiffering());
}
return false;
}
@Override public int hashCode() {
return Objects.hashCode(entriesOnlyOnLeft(), entriesOnlyOnRight(),
entriesInCommon(), entriesDiffering());
}
@Override public String toString() {
if (areEqual()) {
return "equal";
}
StringBuilder result = new StringBuilder("not equal");
if (!onlyOnLeft.isEmpty()) {
result.append(": only on left=").append(onlyOnLeft);
}
if (!onlyOnRight.isEmpty()) {
result.append(": only on right=").append(onlyOnRight);
}
if (!differences.isEmpty()) {
result.append(": value differences=").append(differences);
}
return result.toString();
}
}
static class ValueDifferenceImpl
implements MapDifference.ValueDifference {
private final V left;
private final V right;
static ValueDifference create(@Nullable V left, @Nullable V right) {
return new ValueDifferenceImpl(left, right);
}
private ValueDifferenceImpl(@Nullable V left, @Nullable V right) {
this.left = left;
this.right = right;
}
@Override
public V leftValue() {
return left;
}
@Override
public V rightValue() {
return right;
}
@Override public boolean equals(@Nullable Object object) {
if (object instanceof MapDifference.ValueDifference) {
MapDifference.ValueDifference that =
(MapDifference.ValueDifference) object;
return Objects.equal(this.left, that.leftValue())
&& Objects.equal(this.right, that.rightValue());
}
return false;
}
@Override public int hashCode() {
return Objects.hashCode(left, right);
}
@Override public String toString() {
return "(" + left + ", " + right + ")";
}
}
/**
* Computes the difference between two sorted maps, using the comparator of
* the left map, or {@code Ordering.natural()} if the left map uses the
* natural ordering of its elements. This difference is an immutable snapshot
* of the state of the maps at the time this method is called. It will never
* change, even if the maps change at a later time.
*
* Since this method uses {@code TreeMap} instances internally, the keys of
* the right map must all compare as distinct according to the comparator
* of the left map.
*
*
Note:If you only need to know whether two sorted maps have the
* same mappings, call {@code left.equals(right)} instead of this method.
*
* @param left the map to treat as the "left" map for purposes of comparison
* @param right the map to treat as the "right" map for purposes of comparison
* @return the difference between the two maps
* @since 11.0
*/
public static SortedMapDifference difference(
SortedMap left, Map right) {
checkNotNull(left);
checkNotNull(right);
Comparator comparator = orNaturalOrder(left.comparator());
SortedMap onlyOnLeft = Maps.newTreeMap(comparator);
SortedMap onlyOnRight = Maps.newTreeMap(comparator);
onlyOnRight.putAll(right); // will whittle it down
SortedMap onBoth = Maps.newTreeMap(comparator);
SortedMap> differences =
Maps.newTreeMap(comparator);
doDifference(left, right, Equivalence.equals(), onlyOnLeft, onlyOnRight, onBoth, differences);
return new SortedMapDifferenceImpl(onlyOnLeft, onlyOnRight, onBoth, differences);
}
static class SortedMapDifferenceImpl extends MapDifferenceImpl
implements SortedMapDifference {
SortedMapDifferenceImpl(SortedMap onlyOnLeft,
SortedMap onlyOnRight, SortedMap onBoth,
SortedMap> differences) {
super(onlyOnLeft, onlyOnRight, onBoth, differences);
}
@Override public SortedMap> entriesDiffering() {
return (SortedMap>) super.entriesDiffering();
}
@Override public SortedMap entriesInCommon() {
return (SortedMap) super.entriesInCommon();
}
@Override public SortedMap entriesOnlyOnLeft() {
return (SortedMap) super.entriesOnlyOnLeft();
}
@Override public SortedMap entriesOnlyOnRight() {
return (SortedMap) super.entriesOnlyOnRight();
}
}
/**
* Returns the specified comparator if not null; otherwise returns {@code
* Ordering.natural()}. This method is an abomination of generics; the only
* purpose of this method is to contain the ugly type-casting in one place.
*/
@SuppressWarnings("unchecked")
static Comparator orNaturalOrder(
@Nullable Comparator comparator) {
if (comparator != null) { // can't use ? : because of javac bug 5080917
return comparator;
}
return (Comparator) Ordering.natural();
}
/**
* Returns a live {@link Map} view whose keys are the contents of {@code set}
* and whose values are computed on demand using {@code function}. To get an
* immutable copy instead, use {@link #toMap(Iterable, Function)}.
*
* Specifically, for each {@code k} in the backing set, the returned map
* has an entry mapping {@code k} to {@code function.apply(k)}. The {@code
* keySet}, {@code values}, and {@code entrySet} views of the returned map
* iterate in the same order as the backing set.
*
*
Modifications to the backing set are read through to the returned map.
* The returned map supports removal operations if the backing set does.
* Removal operations write through to the backing set. The returned map
* does not support put operations.
*
*
Warning: If the function rejects {@code null}, caution is
* required to make sure the set does not contain {@code null}, because the
* view cannot stop {@code null} from being added to the set.
*
*
Warning: This method assumes that for any instance {@code k} of
* key type {@code K}, {@code k.equals(k2)} implies that {@code k2} is also
* of type {@code K}. Using a key type for which this may not hold, such as
* {@code ArrayList}, may risk a {@code ClassCastException} when calling
* methods on the resulting map view.
*
* @since 14.0
*/
@Beta
public static Map asMap(
Set set, Function function) {
if (set instanceof SortedSet) {
return asMap((SortedSet) set, function);
} else {
return new AsMapView(set, function);
}
}
/**
* Returns a view of the sorted set as a map, mapping keys from the set
* according to the specified function.
*
* Specifically, for each {@code k} in the backing set, the returned map
* has an entry mapping {@code k} to {@code function.apply(k)}. The {@code
* keySet}, {@code values}, and {@code entrySet} views of the returned map
* iterate in the same order as the backing set.
*
*
Modifications to the backing set are read through to the returned map.
* The returned map supports removal operations if the backing set does.
* Removal operations write through to the backing set. The returned map does
* not support put operations.
*
*
Warning: If the function rejects {@code null}, caution is
* required to make sure the set does not contain {@code null}, because the
* view cannot stop {@code null} from being added to the set.
*
*
Warning: This method assumes that for any instance {@code k} of
* key type {@code K}, {@code k.equals(k2)} implies that {@code k2} is also of
* type {@code K}. Using a key type for which this may not hold, such as
* {@code ArrayList}, may risk a {@code ClassCastException} when calling
* methods on the resulting map view.
*
* @since 14.0
*/
@Beta
public static SortedMap asMap(
SortedSet set, Function function) {
return Platform.mapsAsMapSortedSet(set, function);
}
static SortedMap asMapSortedIgnoreNavigable(SortedSet set,
Function function) {
return new SortedAsMapView(set, function);
}
/**
* Returns a view of the navigable set as a map, mapping keys from the set
* according to the specified function.
*
* Specifically, for each {@code k} in the backing set, the returned map
* has an entry mapping {@code k} to {@code function.apply(k)}. The {@code
* keySet}, {@code values}, and {@code entrySet} views of the returned map
* iterate in the same order as the backing set.
*
*
Modifications to the backing set are read through to the returned map.
* The returned map supports removal operations if the backing set does.
* Removal operations write through to the backing set. The returned map
* does not support put operations.
*
*
Warning: If the function rejects {@code null}, caution is
* required to make sure the set does not contain {@code null}, because the
* view cannot stop {@code null} from being added to the set.
*
*
Warning: This method assumes that for any instance {@code k} of
* key type {@code K}, {@code k.equals(k2)} implies that {@code k2} is also
* of type {@code K}. Using a key type for which this may not hold, such as
* {@code ArrayList}, may risk a {@code ClassCastException} when calling
* methods on the resulting map view.
*
* @since 14.0
*/
@Beta
@GwtIncompatible("NavigableMap")
public static NavigableMap asMap(
NavigableSet set, Function function) {
return new NavigableAsMapView(set, function);
}
private static class AsMapView extends ImprovedAbstractMap {
private final Set set;
final Function function;
Set backingSet() {
return set;
}
AsMapView(Set set, Function function) {
this.set = checkNotNull(set);
this.function = checkNotNull(function);
}
@Override
public Set createKeySet() {
return removeOnlySet(backingSet());
}
@Override
Collection createValues() {
return Collections2.transform(set, function);
}
@Override
public int size() {
return backingSet().size();
}
@Override
public boolean containsKey(@Nullable Object key) {
return backingSet().contains(key);
}
@Override
public V get(@Nullable Object key) {
if (Collections2.safeContains(backingSet(), key)) {
@SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
K k = (K) key;
return function.apply(k);
} else {
return null;
}
}
@Override
public V remove(@Nullable Object key) {
if (backingSet().remove(key)) {
@SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
K k = (K) key;
return function.apply(k);
} else {
return null;
}
}
@Override
public void clear() {
backingSet().clear();
}
@Override
protected Set> createEntrySet() {
return new EntrySet() {
@Override
Map map() {
return AsMapView.this;
}
@Override
public Iterator> iterator() {
return asMapEntryIterator(backingSet(), function);
}
};
}
}
static Iterator> asMapEntryIterator(
Set set, final Function function) {
return new TransformedIterator>(set.iterator()) {
@Override
Entry transform(final K key) {
return immutableEntry(key, function.apply(key));
}
};
}
private static class SortedAsMapView extends AsMapView
implements SortedMap {
SortedAsMapView(SortedSet set, Function function) {
super(set, function);
}
@Override
SortedSet backingSet() {
return (SortedSet) super.backingSet();
}
@Override
public Comparator comparator() {
return backingSet().comparator();
}
@Override
public Set keySet() {
return removeOnlySortedSet(backingSet());
}
@Override
public SortedMap subMap(K fromKey, K toKey) {
return asMap(backingSet().subSet(fromKey, toKey), function);
}
@Override
public SortedMap headMap(K toKey) {
return asMap(backingSet().headSet(toKey), function);
}
@Override
public SortedMap tailMap(K fromKey) {
return asMap(backingSet().tailSet(fromKey), function);
}
@Override
public K firstKey() {
return backingSet().first();
}
@Override
public K lastKey() {
return backingSet().last();
}
}
@GwtIncompatible("NavigableMap")
private static final class NavigableAsMapView
extends AbstractNavigableMap {
/*
* Using AbstractNavigableMap is simpler than extending SortedAsMapView and rewriting all the
* NavigableMap methods.
*/
private final NavigableSet set;
private final Function function;
NavigableAsMapView(NavigableSet ks, Function vFunction) {
this.set = checkNotNull(ks);
this.function = checkNotNull(vFunction);
}
@Override
public NavigableMap subMap(
K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
return asMap(set.subSet(fromKey, fromInclusive, toKey, toInclusive), function);
}
@Override
public NavigableMap headMap(K toKey, boolean inclusive) {
return asMap(set.headSet(toKey, inclusive), function);
}
@Override
public NavigableMap tailMap(K fromKey, boolean inclusive) {
return asMap(set.tailSet(fromKey, inclusive), function);
}
@Override
public Comparator comparator() {
return set.comparator();
}
@Override
@Nullable
public V get(@Nullable Object key) {
if (Collections2.safeContains(set, key)) {
@SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
K k = (K) key;
return function.apply(k);
} else {
return null;
}
}
@Override
public void clear() {
set.clear();
}
@Override
Iterator> entryIterator() {
return asMapEntryIterator(set, function);
}
@Override
Iterator> descendingEntryIterator() {
return descendingMap().entrySet().iterator();
}
@Override
public NavigableSet navigableKeySet() {
return removeOnlyNavigableSet(set);
}
@Override
public int size() {
return set.size();
}
@Override
public NavigableMap descendingMap() {
return asMap(set.descendingSet(), function);
}
}
private static Set removeOnlySet(final Set set) {
return new ForwardingSet() {
@Override
protected Set delegate() {
return set;
}
@Override
public boolean add(E element) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(Collection es) {
throw new UnsupportedOperationException();
}
};
}
private static SortedSet removeOnlySortedSet(final SortedSet set) {
return new ForwardingSortedSet() {
@Override
protected SortedSet delegate() {
return set;
}
@Override
public boolean add(E element) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(Collection es) {
throw new UnsupportedOperationException();
}
@Override
public SortedSet headSet(E toElement) {
return removeOnlySortedSet(super.headSet(toElement));
}
@Override
public SortedSet subSet(E fromElement, E toElement) {
return removeOnlySortedSet(super.subSet(fromElement, toElement));
}
@Override
public SortedSet tailSet(E fromElement) {
return removeOnlySortedSet(super.tailSet(fromElement));
}
};
}
@GwtIncompatible("NavigableSet")
private static NavigableSet removeOnlyNavigableSet(final NavigableSet set) {
return new ForwardingNavigableSet() {
@Override
protected NavigableSet delegate() {
return set;
}
@Override
public boolean add(E element) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(Collection es) {
throw new UnsupportedOperationException();
}
@Override
public SortedSet headSet(E toElement) {
return removeOnlySortedSet(super.headSet(toElement));
}
@Override
public SortedSet subSet(E fromElement, E toElement) {
return removeOnlySortedSet(
super.subSet(fromElement, toElement));
}
@Override
public SortedSet tailSet(E fromElement) {
return removeOnlySortedSet(super.tailSet(fromElement));
}
@Override
public NavigableSet headSet(E toElement, boolean inclusive) {
return removeOnlyNavigableSet(super.headSet(toElement, inclusive));
}
@Override
public NavigableSet tailSet(E fromElement, boolean inclusive) {
return removeOnlyNavigableSet(super.tailSet(fromElement, inclusive));
}
@Override
public NavigableSet subSet(E fromElement, boolean fromInclusive,
E toElement, boolean toInclusive) {
return removeOnlyNavigableSet(super.subSet(
fromElement, fromInclusive, toElement, toInclusive));
}
@Override
public NavigableSet descendingSet() {
return removeOnlyNavigableSet(super.descendingSet());
}
};
}
/**
* Returns an immutable map whose keys are the distinct elements of {@code
* keys} and whose value for each key was computed by {@code valueFunction}.
* The map's iteration order is the order of the first appearance of each key
* in {@code keys}.
*
* If {@code keys} is a {@link Set}, a live view can be obtained instead of
* a copy using {@link Maps#asMap(Set, Function)}.
*
* @throws NullPointerException if any element of {@code keys} is
* {@code null}, or if {@code valueFunction} produces {@code null}
* for any key
* @since 14.0
*/
@Beta
public static ImmutableMap toMap(Iterable keys,
Function valueFunction) {
return toMap(keys.iterator(), valueFunction);
}
/**
* Returns an immutable map whose keys are the distinct elements of {@code
* keys} and whose value for each key was computed by {@code valueFunction}.
* The map's iteration order is the order of the first appearance of each key
* in {@code keys}.
*
* @throws NullPointerException if any element of {@code keys} is
* {@code null}, or if {@code valueFunction} produces {@code null}
* for any key
* @since 14.0
*/
@Beta
public static ImmutableMap toMap(Iterator keys,
Function valueFunction) {
checkNotNull(valueFunction);
// Using LHM instead of a builder so as not to fail on duplicate keys
Map builder = newLinkedHashMap();
while (keys.hasNext()) {
K key = keys.next();
builder.put(key, valueFunction.apply(key));
}
return ImmutableMap.copyOf(builder);
}
/**
* Returns an immutable map for which the {@link Map#values} are the given
* elements in the given order, and each key is the product of invoking a
* supplied function on its corresponding value.
*
* @param values the values to use when constructing the {@code Map}
* @param keyFunction the function used to produce the key for each value
* @return a map mapping the result of evaluating the function {@code
* keyFunction} on each value in the input collection to that value
* @throws IllegalArgumentException if {@code keyFunction} produces the same
* key for more than one value in the input collection
* @throws NullPointerException if any elements of {@code values} is null, or
* if {@code keyFunction} produces {@code null} for any value
*/
public static ImmutableMap uniqueIndex(
Iterable values, Function keyFunction) {
return uniqueIndex(values.iterator(), keyFunction);
}
/**
* Returns an immutable map for which the {@link Map#values} are the given
* elements in the given order, and each key is the product of invoking a
* supplied function on its corresponding value.
*
* @param values the values to use when constructing the {@code Map}
* @param keyFunction the function used to produce the key for each value
* @return a map mapping the result of evaluating the function {@code
* keyFunction} on each value in the input collection to that value
* @throws IllegalArgumentException if {@code keyFunction} produces the same
* key for more than one value in the input collection
* @throws NullPointerException if any elements of {@code values} is null, or
* if {@code keyFunction} produces {@code null} for any value
* @since 10.0
*/
public static ImmutableMap uniqueIndex(
Iterator values, Function keyFunction) {
checkNotNull(keyFunction);
ImmutableMap.Builder builder = ImmutableMap.builder();
while (values.hasNext()) {
V value = values.next();
builder.put(keyFunction.apply(value), value);
}
return builder.build();
}
/**
* Creates an {@code ImmutableMap} from a {@code Properties}
* instance. Properties normally derive from {@code Map}, but
* they typically contain strings, which is awkward. This method lets you get
* a plain-old-{@code Map} out of a {@code Properties}.
*
* @param properties a {@code Properties} object to be converted
* @return an immutable map containing all the entries in {@code properties}
* @throws ClassCastException if any key in {@code Properties} is not a {@code
* String}
* @throws NullPointerException if any key or value in {@code Properties} is
* null
*/
@GwtIncompatible("java.util.Properties")
public static ImmutableMap fromProperties(
Properties properties) {
ImmutableMap.Builder builder = ImmutableMap.builder();
for (Enumeration e = properties.propertyNames(); e.hasMoreElements();) {
String key = (String) e.nextElement();
builder.put(key, properties.getProperty(key));
}
return builder.build();
}
/**
* Returns an immutable map entry with the specified key and value. The {@link
* Entry#setValue} operation throws an {@link UnsupportedOperationException}.
*
* The returned entry is serializable.
*
* @param key the key to be associated with the returned entry
* @param value the value to be associated with the returned entry
*/
@GwtCompatible(serializable = true)
public static Entry immutableEntry(
@Nullable K key, @Nullable V value) {
return new ImmutableEntry(key, value);
}
/**
* Returns an unmodifiable view of the specified set of entries. The {@link
* Entry#setValue} operation throws an {@link UnsupportedOperationException},
* as do any operations that would modify the returned set.
*
* @param entrySet the entries for which to return an unmodifiable view
* @return an unmodifiable view of the entries
*/
static