com.hazelcast.org.apache.calcite.util.ImmutableNullableMap Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you 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.hazelcast.org.apache.calcite.util;
import com.hazelcast.com.google.common.collect.ImmutableMap;
import com.hazelcast.com.google.common.collect.ImmutableSortedMap;
import java.util.AbstractMap;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* An immutable map that may contain null values.
*
* If the map cannot contain null values, use {@link ImmutableMap}.
*
* @param Key type
* @param Value type
*/
public abstract class ImmutableNullableMap extends AbstractMap {
private static final Map SINGLETON_MAP =
Collections.singletonMap(0, 0);
private ImmutableNullableMap() {
}
/**
* Returns an immutable map containing the given elements.
*
* Behavior is as {@link ImmutableMap#copyOf(Iterable)}
* except that this map allows nulls.
*/
@SuppressWarnings({"JdkObsolete", "unchecked", "rawtypes"})
public static Map copyOf(Map map) {
if (map instanceof ImmutableNullableMap
|| map instanceof ImmutableMap
|| map == Collections.emptyMap()
|| map == Collections.emptyNavigableMap()
|| map.getClass() == SINGLETON_MAP.getClass()) {
return (Map) map;
}
if (map instanceof SortedMap) {
final SortedMap sortedMap = (SortedMap) map;
try {
Comparator comparator = sortedMap.comparator();
if (comparator == null) {
return ImmutableSortedMap.copyOf(sortedMap);
} else {
return ImmutableSortedMap.copyOf(sortedMap, comparator);
}
} catch (NullPointerException e) {
// Make an effectively immutable map by creating a mutable copy
// and wrapping it to prevent modification. Unfortunately, if we see
// it again we will not recognize that it is immutable and we will make
// another copy.
return Collections.unmodifiableNavigableMap(new TreeMap<>(sortedMap));
}
} else {
try {
return ImmutableMap.copyOf(map);
} catch (NullPointerException e) {
// Make an effectively immutable map by creating a mutable copy
// and wrapping it to prevent modification. Unfortunately, if we see
// it again we will not recognize that it is immutable and we will make
// another copy.
return Collections.unmodifiableMap(new HashMap<>(map));
}
}
}
/**
* Returns an immutable navigable map containing the given entries.
*
* Behavior is as {@link ImmutableSortedMap#copyOf(Map)}
* except that this map allows nulls.
*/
@SuppressWarnings({"JdkObsolete", "unchecked", "rawtypes"})
public static Map copyOf(
SortedMap map) {
if (map instanceof ImmutableNullableMap
|| map instanceof ImmutableMap
|| map == Collections.emptyMap()
|| map == Collections.emptyNavigableMap()) {
return (Map) map;
}
final SortedMap sortedMap = (SortedMap) map;
try {
Comparator comparator = sortedMap.comparator();
if (comparator == null) {
return ImmutableSortedMap.copyOf(sortedMap);
} else {
return ImmutableSortedMap.copyOf(sortedMap, comparator);
}
} catch (NullPointerException e) {
// Make an effectively immutable map by creating a mutable copy
// and wrapping it to prevent modification. Unfortunately, if we see
// it again we will not recognize that it is immutable and we will make
// another copy.
return Collections.unmodifiableNavigableMap(new TreeMap<>(sortedMap));
}
}
}