io.trino.util.MoreMaps Maven / Gradle / Ivy
/*
* 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 io.trino.util;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.BinaryOperator;
import java.util.stream.Stream;
import static java.util.stream.Collectors.toMap;
public final class MoreMaps
{
private MoreMaps() {}
public static Map mergeMaps(Map map1, Map map2, BinaryOperator merger)
{
return mergeMaps(Stream.of(map1, map2), merger);
}
public static Map mergeMaps(Stream> mapStream, BinaryOperator merger)
{
return mapStream
.map(Map::entrySet)
.flatMap(Collection::stream)
.collect(toMap(Map.Entry::getKey, Map.Entry::getValue, merger));
}
// this help function should only be used when the map contains null value
// otherwise, use ImmutableMap.of()
public static Map asMap(List keyList, List valueList)
{
if (keyList.size() != valueList.size()) {
throw new AssertionError("keyList should have same size with valueList");
}
Map map = new HashMap<>();
for (int i = 0; i < keyList.size(); i++) {
if (map.put(keyList.get(i), valueList.get(i)) != null) {
throw new AssertionError("keyList should have same size with valueList");
}
}
return map;
}
}