org.teavm.common.CollectionUtil Maven / Gradle / Ivy
/*
* Copyright 2022 Alexey Andreev.
*
* 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 org.teavm.common;
import java.util.Comparator;
import java.util.List;
import java.util.function.Function;
public final class CollectionUtil {
private CollectionUtil() {
}
public static > int binarySearch(List list, K key,
Function keyExtractor) {
return binarySearch(list, key, keyExtractor, Comparable::compareTo);
}
public static int binarySearch(List list, K key, Function keyExtractor,
Comparator comparator) {
var l = 0;
var u = list.size() - 1;
while (true) {
var i = (l + u) / 2;
var t = keyExtractor.apply(list.get(i));
var cmp = comparator.compare(key, t);
if (cmp == 0) {
return i;
} else if (cmp > 0) {
l = i + 1;
if (l > u) {
return -i - 2;
}
} else {
u = i - 1;
if (u < l) {
return -i - 1;
}
}
}
}
}