org.graylog2.utilities.LenientExplicitOrdering Maven / Gradle / Ivy
/*
* Copyright (C) 2020 Graylog, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* .
*/
package org.graylog2.utilities;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;
import java.util.List;
import java.util.Map;
/**
* An ordering that compares objects according to a given order, sorting unknown elements by their natural comparison or last.
*/
public class LenientExplicitOrdering extends Ordering {
private final Map idxMap;
public LenientExplicitOrdering(List order) {
this.idxMap = Maps.newHashMapWithExpectedSize(order.size());
int idx = 0;
for (T s : order) {
idxMap.put(s, idx);
idx++;
}
}
@Override
public int compare(T left, T right) {
final Integer leftIdx = idxMap.get(left);
final Integer rightIdx = idxMap.get(right);
if (leftIdx != null && rightIdx != null) {
//noinspection SuspiciousNameCombination
return Integer.compare(leftIdx, rightIdx);
}
if (left instanceof Comparable && leftIdx == null && rightIdx == null) {
//noinspection unchecked
return ((Comparable) left).compareTo(right);
}
if (leftIdx == null) {
return -1;
}
return 1;
}
}