/*
* 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 org.apache.isis.core.metamodel.util;
import java.util.Comparator;
import java.util.List;
import com.google.common.base.Function;
import com.google.common.base.Splitter;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
public class DeweyOrderComparator implements Comparator<String> {
public DeweyOrderComparator() {}
@Override
public int compare(String o1, String o2) {
final Parsed<String> p1 = new Parsed<String>(o1);
final Parsed<String> p2 = new Parsed<String>(o2);
return p1.compareTo(p2);
}
private static class Parsed<V> implements Comparable<Parsed<V>> {
private static final Function<String, Integer> PARSE = new Function<String, Integer>() {
@Override
public Integer apply(String input) {
try {
return Integer.parseInt(input);
} catch (NumberFormatException e) {
return Integer.MAX_VALUE;
}
}
};
private final List<Integer> parts;
private final String key;
Parsed(String key) {
this.key = key;
final Iterable<String> iter = Splitter.on(".").split(key);
parts = Lists.newArrayList(Iterators.transform(iter.iterator(), PARSE));
}
@Override
public int compareTo(Parsed<V> other) {
for (int i = 0; i < parts.size(); i++) {
Integer p = parts.get(i);
if (other.parts.size() == i) {
// run out of parts for other, put it before us
return +1;
}
final Integer q = other.parts.get(i);
final int comparison = p.compareTo(q);
if(comparison != 0) {
return +comparison;
}
}
if(other.parts.size() > parts.size()) {
// run out of parts on our side, still more on others; put us before it
return -1;
}
return 0;
}
}
}