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* 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.brooklyn.util.text;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import org.apache.brooklyn.util.text.NaturalOrderComparator;
import org.apache.brooklyn.util.text.Strings;
import com.google.common.annotations.VisibleForTesting;
/**
* {@link Comparator} for version strings.
* <p>
* SNAPSHOT items always lowest rated,
* then splitting on dots,
* using natural order comparator (so "9" < "10" and "4u8" < "4u20"),
* and preferring segments without qualifiers ("4" > "4beta").
* <p>
* Impossible to follow semantics for all versioning schemes but
* does the obvious right thing for normal schemes
* and pretty well in fringe cases.
* <p>
* See test case for lots of examples.
*/
public class VersionComparator implements Comparator<String> {
private static final String SNAPSHOT = "SNAPSHOT";
public static final VersionComparator INSTANCE = new VersionComparator();
public static VersionComparator getInstance() {
return INSTANCE;
}
@Override
public int compare(String v1, String v2) {
if (v1==null && v2==null) return 0;
if (v1==null) return -1;
if (v2==null) return 1;
boolean isV1Snapshot = v1.toUpperCase().contains(SNAPSHOT);
boolean isV2Snapshot = v2.toUpperCase().contains(SNAPSHOT);
if (isV1Snapshot == isV2Snapshot) {
// if snapshot status is the same, look at dot-split parts first
return compareDotSplitParts(splitOnDot(v1), splitOnDot(v2));
} else {
// snapshot goes first
return isV1Snapshot ? -1 : 1;
}
}
@VisibleForTesting
static String[] splitOnDot(String v) {
return v.split("(?<=\\.)|(?=\\.)");
}
private int compareDotSplitParts(String[] v1Parts, String[] v2Parts) {
for (int i = 0; ; i++) {
if (i >= v1Parts.length && i >= v2Parts.length) {
// end of both
return 0;
}
if (i == v1Parts.length) {
// sequence depends whether the extra part *starts with* a number
// ie
// 2.0 < 2.0.0
// and
// 2.0.qualifier < 2.0 < 2.0.0qualifier < 2.0.0-qualifier < 2.0.0.qualifier < 2.0.0 < 2.0.9-qualifier
return isNumberInFirstCharPossiblyAfterADot(v2Parts, i) ? -1 : 1;
}
if (i == v2Parts.length) {
// as above but inverted
return isNumberInFirstCharPossiblyAfterADot(v1Parts, i) ? 1 : -1;
}
// not at end; compare this dot split part
int result = compareDotSplitPart(v1Parts[i], v2Parts[i]);
if (result!=0) return result;
}
}
private int compareDotSplitPart(String v1, String v2) {
String[] v1Parts = splitOnNonWordChar(v1);
String[] v2Parts = splitOnNonWordChar(v2);
for (int i = 0; ; i++) {
if (i >= v1Parts.length && i >= v2Parts.length) {
// end of both
return 0;
}
if (i == v1Parts.length) {
// shorter set always wins here; i.e.
// 1-qualifier < 1
return 1;
}
if (i == v2Parts.length) {
// as above but inverted
return -1;
}
// not at end; compare this dot split part
String v1p = v1Parts[i];
String v2p = v2Parts[i];
if (v1p.equals(v2p)) continue;
if (isNumberInFirstChar(v1p) || isNumberInFirstChar(v2p)) {
// something starting with a number is higher than something not
if (!isNumberInFirstChar(v1p)) return -1;
if (!isNumberInFirstChar(v2p)) return 1;
// both start with numbers; can use natural order comparison *unless*
// one is purely a number AND the other *begins* with that number,
// followed by non-digit chars, in which case prefer the pure number
// ie:
// 1beta < 1
// but note
// 1 < 2beta < 11beta
if (isNumber(v1p) || isNumber(v2p)) {
if (!isNumber(v1p)) {
if (v1p.startsWith(v2p)) {
if (!isNumberInFirstChar(Strings.removeFromStart(v1p, v2p))) {
// v2 is a number, and v1 is the same followed by non-numbers
return -1;
}
}
}
if (!isNumber(v2p)) {
// as above but inverted
if (v2p.startsWith(v1p)) {
if (!isNumberInFirstChar(Strings.removeFromStart(v2p, v1p))) {
return 1;
}
}
}
// both numbers, skip to natural order comparison
}
}
// otherwise it is in-order
int result = NaturalOrderComparator.INSTANCE.compare(v1p, v2p);
if (result!=0) return result;
}
}
@VisibleForTesting
static String[] splitOnNonWordChar(String v) {
Collection<String> parts = new ArrayList<String>();
String remaining = v;
// use lookahead to split on all non-letter non-numbers, putting them into their own buckets
parts.addAll(Arrays.asList(remaining.split("(?<=[^0-9\\p{L}])|(?=[^0-9\\p{L}])")));
return parts.toArray(new String[parts.size()]);
}
@VisibleForTesting
static boolean isNumberInFirstCharPossiblyAfterADot(String[] parts, int i) {
if (parts==null || parts.length<=i) return false;
if (isNumberInFirstChar(parts[i])) return true;
if (".".equals(parts[i])) {
if (parts.length>i+1)
if (isNumberInFirstChar(parts[i+1]))
return true;
}
return false;
}
@VisibleForTesting
static boolean isNumberInFirstChar(String v) {
if (v==null || v.length()==0) return false;
return Character.isDigit(v.charAt(0));
}
@VisibleForTesting
static boolean isNumber(String v) {
if (v==null || v.length()==0) return false;
return v.matches("[\\d]+");
}
}