RetroZilla/extensions/java/xpcom/interfaces/VersionComparator.java

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Java XPCOM Bindings.
*
* The Initial Developer of the Original Code is
* IBM Corporation.
* Portions created by the Initial Developer are Copyright (C) 2005
* IBM Corporation. All Rights Reserved.
*
* Contributor(s):
* Javier Pedemonte (jhpedemonte@gmail.com)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.xpcom;
import java.util.Enumeration;
import java.util.StringTokenizer;
import org.mozilla.interfaces.nsISupports;
import org.mozilla.interfaces.nsIVersionComparator;
/**
* Version strings are dot-separated sequences of version-parts.
* <p>
* A version-part consists of up to four parts, all of which are optional:
* <br><code>
* &lt;number-a&gt;&lt;string-b&gt;&lt;number-c&gt;
* &lt;string-d (everything else)&gt;
* </code> <p>
* A version-part may also consist of a single asterisk "*" which indicates
* "infinity".
* <p>
* Numbers are base-10, and are zero if left out.
* Strings are compared bytewise.
* <p>
* For additional backwards compatibility, if "string-b" is "+" then
* "number-a" is incremented by 1 and "string-b" becomes "pre".
* <p> <pre>
* 1.0pre1
* < 1.0pre2
* < 1.0 == 1.0.0 == 1.0.0.0
* < 1.1pre == 1.1pre0 == 1.0+
* < 1.1pre1a
* < 1.1pre1
* < 1.1pre10a
* < 1.1pre10
* </pre>
* Although not required by this interface, it is recommended that
* numbers remain within the limits of a signed char, i.e. -127 to 128.
*/
public class VersionComparator implements nsIVersionComparator {
public nsISupports queryInterface(String aIID) {
return Mozilla.queryInterface(this, aIID);
}
/**
* Compare two version strings
* @param A a version string
* @param B a version string
* @return a value less than 0 if A < B;
* the value 0 if A == B;
* or a value greater than 0 if A > B
*/
public int compare(String A, String B) {
int result;
String a = A, b = B;
do {
VersionPart va = new VersionPart();
VersionPart vb = new VersionPart();
a = parseVersionPart(a, va);
b = parseVersionPart(b, vb);
result = compareVersionPart(va, vb);
if (result != 0) {
break;
}
} while (a != null || b != null);
return result;
}
private class VersionPart {
int numA = 0;
String strB;
int numC = 0;
String extraD;
}
private static String parseVersionPart(String aVersion, VersionPart result) {
if (aVersion == null || aVersion.length() == 0) {
return aVersion;
}
StringTokenizer tok = new StringTokenizer(aVersion.trim(), ".");
String part = tok.nextToken();
if (part.equals("*")) {
result.numA = Integer.MAX_VALUE;
result.strB = "";
} else {
VersionPartTokenizer vertok = new VersionPartTokenizer(part);
try {
result.numA = Integer.parseInt(vertok.nextToken());
} catch (NumberFormatException e) {
// parsing error; default to zero like 'strtol' C function
result.numA = 0;
}
if (vertok.hasMoreElements()) {
String str = vertok.nextToken();
// if part is of type "<num>+"
if (str.charAt(0) == '+') {
result.numA++;
result.strB = "pre";
} else {
// else if part is of type "<num><alpha>..."
result.strB = str;
if (vertok.hasMoreTokens()) {
try {
result.numC = Integer.parseInt(vertok.nextToken());
} catch (NumberFormatException e) {
// parsing error; default to zero like 'strtol' C function
result.numC = 0;
}
if (vertok.hasMoreTokens()) {
result.extraD = vertok.getRemainder();
}
}
}
}
}
if (tok.hasMoreTokens()) {
// return everything after "."
return aVersion.substring(part.length() + 1);
}
return null;
}
private int compareVersionPart(VersionPart va, VersionPart vb) {
int res = compareInt(va.numA, vb.numA);
if (res != 0) {
return res;
}
res = compareString(va.strB, vb.strB);
if (res != 0) {
return res;
}
res = compareInt(va.numC, vb.numC);
if (res != 0) {
return res;
}
return compareString(va.extraD, vb.extraD);
}
private int compareInt(int n1, int n2) {
return n1 - n2;
}
private int compareString(String str1, String str2) {
// any string is *before* no string
if (str1 == null) {
return (str2 != null) ? 1 : 0;
}
if (str2 == null) {
return -1;
}
return str1.compareTo(str2);
}
}
/**
* Specialized tokenizer for Mozilla version strings. A token can
* consist of one of the four sections of a version string: <code>
* &lt;number-a&gt;&lt;string-b&gt;&lt;number-c&gt;
* &lt;string-d (everything else)&gt;</code>.
*/
class VersionPartTokenizer implements Enumeration {
String part;
public VersionPartTokenizer(String aPart) {
part = aPart;
}
public boolean hasMoreElements() {
return part.length() != 0;
}
public boolean hasMoreTokens() {
return part.length() != 0;
}
public Object nextElement() {
if (part.matches("[\\+\\-]?[0-9].*")) {
// if string starts with a number...
int index = 0;
if (part.charAt(0) == '+' || part.charAt(0) == '-') {
index = 1;
}
while (index < part.length() && Character.isDigit(part.charAt(index))) {
index++;
}
String numPart = part.substring(0, index);
part = part.substring(index);
return numPart;
} else {
// ... or if this is the non-numeric part of version string
int index = 0;
while (index < part.length() && !Character.isDigit(part.charAt(index))) {
index++;
}
String alphaPart = part.substring(0, index);
part = part.substring(index);
return alphaPart;
}
}
public String nextToken() {
return (String) nextElement();
}
/**
* Returns what remains of the original string, without tokenization. This
* method is useful for getting the <code>&lt;string-d (everything else)&gt;
* </code> section of a version string.
*
* @return remaining version string
*/
public String getRemainder() {
return part;
}
}