Re: [xsl] String hashing code

[Sascha Mantscheff <922492@xxxxxx>]

I don't have a XSLT solution. With Saxon I use for a similar problem an 
extension which returns md5 hashes for the serialized content. Find the 
source code below. I call it from within XSLT with

           <xsl:variable name="serialized_content">
               <xsl:value-of 
select="saxon:serialize(current-group()[1],'')"/>
           </xsl:variable>
           <xsl:variable name="hash">
               <xsl:value-of select="md5:md5($serialized_content)"/>
           </xsl:variable>

--- file md5.java ---
import java.util.*;
import java.io.*;
import java.security.*;

/* Saxon extension for generating unique hash values. */

public class Md5  {
   public static String hex(byte[] array) {
       StringBuffer sb = new StringBuffer();
       for (int i = 0; i < array.length; ++i) {
           sb.append(Integer.toHexString((array[i] & 0xFF) | 
0x100).toUpperCase().substring(1,3));
       }
       return sb.toString();
   }
   public static String md5 (String message) throws 
NoSuchAlgorithmException, UnsupportedEncodingException {
       MessageDigest md = MessageDigest.getInstance("MD5");
       return hex (md.digest(message.getBytes("CP1252")));
   }
}


Deborah Pickett schrieb:
> A challenge to the XSLT demigods...
>
> I am processing a number of separate XML documents using an Ant <xslt>
> task, pulling out the MathML that is embedded inside them into their own
> XML files using xsl:result-document (where I render them using Batik).
> I want to make sure that the result document names don't clash, but
> because they are across several source files, generate-id() isn't going
> to suffice.  There are thousands of source files, all with
> English-sounding names spread across many directories.
>
> I was thinking of hashing document-uri(/) to produce a probably-unique
> string that I can then append generate-id(.) to.  I rejected
> encode-for-uri() as producing strings that are too long, and for not
> anonymizing the document uri enough.  All the hashing algorithms I know
> (MD5, for instance) happen to be heavy on bitwise operations, and I feel
> dirty doing bitwise operations with arithmetic.
>
> I prefer not to escape to non-XSLT, because I am providing this as part
> of a library that needs to run on almost any XSLT 2.0 platform.
>
> Any clever ideas?