[xsl] I wrote an XSLT program that converts a mapping XML file into a large, powerful XSLT program

["Roger L Costello costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Folks,

I created an XML file (a "mapping file") that describes how to convert a
legacy XML format into a new XML format.

To implement the conversion, I used a pipeline approach. The first step is an
XSLT program that converts the mappings (in the mapping file) into a bunch of
template rules, one template rule per mapping. In other words, the output of
the first XSLT program is another XSLT program. (Cool! Dynamically generated
XSLT program) The second step ran the generated XSLT program on a legacy XML
file to produce XML in the new format.

Here are some statistics on file sizes:

Size of the mapping file: 383 KB
Size of the XSLT program that converts the mappings (in the mapping file) to
template rules: 154 KB
Size of the XSLT program that was generated: 204622 KB  <-- Huge!

Lesson Learned: With a good description document (e.g., a good mappings
document) and a few lines of XSLT code, you can dynamically generate a huge
XSLT program that can do an enormous amount of work.

I love this approach to programming. It harkens back to my time writing
parsers and compilers.

/Roger