& XSLT On 4/17/05, Dimitre Novatchev <dnovatchev@[...].com>  wrote:
>  On 4/18/05, Lars Marius Garshol <larsga@[...].no> wrote:
>  > * Dimitre Novatchev
>  > | Cyclomatic Complexity (McCabe) [...]
>  > | Halstead Complexity Measures [...]
>  > | Henry and Kafura metrics [...]
>  > | Bowles metrics [...]
>  > | Troy and Zweben metrics [...]
>  > | Ligier metrics [...]

Those traditional metrics feel unsatisfying for XSLT.  They all presume
to be analyzing static program text to produce a single scalar value
called "complexity".

With XSLT, the codepaths are determined by the input, so traditional 
complexity analysis doesn't really address the problem.  For example, 
it's impossible to know if:

    <xsl:apply-templates/> 

can trigger zero, one or many templates in a stylesheet.

>  > These might all be applicable, but does anyone know of any
>  > implementations of these for XSLT?
>  
>  I don't know of any implementations for XSLT -- these would be best
>  implemented as part of an XSLT processor.

This, however, is quite an intriguing idea -- calculate complexity
by tracing stylesheet execution while processing an input document.
Or a series of input documents, varying in complexity.  (Of course,
what constitutes "complexity of an XML document" is a separate
discussion.  ;-) )

Off the top of my head, here are some things that might contribute to
overall stylesheet complexity:

* number of XSLT modules loaded
* overall size of the XSLT stylesheet loaded
  (bytes / nodes post-include, post-import)
* percentage of templates used
* average template size (bytes, nodes, operators, XPath evaluations)
* ratio of input to output size (nodes, bytes)
* percentage of calculated vs. copied output

For example, if I'm processing this DocBook document:

    <book/> 

I think we can all agree that there are 57 ways to call the DocBook XSL
stylesheets "complex", at least compared to this stylesheet, which
produces the same output:

    <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
     version="1.0"/> 

:-)

-- Adam

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