At 2010-12-17 00:23 +0200, Andriy Gerasika wrote:
but what I need, is to separate static portion of xpath to use-when,
both for speed and readability purposes, conditions can be quite complex:
<xsl:template match="some-xpath1"
use-when="$first-config-option=('A','B') or $another-config-option='C'">
where config options are set on TransformerFactory level
any ideas?
None that are solved by using the syntax. Variables are not
available to you for use-when=. Please see
http://www.w3.org/TR/2007/REC-xslt20-20070123/#conditional-inclusion
in the table titled "Static Context Components for use-when Expressions".
Another approach is to use your own vocabulary to decorate your XSLT
stylesheet constructs and since your stylesheet is an XML document
simply run your stylesheet through another preprocessing stylesheet
that keeps or strips out various constructs based on your vocabulary
and the configuration options:
<xsl:template match="some-xpath1" andriy:include="[1:A,B][2:C]">
... or:
<xsl:template match="some-xpath1" andriy:config1="A B" andriy:config2="C">
... or some expression language you divine to express your concepts
of configuration parameters and their values. How you express those
concepts could make the original stylesheet very readable. Otherwise
I don't see how using use-when= makes a stylesheet more readable than
expressing the concept in a predicate.
After having preprocessed your stylesheet based on your configuration
parameters, the output stylesheet has only the constructs that are
suitable for the configuration, so transform your data with that
output stylesheet instead of the original stylesheet. Your
preprocessing stylesheet doesn't change so you could pre-compile it
when using tools like Saxon to save some time.
What you lose in the preprocessing step you would have to gain back
by the speed you claim is lost in the original stylesheet (though I
don't understand how much slower it could be for you ... a tool like
Saxon works very quickly for template matching ... have you measured
any metrics using Saxon options such as "-t"?).
I hope this helps.
. . . . . . . . . . Ken
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