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Re: Pattern Matching in XSl - find groups defined in o
Subject: Re: Pattern Matching in XSl - find groups defined in one Xml in another Xml.
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Wed, 29 Aug 2012 12:29:09 -0400
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Richard,
This is an idiom we use to filter out values that have whitespace only.
normalize-space(' ') returns '', which (coerced to a Boolean
false) fails a test.
So regex-group(1)[normalize-space(.)] returns an empty sequence when the
value of regex-group(1) is an empty string or only whitespace.
Ken is going to a little extra trouble here to avoid getting
found-key=" "
when $thisGroupedAlarm/@equipment has " ".
In other words, it's defensive programming of the sort you learn to
write when you have to handle data sets that are not well-controlled (an
unfortunate fact of life). You can skip it if you know that your data is
good, and won't be throwing up such cases, or more generally if
garbage-in/garbage-out is fine for you.
Cheers,
Wendell
On 8/29/2012 12:16 PM, Kerry, Richard wrote:
Regarding Ken's solutions from last Wednesday (repeated below), why
is it :
<xsl:analyze-string select="$thisAlarm/@equipment"
regex="^{$thisGroupedAlarm/@equipment}$"> <xsl:matching-substring>
<xsl:for-each select="regex-group(1)[normalize-space(.)]">
<xsl:attribute name="found-key" select="."/> </xsl:for-each>
</xsl:matching-substring> </xsl:analyze-string>
rather than
<xsl:analyze-string select="$thisAlarm/@equipment"
regex="^{$thisGroupedAlarm/@equipment}$"> <xsl:matching-substring>
<xsl:attribute name="found-key" select="regex-group(1)"/>
</xsl:matching-substring> </xsl:analyze-string>
?
What does the [normalize-space(.)] predicate do for us ?
Uncertainly, Richard.
PS. By the way, this does seem to give the right results. I'm only
now getting back to looking at it and working out how it works,
having had a few days off over the (UK) Bank Holiday weekend.
--
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Wendell Piez mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc. http://www.mulberrytech.com
17 West Jefferson Street Direct Phone: 301/315-9635
Suite 207 Phone: 301/315-9631
Rockville, MD 20850 Fax: 301/315-8285
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Mulberry Technologies: A Consultancy Specializing in SGML and XML
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