Best approach(es) for processing varying substrings

CanOfBees · February 17th, 2013, 01:42 PM

Hi all,

I'm wondering if anyone could share their approaches for dealing with lots of
variance in substrings. I have an XML file that looks something like:

Code:

<root>
    <row>
        <subj>foo, bar, baz</subj>
        <subj>qux, grault ==> fred, thud</subj>
    </row>
    <row>
        <subj>waldo, wobble</subj>
        <subj>HIDDEN: garply</subj>
    </row>
    <row>
        <subj>spam, hash</subj>
        <subj>eggs ==> bacon</subj>
        <subj>HIDDEN: garply, wibble ==> wubble</subj>
    </row>
    <row>
        <subj>qux ==> delete</subj>
    </row>
</root>

I'm processing it with an identity transform like so:

Code:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    exclude-result-prefixes="xs"
    version="2.0">
    
    <xsl:output method="xml" indent="yes"/>
    
    <xsl:template match="/">
        <xsl:apply-templates/>
    </xsl:template>
    
    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
    
    <xsl:template match="subj">
        <xsl:for-each select="tokenize(., ',')">
            <subject>
                <xsl:value-of select="normalize-space(.)"/>
            </subject>
        </xsl:for-each>
    </xsl:template>
    
</xsl:stylesheet>

The above stylesheet gives me the following XML:

Code:

<root>
   <row>
      <subject>foo</subject>
      <subject>bar</subject>
      <subject>baz</subject>
      <subject>qux</subject>
      <subject>grault ==&gt; fred</subject>
      <subject>thud</subject>
   </row>
   <row>
      <subject>waldo</subject>
      <subject>wobble</subject>
      <subject>HIDDEN: garply</subject>
   </row>
   <row>
      <subject>spam</subject>
      <subject>hash</subject>
      <subject>eggs ==&gt; bacon</subject>
      <subject>HIDDEN: garply</subject>
      <subject>wibble ==&gt; wubble</subj>
   </row>
   <row>
      <subject>qux ==&gt; delete</subject>
   </row>
</root>

which is very close. But I'd like to be able to render the HIDDEN tokens to one line. E.g.

Code:

<subject>eggs ==&gt; bacon</subject>
<subject>HIDDEN: garply, wibble ==&gt; wubble</subject>

Is there a way to test tokens and group them? Would my approach be better if I used xsl:for-each-group? Thanks, in advance, for any insights you're willing to share.

Martin Honnen · February 17th, 2013, 01:51 PM

You can certainly write a template

Code:

<xsl:template match="subj[starts-with(., 'HIDDEN:')]">
  <subject>
      <xsl:value-of select="."/>
  </subject>
</xsl:template>

then for your template with ' match="subj" ' exclude those e.g

Code:

<xsl:template match="subj[not(starts-with(., 'HIDDEN:'))]">
  <xsl:for-each select="tokenize(...)">...</xsl:for-each>
</xsl:template>

Additionally there is the regular expression support with the "matches" function which would even give you more control if needed.

CanOfBees · February 17th, 2013, 09:16 PM

Martin, et al.,
Thanks for the reply - I forgot about using templates like that.

I've tried to take the `template match="subjects[contains(., 'HIDDEN')]"` a step further, but I'm running into a string-join() issue. The string '==>' denotes a change and I thought I could apply the following template to process those changes. I tokenize the subjects in a variable, and then, after creating a second variable, I try to apply a choose/when/otherwise on the resulting tokens. I want to discard tokens that contain '[Dd]elete' and update the tokens that indicate 'Old value ==> New value'. After that, I'm trying to put them back together. I can put them back together, but I can't get string-join() to insert commas between the values.
XSL:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0"
        exclude-result-prefixes="#all">
        
        <xsl:output method="xml" indent="yes"/>
        <xsl:strip-space elements="*"/>
        
        <xsl:template match="/">
            <xsl:apply-templates/>
        </xsl:template>
        
        <xsl:template match="@*|node()">
            <xsl:copy>
                <xsl:apply-templates select="@*|node()"/>
            </xsl:copy>
        </xsl:template>
        
        <xsl:template match="subjects[starts-with(., 'HIDDEN')]">
            <xsl:variable name="tHIDDEN" select="tokenize(., ',')"/>
            <xsl:variable name="tHIDDEN2">
                <xsl:for-each select="$tHIDDEN">
                    <xsl:choose>
                        <xsl:when test="contains(., '==&gt;') and not(contains(substring-after(., '==&gt;'), '[Dd]elete'))">
                            <xsl:value-of select="normalize-space(substring-after(., '==&gt;'))"/>
                        </xsl:when>
                        <xsl:when test="contains(., '==&gt;') and contains(substring-after(., '==&gt;'), '[Dd]elete')"/>
                        <xsl:otherwise>
                            <xsl:value-of select="."/>
                        </xsl:otherwise>
                    </xsl:choose>
                </xsl:for-each>
            </xsl:variable>
            <xsl:for-each select="$tHIDDEN2">
                <subjectH2>
                    <xsl:value-of select="string-join(., ', ')"/>
                </subjectH2>
            </xsl:for-each>
        </xsl:template>
        
        <xsl:template match="subjects[not(starts-with(., 'HIDDEN'))]">
            <xsl:for-each select="tokenize(., ',')">
                <xsl:choose>
                    <xsl:when
                        test="contains(., '==&gt;') and not(contains(substring-after(., '==&gt;'), '[Dd]elete'))">
                        <subject>
                            <xsl:value-of select="normalize-space(substring-after(., '==&gt;'))"/>
                        </subject>
                    </xsl:when>
                    <xsl:otherwise>
                        <subject>
                            <xsl:value-of select="normalize-space(.)"/>
                        </subject>
                    </xsl:otherwise>
                </xsl:choose>
            </xsl:for-each>
        </xsl:template>
        
    </xsl:stylesheet>
    
</xsl:stylesheet>

updated XML:

Code:

<root>
    <row>
        <subjects>foo, bar, baz</subjects>
        <subjects>qux, grault ==> fred, thud</subjects>
    </row>
    <row>
        <subjects>waldo, wobble</subjects>
        <subjects>HIDDEN: garply</subjects>
    </row>
    <row>
        <subjects>spam, hash</subjects>
        <subjects>eggs ==> bacon</subjects>
        <subjects>HIDDEN: garply, wibble ==> wubble</subjects>
    </row>
    <row>
        <subjects>wobble, wibble, wubble</subjects>
        <subjects>qux ==> delete</subjects>
    </row>
</root>

When I apply the provided template against the example XML, I get the following output:

Code:

<root>
   <row>
      <subject>foo</subject>
      <subject>bar</subject>
      <subject>baz</subject>
      <subject>qux</subject>
      <subject>fred</subject>
      <subject>thud</subject>
   </row>
   <row>
      <subject>waldo</subject>
      <subject>wobble</subject>
      <subjectH2>HIDDEN: garply</subjectH2>
   </row>
   <row>
      <subject>spam</subject>
      <subject>hash</subject>
      <subject>bacon</subject>
      <subjectH2>HIDDEN: garplywubble</subjectH2>
   </row>
   <row>
      <subject>wobble</subject>
      <subject>wibble</subject>
      <subject>wubble</subject>
      <subject>delete</subject>
   </row>
</root>

I also just noticed that my attempt at deleting the subjects containing ==> delete isn't working, either. I'm guessing that these are problems with the way I'm structuring my when tests, but I'm not sure how else to go about this.

Thanks, again, for any suggestions you provide.