XSL conditional formatting - xslt

Question

I am using xsl to transform xml to kml format. I would like to add conditional logic to the xsl to switch the styleUrl based on part of an attribute value. The attribute name is FROM_SYSTEM_ID. The format of the attribute value is "A-123-CAM-1" where "CAM" is part of the string to determine which style definition to use (in this case CAM stands for Camera, CAB stands for Cabinet, etc).
How can I parse this attribute to perform the needed style definition switch?
Following is my xsl template:
<xsl:template match="Line">
<Folder>
<name>
Lines
<!--<xsl:value-of select="#name"/>-->
</name>
<xsl:for-each select="Row">
<Placemark>
<name>
<xsl:value-of select="#FROM_SYSTEM_ID"/>
</name>
<description>
<xsl:value-of select="#TO_SYSTEM_ID"/>
</description>
<styleUrl>#msn_open-diamond00</styleUrl>
<LineString>
<tessellate>1</tessellate>
<coordinates>
<xsl:value-of select="#FromLong"/>,<xsl:value-of select="#FromLat"/>,0 <xsl:value-of select="#ToLong"/>,<xsl:value-of select="#ToLat"/>,0
</coordinates>
</LineString>
</Placemark>
</xsl:for-each>
</Folder>
</xsl:template>
Following is a sample of the XML:
<Line>
<Row PrimaryRoute="A-123" FROM_SYSTEM_ID="A-123-CAB-1"
TO_SYSTEM_ID="A-123-CAM-3" FromLat="42.624948852000"
FromLong="-83.107221652500"
ToLat="42.624940325900" ToLong="-83.107353167000" />
<Row PrimaryRoute="A-123" FROM_SYSTEM_ID="A-123-CAM-1"
TO_SYSTEM_ID="A-123-HH-16" FromLat="42.641662528600"
FromLong="-83.151500129600"
ToLat="42.641709802200" ToLong="-83.151552587600" />
<!-- additional rows here -->
</Line>

Answer 1

You can extract the CAM or CAB portion of the FROM_SYSTEM_ID attribute using a combination of substring-after and substring-before:
<xsl:value-of select="
substring-before(
substring-after(
substring-after(#FROM_SYSTEM_ID, '-'), '-'), '-')"/>
Putting this together with your stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="Line">
<Folder>
<name>
Lines
<!--<xsl:value-of select="#name"/>-->
</name>
<xsl:for-each select="Row">
<Placemark>
<name>
<xsl:value-of select="#FROM_SYSTEM_ID"/>
</name>
<description>
<xsl:value-of select="#TO_SYSTEM_ID"/>
</description>
<styleUrl>
<xsl:value-of select="
substring-before(
substring-after(
substring-after(#FROM_SYSTEM_ID, '-'), '-'), '-')"/>
</styleUrl>
<LineString>
<tessellate>1</tessellate>
<coordinates>
<xsl:value-of select="#FromLong"/>,<xsl:value-of select="#FromLat"/>,0 <xsl:value-of select="#ToLong"/>,<xsl:value-of select="#ToLat"/>,0
</coordinates>
</LineString>
</Placemark>
</xsl:for-each>
</Folder>
</xsl:template>
</xsl:stylesheet>
Applied to this input:
<Line>
<Row PrimaryRoute="A-123" FROM_SYSTEM_ID="A-123-CAB-1"
TO_SYSTEM_ID="A-123-CAM-3" FromLat="42.624948852000"
FromLong="-83.107221652500"
ToLat="42.624940325900" ToLong="-83.107353167000" />
<Row PrimaryRoute="A-123" FROM_SYSTEM_ID="A-123-CAM-1"
TO_SYSTEM_ID="A-123-HH-16" FromLat="42.641662528600"
FromLong="-83.151500129600"
ToLat="42.641709802200" ToLong="-83.151552587600" />
</Line>
Produces the following result:
<Folder>
<name>Lines</name>
<Placemark>
<name>A-123-CAB-1</name>
<description>A-123-CAM-3</description>
<styleUrl>CAB</styleUrl>
<LineString>
<tessellate>1</tessellate>
<coordinates>-83.107221652500,42.624948852000,0
-83.107353167000,42.624940325900,0
</coordinates>
</LineString>
</Placemark>
<Placemark>
<name>A-123-CAM-1</name>
<description>A-123-HH-16</description>
<styleUrl>CAM</styleUrl>
<LineString>
<tessellate>1</tessellate>
<coordinates>-83.151500129600,42.641662528600,0
-83.151552587600,42.641709802200,0
</coordinates>
</LineString>
</Placemark>
</Folder>