XSLT, 2nd Edition

[2.0] Comments in XPath Expressions

Another addition to the XPath 2.0 syntax is the ability to add comments. Using delightfully happy syntax, a comment begins with (: and ends with :). We’ll use a stylesheet with a complicated if statement:

<?xml version="1.0"?>
<!-- comments.xsl -->
<xsl:stylesheet version="2.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="text"/>

  <xsl:template match="/">
    <xsl:for-each select="cars/make">
      <xsl:text>&#xA;  Car: </xsl:text>
      <xsl:value-of select="."/>
      <xsl:text> - </xsl:text>
      <xsl:value-of 
        select="(: Most of our cars are from North America, 
                   so we look there first :)
                if (@geography = 'North America') then 
                  'Domestic car'

                (: Next, see if the car is from Europe :)
                else if (@geography = 'Europe') then 
                  'Import from Europe'

                (: Check for Asia :)
                else if (@geography = 'Asia') then 
                  &quot;It's from Asia&quot;

                (: If it's anything else, just say
                  'We don't know' :)
                else 
                  'We don''t know!'"/>

    </xsl:for-each>
  </xsl:template>

</xsl:stylesheet>

The stylesheet has three if statements that check the value of the geography attribute of an element. We’ve used spacing and comments liberally here to make the code more legible. In the last comment, you can see that we don’t have to escape quote marks inside the comment, although we do have to handle them appropriately outside the comment. For one quote that contains an apostrophe, we wrap the text in double quotes ("It's from Asia"). For the next quote, we use a doubled apostrophe ('We ...