Example E-8. camelhistory.xml
<?xml version="1.0"?>
<book>
<title>Camels: An Historical Perspective</title>
<chapter>
<title>Chapter One</title>
<para>
It was a dark and <emphasis>stormy</emphasis> night...
</para>
</chapter>
</book>
First we need to alter the root template of our stylesheet:
<xsl:template match="/">
<html>
<head><xsl:copy-of select="/book/title"/></head>
<body>
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
Here we have created the top-level structure of our output document
and copied over the book's
<title> element into the
<head> element of our HTML page. The
<xsl:apply-templates/> element tells the
XSLT processor to pass on the entire contents of the current element
(in this case the <book> element, since it
is the root-level element in the source document) for further
processing.
Now we need to create template rules for the other elements in the
document:
<xsl:template match="chapter">
<div class="chapter">
<xsl:attribute name="id">chapter_id<xsl:number
value="position( )" format="A"/></xsl:attribute>
<xsl:apply-templates/>
</div>
</xsl:template>
<xsl:template match="para">
<p><xsl:apply-templates/></p>
</xsl:template>
Here we see more examples of recursive processing. The
<para> and
<chapter> elements are transformed into
<div> and <p>
elements, and the contents of those elements are passed along for
further processing. Note also that the XPath expressions used within
the template rules are evaluated in the context of the current
element being processed. XSLT also maintains what is called the
"current node list," which is the
list of nodes being processed. In the example above, this is the list
of all chapter elements. This is an example of
XSLT using "least surprise".
<xsl:template match="emphasis">
<em><xsl:value-of select="."/></em>
</xsl:template>
<xsl:template match="chapter/title">
<h2><xsl:value-of select="."/></h2>
</xsl:template>
<xsl:template match="book/title">
<h1><xsl:value-of select="."/></h1>
</xsl:template>
</xsl:stylesheet>
Look closely at the last two template elements. Both match a
<title> element, but one defines the rule
for handling titles whose parent is a book
element, while the other handles the chapter
titles. In fact, any valid XPath expression, XSLT function call, or
combination of the two can be used to define the match rule for a
template element.
