XSLT, 2nd Edition

Simple Location Paths

Now that we’ve talked about what a context is and why it matters, we’ll look at some location paths. We’ll start with a variety of simple paths; as we go along, we’ll look at more complex location paths that use all the various features of XPath. We already looked at one of the simplest XSLT patterns:

<xsl:template match="/">

This template selects the root node of the document. We saw another simple XPath expression in the <xsl:value-of> element:

<xsl:value-of select="."/>

This template selects the context node, represented by a period. To complete our tour of very simple location paths, we can use the double period (..) to select the parent of the context node:

<xsl:value-of select=".."/>

All these XPath expressions have one thing in common: they don’t use element names. As you might have noticed in our Hello World example, you can use element names to select elements that have a particular name:

<xsl:apply-templates select="greeting"/>

In this example, we select all of the <greeting> elements in the current context and apply the appropriate template to each of them. Turning to our XML sonnet, we can create location paths that specify more than one level in the document hierarchy:

<xsl:apply-templates select="lines/line"/>

This example selects all <line> elements that are contained in any <lines> elements in the current context. If the current context doesn’t have any <lines> elements, then this expression returns an empty node-set. If the current context has plenty ...