XML in a Nutshell, 3rd Edition

The comment( ), text( ), and processing-instruction( ) Location Steps

Although element, attribute, and root nodes account for 90% or more of what you need to do with XML documents, this still leaves four kinds of nodes that need to be addressed: namespace nodes, text nodes, processing-instruction nodes, and comment nodes. Namespace nodes are rarely handled explicitly. The other three node types have special node tests to match them. These are as follows:

• comment( )

• text( )

• processing-instruction( )

Since comments and text nodes don’t have names, the comment( ) and text( ) location steps match any comment or text node child of the context node. Each comment is a separate comment node. Each text node contains the maximum possible contiguous run of text not interrupted by any tag. Entity references and CDATA sections are resolved into text and markup and do not interrupt text nodes.

By default, XSLT stylesheets do process text nodes but do not process comment nodes. You can add a comment template rule to an XSLT stylesheet so it will process comments too. For example, this template rule replaces each comment with the text “Comment Deleted” in italic:

<xsl:template match="comment( )">
  <i>Comment Deleted</i>
</xsl:template>

With no arguments, the processing-instruction( ) location step selects all processing-instruction children of the context node. If it has an argument, then it only selects the processing-instruction children with the specified target. For example, the XPath expression ...