Obtaining the Current Node for the Current XSLT Template

In a stylesheet, the current node is the node for which the XSLT processor instantiates a template. When the XPath processor evaluates an expression during stylesheet processing, the initial context node for the expression is set to the current node for the stylesheet instruction that contains the expression. Because the context node can change during evaluation of subexpressions, it is useful to be able to retrieve, from within a subexpression, the original context node for which the expression is being evaluated. You can use the current() function for this purpose. The format is

node-set current()  

The current() function returns a node set that contains only the current node for the current template. The current() function is specified in the W3C XSLT Recommendation.

For example, the following stylesheet causes the XSLT processor to pass the bookstore node to the outer xsl:for-each instruction:

<xsl:stylesheet  
xmlns:xsl="http://www.w3.org/XSL/Transform" version="1.0" > 
<xsl:template match="/">  
<xsl:for-each select="bookstore">  
<xsl:for-each select= 
"book[@style=current()/@specialty]">  
...  
</xsl:for-each>  
</xsl:for-each>  
</xsl:template>  
</xsl:stylesheet>

The bookstore node is the current node within the outer xsl:for-each instruction. Within the inner xsl:for-each instruction, a book node is the current node.

The current() function in the inner expression returns the bookstore element because the bookstore element is the current node for the inner xsl:for-each instruction. The result of the query contains book elements if the value of their style attribute is the same as the value of the specialty attribute of the bookstore element (novel).

Suppose the select attribute in the inner xsl:for-each instruction specified the dot (.) instead of the current() function:

<xsl:for-each select="book[@style=./@specialty]"> 

In a query, the dot specifies the context node. This query would return a book if the value of its style attribute was the same as the value of its specialty attribute.

You can nest xsl:for-each instructions more than one level deep. In any given nested xsl:for-each instruction, the current() function returns the current node for the closest enclosing xsl:for-each instruction.

 
Free Stylus Studio XML Training:
W3C Member