为什么 //descendant 也在这个 XSLT 模板中评估兄弟姐妹？

Question

I am curious why this XSLT:

 <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:template match="/"> <xsl:apply-templates select="//ca"/> </xsl:template> <xsl:template match="ca"> <xsl:value-of select="."/> <xsl:value-of select="//cd"/> </xsl:template> </xsl:stylesheet>

over this XML document

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <!DOCTYPE a> <a> <b> <c> <ca>CA</ca> <cd>CD</cd> </c> </b> </a>

has the result: CACD

I'm mostly interested in why CD evaluates properly because I thought current context in a template is defined by match attribute, that is to say, ca in the second template. If that was correct, in the context of ca , with //cd, as far as I know, the XSLT processor should be searching by any descendant of ca of any level with name cd .

cd is a sibling of ca , so I am very confused.

I would appreciate any help which sheds light on this.

Thank you in advance.

Answer 1

Use .//cd to select relative to the context node, a path starting with / always selects starting at the document node/root node, ie //cd is /descendant-or-self::node()/cd .