Question

 <a>
   <x/>
   <m/>
   <y/>
   <m/>
 </a>

Inside a template that matches ‘a’, I want to match (first) any ‘m’s before ‘y’, and then
separately any ‘m’s after ‘y’.

<xsl:apply-templates select="./m[following::y]"/>

is what I thought of, but I can’t get it to work, and, further, I can’t see how to prevent the template that matches on ‘m’ from being applied in the normal flow as well as in the particular place i want to insert the m-related content.

Answer 1

Your template looks OK, but are you sure you want to use following? For example, this template:

<xsl:template match="a">
    <a><xsl:apply-templates select="m[following::y]"/></a>
    <b><xsl:apply-templates select="m[following-sibling::y]"/></b>  
</xsl:template>

…applied to the following XML:

<a>
   <x/>
   <m>match</m>
   <y/>
   <m>no match</m>
   <nested>
       <m>match 2</m>
       <y/>
   </nested>
</a>

…outputs the following result:

<a>matchno match</a>
<b>match</b>

The first apply-templates matches <m>no match</m> because following includes all nodes that are after the context node in document order, which includes the nested <y/>.

The second template matches only siblings.

For completeness, I’ll add the following template, which matches only those <m> nodes whose immediate following sibling is a <y>:

<xsl:template match="a">
   <a><xsl:apply-templates select="m[following-sibling::*[1][self::y]]"/></a>
</xsl:template>

This template outputs the following, given the above XML:

<a>match</a>