XSLT parse document($file) before use in a key

Question

I've got a stupid question.

I am loading an external document, and then using it to add an attribute to a certain element in the main document. A bit like this:

<xsl:variable name="dictstrings" select="document($dictionary_file)"/>
<xsl:key name="ui_ids" match="DICT_ENTRY" use="LANG_ENTRY"/>

<!--Identity template, copies all content -->
<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

 <!--Template for uicontrol that provides custom behavior -->
 <xsl:template match="uicontrol[key('ui_ids', ., $dictstrings)]">  
     <xsl:apply-templates select="key('ui_ids', ., $dictstrings)"/>
 </xsl:template>

This matches the appropriate LANG_ENTRY element(s) in the external document to the corresponding uicontrol element in the main document. (I have another xsl:template command that adds the DICT_ID attribute.) All good so far.

My problem is that sometimes the LANG_ENTRY element in my $dictionary_file starts with an extraneous ampersand. Like so:

  <DICT_ENTRY DICT_ID="21625">
    <LANG_ENTRY><![CDATA[Test list]]></LANG_ENTRY>
  </DICT_ENTRY>
  <DICT_ENTRY DICT_ID="2163">
    <LANG_ENTRY><![CDATA[&Insert new test]]></LANG_ENTRY>
  </DICT_ENTRY>

I'd like to strip this ampersand out. Otherwise, the match won't work.

I was trying to do this, in a vague dreamy haze:

<xsl:variable name="dictstrings">
    <xsl:apply-templates select="document($dictionary_file)"/>
</xsl:variable>

and then have a template that caught the LANG_ENTRY

<xsl:template match="LANG_ENTRY[starts-with(.,'&amp;')]">
    <xsl:element name="LANG_ENTRY">
        <xsl:value-of select="substring(.,2)"/>
    </xsl:element>
</xsl:template>

But, as you know, it objects to the declaration of the dictstrings variable, now, saying

XTDE0640: Circular variable or parameter declaration

How should I go about parsing and editing the external document nodes, before using them in the key() function?

I am also nervous about making sure the context is correct between the main and the external document, but I haven't got to that problem yet.

Answer 1

You don't really need to "edit" the external nodes as such, simply ensure that the use expression in the key definition strips off the leading ampersand, if there is one, when it constructs the key value:

<xsl:key name="ui_ids" match="DICT_ENTRY" use="replace(LANG_ENTRY, '^&amp;', '')"/>

(You haven't said so explicitly but I assume you're in XSLT 2.0 given you're using variables in match patterns and the three-argument form of the key function).