<?xml version='1.0'?>
<!DOCTYPE xsl:stylesheet SYSTEM "file:///C:/C64/home/ht/lib/xml/xsl.dtd" >
<xsl:stylesheet xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:e="http://markup.co.uk/excel" version="3.0">
 <xsl:variable name="codeBase" select="string-to-codepoints('A')-1"/>
 
 <xsl:function name="e:n2aa" as="xs:integer*">
  <!-- Does the real work for e:n2a -->
  <xsl:param name="n" as="xs:integer"/>
  <xsl:sequence select="let $least := $codeBase+(($n - 1) mod 26)+1
                         return if ($n &lt; 27) then $least
                          else (e:n2aa(($n - 1) idiv 26),$least)"/>
 </xsl:function>

 <xsl:function name="e:n2a" as="xs:string">
  <!-- Invert the a2n computation -->
  <xsl:param name="n" as="xs:integer"/>
  <xsl:value-of select="codepoints-to-string(e:n2aa($n))"/>
 </xsl:function>
 
 <xsl:function name="e:crnf" as="xs:string">
  <!-- compute CR-normal-form of a singleton reference -->
  <xsl:param name="s" as="element(e:s)"/>
  <xsl:value-of select="concat(e:snf(($s/*)[1]),e:snf(($s/*)[2]))"/>
 </xsl:function>
 
 <xsl:function name="e:snf" as="xs:string">
  <xsl:param name="s" as="element(*)"/><!-- either a(bsolute) or r(elative)-->
  <xsl:value-of select="if (local-name($s)='a')
                         then concat('&#xAA;',$s)
                         else concat('&#xBA;',$s/@d)"/>
 </xsl:function>
 
 <xsl:function name="e:rnf" as="xs:string">
  <!-- CRNF for a range or singleton reference -->
  <xsl:param name="b" as="element(*)"/>
  <xsl:value-of select="if (local-name($b)='s') then e:crnf($b)
                           else if (local-name($b)='r')
                                 then
                                  let $l := ($b/e:s)[1],
                                      $r := ($b/e:s)[2] return
                                     concat(e:crnf($l),
                                            ':',
                                            e:crnf($r))
                                 else if (local-name($b)='v')
                                  then $b/text()
                                 else e:shouldnt()"/>
 </xsl:function>
 
 <xsl:function name="e:fnf" as="xs:string">
  <!-- rebuild a formula from its parts, but using CRNF for all references -->
  <xsl:param name="bits" as="element(*)*"/>
  <xsl:value-of select="string-join(
                          for $b in $bits return
                           if (local-name($b)=('s','r')) then e:rnf($b)
                           else if (local-name($b)='e')
                                 then concat($b/@x,'!',e:rnf($b/*))
                          else $b/text())"/>
 </xsl:function>
 
 <xsl:function name="e:shouldnt">
  <xsl:message terminate="yes">shouldn't happen</xsl:message>
 </xsl:function>
</xsl:stylesheet>