How to find smallest string in result tree fragment(RTF) containing two strings without using extension function e.g. node-set in xslt 1.0 - xslt

Question

I have two strings variables basically storing currency codes which can have values like USD or EUR or JPY etc.
Examples:
If variable boughtccy contains 'JPY' and variable soldccy contains 'USD' then it should return a string 'BOUGHTCCY' signifying that it is the variable named boughtccy actually contains the smallest currency.
Similarly, if variable boughtccy contains 'EUR' and variable soldccy contains 'AUD' then it should return a string 'SOLDCCY' signifying that it is the variable named soldccy actually contains the smallest currency.
I have written following code which works perfectly fine except for in Altova XMLSpy. I have a requirement that it should also work in XMLSpy.
Here is the code:
xsl:variable name="smallerccy">
<xsl:variable name="nodes">
<node>
<xsl:value-of select="$boughtccy"/>
</node>
<node>
<xsl:value-of select="$soldccy"/>
</node>
</xsl:variable>
<xsl:for-each select="common:node-set($nodes)/*">
<xsl:sort select="."/>
<xsl:choose>
<xsl:when test="position()=1 and .=$boughtccy">BOUGHTCCY</xsl:when>
<xsl:when test="position()=1 and .=$soldccy">SOLDCCY</xsl:when>
</xsl:choose>
</xsl:for-each>
</xsl:variable>
How do I achieve this without using exslt:node-set() function? I cannot use xslt 2.0.

Answer 1

I believe the underlying problem you are having is that in XSLT 1.0 strings can only compared only for equality (or inequality), and so you can simply do <xsl:when test="$boughtccy > $soldccy">
In you particular case, where you are dealing with a finite number of strings, you could define a variable containing all possible currency codes, and use string handling to find one is first.
Try this XSLT (You would, of course, have to amend $AllCurrencies to have all possible currency codes).
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:variable name="AllCurrencies" select="'AUS|EUR|JPY|USD'" />
<xsl:param name="boughtccy" select="'JPY'" />
<xsl:param name="soldccy" select="'USD'" />
<xsl:template match="/">
<xsl:choose>
<xsl:when test="string-length(substring-before($AllCurrencies, $boughtccy)) < string-length(substring-before($AllCurrencies, $soldccy))">BOUGHTCCY</xsl:when>
<xsl:otherwise>SOLDCCY</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>

Answer 2

I would write conditional logic, using system-property() and function-available(), that implements this in different ways for different processors:
if it's XSLT 2.0, use min(($boughtccy, $soldccy))
if it's XSLT 1.0 with a node-set extension, use the sorting technique that you're already using
otherwise give up. (There is no way to compare two strings for "<" in XSLT 1.0 other than creating a node-set and sorting it, and that requires the node-set extension).