XSLT: How to reverse output without sorting by content - xslt

Question

I have a list of items:
<item>a</item>
<item>x</item>
<item>c</item>
<item>z</item>
and I want as output
z
c
x
a
I have no order information in the file and I just want to reverse the lines. The last line in the source file should be first line in the output. How can I solve this problem with XSLT without sorting by the content of the items, which would give the wrong result?

Answer 1

I will present two XSLT solutions:
I. XSLT 1.0 with recursion Note that this solution works for any node-set, not only in the case when the nodes are siblings:
This transformation:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:template match="/*">
<xsl:call-template name="reverse">
<xsl:with-param name="pList" select="*"/>
</xsl:call-template>
</xsl:template>
<xsl:template name="reverse">
<xsl:param name="pList"/>
<xsl:if test="$pList">
<xsl:value-of
select="concat($pList[last()], '
')"/>
<xsl:call-template name="reverse">
<xsl:with-param name="pList"
select="$pList[not(position() = last())]"/>
</xsl:call-template>
</xsl:if>
</xsl:template>
</xsl:stylesheet>
when applied on this XML document:
<t>
<item>a</item>
<item>x</item>
<item>c</item>
<item>z</item>
</t>
produces the wanted result:
z
c
x
a
II. XSLT 2.0 solution :
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xsl:output method="text"/>
<xsl:template match="/*">
<xsl:value-of select="reverse(*)/string(.)"
separator="
"/>
</xsl:template>
</xsl:stylesheet>
When this transformation is applied on the same XML document, the same correct result is produced.

Answer 2

XML CODE:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!-- Edited by XMLSpy® -->
<device>
<element>a</element>
<element>x</element>
<element>c</element>
<element>z</element>
</device>
XSLT CODE:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!-- Edited by XMLSpy® -->
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="//device">
<xsl:for-each select="element">
<xsl:sort select="position()" data-type="number" order="descending"/>
<xsl:text> </xsl:text>
<xsl:value-of select="."/>
<xsl:text> </xsl:text>
</xsl:for-each>
</xsl:template>
note: if you're using data-type="number", and any of the values aren't numbers, those non-numeric values will sort before the numeric values. That means if you're using order="ascending", the non-numeric values appear first; if you use order="descending", the non-numeric values appear last.
Notice that the non-numeric values were not sorted; they simply appear in the output document in the order in which they were encountered.
also, you may find usefull to read this:
http://docstore.mik.ua/orelly/xml/xslt/ch06_01.htm

Answer 3

Not sure what the full XML looks like, so I wrapped in a <doc> element to make it well formed:
<doc>
<item>a</item>
<item>x</item>
<item>c</item>
<item>z</item>
</doc>
Running that example XML against this stylesheet:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" encoding="UTF-8" omit-xml-declaration="yes"/>
<xsl:template match="/">
<xsl:call-template name="reverse">
<xsl:with-param name="item" select="doc/item[position()=last()]" />
</xsl:call-template>
</xsl:template>
<xsl:template name="reverse">
<xsl:param name="item" />
<xsl:value-of select="$item" />
<!--Adds a line feed-->
<xsl:text>
</xsl:text>
<!--Move on to the next item, if we aren't at the first-->
<xsl:if test="$item/preceding-sibling::item">
<xsl:call-template name="reverse">
<xsl:with-param name="item" select="$item/preceding-sibling::item[1]" />
</xsl:call-template>
</xsl:if>
</xsl:template>
</xsl:stylesheet>
Produces the requested output:
z
c
x
a
You may need to adjust the xpath to match your actual XML.

Answer 4

Consider this XML input:
<?xml version="1.0" encoding="utf-8" ?>
<items>
<item>a</item>
<item>x</item>
<item>c</item>
<item>z</item>
</items>
The XSLT:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" />
<xsl:template match="/items[1]">
<xsl:variable name="items-list" select="." />
<xsl:variable name="items-count" select="count($items-list/*)" />
<xsl:for-each select="item">
<xsl:variable name="index" select="$items-count+1 - position()"/>
<xsl:value-of select="$items-list/item[$index]"/>
<xsl:value-of select="'
'"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
And the result:
z
c
x
a