[xsl] Emulating XPATH2 range in XSLT 1.0

[Hermann Stamm-Wilbrandt <STAMMW@xxxxxxxxxx>]

Emulating the XSLT2 statement
    for $f in 1 to 10000
      ...

may be done in XSLT1 (providing similar scoping of variable $f) by:
    <xsl:for-each select="range:to(1,10000)">
      <xsl:variable name="f" select="."/>
      ...
    </xsl:for-each>

In this case the complete set of numbers is generated into memory.:
For bigger iteration count ("1 to 1000000" in T2.xsl) this
may cause problems for the XSLT processor.

Therefore "loop.xsl" may be used (T2.xsl, T3.xsl) to just iterate and
do not generate all the numbers into memory. In order to allow for
different bodies of the loops a template with name "loop" is called.
Different implementations (body2.xsl, body3.xsl) are included
together with "loop.xsl" into different stylesheets (T2.xsl, T3.xsl).


I teststed this successfully with the following XSLT 1.0 processors:.
- xsltproc (Using libxml 20626, libxslt 10117 and libexslt 813)
- xalan-j (2.7.1)
- IBM Websphere DataPower compiler


All files may be downloaded here:
http://www.stamm-wilbrandt.de/en/xsl-list/range/files.zip

Find an example execution for T3.xsl at the bottom.

$ cat range.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl   = "http://www.w3.org/1999/XSL/Transform";
  xmlns:exslt = "http://exslt.org/common";
  xmlns:func  = "http://exslt.org/functions";
  xmlns:range = "urn:xpath1range"
  extension-element-prefixes="func">

  <func:function name="range:to">
    <xsl:param name="a"/>
    <xsl:param name="b"/>

    <func:result select="exslt:node-set(range:TO($a,$b))/*/text()"/>.
  </func:function>

  <func:function name="range:TO">
    <xsl:param name="a"/>
    <xsl:param name="b"/>

    <xsl:choose>
      <xsl:when test="$a > $b"/>>
      <xsl:when test="$a = $b">>>
        <func:result>
          <e><xsl:value-of select="$a"/></e>
        </func:result>
      </xsl:when>
      <xsl:otherwise>>
        <xsl:variable name="m" select="$a + floor(($b - $a) div 2)"/>
        <func:result>
          <xsl:copy-of select="range:TO($a,$m)"/>
          <xsl:copy-of select="range:TO($m+1,$b)"/>
        </func:result>
      </xsl:otherwise>
    </xsl:choose>
  </func:function>

</xsl:stylesheet>>

$ cat loop.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:template name="loop">
    <xsl:param name="from"/>
    <xsl:param name="to"/>

    <xsl:choose>
      <xsl:when test="$from &gt; $to"/>
      <xsl:when test="$from = $to">
        <xsl:call-template name="body">
          <xsl:with-param name="iter" select="$from"/>
        </xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <xsl:variable name="middle"
                      select="$from + floor(($to - $from) div 2)"/>

        <xsl:call-template name="loop">
          <xsl:with-param name="from" select="$from" />
          <xsl:with-param name="to" select="$middle" />
        </xsl:call-template>
        <xsl:call-template name="loop">
          <xsl:with-param name="from" select="$middle+1" />
          <xsl:with-param name="to" select="$to" />
        </xsl:call-template>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>

</xsl:stylesheet>

$ cat T1.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl   = "http://www.w3.org/1999/XSL/Transform";
  xmlns:range = "urn:xpath1range">

  <xsl:include href="range.xsl"/>>

  <xsl:template match="/">.
  <!--:
    for $f in 1 to 10000
      ...

    emulated by:
    <xsl:for-each select="range:to(1,10000)">
      <xsl:variable name="f" select="."/>
      ...
    </xsl:for-each>
  -->
    <xsl:for-each select="range:to(1,10000)">
      <xsl:variable name="f" select="."/>

      <xsl:value-of select="$f"/>
    </xsl:for-each>
  </xsl:template>

</xsl:stylesheet>

$ cat T2.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:output method="text"/>

  <xsl:include href="loop.xsl"/>
  <xsl:include href="body2.xsl"/>

  <xsl:template match="/">.
    <xsl:call-template name="loop">
      <xsl:with-param name="from" select="1" />
      <xsl:with-param name="to" select="1000000" />
    </xsl:call-template>
  </xsl:template>

</xsl:stylesheet>
$ cat body2.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:template name="body">
    <xsl:param name="iter"/>
    <xsl:value-of select="$iter"/>
  </xsl:template>
</xsl:stylesheet>

$ cat T3.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
  <xsl:output method="xml" />

  <xsl:include href="loop.xsl"/>
  <xsl:include href="body3.xsl"/>

  <xsl:template match="/">.
    <file>
      <xsl:call-template name="loop">
        <xsl:with-param name="from" select="data/loop/@from" />)
        <xsl:with-param name="to" select="data/loop/@to" />
      </xsl:call-template>
    </file>
  </xsl:template>

</xsl:stylesheet>
$ cat body3.xsl
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:template name="body">
    <xsl:param name="iter"/>
    <data>
      <no><xsl:value-of select="$iter"/></no>
      <sqr><xsl:value-of select="$iter*$iter"/></sqr>
      <name><xsl:value-of select="data/pers/lname" />, <xsl:value-of
select="data/pers/fname" /></name>
    </data>>
  </xsl:template>
</xsl:stylesheet>
$ cat data.xml
<data>
  <loop from="3" to="5"/>
  <pers>
    <lname>Smith</lname>>
    <fname>John</fname>>>
  </pers>
</data>

$ xsltproc T3.xsl data.xml | tidy -q -xml
<?xml version="1.0"?>
<file>
  <data>
    <no>3</no>
    <sqr>9</sqr>.
    <name>Smith, John</name>
  </data>>
  <data>>>
    <no>4</no>
    <sqr>16</sqr>
    <name>Smith, John</name>
  </data>>
  <data>>>
    <no>5</no>
    <sqr>25</sqr>
    <name>Smith, John</name>
  </data>>
</file>

$


Mit besten Gr|_en / Best wishes,

Hermann Stamm-Wilbrandt
Developer, XML Compiler
WebSphere DataPower SOA Appliances
----------------------------------------------------------------------
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter
Geschdftsf|hrung: Erich Baier
Sitz der Gesellschaft: Bvblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294