[XSL-LIST Mailing List Archive Home] [By Thread] [By Date]

[xsl] Recursion


Subject: [xsl] Recursion
From: Vasu Chakkera <vasucv@xxxxxxxxx>
Date: Mon, 28 May 2012 11:58:09 +0100

Guys,

I had this issue, which I solved, but thought someone here could
probably recreate with some better ideas?? I did not refractor this..
so , I am sure the code can be refractored or rearranged/ beautified
.. But I am wanting to see if there is a completely different
approach...


The problem is as folllows..

XSLT is written for an XSD. This XSD may include another XSD and that
may include more XSDs and so on and so forth,. This can end up
becoming a huge tree.
Some where, one of the XSDs can actually refer to another XSD which
could have been already in the tree. So a normall thought process is
that your XSLT will fail because it will end up into the infinite
recursion ( circular reference).. So I wrote this XSLT to process such
a tree...  I have simulated this one with XMLS with nodes that are
called <includes> //

Main XML :
=======
<xml1>
    <includes>file1.xml</includes>
    <includes>file2.xml</includes>
</xml1>

file1.xml
=======
<xml1>
    <includes>file1.1.xml</includes>
    <includes>file1.2.xml</includes>
</xml1>

file2.xml
=======
<xml1>
    <includes>file2.1.xml</includes>
    <includes>file2.2.xml</includes>
</xml1>
file1.1.xml
=======
<xml1>
    <includes>file1.1.1xml</includes>
    <includes>file1.xml
 <!-- this one is bad circular reference -->
</includes>
</xml1>

 and so on...

The XSLT is
========

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:template match="xml1">
        <xsl:call-template name="get-include">
            <xsl:with-param name="init" select="0"/>
        </xsl:call-template>
    </xsl:template>
    <xsl:template name="get-include">
        <xsl:param name="document-name"/>
        <xsl:param name="init"/>
        <xsl:param name="include-tree"/>
        <xsl:choose>
            <xsl:when test="$init = 1">
                <xsl:for-each select="document($document-name)//includes">
                    <xsl:variable name="doc-name" select="."/>
                    <xsl:value-of select="."/>
                    <xsl:choose>
                        <xsl:when test="contains($include-tree,$doc-name)">
                            <xsl:text>: This file is ignored :
Circular Reference </xsl:text>
                            <xsl:text>&#xa;</xsl:text>
                        </xsl:when>
                        <xsl:otherwise>
                            <xsl:text>,</xsl:text>
                            <xsl:call-template name="get-include">
                                <xsl:with-param name="document-name"
select="$doc-name"/>
                                <xsl:with-param name="init" select="1"/>
                                <xsl:with-param name="include-tree"

select="concat($include-tree,'/',$doc-name,'/')"/>
                            </xsl:call-template>
                        </xsl:otherwise>
                    </xsl:choose>
                    <xsl:text>&#xa;</xsl:text>
                </xsl:for-each>
            </xsl:when>
            <xsl:otherwise>
                <xsl:for-each select="//includes">
                    <xsl:text> &#xa; </xsl:text>
                    <xsl:variable name="doc-name" select="."/>
                    <xsl:value-of select="."/>
                    <xsl:call-template name="get-include">
                        <xsl:with-param name="document-name" select="."/>
                        <xsl:with-param name="init" select="1"/>
                        <xsl:with-param name="include-tree"
                            select="concat($include-tree,'/',$doc-name)"/>
                    </xsl:call-template>
                </xsl:for-each>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

</xsl:stylesheet>

Any Ideas??

Vasu Chakkera


Current Thread
Keywords