XSLT concat() problem.

Question

Help guys, this XSLT is getting me down!
Im quite simply trying to take a string, and replace tabs with 4 non-breaking space characters.
Can someone please explain to me why the following template doesnt work? It should take in a string, perform the replacement in a recursive fashion, and finally print it out.
Any help is greatly appreciated.
Cheers,
Lee.
     <xsl:template name="substitute">
          <xsl:param name="string" />
          <xsl:param name="from" select="'&#9;'" />
          <xsl:param name="to">
               &#160;&#160;&#160;&#160;
          </xsl:param>
          <xsl:choose>
               <xsl:when test="contains($string, $from)">                    
                    <xsl:call-template name="substitute">                         
                         <xsl:with-param name="string" select="concat(substring-before($string, $from), $to, substring-after($string, $from))" />
                         <xsl:with-param name="from" select="$from" />
                         <xsl:with-param name="to" select="$to" />
                    </xsl:call-template>
               </xsl:when>
          <xsl:otherwise>
               NO MORE SUBSTITUTION REQUIRED - FINAL STRING IS : <xsl:value-of select="$string"/>
          </xsl:otherwise>
          </xsl:choose>
     </xsl:template>

Answer 1

Help guys, this XSLT is getting me down!
Im quite simply trying to take a string, and replace
tabs with 4 non-breaking space characters.
Can someone please explain to me why the following
template doesnt work? It should take in a string,
perform the replacement in a recursive fashion, and
finally print it out.
Any help is greatly appreciated.
Cheers,
Lee.
     <xsl:template name="substitute">
          <xsl:param name="string" />
          <xsl:param name="from" select="'     '" />
          <xsl:param name="to">
               ����
          </xsl:param>
          <xsl:choose>
               <xsl:when test="contains($string, $from)">                    
                    <xsl:call-template name="substitute">                         
<xsl:with-param name="string"
ing" select="concat(substring-before($string, $from),
$to, substring-after($string, $from))" />
                         <xsl:with-param name="from" select="$from" />
                         <xsl:with-param name="to" select="$to" />
                    </xsl:call-template>
               </xsl:when>
          <xsl:otherwise>
NO MORE SUBSTITUTION REQUIRED - FINAL STRING IS :
: <xsl:value-of select="$string"/>
          </xsl:otherwise>
          </xsl:choose>
     </xsl:template>
It is not concat() problem, it is a recursion problem -- too many recursive calls.
I wouldn't recommand using recursion in XSL, yeah, it works, but you can't increase the stack size without restarting the JVM...
anyway, you can use translate function to do replacing, also you can call a java extension method to do string replacement. it is cleaner anyway and more efficient anyway.