XSLT: Generating a format mask string based on the content of a node?

[Dag Sunde]

I want to use the format-number function to output
a number with a specific number of decimals, based on the content
of a node... Is there any smart way to generate differnet strings
based on a node-value?

if decimals = 0, I want "###,###"
decimals = 1, I want "###,###.0"
decimals = 2, I want "###,###.00"
decimals = n, I want "###,###.000..n"

Today I'm using <xsl:choose>, but that is limited to
hand-coding the alternatives.

I have the following xml:
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="Transform.xslt"?>
<root>
<valuedef>
<value>7</value>
<decimals>2</decimals>
</valuedef>
<valuedef>
<value>42</value>
<decimals>3</decimals>
</valuedef>
</root>

And I transform it like this:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xslutput method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:template match="/">
<xsl:apply-templates select="/root/valuedef" />
</xsl:template>

<xsl:template match="valuedef">
<value>
<xsl:variable name="tall" select="value"/>
<xsl:variable name="maske">
<xsl:choose>
<xsl:when test="decimals[.='0']"> ###,### </xsl:when>
<xsl:when test="decimals[.='1']"> ###,###.0</xsl:when>
<xsl:when test="decimals[.='2']"> ###,###.00</xsl:when>
<xsl:when test="decimals[.='3']"> ###,###.000</xsl:when>
<xsltherwise> ###,### </xsltherwise>
</xsl:choose>
</xsl:variable>
<xsl:value-of select='format-number($tall, $maske)' />
</value>
</xsl:template>
</xsl:stylesheet>

TIA...

 

[Joe Kesselman]

Your question is really that you want a better solution for

<xsl:choose>
<xsl:when test="decimals[.='0']"> ###,### </xsl:when>
<xsl:when test="decimals[.='1']"> ###,###.0</xsl:when>
<xsl:when test="decimals[.='2']"> ###,###.00</xsl:when>
<xsl:when test="decimals[.='3']"> ###,###.000</xsl:when>
</xsl:choose>

The traditional quick-and-dirty answer involves using the value to
control the length of a substring extraction from ".000000000000000",
and appending that to ###,###. (A bit more work is needed to suppress
the decimal point when the value is 0, but you get the idea.) The upper
limit is however many zeros you provide in the literal string, but
realistically your floating-point system also has accuracy limits so
asking for too high a precision's not useful anyway.

The completely general answer is a recursive named-template with
parameter (in lieu of counter loop), which appends a zero each time the
count is advanced.

 

[p.lepin]

I want to use the format-number function to output
a number with a specific number of decimals, based on the
content of a node... Is there any smart way to generate
differnet strings based on a node-value?

<xsl:choose>
<xsl:when test="decimals[.='0']"> ###,### </xsl:when>
<xsl:when test="decimals[.='1']"> ###,###.0</xsl:when>
<xsl:when test="decimals[.='2']"> ###,###.00</xsl:when>
<xsl:when test="decimals[.='3']"> ###,###.000</xsl:when>
<xsltherwise> ###,### </xsltherwise>
</xsl:choose>

Divide and conquer.

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="valuedef">
<xsl:variable name="fmt">
<xsl:apply-templates select="decimals"/>
</xsl:variable>
<xsl:value-of select="format-number(value,$fmt)"/>
</xsl:template>
<xsl:template match="decimals">
<xsl:text>###,###.</xsl:text>
<xsl:call-template name="dec"/>
</xsl:template>
<xsl:template name="dec">
<xslaram name="n" select="."/>
<xsl:choose>
<xsl:when test="$n &lt; 2">
<xsl:text>0</xsl:text>
</xsl:when>
<xsltherwise>
<xsl:variable name="f" select="floor($n div 2)"/>
<xsl:call-template name="dec">
<xsl:with-param name="n" select="$f"/>
</xsl:call-template>
<xsl:call-template name="dec">
<xsl:with-param name="n" select="$n - $f"/>
</xsl:call-template>
</xsltherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>

 

[Dag Sunde]

I want to use the format-number function to output
a number with a specific number of decimals, based on the content
of a node... Is there any smart way to generate differnet strings
based on a node-value?

if decimals = 0, I want "###,###"
decimals = 1, I want "###,###.0"
decimals = 2, I want "###,###.00"
decimals = n, I want "###,###.000..n"

<snipped/>

Thank you both, Joe and Pavel!

Now I can get a little more flexibility...

 

[Dimitre Novatchev]

For the unconstrained solution in XSLT 2.0 one would simply use:

<xsl:value-of separator="" select=
"'###,###', if(decimals gt 0) then '.' else (), f:repeat('0',
decimals)"/>

where f:repeat is defined very simply in FXSL 2.0 as:

<xsl:function name="f:repeat" as="item()+">
<xslaram name="pThis" as="item()"/>
<xslaram name="pTimes" as="xs:integer"/>

<xsl:for-each select="1 to $pTimes">
<xsl:sequence select="$pThis"/>
</xsl:for-each>
</xsl:function>


For an efficient solution of the string-allocation problem in XSLT 1.0 see
something I published many years ago, which since then was used in the
implementation of the EXSLT stradding() function:

http://sources.redhat.com/ml/xsl-list/2001-07/msg01040.html

Hope this helped.


Cheers,
Dimitre Novatchev

 

[Dag Sunde]

For the unconstrained solution in XSLT 2.0 one would simply use:

<xsl:value-of separator="" select=
"'###,###', if(decimals gt 0) then '.' else (), f:repeat('0',
decimals)"/>

where f:repeat is defined very simply in FXSL 2.0 as:

<xsl:function name="f:repeat" as="item()+">
<xslaram name="pThis" as="item()"/>
<xslaram name="pTimes" as="xs:integer"/>

<xsl:for-each select="1 to $pTimes">
<xsl:sequence select="$pThis"/>
</xsl:for-each>
</xsl:function>


For an efficient solution of the string-allocation problem in XSLT
1.0 see something I published many years ago, which since then was
used in the implementation of the EXSLT stradding() function:

http://sources.redhat.com/ml/xsl-list/2001-07/msg01040.html

Hope this helped.

Now *That* was elegant!

Thanks...

 

[Dag Sunde]

Now *That* was elegant!

....Only to discover that there is now version of msxml that supports
XSLT 2.0...

Oh, well...

 

[Dimitre Novatchev]

Now *That* was elegant!

...Only to discover that there is now version of msxml that supports
XSLT 2.0...

Oh, well...

If one does have to work in an Microsoft XML/XSLT environment and wants to
use XSLT 2.0, then a good choice is Saxon.NET.


Cheers,
Dimitre Novatchev.