How to express a select attr in for-each for condition

Hi, listers,

I use contains function to get the selected item defined
by select attr of param element. such as;

<xsl:for-each select="$source[contains($keywrd,.)]">

Of course using this expression for empty param, nothing will be
displayed.

I wonder how to modify the above select att to be able to display

 1. selected items when keywrd is not empty.
 2. all items when keywrd is empty.  

Thanks for any help in advance.

Sun-fu Yang

sfyang@xxxxxxxxxxxxx

***  simplified xml file  **
<?xml-stylesheet href="test.xsl" type="text/xsl"?>
<docs>
<item>a</item>
<item>b</item>
<item>c</item>
</docs>


***   xsl   file  **
<?xml version='1.0'?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xsl:key name="sourcekey" match="item" use="."/>
<xsl:variable name="source"
select="/docs/item[generate-id(.)=generate-id(key('sourcekey',.)[1])]"/>
<xsl:param name="keywrd" select="'a,b'"/>
<xsl:template match="/">

<xsl:for-each select="$source[contains($keywrd,.)]">
<xsl:value-of select="."/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>



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