Cleaning up namespace declarations

Ever been bothered by redundant namespace declarations? Some tools generate tons and tons of these, and they really clutter up your XML, making it hard to read and maintain, as well as increasing file size for no reason.

Here's a handy XSLT to move all declarations to the top element of your document, removing duplicates. (It even moves seemingly unused declarations. This is intended behavior, as the declarations may still be referenced in the text, e.g. in the XPath expressions of a BPEL file.)


<!-- Copyright J.W. v/d Broek 2010. Do with this code as you will. -->
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" exclude-result-prefixes="#all">

<xsl:template match="/*">
<xsl:copy copy-namespaces="no">
<xsl:for-each-group select="for $x in //* return for $y in in-scope-prefixes($x)[.!='' and .!='xml'] return concat($y, ':',namespace-uri-for-prefix($y, $x))" group-by=".">
<xsl:namespace name="{substring-before(., ':')}" select="substring-after(., ':')"/>
</xsl:for-each-group>
<xsl:apply-templates select="node()|@*"/>
</xsl:copy>
</xsl:template>

<xsl:template match="node()|@*">
<xsl:copy copy-namespaces="no">
<xsl:apply-templates select="node()|@*"/>
</xsl:copy>
</xsl:template>

</xsl:stylesheet>