Answer: XSLT Question: Inserting a DOCTYPE decl

[Roger L. Costello]

Hi Folks,

The solution to the problem that I posed of writing a stylesheet which
inserts a DOCTYPE declaration into the input XML document, where the DTD
file is found as the text value of an element in the input XML file, is
listed below.  Thanks to all those who made suggestions, particularly
Michael Kay who created the below solution.

                     DoctypeInserter.xsl
------------------------------------------------------------------
<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">
 
    <xsl:variable name="doctype">
        <xsl:value-of select="//DoctypeFile"/>
    </xsl:variable>

    <xsl:variable name="rootnode">
        <xsl:value-of select="name(*)"/>
    </xsl:variable>

    <xsl:template match="/">
        <xsl:variable name="quote">"</xsl:variable>  
        <xsl:value-of disable-output-escaping="yes" 
             select="concat('&lt;!DOCTYPE ', $rootnode, ' SYSTEM ', 
                            $quote, $doctype, $quote, '&gt;')"/>
        <xsl:apply-templates/>
    </xsl:template>

    <xsl:template match="*|@*|comment()|
                         processing-instruction()|text()">
        <xsl:copy>
            <xsl:apply-templates select="*|@*|comment()| 
                                    processing-instruction()|text()"/>
        </xsl:copy>
    </xsl:template>

</xsl:stylesheet>
------------------------------------------------------------------

As you can see, the trick was not to use xsl:output at all. Instead, the
DOCTYPE delcaration must be built "by hand".  After the DTD file is
found (and stored in doctype) the root node is found (and stored in
rootnode).  In the template rule for the document, before any of the XML
elements are copied, the DOCTYPE declaration is constructed by
concatenating together the various components.

With this XML document as input:

<?xml version="1.0"?>
<Numbers>
        <DoctypeFile>Number.dtd</DoctypeFile>
        <Number>27</Number>
        <Number>34</Number>
        <Number>18</Number>
        <Number>67</Number>
        <Number>99</Number>
        <Number>16</Number>
</Numbers>

The result of running it through the above stylesheet is:

<?xml version="1.0"?>
<!DOCTYPE Numbers SYSTEM "Number.dtd">
<Numbers>
        <DoctypeFile>Number.dtd</DoctypeFile>
        <Number>27</Number>
        <Number>34</Number>
        <Number>18</Number>
        <Number>67</Number>
        <Number>99</Number>
        <Number>16</Number>
</Numbers>

Which is, of course, exactly what I wanted!  

Thanks again.  /Roger


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