• From: "Costello, Roger L." <costello@m...>
• To: "xml-dev@l..." <xml-dev@l...>
• Date: Wed, 16 Oct 2013 20:01:33 +0000

Hi Folks,

[Definition] 
	A quine is a computer program which takes no input 
	and produces a copy of its own source code as its only 
	output. The standard terms for these programs in the 
	computability theory and computer science literature 
	are self-replicating programs, self-reproducing programs, 
	and self-copying programs. [1]

Below is an XSLT program that is quine.

I wonder if it is possible to implement a quine in vanilla XML, perhaps using some clever tricks with entities and/or XInclude? That is, after parsing, the XML document contains a copy of itself, embedded in itself.

/Roger

-----------------------------------------------------------------
            quine.xsl
-----------------------------------------------------------------
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                          version="2.0">
    
    <xsl:output method="xml" />
    
    <xsl:template match="/">
        <xsl:sequence select="document('')" />
    </xsl:template>
    
</xsl:stylesheet>

[1] http://en.wikipedia.org/wiki/Quine_%28computing%29

• Follow-Ups:
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    • From: Michael Kay <mike@s...>
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