Test whether a node contains escaped XML using XSL?

Question

I'm attempting to clean-up a batch of XML I've been provided. There are three situations I need to account for:

some elements have plain text within them, eg. <item>some text</item>, which need to be wrapped in another tag, eg. <item>some text</item>
some elements have escaped XML within them, eg. <item>some text</item>, which needs to be output without escaping: <item>some text</item>
some elements have escaped XML which needs to be wrapped, eg. <item>some text</item> needs to become <item>some text</item>

<item> is used as a container in both instances.

I can satisfy condition one relatively easily, and I can satisfy condition 2 with disable-output-escaping, but I can't satisfy condition 3 with this approach.

I think I can satisfy 2 (& possibly 3) if I can test whether the text within <item> is escaped, but a test using contains(., '&lt;') doesn't match. So...

How can I test whether text within a node is escaped XML?

Which XSLT 1.0 processor exactly do you use? Have you checked whether an extension function is available or can be easily implemented that parses the content of the `item` elements into a tree fragment which could then be processed with normal templates as needed? — Martin Honnen, Jul 09 '13 at 17:56
@MaxToro No, since that's essentially searching for `<` escaped for use within the test attribute of XSL. — Phillip B Oldham, Jul 10 '13 at 07:12
@MartinHonnen updated the tags with relevant information, but essentially I'm using `libxml2` and `libxslt`. — Phillip B Oldham, Jul 10 '13 at 07:58

score 0 · Answer 1 · answered Jul 10 '13 at 12:18

and 3. both need wrapping and disable-output-escaping in 1. won't hurt so I think you can treat them together with the same template.

I don't see a clear check whether an element content contains an escaped element markup with pure XSLT 1.0 means, so I simply tried

<xsl:stylesheet
  version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/root">
  <html>
    <body>
      <xsl:apply-templates/>
    </body>
  </html>
</xsl:template>

<xsl:template match="@* | node()">
  <xsl:copy>
    <xsl:apply-templates select="@* | node()"/>
  </xsl:copy>
</xsl:template>

<xsl:template match="item[not(*) and not(starts-with(., '&lt;') and substring(., string-length(.)) = '&gt;')]">
  <xsl:copy>
    <p>
      <xsl:value-of select="." disable-output-escaping="yes"/>
    </p>
  </xsl:copy>
</xsl:template>

<xsl:template match="item[not(*)
                          and starts-with(., '&lt;') and substring(., string-length(.)) = '&gt;']">
  <xsl:copy>
    <xsl:value-of select="." disable-output-escaping="yes"/>
  </xsl:copy>
</xsl:template>

</xsl:stylesheet>

which transforms

<root>
<item>some text</item>
<item>&lt;p>some text&lt;/p></item>
<item>some &lt;em>text&lt;/em></item>
</root>

into

<html><body>
<item><p>some text</p></item>
<item><p>some text</p></item>
<item><p>some <em>text</em></p></item>
</body></html>

Obviously it would transform <item><...></item> as well into <item><...></item>. You could try to implement some more string checks but without a complete parser for the escaped XML fragment it is always possible to construct input samples where the string checks fail.

Thanks Martin. I've come to the same conclusion that I'll need to parse the escaped content to ensure it is well-formed, so I'm going to add a callback to the language I'm using (Python+lxml) to handle this. — Phillip B Oldham, Jul 10 '13 at 12:26

Test whether a node contains escaped XML using XSL?

1 Answers1