Re: [xsl] Can't have both " and ' in an XPath literal

Subject: Re: [xsl] Can't have both " and ' in an XPath literal
From: rolf@xxxxxxxxxxxx
Date: Sun, 23 Apr 2006 04:45:49 +0200 (CEST)
Thanks for answering Ken, but ...

On 22 Apr, G. Ken Holman wrote:
> At 2006-04-23 02:27 +0200, rolf@xxxxxxxxxxxx wrote:
>>As far as I see, there is no way to have both ' (') and " (")
>>in one XPath literal.
> Correct ... but literal operands can be constructed easily enough.
> (copied and modified below)
> [...] 
> How about the following?
> [...]
> T:\ftemp>type rolf.xml
> <doc>
>    <e att="foo">foo</e>
>    <e att="a&apos;&quot;b">bar</e>
>    <e att="grill">grill</e>
> </doc>
> T:\ftemp>type rolf.xsl
> <?xml version="1.0"?>
> <xsl:stylesheet version="1.0" xmlns:xsl="";>
>    <xsl:template match="doc">
>      <xsl:for-each select="e[@att=concat(&quot;a'&quot;,'&quot;b')]">
>        <xsl:value-of select="."/>
>      </xsl:for-each>
>    </xsl:template>
> </xsl:stylesheet>

Nice workaround for the my example. But as I wrote, that example is not
the real problem. I provided it only to illustrate the underlying
problem, I see with the XPath syntax.

The question (or problem) is not (only) an XSLT one, but more an XPath

Imagine a script language (in fact, that's the real scenario), which
got a DOM tree and is able to execute XPath expressions on that
tree. Now, the programmer want to select the elements with an
attribute x with an attribute value given by outside (say: user
input). If you want to programmatically create the needed XPath expr
(simplified something like: e[@x='<that random value comming from
elsewhere, you've no control over>']) then the question arises how to
escape the XPath literal delimiter character in that string.

There is no way to escape the XPath literal delimiter character
within a literal with the XPath syntax rules, as you confirm. OK, in
the scribbled case, the programmer could write a complex parsing rule,
to rewrite the wanted expression along the line you showed, but that
is, to word tempered, tedious.


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