[xsl] select="substring-before($str,"'")" !!!

[phil_endecott at spamcop dot net]

Dear XSL experts,

This question is about quoting and escaping string literals.

I have an XSLT stylesheet that transforms an XML document to HTML.
The HTML contains some javascript.  The XML document contains people's
names that come out in writeln() statements in the javascript.  For
example:

  <name>Fred Bloggs</name>

gets transformed to

  document.writeln('Fred Bloggs');

with the crucial bit of XSLT being something like

  document.writeln('<xsl:value-of select="name"/>');

This all worked fine until someone came along called Sandra O'Boyle.
My naive implementation translates this to

  document.writeln('Sandra O'Boyle');

which isn't valid javascript, because of the mismatched quotes.  What
it needs to say is

  document.writeln('Sandra O\'Boyle');

I noticed that XSLT (or more correctly XPath) has a translate function
but this doesn't seem to do quite what I want.  translate() will only
replace one character with one character.  So I have to do it the hard
way:

  <xsl:template name="escape-string-for-javascript">
    <xsl:param name="str"/>
    <xsl:choose>
      <xsl:when test="contains($str,"'")">
        <xsl:variable name="before-first-apostrophe"><xsl:value-of select="substring-before($str,"'")"/></xsl:variable>
        <xsl:variable name="after-first-apostrophe"><xsl:value-of select="substring-after($str,"'")"/></xsl:variable>
        <xsl:value-of select="$before-first-apostrophe"/>\'<xsl:call-template name="escape-string-for-javascript"><xsl:with-param name="str"><xsl:value-of select="$after-first-apostrophe"></xsl:with-param></xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <xsl:value-of select="$str">
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>

and call it like this:

  document.writeln('<xsl:call-template name="escape-string-for-javascript"><xsl:with-param name="str"><xsl:value-of select="name"/></xsl:with-param></xsl:call-template>');

OK, all fine except for one problem.  In a couple of places I have the
string "'".  XPath allows two forms for string literals: "...." and
'....'.  If I delimit the string with ""s I'm allowed 's inside.  If I
delimit it with "s I'm allowed "s inside.  So I'm using ""s to
enclose the ' that I want to match.  But ""s are also used to delimit
the value for the select attribute that encloses all of this.

This has reached the limit of my understanding of XSL.  Is there some
magic I can do with &quot;?  Some alternative XML syntax to allow
quotes inside attribute values?

Any help much appreciated.

Regards,

--Phil.



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