Re: [xsl] problem with transforming mixed content

Subject: Re: [xsl] problem with transforming mixed content
From: "Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 15 Aug 2020 09:16:13 -0000
This problem comes up from time to time, and it's not easy.

There seem to be three general approaches:

(a) turn the punctuation into markup (e.g. turn ":" into <colon/>), then do
the manipulation on a tree of nodes

(b) turn the markup into punctuation, then do the manipulation on the
resulting text.

(c) do it all in one pass

I see that Graydon's solution uses serialize() and parse-xml(), so that's a
modern approach to doing (b); while Dimitre's solution does (c). In general I
think the one-pass solution is often more complicated and runs the risk of not
being extensible when the problem "evolves".

One of the things that can cause the problem to "evolve" is error handling:
dealing with situations where the input isn't quite as simple as in your
example. For example, multiple colons, no colons, colons that are there for a
different purpose, etc,. You haven't included any such cases in your
requirements statement.

If we ignore error handling, this example of the problem is simpler than some
because the ":" is always going to be in an immediate child text node; we've
seen other examples (like splitting a table) where we need to look for
conditions much deeper in the structure. This is probably what makes a
one-pass solution feasible in this case.

Intuitively, my feeling is that (a) is the most rigorous approach, the one
that is least likely to fail because of unanticipated input conditions. For
example, Graydon's solution fails if the input contains tags with upper-case
names, or if it contains comments with a colon in the text.

Michael Kay
Saxonica

> On 15 Aug 2020, at 03:16, Wolfhart Totschnig wolfhart.totschnig@xxxxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Dear list,
>
> I would like to ask for your help with the following mixed-content problem.
I am receiving, from an external source, data in the following form:
>
> <title>THE TITLE OF THE BOOK WITH SOME <i>ITALICS</i> AND SOME MORE WORDS:
THE SUBTITLE OF THE BOOK WITH SOME <i>ITALICS</i></title>
>
> What I would like to do is
> 1) separate the title from the subtitle (i.e., divide the data at the colon)
and put each in a separate element node;
> 2) all the while maintaining the <i> markup;
> 3) and perform certain string manipulations on all of the text nodes; for
the purposes of this post, I will use the example of converting upper-case to
lower-case.
>
> So the desired output is the following:
>
> <title>the title of the book with some <i>italics</i> and some more
words</title>
> <subtitle>the subtitle of the book with some <i>italics</i></subtitle>
>
> How can this be done?
>
> I know that I can perform string manipulations while maintaining the <i>
markup with templates, i.e., <xsl:template match="text()"/> and <xsl:template
match="i"/>. But in this case I do not know how to divide the data at the
colon. And I know that I can divide the data at the colon with <xsl:value-of
select="substring-before(.,': ')"/>, but then I loose the <i> markup. So I am
at a loss.
>
> Thanks in advance for your help!
> Wolfhart

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