DocBook change: use a stack of fonts

[Richard Kimberly Heck]

On 12/26/22 21:46, Thibaut Cuvelier wrote:
> On Tue, 27 Dec 2022 at 03:20, Richard Kimberly Heck 
> <rikiheck at gmail.com> wrote:
>
>     On 12/26/22 20:13, Thibaut Cuvelier wrote:
>     > Dear list,
>     >
>     > To solve https://www.lyx.org/trac/ticket/12585, I wrote the
>     attached
>     > patch. Basically, LyX now considers the order of font tags when
>     > closing them, otherwise you get strange results like in the ticket.
>     > The bug is quite serious, actually, even though I don't believe
>     many
>     > users will hit it.
>
>     I struggled with that when writing the original XHTML code. It's
>     hard to
>     get right. I know it sometimes would fail. Is this same code also
>     used
>     with XHTML now? Or would it need to be adapted for that case?
>
>
> I've tested this case and it looks like the XHTML code did the right 
> thing there. It's a part I rewrote for DocBook, introducing a few 
> bugs.Here is the output from XHTML for the same file:
>
> <div class='standard' id='magicparlabel-1'>norm <em>emph 
> <b>emph-bold</b></em><b> bold</b> norm</div>
>
> I don't understand why it is producing the right output while DocBook 
> did not. Maybe the pending tags or the special code for font tags from 
> XMLStream kick in. If that's the case, it's a bit strange that 
> XMLStream deals with this kind of issue (it feels like XMLStream is 
> doing work at multiple levels of abstraction).
>
I wish I'd commented this code a bit more. I thought I did that pretty well.

Anyway, after digging into it, the magic happens in 
XMLStream::operator<<(EndTag), though the font part specifically is 
handled in Paragraph::simpleLyXHTMLOnePar.


>     > +    DocBookFontOperation endTransaction() {
>     > +        return {.fontsToClose = fontsToClose_, .fontsToOpen =
>     > fontsToOpen_};
>     > +    }
>     > +
>     What is ".fontsToClose"? What's the dot doing? Is the "=" right? This
>     code just confuses me.
>
>
> It looks like the name of this C99 feature is "designated 
> initializers": when building a struct instance, you can give the name 
> of the fields you are filling. This is especially useful here to 
> ensure that you are not mixing the open and close sets (they have the 
> same type).

That's a nice feature, but my limited searching only turns up C++20 for 
this feature. E.g.:

https://pdimov.github.io/blog/2020/09/07/named-parameters-in-c20/

Riki

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