Re: convert-ly for note/rest-markup

[Michael Käppler]

Am 03.02.2021 um 09:05 schrieb Michael Käppler:
> Hi Harm,
>
> Am 02.02.2021 um 22:52 schrieb Thomas Morley:
> > Hi,
> >
> > with e35b7959dfe the note-markup-command was changed to need a
> > duration-argument, before it was a string.
> > With, MR 627 "Revisit rest-markup-commands"
> > https://gitlab.com/lilypond/lilypond/-/merge_requests/627
> > I attempt to do similar for the rest-markup-command.
> >
> > This change would need a convert-rule, imho.
> > Alas, this is beyond my capabilities.
> >
> > Any volunteer?
> >
> > Btw, e35b7959dfe contains a convert-rule for the note-markup, though
> > it does not seem to work.
> I had a quick look on this, the problem is not in e35b7959dfe,
> the regex 'matchfullmarkup' (see convertrules.py:3471) which is used in
> said commit assumes that \markup is followed by at least one set of
> braces.
>
> You can verify this by converting
>
> %%%%%%%%%%%%%%
> \version "2.18.2"
> \markup { \note #"4." #UP }
>
> %%%%%%%%%%%%%%
>
> which works as expected.
Unfortunately, I was wrong. The problem is a more fundamental one.
'matchfullmarkup' tries to match the full markup, but nothing more than
that.
In other words, it has to make assumptions where the \markup environment
ends.
In a case like

\markup { ... } this is simple, because it can simply "wait" for the
closing brace.

However, when \markup is followed by a single markup command or a
sequence of markup commands, like

\markup \center-align \fontsize #2 "foo"

this does not work. Instead it assumes that the \markup environment ends
with a string or another set of balanced braces.
For markup commands that do not take a markup as last argument, this
will not work.
The problem is not limited to \note, it would affect commands like
\beam, \draw-circle etc. as well, if syntax conversions
would have to be added to 'convert-ly'.

AFAICT the parser solves this problem by checking the call signature of
the markup command to
know how many arguments should be there. (and of which type)
Since \markup commands are user-definable, I don't have any idea how to
solve this in a general way
within convert-ly.

Cc'ing David, maybe you have some inspiration for us?

Michael


> Cheers,
> Michael
>
> > Using convert-ly from recent master, running over a file containing:
> >
> > %%%%%%%%%%%%%%
> > \version "2.18.2"
> > \markup \note #"4." #UP
> >
> > %%%%%%%%%%%%%%
> >
> > returns:
> >
> > convert-ly atest-107.ly
> > convert-ly (GNU LilyPond) 2.23.1
> >
> > convert-ly: Processing `atest-107.ly'...
> > Applying conversion: 2.19.2, 2.19.7, 2.19.11, 2.19.16, 2.19.22,
> > 2.19.24, 2.19.28, 2.19.29, 2.19.32, 2.19.39, 2.19.40, 2.19.46,
> > 2.19.49, 2.20.0, 2.21.0, 2.21.2
> >
> >
> > \version "2.21.2"
> > \markup \note #"4." #UP
> >
> >
> > cc-ing David
> >
> >
> > Thanks,
> >    Harm