Re: UTF-8-aware backwards string searching in Guile, or: fixing centered lyrics ignoring punctuation

[Aaron Hill]

On 2018-10-30 4:56 pm, Aaron Hill wrote:
> On 2018-10-30 10:01 am, Alexander Kobel wrote:
> > Does anyone have a hint how to approach this one? (Or is the answer
> > just: be patient and hope for Guile v2?)
>
> The only hint here is to replace the built-in functions with ones
> which understand UTF8 encoding and can perform the work needed.  There
> very well might be someone online who has already done this work,
> which would save on having to do it yourself.
>
> Otherwise, the basic strategy is to replace string->list with a
> version that decodes UTF8 and returns a list of integers (essentially
> UTF32).  Then, all of the string work is being done with these lists
> of integers instead.  (The character set would also just be a set of
> integers representing the unique Unicode code points.)  After you find
> the subsets of the list that are interesting to measure, you'll then
> need to convert the list back into a string.  This means encoding back
> into UTF8 and emitting a string.

Here's a quick-n-dirty patch to address the issue.

%%%%
\version "2.19.82"
\include "center-lyrics-ignoring-punctuation.ily"
{ d'4 4 4 }
\addlyrics { Å Ɓ† «Ḉ…» }
%%%%

-- Aaron Hill

center-lyrics-ignoring-punctuation.ily
Description: Text document

utf8.cropped.png
Description: PNG image