[Rd] R2HTML doesn't split paragraphs originating from \Sexpr[results=rd]

[Sebastian Meyer]

I can confirm this is a bug, more specifically, a regression in R >= 
3.6.0. I think a report in R's Bugzilla would be useful.

A possible workaround seems to be to start the Rd-generating \Sexpr in 
column 1 of the Rd file, so to remove the indentation before \Sexpr.

AFAICS, fixing this will require tools:::processRdChunk() to keep two 
types of source references for dynamically generated Rd code: the 
effective "srcref" from parsing the Rd fragment, and the one that refers 
to the source Sexpr block (possibly called "wholeSrcref"), to be used by 
checkRd() in preference to "srcref" when reporting the location of Rd 
problems.

	Sebastian Meyer


Am 05.02.23 um 14:04 schrieb Ivan Krylov:
> Hello,
> 
> Here's an example that renders correctly using Rd2txt / Rd2latex / R
> CMD Rd2pdf, but has problems under Rd2HTML:
> 
> \name{foo}
> \title{foo}
> \section{foo}{
>    This should be on a separate paragraph
> 
>    This should be on a separate paragraph
> 
>    This should be on a separate paragraph
> 
>    \Sexpr[stage=render,results=rd]{
>      paste(
>        rep('Sexpr: This should be on a separate paragraph', 3),
>        collapse = '\n\n'
>      )
>    }
> }
> 
> For the text I've typed manually, there are <p>...</p> tags splitting
> the text separated by empty lines into paragraphs. The \Sexpr return
> value only has newlines, which joints the paragraphs together:
> 
> <p>This should be on a separate paragraph
> </p>
> <p>This should be on a separate paragraph
> </p>
> <p>This should be on a separate paragraph
> </p>
> <p>Sexpr: This should be on a separate paragraph
> 
> Sexpr: This should be on a separate paragraph
> 
> Sexpr: This should be on a separate paragraph
> </p>
> 
> addParaBreaks() is prevented from closing the paragraph tag because
> tools:::isBlankLineRd() returns FALSE for blank lines produced by a
> \Sexpr. This happens because utils:::getSrcByte() not 1 for these blank
> lines. That, in turn, is because the source reference for \Sexpr values
> is the whole \Sexpr tag:
> 
> # blank line from a \Sexpr
> Rd[[3]][[2]][[9]][[2]]
> # [1] "\n"
> # attr(,"Rd_tag")
> # [1] "TEXT"
> getSrcref(Rd[[3]][[2]][[9]][[2]])
> # \Sexpr[stage=render,results=rd]{
> #   paste(
> #     rep('Sexpr: This should be on a separate paragraph', 3),
> #     collapse = '\n\n'
> #   )
> # }
> 
> # artisanal hand-crafted blank line
> Rd[[3]][[2]][[7]]
> # [1] "\n"
> # attr(,"Rd_tag")
> # [1] "TEXT"
> summary(getSrcref(Rd[[3]][[2]][[7]]))
> # <srcref: file "~/foo.Rd" chars 9:1 to 9:1>
> 
> I think I understand that tools:::isBlankLineRd requires
> utils:::getSrcByte(x) == 1L because it may be called on things like
> "\\eqn{0}\n" where the terminal "\n" might otherwise be considered a
> "blank line". How to reconcile isBlankLineRd with blank lines not
> directly originating from Rd source?
> 
> Rd2latex might have a similar problem (its addParaBreaks() checks for
> isBlankLineRd()), but then it works anyway because Rd rules for
> paragraph breaks on blank lines are the same as in LaTeX.
>