incompability with booktabs

[u-fischer]

(extracted from https://github.com/latex3/tagging-project/issues/38#issuecomment-2000322368)

In some cases booktabs inserts a \multispan into the table (through the commands \@cmidruleb and \@cmidrulea and this then errors with the tagging code. This affects both tabular and longtable (but longtable more as booktabs handles lines in longtable differently)

\DocumentMetadata{testphase={phase-I,tabular}}
\documentclass{article}
\usepackage{booktabs}
\usepackage{longtable}

\begin{document}
\begin{tabular}{r}
aaa\\
\midrule %works
bbb
\end{tabular}    

\begin{tabular}{r}
aaa\\
 \cmidrule{1-1} %fails
bbb
\end{tabular}    

\begin{longtable}{r}
aaaa\\
 \midrule %fails
bbbb
\end{longtable}

\begin{tabular}{r}
aaa\\
\multispan 1 xxx \cr %fails
bbb
\end{tabular}    

\end{document}

! Undefined control sequence.
<argument> \ERRORtbl 
                     /row
l.192 \end{tabular}

[u-fischer]

Something like this could work, but needs more testing ...

\DocumentMetadata{uncompress,testphase={phase-I,table},pdfversion=2.0}
\documentclass{article}
\usepackage{array,booktabs,longtable}
\makeatletter
\tagpdfsetup{role/new-tag=rule/Artifact}
\ExplSyntaxOn
\def\@cmidrulea{%
   \multispan\@cmidla
   %?????????? something needed here??
   &\multispan\@cmidlb
   \unskip\hskip\cmrkern@l%
  {%
   {\tl_set:Nn\l__tbl_rowtag_tl{rule}\exp_args:No\tbl_update_multicolumn_cell_data:n {\@cmidlb}}
  \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
   \hskip\cmrkern@r\cr}%

\def\@cmidruleb{%
    \multispan\@cmidlb
    \unskip\hskip \cmrkern@l%
   {{\tl_set:Nn\l__tbl_rowtag_tl{rule}\exp_args:No\tbl_update_multicolumn_cell_data:n {\@cmidlb}}%
    \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
    \hskip\cmrkern@r\cr}%
\ExplSyntaxOff

\begin{document}
\begin{tabular}{l}
aaaa\\
\cmidrule{1-1} 
bbbb
\end{tabular}

\begin{tabular}{lll}
aaaa&aaa&bbb\\
\cmidrule{1-2} 
bbbb&aaa&bbb
\end{tabular}  

\begin{longtable}{r}
aaaa\\
 \midrule %fails
bbbb
\end{longtable}

\end{document}

[u-fischer]

The above code doesn't work: the row count gets confused as every cmidrule is effectively a row and it is then e.g. no longer possible to set rows below a cmidrule as header.

This here works better and makes the rules to artifacts:

\DocumentMetadata{uncompress,testphase={phase-III,table}}
\documentclass{article}
\usepackage{booktabs}
\usepackage{longtable}
\makeatletter
\ExplSyntaxOn
\DebugTablesOn
\def\@cmidrulea{%
   \multispan\@cmidla
   &\multispan\@cmidlb
   \unskip\hskip\cmrkern@l%
  {%
   \tag_mc_begin:n{artifact}
   \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
   \hskip\cmrkern@r
   \tag_mc_end: \int_gdecr:N \g__tbl_row_int 
   \cr}%

\def\@cmidruleb{%
    \multispan\@cmidlb
    \unskip\hskip \cmrkern@l%
   {%
    \tag_mc_begin:n{artifact}
    \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
    \hskip\cmrkern@r
    \tag_mc_end: \int_gdecr:N \g__tbl_row_int 
    \cr}%
\ExplSyntaxOff

\begin{document}

\tagpdfsetup{table/header-rows=2}
\begin{tabular}{rl}
\toprule
aaa & ccc\\
 \cmidrule(lr){1-1}\cmidrule(lr){2-2} 
bbb\\
cccc
\end{tabular} 

\begin{tabular}{r}
aaa\\
\midrule 
bbb
\end{tabular}    

\begin{tabular}{rl}
aaa & ccc\\
 \cmidrule(lr){1-1}\cmidrule(lr){2-2} 
bbb
\end{tabular}    

\begin{longtable}{r}
aaaa\\
 \midrule 
bbbb
\end{longtable}

\ExplSyntaxOn
\begin{tabular}{r}
aaa\\
\multispan 1~\tagmcbegin{artifact}xxx\tagmcend \int_gdecr:N \g__tbl_row_int \cr %fails
bbb
\end{tabular} 
\ExplSyntaxOff   

\end{document}