Allow U-Z row selectors in cell span arguments

[philippewarren]

Allowing U-Z special values as row selectors for cell span would be useful when you have a cell that should expand when new rows are added to the table.

[muzimuzhi]

An attempt that adds two new span options to row=<selector> and to col=<selector>.

For a 4x5 tabular, the three (inner style) settings below are equivalent to each other:

• cell{2}{2}={r=2,c=3}{<styles>}
• cell{2}{2}={to row=3, to col=4}{<styles>}
• cell{2}{2}={to row=Y, to col=Y}{<styles>}

Full example

\documentclass[twocolumn]{article}
\usepackage{tabularray}
\usepackage{xcolor}

\makeatletter
\ExplSyntaxOn
% can be replaced by two temp tl args
% (I'm not familiar enough with tabularray implementation.)
\tl_new:N \l__tblr_span_to_row_tl
\tl_new:N \l__tblr_span_to_col_tl

\keys_define:nn { tblr-cell-span }
  {
    % both are inclusive
    to~row .code:n =
      {
        \group_begin:
        \tl_set:Nx \l_tblr_childs_total_tl { \int_use:N \c@rowcount }
        \__tblr_child_name_to_index:nN {#1} \l__tblr_span_to_row_tl
        \use:e
          {
            \group_end:
            \int_compare:nNnF {\l__tblr_span_to_row_tl} < {\c@rownum}
              {
                \tl_set:Nn \exp_not:N \l__tblr_row_span_num_tl
                  {
                    \int_eval:n { \l__tblr_span_to_row_tl - \c@rownum + 1 }
                  }
              }
          }
      },
    to~col .code:n =
      {
        % is it safe to alter \l_tblr_childs_total_tl directly (not without an extra group)?
        \group_begin:
        \tl_set:Nx \l_tblr_childs_total_tl { \int_use:N \c@colcount }
        \__tblr_child_name_to_index:nN {#1} \l__tblr_span_to_col_tl
        \use:e
          {
            \group_end:
            \int_compare:nNnF {\l__tblr_span_to_col_tl} < {\c@colnum}
              {
                \tl_set:Nn \exp_not:N \l__tblr_col_span_num_tl
                  {
                    \int_eval:n { \l__tblr_span_to_col_tl - \c@colnum + 1 }
                  }
              }
          }
      }
  }
\ExplSyntaxOff
\makeatother

\SetTblrInner{
  cells={preto={(\therownum, \thecolnum)}},
  hline{1,Z},
  vline{1,Z},
  baseline=T
}

\begin{document}
\newcommand\testSpan[3]{
  \noindent\texttt{\detokenize{cell#1={#2}{...}}}\par
  \begin{tblr}{
    cell#1={#2}{m,c,font=\large\bfseries}
  }
    #3
  \end{tblr}
  \par\medskip
}

\testSpan{{2}{2}}{r=2, c=3}          {& & & & \\ \\ \\ \\}      % size is 4x5
\testSpan{{2}{2}}{to row=3, to col=4}{& & & & \\ \\ \\ \\}
\testSpan{{2}{2}}{to row=Y, to col=Y}{& & & & \\ \\ \\ \\}

\testSpan{{2}{2}}{to row=Y, to col=Y}{& & & & & \\ \\ \\ \\ \\} % 5x6
\newpage

% degenerated cases
\testSpan{{2}{3}}{to row=Z, to col=Z}{& & & \\ \\ \\} % 3x4
\testSpan{{2}{3}}{to row=Z, to col=Z}{& & \\ \\ \\}   % 3x3
\testSpan{{2}{3}}{to row=Z, to col=Z}{& & & \\ \\}    % 2x4
\testSpan{{2}{3}}{to row=Z, to col=Z}{& & \\ \\}      % 2x3
\end{document}

Another option is to provide a new inner option span{<row range>}{<col range>}={<styles>}.

[lvjr]

If multiple-word key names are needed, I would prefer to use dash characters instead of space characters in the names (like nicematrix and siunitx).

[philippewarren]

Let me clarify: I was thinking about cell spans in the \SetCell command.

[muzimuzhi]

From its syntax\SetCell[<span>]{<styles>}, \SetCell[to row=<selector>, to col=<selector>]{<styles>} (or the to-row=..., to-col=... form) is supported in my (first) attempt in https://github.com/lvjr/tabularray/issues/417#issuecomment-1627829786.

[philippewarren]

From its syntax\SetCell[<span>]{<styles>}, \SetCell[to row=<selector>, to col=<selector>]{<styles>} (or the to-row=..., to-col=... form) is supported in my (first) attempt in #417 (comment).

Great! It was just to be sure since you were using a different syntax in your examples.

[lvjr]

I think there is no need to add to-row and to-col keys, because it is just a simple application of future keyvalue library (see https://github.com/lvjr/tabularray/issues/270).