diff options
Diffstat (limited to 'Master/texmf-dist/source/latex-dev/tools/array.dtx')
-rw-r--r-- | Master/texmf-dist/source/latex-dev/tools/array.dtx | 179 |
1 files changed, 136 insertions, 43 deletions
diff --git a/Master/texmf-dist/source/latex-dev/tools/array.dtx b/Master/texmf-dist/source/latex-dev/tools/array.dtx index f141f069e3a..f4c8ab28d8d 100644 --- a/Master/texmf-dist/source/latex-dev/tools/array.dtx +++ b/Master/texmf-dist/source/latex-dev/tools/array.dtx @@ -39,7 +39,7 @@ % \begin{macrocode} %<+package>\NeedsTeXFormat{LaTeX2e}[2024/06/01] %<+package>\ProvidesPackage{array} -%<+package> [2024/10/12 v2.6g Tabular extension package (FMi)] +%<+package> [2024/10/17 v2.6g Tabular extension package (FMi)] % % \fi % @@ -259,7 +259,7 @@ % \begin{table}[!t] % \begin{center} % \setlength{\extrarowheight}{1pt} -% \begin{tabular}{|>{\tt}c|m{9cm}|} +% \begin{tabular}{|>{\ttfamily}c|m{9cm}|} % \hline % \multicolumn{2}{|c|}{Unchanged options}\\ % \hline @@ -382,6 +382,20 @@ % \end{itemize} % % +% +% \subsection{A note on the allowed content of \texttt{>\{...\}} and +% \texttt{<\{...\}}} +% +% These specifiers are meant to hold declarations, such as +% \verb=>{\itshape}=. They cannot end in commands that take arguments +% without providing these arguments as part of the \verb={...}=. It +% would be a mistaken assumption that they pick up all or parts of the +% alignment entry data if their argument is not provided. E.g., +% \verb=>{\textbf}= would not make the whole column bold nor would it +% make the first character bold (technically it would try to +% bolden \cs{ignorespaces}). Thus, it would not fail with an error, +% but effectively the output would be wrong and not as expected. +% % \subsection{The behavior of the \texttt{\string\\} command} % % In the basic \texttt{tabular} implementation of \LaTeX{} the \cs{\bslash} @@ -464,16 +478,16 @@ % "\newcolumntype{L}{>{$}l<{$}}" \\ % "\newcolumntype{R}{>{$}r<{$}}" % \end{quote} -% Then we can use \texttt{C} to get centred LR-mode in an -% \texttt{array}, or centred math-mode in a \texttt{tabular}. +% Then we can use \texttt{C} to get centered LR-mode in an +% \texttt{array}, or centered math-mode in a \texttt{tabular}. % -% The example given above for `centred decimal points' could be +% The example given above for `center decimal points' could be % assigned to a \texttt{d} specifier with the following command. % \begin{quote} % "\newcolumntype{d}{>{\centerdots}c<{\endcenterdots}}" % \end{quote} % -% The above solution always centres the dot in the +% The above solution always centers the dot in the % column. This does not look too good if the column consists of large % numbers, but to only a few decimal places. An alternative definition % of a \texttt{d} column is @@ -734,7 +748,7 @@ % user the opportunity of overriding the settings of a % "\newcolumntype" defined using these declarations. For example, % suppose in an \texttt{array} environment we use a \texttt{C} -% column defined as above. The \texttt{C} specifies a centred text +% column defined as above. The \texttt{C} specifies a centered text % column, however ">{\bfseries}C", which re-writes to % ">{\bfseries}>{$}c<{$}" would not specify a bold column as might % be expected, as the preamble would essentially expand to @@ -896,14 +910,14 @@ Bug reports can be opened (category \texttt{#1}) at\\% % % \section{A note on the updates done December 2023} % -% We introduced support for tagged PDf and at the same time we added +% We introduced support for tagged PDF and at the same time we added % code to determine row and column numbers for each cell in % preparation for supporting formatting or type specifications for individual % cells (or group of cells) from the outside, e.g., \enquote{rows 1, % 2, and 10 are header rows} (syntax to be decided). % % This new code is already written with L3 programming layer conventions -% while most of the legay code is still as it was before. This make the code +% while most of the legacy code is still as it was before. This make the code % currently somewhat clattered, unfortunately. Eventually this will all move to L3 % programming layer but this will take time. % @@ -1345,7 +1359,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % of \textsf{token} register $15$ instead of $1$ later on. % % The example above referred to an older version of =\save@decl= which -% inserted a =\relex= inside the token register. This is now moved to +% inserted a =\relax= inside the token register. This is now moved to % the places where the actual token registers are inserted (look for % =\the@toks=) because the old version would still make =@= % expressions to moving arguments since after expanding the second @@ -1386,33 +1400,112 @@ Bug reports can be opened (category \texttt{#1}) at\\% % \begin{macrocode} \UseTaggingSocket{tbl/cell/begin}% % \end{macrocode} -% Here, we assume that the \textsf{count} register +% Next we have to insert the toks register holding the content of +% \verb=>{...}=. Here, we assume that the \textsf{count} register % =\@tempcnta= has saved the value $=\count@= - 1$. % -% To keep \TeX{} happy if there is a look ahead in the tabular preamble -% which uses the Appendix~D trick (for example anything with a trailing -% optional argument defined by \pkg{ltcmd}), we wrap everything here in -% a protected version of \cs{@firstofone}.\footnote{The reason this -% works is not really clear: almost certainly there is a bug in \TeX{} -% here that we are simply avoiding, but as the master counter doesn't -% show up in a trace, a full understanding likely means working through -% the code that implements \cs{halign}!} -% \TeX{} otherwise can get +% To keep \TeX{} happy if there is a look ahead in the tabular +% preamble, i.e., starting in \verb=>{...}=, which uses the +% Appendix~D trick (for example, anything with a trailing optional +% argument defined by \pkg{ltcmd}), we wrap everything here in a +% protected version of \cs{@firstofone}. \TeX{} otherwise can get % confused about the value of the master counter, and we get some -% strange errors. (Quite possibly the underlying issue is a \TeX{} -% bug, but rather than try to fix in 2024 we accept it's there and -% work-around.) As an example, without this approach, something -% like +% strange errors. We suspected that there was an underlying issue +% is the \TeX{} engine, but it turned out to be rather hard to get +% to the bottom of it, because the master counter is not accessible +% through \TeX{}'s tracing tools. Thus, all we could do was +% producing various example documents, observing results, as well +% as staring at a printout of the \TeX{} program. As an example, +% without this approach, something like % \begin{verbatim} -%\NewDocumentCommand\foo{o}{x} -%\begin{tabular}{>{\foo}l} -% Foo -%\end{tabular} +% \NewDocumentCommand\foo{o}{x} +% \begin{tabular}{>{\foo}l} +% Foo +% \end{tabular} % \end{verbatim} -% will fail; that can be fixed by adding a \cs{relax} after the \cs{@tempcnta}, -% but that then leads to issues if you are collecting whole cells (tagging code -% or \\pkg{collcell}), where you can no longer alter the meaning of \cs{cr} -% as the master counter goes wrong. +% failed. That can be fixed by adding a \cs{relax} after the +% \cs{@tempcnta}, but that then leads to issues if you are +% collecting whole cells (tagging code or \pkg{collcell}), where +% you can no longer alter the meaning of \cs{cr} as the master +% counter goes wrong due to an obscure bug (or perhaps, say, an +% undocumented feature of \TeX{}). Eventually, we were able to pin +% down the root cause and really understand why +% \cs{@protected@firstofone} solves the problem, even though it +% looks like a nonsense addition to the code that does nothing +% useful.\footnote{So it is a \TeX{} engine bug that was in there +% from day one, or if you like, it is a hidden feature that is not +% explained; neither in the \TeX{}book nor in the program code. We +% don't really expect this to change in \TeX{} after such a long +% time, other than perhaps documenting it as a feature, so this is +% a proper solution to the problem and not just a workaround.} +% +% The problem is that \TeX{} tries to conserve stack space, and +% when the last token of an existing token list is a macro, then +% this token list is \emph{first} removed from memory (reducing the +% stack) \emph{before} the macro replacement text (as a new +% token list) is given to the parser adding a new stack level. This +% is done using the routine \texttt{end\_token\_list} in the \TeX{} +% program and ending the u-part of an \cs{halign} column with this +% routine immediately sets the \emph{master counter} used by alignments to +% zero (see chapter~22 and Appendix~D of the \TeX{}book). This +% means that technically the expansion of the last token in the u-part (if it +% is a macro) is not executed in the context of the u-part, but in +% the context of the alignment entry in the document. That normally +% doesn't make any difference whatsoever --- unless you play +% around (as we sometimes have to) with tricks like those from +% Appendix~D. +% +% To illustrate the issue we show a bit of strange low-level plain +% \TeX{} code.\footnote{If all of this looks mighty strange to you, +% don't worry. You will be unlikely to need to know about it. It is +% just there so that programmers at some point in the future do not +% have to wonder too much why there is this odd +% \cs{@protected@firstofone} that apparently does nothing +% useful. It took us several nights of head scratching to come up +% with these minimal examples and then some more time to understand +% what the heck is going on inside \TeX{}---thanks to Bruno for the +% right ideas on the latter.} Below are two very special grouping +% commands that are like \cs{bgroup} and \cs{egroup} but also +% affect the alignment master counter when expanded (see +% \TeX{}book p.385). If one of them is used as the +% last macro in the u-part of a column, then you get strange errors +% that you shouldn't get. +% \begin{verbatim} +% \def\bbgroup{{\ifnum0=`}\fi} +% \def\eegroup{\ifnum0=`{\fi}} +% +% % Fails with an error message, but there should be none: +% \halign{% +% \message{u-part^^J}% +% \bbgroup % <-- in the u-part +% \eegroup % <-- in the u-part +% #% +% \message{v-part^^J}% +% \hfill\cr +% \message{body^^J}x +% \cr +% } +% +% % Fails but should work, the v-part is never reached: +% \halign{% +% \message{u-part^^J}% +% \bbgroup % <-- in the u-part +% #% +% \message{v-part^^JJ}% +% \eegroup % <-- in the v-part +% \hfill\cr +% \message{body^^J}x +% \cr +% } +% \end{verbatim} +% +% So the trick we use now is making \cs{@protected@firstofone} the +% last macro in the u-part, i.e., before the \cs{@sharp}. That way +% its argument is always fully expanded as part of the alignment +% entry and not as part of the u-part and this way we know exactly +% what the master counter value is at this point, regardless of the content of +% \verb=>{...}=. +% % \changes{v2.6f}{2024/09/13}{Stop parsing for optional argument (gh/1468)} % \changes{v2.6g}{2024/10/12}{Further work to support optional args in preamble (gh/1468)} % \begin{macrocode} @@ -1429,7 +1522,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % afterwards; in math mode, the latter is suppressed while the % \cs{ignorespaces} makes no difference. % \changes{v2.0e}{1991/02/07}{Added \{\} around \cs{@sharp} for new ftsel} -% \changes{v2.0h}{1992/06/22}{Removed \{\} again in favour of +% \changes{v2.0h}{1992/06/22}{Removed \{\} again in favor of % \cs{d@llarbegin}} % \changes{v2.6b}{2024/04/08}{Do not \cs{unskip} if in math mode (gh/1323)} % \begin{macrocode} @@ -1920,7 +2013,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % For that reason the new implementation does the centering % manually: First we check the height of the cell and if that is % less or equal to =\ht\strutbox= we assume that this is a -% single line cell. In that case we don't do any vertical maneuvre +% single line cell. In that case we don't do any vertical maneuver % and simply output the box, i.e., make it behave like a single % line p-cell. % @@ -2363,7 +2456,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% \lineskip \z@ \baselineskip \z@ % \end{macrocode} -% Don't use \cs{m@th} here as that signals to the math taggingg +% Don't use \cs{m@th} here as that signals to the math tagging % code that this is fake math that should not be tagged. % \changes{v2.6a}{2023/12/11}{Support for tagged PDF} % \begin{macrocode} @@ -2489,7 +2582,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % % We then start a special brace which I have directly % copied from the original definition. It is -% necessary, because the =\futurlet= in =\@ifnextchar= +% necessary, because the =\futurelet= in =\@ifnextchar= % might % expand a following =&= \textsf{token} in a construction like % =\\ &=. This would otherwise end the alignment template at a @@ -2502,7 +2595,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % that a =&= will not be considered belonging to the current % =\halign= while we are looking for a =*= or =[=. % For further information see -% \cite[Appendix D]{bk:knuth}. +% \cite[Appendix~D]{bk:knuth}. % \begin{macrocode} \iffalse{\fi\ifnum 0=`}\fi % \end{macrocode} @@ -2687,7 +2780,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % \section{The Environment Definitions} % % After these preparations we are able to define the environments. They -% only differ in the initialisations of =\d@llar...=, =\col@sep= +% only differ in the initializations of =\d@llar...=, =\col@sep= % and =\@halignto=. % % \begin{macro}{\@halignto} @@ -2702,7 +2795,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % able overwrite the =\@halignto= % setting of a tabular in the main text resulting in a very weird error. % \changes{v2.4d}{2016/10/06}{\cs{@halignto} set locally (pr/4488)} -% \changes{v2.0g}{1992/06/18}{`d@llarbegin defined on toplevel.} +% \changes{v2.0g}{1992/06/18}{`d@llarbegin defined on top-level.} % When the new font selection scheme is in force we have to % we surround all =\halign= entries % with braces. See remarks in TUGboat 10\#2. Actually we are going @@ -2752,7 +2845,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % \begin{macro}{\tabular} % \begin{macro}{\tabular*} % The environments \textsf{tabular} and \textsf{tabular$*$} differ -% only in the initialisation of the command =\@halignto=. Therefore +% only in the initialization of the command =\@halignto=. Therefore % we define % \changes{v2.4d}{2016/10/06}{\cs{@halignto} set locally (pr/4488)} % \begin{macrocode} @@ -3034,7 +3127,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % rewrites (in the token register "\NC@list") will look like % "\NC@do *" "\NC@do C" "\NC@do L". % So we need to define "\NC@do" as a one argument macro which -% initialises the rewriting of the specified column. Let us assume that +% initializes the rewriting of the specified column. Let us assume that % `C' is the argument. % \begin{macrocode} \def\NC@do#1{% @@ -3102,7 +3195,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % \end{macro} % % \subsection{The $*$--form} -% We view the $*$-form as a slight generalisation of the system +% We view the $*$-form as a slight generalization of the system % described in the previous subsection. The idea is to define a $*$ % column by a command of the form: % \begin{verbatim} @@ -3540,7 +3633,7 @@ Bug reports can be opened (category \texttt{#1}) at\\% % the cell content is too wide. % \changes{v2.4f}{2017/11/07}{Column type added} % \changes{v2.5a}{2020/04/06}{Use \cs{d@llarbegin} and \cs{d@llarend} so -% that cell is typeset in mathmode inside \texttt{array} (gh/297)} +% that cell is typeset in math mode inside \texttt{array} (gh/297)} % \begin{macrocode} \newcolumntype{W}[2] {>{\begin{lrbox}\ar@cellbox\d@llarbegin}% |