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-rw-r--r--macros/latex-dev/base/ltlists.dtx133
1 files changed, 123 insertions, 10 deletions
diff --git a/macros/latex-dev/base/ltlists.dtx b/macros/latex-dev/base/ltlists.dtx
index 8d4c25d916..5858cbddfb 100644
--- a/macros/latex-dev/base/ltlists.dtx
+++ b/macros/latex-dev/base/ltlists.dtx
@@ -31,7 +31,7 @@
%<*driver>
% \fi
\ProvidesFile{ltlists.dtx}
- [2023/05/17 v1.0t LaTeX Kernel (List Environments)]
+ [2024/06/23 v1.0u LaTeX Kernel (List Environments)]
% \iffalse
\documentclass{ltxdoc}
\GetFileInfo{ltlists.dtx}
@@ -428,13 +428,13 @@
%
% DEFINE \dimen's and \count
% \end{oldcomments}
-% \begin{macro}{\topskip}
+% \begin{macro}{\topsep}
% \begin{macro}{\partopsep}
% \begin{macro}{\itemsep}
% \begin{macro}{\parsep}
% \begin{macro}{\@topsep}
% \begin{macro}{\@topsepadd}
-% \begin{macro}{\outerparskip}
+% \begin{macro}{\@outerparskip}
% \begin{macrocode}
%<*2ekernel>
\newskip\topsep
@@ -450,6 +450,7 @@
% \begin{macro}{\leftmargin}\begin{macro}{\rightmargin}
% \begin{macro}{\listparindent}\begin{macro}{\itemindent}
% \begin{macro}{\labelwidth}\begin{macro}{\labelsep}
+% \begin{macro}{\linewidth}
% \begin{macro}{\@totalleftmargin}
% \begin{macrocode}
\newdimen\leftmargin
@@ -462,7 +463,7 @@
\newdimen\@totalleftmargin \@totalleftmargin=\z@
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
-% \end{macro}\end{macro}
+% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\leftmargini}
% \begin{macro}{\leftmarginii}
@@ -715,6 +716,66 @@
%
% This allows paragraph-making environments to work right when called
% by other environments. (Changed 27 Oct 86)
+%
+% In 2024 this logic was partially replaced with a new algorithm:
+% \begin{itemize}
+% \item
+% \cs{if@endpe} is now set globally to \texttt{true} or \texttt{false}.
+% \item
+% In addition \cs{@endpetrue} initiates an \cs{aftergroup} call
+% to \cs{propagate@doendpe} if it is used inside a group.
+% \item
+% \cs{propagate@doendpe} in turn checks the status of \cs{if@endpe}
+% and if that is \texttt{true} it calls \cs{@doendpe} otherwise it
+% does nothing.
+% \item
+% \cs{@doendpe} in turn calls \cs{@endpetrue} and also makes the
+% necessary changes to
+% \cs{par} and \cs{everypar} so that they handle as before any
+% empty line that follows the environment.
+% \item
+% Because of the \cs{@endpetrue} we get another \cs{aftergroup}, so the
+% mechanisnm slowly migrates out of several groups if those follow
+% immediately after the end of the environment. If, however, there is a new
+% paragraph started or an explicit \cs{par} before the next group ends then this will
+% result in a call to \cs{@endpefalse} and the migration stops
+% (note that \cs{propagate@doendpe} is still called once after the group but does nothing).
+% \item
+% Using this approach something like
+%\begin{verbatim}
+% {% some customization here
+% \begin{equation}
+% x=y
+% \end{equation}}
+% some text
+%\end{verbatim}
+% is still correctly identified as a paragraph continuation so that
+% there is no indentation before \texttt{some text}.
+% \item
+% We can get away with using global settings of \cs{if@endpe} even
+% in nested situations (without keeping track of the status in a
+% stack), because the switch change is made only at
+% the very end of such environments, basically directly before the
+% \cs{endgroup} in \cs{end}, and it is later set back to \texttt{false} by
+% the next \cs{everypar} or the next \cs{par}. Even if the
+% environment is called without using \cs{begin} \cs{end}, the
+% situation doesn't change (or rather cause a problem).
+% \item
+% However, there is one scenario where the new approach would
+% change the behavior. If a box is being built, e.g., with
+% \cs{setbox}, we have now the case that a \cs{@endpetrue}
+% inside would migrate out into a context in which it should not be
+% true (because the box might get used elsewhere, e.g., a float).
+% In the past, due to local switch changes, that didn't happen, i.e.,
+% \cs{if@endpe} would revert to \texttt{false} at the end of the box
+% definition.
+% \item
+% Thus, to avoid that one has to explicitly set it back to false at
+% the end of such constructions, just as we also need to prevent
+% colors from
+% migrating out. Thus the correct place to do this is
+% in \cs{color@endgroup} because that is always called at that point.
+% \end{itemize}
% \begin{macrocode}
\def\@endparenv{%
\addpenalty\@endparpenalty\addvspace\@topsepadd\@endpetrue}
@@ -732,9 +793,12 @@
% |\clubpenalty| back to its default.
% \changes{v1.0t}{2015/05/10}{Explicitly reset \cs{clubpenalty} before
% clearing \cs{everypar}; see also pr/0462 and pr/4065}
+% \changes{v1.0u}{2024/06/23}{Set \cs{if@endpe} to \texttt{false}
+% before calling \cs{par} (needed for tagging)}
% \begin{macrocode}
\clubpenalty\@clubpenalty
- \everypar{}\par\@endpefalse}\everypar
+ \@endpefalse
+ \everypar{}\par}%
% \end{macrocode}
%
% Use |\setbox0=\lastbox| instead of |\hskip -\parindent|
@@ -743,8 +807,9 @@
% \changes{v1.0k}{1995/11/07}{Enclosed \cs{setbox0} assignment by a
% group so that it leaves the contents of box $0$ intact.}
% \begin{macrocode}
- {{\setbox\z@\lastbox}%
- \everypar{}\@endpefalse}}
+ \everypar
+ {{\setbox\z@\lastbox}%
+ \everypar{}\@endpefalse}}
%<latexrelease>\EndIncludeInRelease
% \end{macrocode}
%
@@ -761,12 +826,60 @@
%
% \begin{macro}{\if@endpe}
% \begin{macro}{\@endpefalse}
-% \begin{macro}{\@endpeltrue}
+% \begin{macro}{\@endpetrue}
+% \begin{macro}{\propagate@doendpe}
+% As outlined above these are no longer simple switches, but we
+% keep the name because it is used all over the place.
% \begin{macrocode}
\newif\if@endpe
-\@endpefalse
% \end{macrocode}
-% \end{macro}\end{macro}\end{macro}
+%
+% \changes{v1.0u}{2024/06/23}{Set \cs{if@endpe} globally and also set
+% up migration to the outside}
+% \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2024/11/01}%
+%<latexrelease> {\@endpetrue}{New @endpe handling}%
+% \end{macrocode}
+%
+% \begin{macrocode}
+\def\@endpefalse{\global\let\if@endpe\iffalse}
+% \end{macrocode}
+%
+% \begin{macrocode}
+\def\@endpetrue {%
+ \global\let\if@endpe\iftrue
+% \end{macrocode}
+% If we are inside a group then propagate to the outside:
+% \begin{macrocode}
+ \ifnum\currentgrouplevel>\z@
+ \aftergroup\propagate@doendpe
+ \fi
+}
+% \end{macrocode}
+% If \cs{if@endpe} is still true after the group ends, we run \cs{@doendpe}
+% that in turn runs another \cs{@endpetrue} (besides other things),
+% thus propagating further if necessary.
+% However, if the endpe situation got resolved and \cs{if@endpe} is \texttt{false}
+% then nothing further happens.
+% \begin{macrocode}
+\def\propagate@doendpe{\if@endpe \@doendpe \fi}
+% \end{macrocode}
+% \begin{macrocode}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease> {\@endpetrue}{New @endpe handling}%
+%<latexrelease>
+%<latexrelease>
+%<latexrelease>\def\@endpefalse{\let\if@endpe\iffalse}
+%<latexrelease>\def\@endpetrue{\let\if@endpe\iftrue}
+%<latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}
%
%
% \begin{macro}{\@mklab}