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ltmarks.dtx
% \iffalse meta-comment
%
%% File: ltmarks.dtx (C) Copyright 2022
% Frank Mittelbach, LaTeX Team
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version. The latest version
% of this license is in the file
%
% https://www.latex-project.org/lppl.txt
%
%
%%% From File: ltmarks.dtx
%
% \begin{macrocode}
\def\ltmarksversion{v1.0d}
\def\ltmarksdate{2022/06/01}
% \end{macrocode}
%<*driver>
\documentclass{l3doc}
%\usepackage{ltmarks}
% Fixing footnotes in functions and variables: this should be in l3doc!
\newcommand\fixfootnote[2]{\footnotemark
\AddToHookNext{env/#1/after}{\footnotetext{#2}}}
\AddToHook{env/function/begin}{\def\footnote{\fixfootnote{function}}}
\AddToHook{env/variable/begin}{\def\footnote{\fixfootnote{variable}}}
\EnableCrossrefs
\CodelineIndex
\begin{document}
\DocInput{ltmarks.dtx}
\end{document}
%</driver>
%
% \fi
%
% \providecommand\hook[1]{\texttt{#1}}
% \providecommand\env[1]{\texttt{#1}}
%
%
%
% \title{The \texttt{ltmarks.dtx} code\thanks{This file has version
% \ltmarksversion\ dated \ltmarksdate, \copyright\ \LaTeX\
% Project.}}
% \author{^^A
% Frank Mittelbach, \LaTeX{} Project\thanks
% {^^A
% E-mail:
% \href{mailto:latex-team@latex-project.org}
% {latex-team@latex-project.org}^^A
% }^^A
% }
%
% \maketitle
%
%
% \begin{abstract}
% Marks are used to communicate information about the content of a
% page to the output routine. For example, in order to construct
% running headers, the output routine needs information about which
% section names are present on a page, and this information is
% passed to it through the mark system. However, marks may also be
% used for other purposes. This module provides a generalized
% mechanism for marks of independent classes.
% \end{abstract}
%
% \tableofcontents
%
% ^^A \begin{documentation}
%
% \section{Introduction}
%
% The \TeX{} engines offer a low-level mark mechanism to
% communicate information about the content of the current page to
% the asynchronous operating output routine. It works by placing
% \cs{mark} commands into the source document. When the material
% for the current page is assembled in box 255, \TeX{} scans for
% such marks and sets the commands \cs{topmark}, \cs{firstmark} and
% \cs{botmark}. The \cs{firstmark} receives the content of the
% first \cs{mark} seen in box 255 and \cs{botmark} the content of
% the last mark seen. The \cs{topmark} holds the content of the
% last mark seen on the previous page or more exactly the value of
% \cs{botmark} from the previous page. If there are no marks on
% the current page then all three are made equal to the
% \cs{botmark} from the previous page.
%
% This mechanism works well for simple formats (such as plain \TeX)
% whose output routines are only called to generate pages. It
% fails, however, in \LaTeX{} (and other more complex formats),
% because here the output routine is sometimes called without
% producing a page, e.g., when encountering a float and placing it
% into one of the float regions. In that case the output routine is
% called, determines where to place the float, alters the goal for
% assembling text material (if the float was added to the top or
% bottom region) and then it resumes collecting textual material.
%
% As a result the \cs{botmark} gets updated and so \cs{topmark} no
% longer reflects the situation at the top of the next page when that
% page is finally boxed.
%
% Another problem for \LaTeX{} was that it wanted to use several
% \enquote{independent} marks and in the early implementations of
% \TeX{} there was only a single \cs{mark} command available.
% For that reason \LaTeX{} implemented its own mark
% mechanism where the marks always contained two parts with their
% own interfaces: \cs{markboth} and \cs{markright} to set marks and
% \cs{leftmark} and \cs{rightmark} to retrieve them.
%
% However, this extended mechanism (while supporting scenarios such
% as chapter/section marks) was far from general. The mark
% situation at the top of a page (i.e., \cs{topmark}) remained
% unusable and the two marks offered were not really independent of
% each other because \cs{markboth} (as the name indicates) was
% always setting both.
%
% The new mechanism overcomes both
% issues:
% \begin{itemize}
% \item
% It provides arbitrarily many, fully independent named marks, that
% can be allocated and, from that point onwards, used.
% \item
% It offers access for each such marks to retrieve its top,
% first, and bottom values separately.
% \item
% Furthermore, the mechanism is augmented to give access to marks
% in different \enquote{regions} which may not be just full pages.
% \end{itemize}
%
%
% \section{Design-level and code-level interfaces}
%
% The interfaces are mainly meant for package developers, but they
% are usable (with appropriate care) also in the document
% preamble, for example, when setting up special running headers
% with \pkg{fancyhdr}, etc. They are therefore available both as
% CamelCase commands as well as commands for use in the L3
% programming layer. Both are described together below.
%
% \begin{function}{\NewMarkClass,\mark_new_class:n}
% \begin{syntax}
% \cs{NewMarkClass} \Arg{class}
% \cs{mark_new_class:n} \Arg{class}
% \end{syntax}
% Declares a new \meta{class} of marks to be tracked by \LaTeX{}. Each \meta{class}
% must be declared before it is used.
%
% Mark classes can only be declared before \verb=\begin{document}=.
% \end{function}
%
% \begin{function}{\InsertMark,\mark_insert:nn}
% \begin{syntax}
% \cs{InsertMark} \Arg{class} \Arg{text}
% \cs{mark_insert:nn} \Arg{class} \Arg{text}
% \end{syntax}
% Adds a mark to the current galley for the \meta{class}, containing the
% \meta{text}.
%
% It has no effect in places in which you can't place floats, e.g.,
% a mark inside a box or inside a footnote never shows up anywhere.
%
% If used in vertical mode it obeys \LaTeX's internal
% \cs{@nobreak} switch, i.e., it does not introduce a
% breakpoint if used after a heading. If used in horizontal mode it
% doesn't handle spacing (like, for example, \cs{index} or
% \cs{label} does, so it should be attached to material that is
% typeset.
% \end{function}
%
% \begin{variable}{insertmark}
% \begin{syntax}
% \cs{AddToHook} \texttt{\{insertmark\}} \Arg{code}
% \end{syntax}
% When marks are inserted, the mark content may need some special
% treatment, e.g., by default \cs{label}, \cs{index}, and
% \cs{glossary} do not expand at this time (but only later if and when the
% mark content is actually used.
% In order to allow packages to augment or alter this setup there is
% a public hook \hook{insertmark} that is executed at this point. It
% runs in a group so local modification to commands are only applied
% to the \meta{text} argument of \cs{InsertMark} or \cs{mark_insert:nn}.
% \end{variable}
%
% \begin{function}[EXP]{\TopMark, \FirstMark, \LastMark,
% \mark_use_top:nn,\mark_use_first:nn,\mark_use_last:nn,}
% \begin{syntax}
% \cs{TopMark} \oarg{region} \Arg{class}
% \cs{FirstMark} \oarg{region} \Arg{class}
% \cs{LastMark} \oarg{region} \Arg{class}
% \cs{mark_use_top:nn} \Arg{region} \Arg{class}
% \cs{mark_use_first:nn} \Arg{region} \Arg{class}
% \cs{mark_use_last:nn} \Arg{region} \Arg{class}
% \end{syntax}
% These functions expand to the appropriate mark \meta{text} for
% the given \meta{class} in the specified \meta{region}.
% The default \meta{region} in the design-level commands is \texttt{page}.
% Note that with the L3 layer commands there are no
% optional arguments, i.e., both arguments have to be provided.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the \meta{text}
% does not expand further when appearing in an \texttt{x}-type
% or \texttt{e}-type argument expansion.
% \end{texnote}
%
% The \enquote{first} and \enquote{last} marks are
% those seen first and last in the current region/page, respectively. The
% \enquote{top} mark is the last mark of the \meta{class} seen
% in an earlier region, i.e., the \meta{text} what would be \enquote{current} at the
% very top of the region.
%
% \noindent\llap{\bfseries Important!\qquad}\indent
% The commands are only meaningful inside the output routine, in
% other places their result is (while not random) unpredictable due
% to the way \LaTeX{} cuts text material into pages.
%% \end{function}
%
%
%
% Currently, \meta{region} is one of
% \texttt{page},
% \texttt{previous-page},
% \texttt{column}, and
% \texttt{previous-column}.
% If a page has just been finished then the region \texttt{page}
% refers to the current page and \texttt{previous-page}, as the name
% indicates, to the page that has been finished previously. This
% means you are able to access mark information for the current page
% as well as for the page before if you are inside the output
% routine, without the need to explicitly save that information
% beforehand.
%
% In single column documents the \texttt{column} is the same as the
% \texttt{page} region, but in two-column documents, \texttt{column}
% refers to the current column that just got finished and
% \text{previous-column} to the one previously finished. Code for
% running headers are (in standard \LaTeX{}) only evaluated when
% both columns are assembled, which is another way of saying that in
% that case \texttt{previous-column} refers to the left column and
% \texttt{column} to the right column.
% However, to make this a bit nicer to access, there are also alias
% regions named \texttt{first-column} and
% \texttt{last-column}\footnote{This is called \enquote{last} not \enquote{second}
% in anticipation of extending the mechanism to multiple columns,
% where first and last would still make sense.} to
% access these regions.\footnote{At the moment there aren't any
% \texttt{previous-...-column} regions to access the columns from
% the previous page. If necessary, the mechanism could be
% easily augmented to cover them too, though.}
%
% Note that you can only look backwards at already processed regions,
% e.g., in a \texttt{twoside} document finishing a recto (odd,
% right-hand) page you can access the data from the facing verso
% (left-hand) page, but if you are finishing a left-hand page you
% can't integrate data from the upcoming right-hand page. If such a
% scenario needs to be realized then it is necessary to save the
% left-hand page temporarily instead of finalizing it, process
% material for the right-hand page and once both are ready, attach
% running headers and footers and shipout out both in one
% go.\footnote{As of now that scenario is not yet officially supported.}
%
% \begin{function}[EXP]{\IfMarksEqualTF,\mark_if_eq:nnnnTF,\mark_if_eq:nnnnnnTF}
% \begin{syntax}
% \cs{IfMarksEqualTF} \oarg{region} \Arg{class} \Arg{pos_1} \Arg{pos_2} \Arg{true} \Arg{false}
% \cs{mark_if_eq:nnnnTF} \Arg{region} \Arg{class} \Arg{pos_1} \Arg{pos_2} \Arg{true} \Arg{false}
% \cs{mark_if_eq:nnnnnnTF} \Arg{region_1} \Arg{class_1} \Arg{pos_1}
% \verb= = \Arg{region_2} \Arg{class_2} \Arg{pos_2} \Arg{true} \Arg{false}
% \end{syntax}
% These conditionals allow you to compare the content of two marks
% and act based on the result. The commands work in an expansion
% context, if necessary.
% \end{function}
%
% It is quite common when programming with marks to need to
% interrogate conditions such as whether marks have appeared on a
% previous page, or if there are multiple marks present on the
% current page, and so on.
% The tests above allow for the construction of a variety of
% typical test scenarios, with three examples presented below.
%
% The first two conditionals cover only the common scenarios. Both
% marks are picked up from the same \meta{region} (by default
% \texttt{page}) and they have to be of the same
% \meta{class}.\footnote{If an undeclared mark class is used the
% tests return \emph{true} (not an error).}
% The \meta{pos\textsubscript{\itshape i}} argument can be either
% \texttt{top}, \texttt{first}, or \texttt{last}.
%
% If you wish to compare marks across different regions or across
% different classes, you have to do it using the generic test only
% available in the L3 programming layer or do it manually, i.e.,
% get the marks and then compare the values yourself.\footnote{If
% two undeclared mark classes are compared the result is always
% \emph{true}; if a declared and an undeclared mark class is used
% it is always \emph{false}.}
%
% However, the basic version is enough for the following typical use cases:
% \begin{description}
% \item[Test for at most one mark of class \texttt{myclass} on current
% page:]
%
% If the first and last mark in a region are the same then
% either there was no mark at all, or there was at most one. To test
% this on the current page:
%\begin{verbatim}
% \NewMarkClass{myclass}
% \IfMarksEqualTF{myclass}{first}{last}
% { <zero or one mark> }{ <two or more marks> }
%\end{verbatim}
%
% \item[Test for no mark of class \texttt{myclass} in the previous
% page:]
%
% If the top mark is the same as the first mark, there is no mark
% in the region at all. If we wanted to do this test for the
% previous page:
%\begin{verbatim}
% \IfMarksEqualTF[previous-page]{myclass}{top}{first}
% { <no marks> }{ <at least one mark> }
%\end{verbatim}
% Comparing \texttt{top} and \texttt{last} would give you the
% same result.
%
% \item[Test for zero, one, or more than one:]
%
% Combining the two tests from above you can test for zero, one
% or more than one mark.
%\begin{verbatim}
% \IfMarksEqualTF{myclass}{top}{first}
% { <no marks> }
% {\IfMarksEqualTF{myclass}{first}{last}
% { <exactly one mark> }{ <more than one mark> }}
%\end{verbatim}
%
% \end{description}
%
% If you need one of such tests more often (or if you want a separate
% command for it for readability), then consider defining:
%\begin{verbatim}
% \providecommand\IfNoMarkTF[2][page]{\IfMarksEqualTF[#1]{#2}{first}{last}}
%\end{verbatim}
%
%
%
% \subsection{Debugging mark code}
%
%
% \begin{function}{\DebugMarksOn,\DebugMarksOff,
% \mark_debug_on:,\mark_debug_off:}
% \begin{syntax}
% \cs{DebugMarksOn} ... \cs{DebugMarksOff}
% \end{syntax}
%
% Commands to turn the debugging of mark code on or off. The
% debugging output is rather coarse and not really intended for
% normal use at this point in time.
%
% \end{function}
%
%
%
% \section{Application examples}
%
% If you want to figure out if a break was taken at a specific point,
% e.g., whether a heading appears at the top of the page,
% you can do something like this:
%\begin{verbatim}
% \newcounter{breakcounter}
% \NewMarkClass{break}
% \newcommand\markedbreak[1]{\stepcounter{breakcounter}%
% \InsertMark{break}{\arabic{breakcounter}%
% \penalty #1\relax
% \InsertMark{break}{-\arabic{breakcounter}}
%\end{verbatim}
% To test if the break was taken you can test if
% \verb=\TopMark{break}= is positive (taken) or negative (not taken)
% or zero (there was never any marked break so far).
% The absolute value can be used to keep track of which break it
% was (with some further coding).
%
%
% \emph{to be extended with additional application examples}
%
%
%
% \section{Legacy \LaTeXe{} interface}
%
% Here we describe the interfaces that \LaTeXe{} offered since the
% early nineties and some minor extensions.
%
% \subsection{Legacy design-level and document-level interfaces}
%
% \begin{function}{\markboth, \markright}
% \begin{syntax}
% \cs{markboth} \Arg{left} \Arg{right}
% \cs{markright} \Arg{right}
% \end{syntax}
% \LaTeXe{} uses two marks which aren't fully independent. A
% \enquote{left} mark generated by the first argument of \cs{markboth}
% and a \enquote{right} mark generated by the second argument of
% \cs{markboth} or by the only argument of \cs{markright}. The
% command \cs{markboth} and \cs{markright} are in turn called from
% heading commands such as \cs{chaptermark} or \cs{sectionmark} and
% their behavior is controlled by the document class.
%
% For example, in the \cls{article} class with \texttt{twoside} in
% force the \cs{sectionmark} will issue \cs{markboth} with an empty
% second argument and \cs{subsectionmark} will issue
% \cs{markright}. As a result the left mark will contain chapter
% titles and the right mark subsection titles.
%
% Note, however, that in one-sided documents the standard behavior is
% that only \cs{markright} is used, i.e., there will only be
% right-marks but no left marks!
% \end{function}
%
% \begin{function}[EXP]{\leftmark, \rightmark}
% \begin{syntax}
% \cs{leftmark}
% \cs{rightmark}
% \end{syntax}
% These functions return the appropriate mark value from the current page
% and work as before, that is \cs{leftmark} will get the last (!)
% left mark from the page and \cs{rightmark} the first (!) right
% mark.
%
% In other words they work reasonably well if you want to show the
% section title that is current when you are about to turn the page and
% also show the first subsection title on the current page (or the last
% from the previous page if there wasn't one). Other combinations
% can't be shown using this interface.
%
% The commands are fully expandable, because this is how they have
% been always defined in \LaTeX{}. However, this is of course
% only true if the content of the mark they return is itself
% expandable and does not contain any fragile material. Given that
% this can't be guaranteed for arbitrary content, a programmer using
% them in this way should use \cs{protected@edef} and \emph{not}
% \cs{edef} to avoid bad surprises as far as this is possible, or use
% the new interfaces (\cs{TopMark}, \cs{FirstMark}, and \cs{LastMark})
% which return the \meta{text} in \cs{exp_not:n} to prevent
% uncontrolled expansion.
% \end{function}
%
%
% \subsection{Legacy interface extensions}
%
% The new implementation adds three mark classes: \texttt{2e-left},
% \texttt{2e-right} and \texttt{2e-right-nonempty} and patches
% \cs{markboth} and \cs{markright} slightly so that they also update
% these new mark classes, so that the new classes work with existing
% document classes.
%
% As a result you can use \verb=\LastMark{2e-left}= and
% \verb=\FirstMark{2e-right}= instead of \cs{leftmark} and
% \cs{rightmark}. But more importantly, you can use any of the other
% retrieval commands to get a different status value from those
% marks, e.g., \verb=\LastMark{2e-right}= would return the last
% subsection on the page (instead of the first as
% returned by \cs{rightmark}).
%
% The difference between \texttt{2e-right} and
% \texttt{2e-right-nonempty} is that the latter will only be updated
% if the material for the mark is not empty. Thus
% \verb=\markboth{title}{}= as issued by, say, \cs{sectionmark},
% sets a \texttt{2e-left} mark with \texttt{title} and a
% \texttt{2e-right} mark with the empty string but does not add a
% \texttt{2e-right-nonempty} mark.
%
% Thus, if you have a section at the start of a page and you would
% ask for \verb=\FirstMark{2e-right}= you would get an empty string
% even if there are subsections on that page. But
% \texttt{2e-right-nonempty} would then give you the first or last subsection
% on that page. Of course, nothing is simple. If there are no
% subsections it would tell you the last subsection from an earlier
% page. We therefore need comparison tools, e.g., if top and
% first are identical you know that the value is
% bogus, i.e., a suitable implementation would be
%\begin{verbatim}
% \IfMarksEqualTF{2e-right-nonempty}{top}{first}
% { <appropriate action if there was no real mark> }
% {\FirstMark{2e-right-nonempty}}
%\end{verbatim}
%
%
%
% \section{Notes on the mechanism}
%
% In contrast to vanilla \TeX, \eTeX{} extends the mark system to
% allow multiple independent marks. However, it does not solve the
% \cs{topmark} problem which means that \LaTeX{} still needs to manage
% marks almost independently of \TeX{}. The reason for this is that
% the more complex output routine used by \LaTeX{} to handle floats
% (and related structures) means that \tn{topmark(s)} remain
% unreliable. Each time the output routine is fired up, \TeX{} moves
% \tn{botmark} to \tn{topmark}, and while \eTeX{} extends this to
% multiple registers the fundamental concept remains the same. That
% means that the state of marks needs to be tracked by \LaTeX{}
% itself. An early implementation of this package used \TeX{}'s
% \tn{botmark} only to ensure the correct interaction with the output
% routine (this was before the \eTeX{} mechanism was even
% available). However, other than in a prototype implementation for
% \LaTeX3, this package was never made public.
%
% The new implementation now uses \eTeX{}'s marks as they have some
% advantages, because with them we can leave the mark text within the
% galley and only extract the marks during the output routine when we
% are finally shipping out a page or storing away a column for use in
% the next page. That means we do not have to maintain a global data
% structure that we have to keep in sync with informational marks in
% the galley but can rely on everything being in one place and thus
% manipulations (e.g.~reordering of material) will take the marks with
% them without a need for updating a fragile linkage.
% To allow for completely independent marks we use the following
% procedure:
% \begin{itemize}
% \item
%
% For every type of marks we allocate a mark class so
% that in the output routine \TeX{} can calculate for each class
% the current
% top, first, and bottom mark independently. For this we use
% \cs{newmarks}, i.e., one marks register per class.
%
% \item
%
% As already mentioned firing up an output routine without
% shipping out a page means that \TeX's top marks get wrong so it
% is impossible to rely on \TeX's approach directly. What we do
% instead is to keep track of the real marks (for the last page or
% more generally last region) in some global variables.
%
% \item
%
% These variables are updated in the output routine at defined
% places, i.e., when we do real output processing but not if we
% use special output routines to do internal housekeeping.
%
% \item
%
% The trick we use to get correctly updated variables is the
% following: the material that contains new marks (for example the
% page to be shipped out) is stored in a box. We then use \TeX{}
% primitive box splitting functions by splitting off the largest
% amount possible (which should be the whole box if nothing goes
% really wrong). While that seems a rather pointless thing to do, it
% has one important side effect: \TeX{} sets up first and bottom
% marks for each mark class from the material it has split off. This
% way we get the first and last marks (if there have been any) from
% the material in the box.
%
% \item
%
% The top marks are simply the last marks from the previous
% page or region. And if there hasn't been a first or bottom mark in
% the box then the new top mark also becomes new first and last mark
% for that class.
%
% \item
%
% That mark data is then stored in global token lists for use
% during the output routine and legacy commands such as
% \cs{leftmark} or new commands such as \cs{TopMark} simply access
% the data stored in these token lists.
% \end{itemize}
% That's about it in a nutshell. Of course, there are some details to
% be taken care of---those are discussed in the implementation sections.
%
%
% \section{Internal output routine functions}
%
% The functions in this section are tied to the output routine and used in the
% interface to \LaTeXe{} and perhaps at some later time within a new
% output routine
% for \LaTeX. They are not meant for general use and are therefore made internal.
% Internal means that \verb|@@| automatically gets
% replaced in the code (and in the documentation) so we have to give
% it a suitable value.
% \begin{macrocode}
%<@@=mark>
% \end{macrocode}
%
% \begin{function}{\@@_update_singlecol_structures:}
% \begin{syntax}
% \cs{@@_update_singlecol_structures:}
% \end{syntax}
% \LaTeXe{} integration function in case we are doing single column
% layouts. It assumes that the page content is already stored in
% \cs{@outputbox} and processes the marks inside that box. It is
% called as part of \cs{@opcol}.
% \end{function}
%
%
% \begin{function}{\@@_update_dblcol_structures:}
% \begin{syntax}
% \cs{@@_update_singlecol_structures:}
% \end{syntax}
% \LaTeXe{} integration function mark used when we are doing double
% column documents. It assumes that the page content is already
% stored in \cs{@outputbox} and processes the marks inside that
% box. It then does different post-processing depending on the start
% of the switch \cs{if@firstcolumn}. If we are in the second column
% it also has to update page marks, otherwise it only updates column
% marks. It too is called as part of \cs{@opcol}.
% \end{function}
%
% \begin{function}{\@@_update_structure:nn}
% \begin{syntax}
% \cs{@@_update_structure:nn} \Arg{region} \Arg{material with marks}
% \end{syntax}
% Helper function that inspects the marks
% inside the second argument and assigns new mark values based on
% that to the \meta{region} given in the first argument.
% For this it first copies the mark structure from \meta{region} to
% \texttt{previous-}\meta{region} and then takes all last mark
% values currently in the region and makes them the new top mark
% values. Finally it assigns new first and last values for all mark
% classes based on what was found in the second argument.
%
% As a consequence, the allowed values for \meta{region} are
% \texttt{page} and \texttt{column} because only they have
% \texttt{previous-...} counterparts.
%
% Another important part to keep in mind is that marks are only
% recognized if they appear on top-level, e.g., if we want to
% process material stored in boxes we need to put it unboxed (using
% \cs{unvcopy} etc.)\ into the second argument.
% \end{function}
%
%
%
% \begin{function}{\@@_update_structure_alias:nn}
% \begin{syntax}
% \cs{@@_update_structure_alias:nn} \Arg{alias} \Arg{source}
% \end{syntax}
% Helper function that copies all mark values in the \meta{source}
% region to \meta{alias}, i.e., make the structures identical. Used
% to update the \texttt{previous-...} structures inside
% \cs{@@_update_structure:nn} and \texttt{first-column} and
% \texttt{last-column} structures inside
% \cs{@@_update_singlecol_structures:} or
% \cs{@@_update_dblcol_structures:}.
% \end{function}
%
%
%
%
% \begin{function}{\@@_update_structure_to_err:n}
% \begin{syntax}
% \cs{@@_update_structure_to_err:n} \Arg{region}
% \end{syntax}
% Helper function that sets all mark values in the \meta{region} to
% an error message. This is currently used for \texttt{last-column}
% at times where using marks from it would be questionable/wrong, i.e.,
% when we have just processed the first column in a two-column document.
% \end{function}
%
%
%
% ^^A \end{documentation}
%
%
%
%
%
% \StopEventually{\setlength\IndexMin{200pt} \PrintIndex }
%
%
% \section{The Implementation}
%
%
%
% \begin{macrocode}
%<*2ekernel|latexrelease>
% \end{macrocode}
%
% \begin{macrocode}
\ExplSyntaxOn
% \end{macrocode}
%
% \begin{macrocode}
%<latexrelease>\NewModuleRelease{2022/06/01}{ltmarks}
%<latexrelease> {Marks~handling}
% \end{macrocode}
%
% \subsection{Allocating new mark classes}
%
%
% \begin{variable}{\g_@@_classes_seq}
% A list holding all the mark classes that have been declared.
% \begin{macrocode}
\seq_new:N \g_@@_classes_seq
% \end{macrocode}
% \end{variable}
%
%
%
%
% \begin{macro}{\mark_new_class:n,\@@_new_class:nn}
% A mark class is created by initializing a number of data
% structures. First, we get a register number to refer to the mark class.
% The new mark class is then added to the \cs{g_@@_classes_seq}
% sequence to be able to easily loop over all classes. Finally a
% number of top-level global token lists are declared that hold
% various versions of the mark for access.
% \begin{macrocode}
\cs_new_protected:Npn \mark_new_class:n #1
{
\seq_if_in:NnTF \g_@@_classes_seq {#1}
{
\msg_error:nnn { mark } { class-already-defined }
{#1}
}
{ \@@_new_class:nn {#1} }
}
% \end{macrocode}
% This is only available in the preamble.
% \changes{v1.0c}{2022/05/06}{Wrong command made \cs{@onlypreamble}}
% \begin{macrocode}
\@onlypreamble \mark_new_class:n
% \end{macrocode}
% The internal command carries out the necessary allocations.
% \begin{macrocode}
\cs_new_protected:Npn \@@_new_class:nn #1
{
%<*trace>
\@@_debug:n { \iow_term:x { Marks:~new~mark:~#1~\msg_line_context: } }
%</trace>
% \end{macrocode}
% Use the \LaTeXe{} interface for now as the L3 programming layer
% doesn't have one for marks yet.
% \begin{macrocode}
\exp_args:Nc \newmarks {c_@@_class_ #1 _mark}
% \end{macrocode}
% Remember the new class in the sequence.
% \begin{macrocode}
\seq_gput_right:Nn \g_@@_classes_seq {#1}
% \end{macrocode}
% We need three token lists for each region, one for top, first,
% and last.
% \begin{macrocode}
\tl_new:c { g_@@_page_top_ #1 _tl }
\tl_new:c { g_@@_page_first_ #1 _tl }
\tl_new:c { g_@@_page_last_ #1 _tl }
% \end{macrocode}
% For the \texttt{page} region we also keep track of the
% \texttt{previous-page}.
% \begin{macrocode}
\tl_new:c { g_@@_previous-page_top_ #1 _tl }
\tl_new:c { g_@@_previous-page_first_ #1 _tl }
\tl_new:c { g_@@_previous-page_last_ #1 _tl }
% \end{macrocode}
% Same game for \texttt{column} and \texttt{previous-column}
% \begin{macrocode}
\tl_new:c { g_@@_column_top_ #1 _tl }
\tl_new:c { g_@@_column_first_ #1 _tl }
\tl_new:c { g_@@_column_last_ #1 _tl }
\tl_new:c { g_@@_previous-column_top_ #1 _tl }
\tl_new:c { g_@@_previous-column_first_ #1 _tl }
\tl_new:c { g_@@_previous-column_last_ #1 _tl }
% \end{macrocode}
% But for columns we also allocate token lists for the alias
% regions \texttt{first-column} and \texttt{last-column}.
% \begin{macrocode}
\tl_new:c { g_@@_first-column_top_ #1 _tl }
\tl_new:c { g_@@_first-column_first_ #1 _tl }
\tl_new:c { g_@@_first-column_last_ #1 _tl }
\tl_new:c { g_@@_last-column_top_ #1 _tl }
\tl_new:c { g_@@_last-column_first_ #1 _tl }
\tl_new:c { g_@@_last-column_last_ #1 _tl }
}
% \end{macrocode}
% \end{macro}
%
%
%
%
% \subsection{Updating mark structures}
%
%
% \begin{macro}{\l_@@_box,\g_@@_tmp_tl,\g_@@_new_top_tl}
% For some operations we need a temporary private box and two
% private global token lists.
% \begin{macrocode}
\box_new:N \l_@@_box
\tl_new:N \g_@@_tmp_tl
\tl_new:N \g_@@_new_top_tl
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\@@_update_structure:nn}
%
% This function updates the mark structures. The first argument is
% the region to update and second argument receives the material
% that holds the marks. Out of this material we extract the first
% and last marks for all classes (if there are any) to do the
% assignments.
%
% \begin{macrocode}
\cs_new_protected:Npn \@@_update_structure:nn #1#2
{
% \end{macrocode}
% First thing we do is copying the current structure to
% \texttt{previous-...}; this leaves the current structure
% untouched so we can update it class by class (which is necessary).
% \begin{macrocode}
\@@_update_structure_alias:nn { previous-#1 } {#1}
% \end{macrocode}
% Getting the first and last marks out of the material in \verb=#2=
% is done by putting the material in a box and then doing a
% split operation to the maximum size possible (which hopefully
% means all of the content).\footnote{We could verify this, maybe we
% should.} Because this is an action only for the sake of getting
% at the mark values we don't want any underfull
% box warnings so we turn those (locally) off.
% \begin{macrocode}
\group_begin:
\dim_set_eq:NN \tex_splitmaxdepth:D \c_max_dim
\int_set_eq:NN \tex_vbadness:D \c_max_int
\dim_set_eq:NN \tex_vfuzz:D \c_max_dim
% \end{macrocode}
% There is a further complication: if the region contains infinite
% shrinking glue then a \tn{vsplit} operation will balk with a
% low-level error. Now pages or columns, which are our main concern here, can't
% have such infinite shrinkage if they are cut straight from the
% galley, however the use of \tn{enlargethispage} actually does add
% some at the very bottom (and also wraps the whole page into a box
% by itself, so if we leave it this way then a) we get this error
% and b) we don't see any marks because they are hidden one level
% down).
%
% Another possible issue are packages or user code that place stray
% \tn{vbox}es directly into the main galley (an example is
% \pkg{marginnote} that attaches its marginals in this way). If such
% boxes end up as the last item on the page we should not unpack
% them.
%
% We therefore do an \tn{unskip} to get rid of that glue if present and
% also check if we have then a \tn{vbox} as the last item and if so
% unpack that too, but only under certain conditions, see
% below. All this is temporary, just for getting the
% marks out, so it doesn't affect the final page production.
%
% In fact, we go one step further and set the box to a large
% negative height possible and afterwards take a look at the
% reported badness: if it is zero we know that there has still been
% infinite shrinkage in the box so that we can't do a
% \tn{vsplit}. If that is the case we generate an error message and
% bypass extracting the marks. We use only half of \cs{c_max_dim}
% because otherwise \TeX{} will report an overfull vbox despite our
% setting of \cs{tex_vfuzz:D}. This test will not find existing
% infinite shrinkage in all cases, e.g., if there are several glues
% that cancel each other, but it is the best we can do.
% \begin{macrocode}
\vbox_set_to_ht:Nnn \l_@@_box { -.5\c_max_dim }
{
#2
\tex_unskip:D
\box_set_to_last:N \l_@@_box
% \end{macrocode}
% After having removed the last box from the current list (if there
% was one)
% we check if the list is now empty. If not, the the last box is
% definitely not the one from \tn{enlargethispage} and so we can
% and should leave it alone. Otherwise we check if this last box is
% a \tn{vbox}.
% \changes{v1.0d}{2022/06/01}{Extend the logic for detecting the marks
% in the box (gh/836)}
% \begin{macrocode}
\int_compare:nNnT \tex_lastnodetype:D < 0
{
\box_if_vertical:NT \l_@@_box
{
% \end{macrocode}
% If it is we do a further test and reset the \cs{l_@@_box}
% to check if it contains infinitely shrinkable glue.
% \begin{macrocode}
\vbox_set_to_ht:Nnn \l_@@_box { -.5\c_max_dim }
{
\vbox_unpack:N \l_@@_box
\tex_kern:D \c_zero_dim % ensure that box
% is not empty
}
% \end{macrocode}
% If not, then we unpack it, if yes we still ignore it for the process of
% mark extraction. We do not generate an error though, because in all
% likelihood this is an ordinary box like a marginal that does
% contain something like \tn{vss}.
% \begin{macrocode}
\int_compare:nNnT \tex_badness:D > 0
{ \vbox_unpack:N \l_@@_box }
}
}
% \end{macrocode}
% If it wasn't a vbox, it was either an hbox or there was no box.
% Given that we are only interested in the marks we don't need put
% it back in that case. However, we have to make sure that the
% outer box under construction
% is not totally empty (which it might have been from the start, or
% now), because \TeX{} does not report a badness for empty boxes
% and that means our test would incorrectly conclude that we have
% infinite shrinking glue. A simple \tn{kern} is enough to avoid
% this (the same was already done above).
% \begin{macrocode}
\tex_kern:D \c_zero_dim
}
\int_compare:nNnTF \tex_badness:D > 0
% \end{macrocode}
% If the box had no infinite shrinkage (or rather if our test
% didn't show any) we vsplit it. Note that it
% doesn't matter that we set it to this strange size first. If there
% was infinite shrinkage after all, we end up with a low-level
% \TeX{} error, but if there is, it is a coding error and needs
% correcting.
% \begin{macrocode}
{
\vbox_set_split_to_ht:NNn \l_@@_box \l_@@_box \c_max_dim
% \end{macrocode}
% After this action we can get first and last marks of the various
% classes through \cs{tex_splitfirstmarks:D} and
% \cs{tex_splitbotmarks:D}. So now we loop over all classes stored in
% \cs{g_@@_classes_seq}.
% \begin{macrocode}
\seq_map_inline:Nn \g_@@_classes_seq
{
% \end{macrocode}
% First action: get the last mark from the previous region, i.e.,
% \verb=previous-#1=. But because it is also still inside \verb=#1=,
% at the moment we use that to construct the name because this is a
% tiny bit faster. Given that we
% need this value in various assignments we store it away which
% avoids unnecessary further csname generations.
% \begin{macrocode}
\tl_gset_eq:Nc \g_@@_new_top_tl { g_@@_#1_last_##1_tl }
% \end{macrocode}
% This will first of all become the new top mark for the current class.
% \begin{macrocode}
\tl_gset_eq:cN { g_@@_#1_top_##1_tl } \g_@@_new_top_tl
% \end{macrocode}
% Next action is to get ourselves the new last mark from the
% material supplied.
% \begin{macrocode}
\tl_gset:No \g_@@_tmp_tl
{ \tex_splitbotmarks:D \use:c { c_@@_class_##1_mark } }
% \end{macrocode}
% If this mark doesn't exist then obviously first mark does
% neither, so both become the last mark from the previous region. We
% have to be a little careful here: something like
% \verb=\mark_insert:nn{foo}{}= adds an \enquote{empty} mark that should
% not be confused with no mark at all. But no mark in our material
% will result in \cs{g_@@_tmp_tl} being fully empty. This is why we
% have to make sure that \enquote{empty} from \cs{mark_insert:nn} only
% appears to be empty but fails the next test (see below how this
% is done).
% \begin{macrocode}
\tl_if_empty:NTF \g_@@_tmp_tl
{
\tl_gset_eq:cN { g_@@_#1_last_ ##1_tl }
\g_@@_new_top_tl
\tl_gset_eq:cN { g_@@_#1_first_##1_tl }
\g_@@_new_top_tl
}
% \end{macrocode}
% If it wasn't empty, i.e., if it had a real value then we use this
% value for our new last mark instead.
% \begin{macrocode}
{
\tl_gset_eq:cN { g_@@_#1_last_##1_tl } \g_@@_tmp_tl
% \end{macrocode}
% Because we had a last mark we also have a first mark (which
% might be the same, but might be not), so we pick that up and
% assign it to the appropriate token list. This explains why we first
% checked for the last mark because that makes the processing
% faster in case there is none.
% \begin{macrocode}
\tl_gset:co { g_@@_#1_first_##1_tl }
{
\tex_splitfirstmarks:D
\use:c { c_@@_class_##1_mark }
}
}
}
}
% \end{macrocode}
% If the badness was zero (we actually tested for${}>0$ but it
% can't get negative) then we had infinite shrinkage, so we report
% that and set all marks to the value the last mark had before.
% \begin{macrocode}
{
\msg_error:nnn { mark } { infinite-shrinkage } {#1}
\seq_map_inline:Nn \g_@@_classes_seq
{
\tl_gset_eq:cc { g_@@_#1_top_ ##1_tl }
{ g_@@_#1_last_ ##1_tl }
\tl_gset_eq:cc { g_@@_#1_first_##1_tl }
{ g_@@_#1_last_ ##1_tl }
}
}
% \end{macrocode}
% Once all mark classes have been processed the data structures are
% updated and we can close the group which undoes our local
% changes and retains only the global ones.
% \begin{macrocode}
\group_end:
}
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\@@_update_structure_alias:nn}
% This function copies the structure for one region to another
% (name), e.g., from \texttt{page} to \texttt{previous-page} above,
% or later from \texttt{column} to \texttt{first-column}, etc.
% \begin{macrocode}
\cs_new_protected:Npn \@@_update_structure_alias:nn #1#2 {
% \end{macrocode}
% This requires a simple loop through all mark classes copying the
% token list from one name to the next.
% \begin{macrocode}
\seq_map_inline:Nn \g_@@_classes_seq
{
\tl_gset_eq:cc { g_@@_ #1 _top_ ##1 _tl }
{ g_@@_ #2 _top_ ##1 _tl }
\tl_gset_eq:cc { g_@@_ #1 _first_ ##1 _tl }
{ g_@@_ #2 _first_ ##1 _tl }
\tl_gset_eq:cc { g_@@_ #1 _last_ ##1 _tl }
{ g_@@_ #2 _last_ ##1 _tl }
}
}
% \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\@@_update_structure_to_err:n,\@@_error:n}
% A slight variation is to install a fixed error message as the value.
% \begin{macrocode}
\cs_new_protected:Npn \@@_update_structure_to_err:n #1 {
\seq_map_inline:Nn \g_@@_classes_seq
{
\tl_gset:cn { g_@@_ #1 _top_ ##1 _tl } { \@@_error:n {#1} }
\tl_gset:cn { g_@@_ #1 _first_ ##1 _tl } { \@@_error:n {#1} }
\tl_gset:cn { g_@@_ #1 _last_ ##1 _tl } { \@@_error:n {#1} }
}
}
% \end{macrocode}
% Given that this is used in only one place, we could hardwire the
% argument which would be a bit more compact, but who knows,
% perhaps we end up with another reason to use this error command
% elsewhere, so for now we keep the argument.
% \begin{macrocode}
\cs_new_protected:Npn \@@_error:n #1 {
\msg_error:nnn { mark } { invalid-use } {#1}
}
% \end{macrocode}
% \end{macro}
%
%
%
%
% \subsection{Placing and retrieving marks}
%
%
%
% \begin{macro}{\mark_insert:nn}
% This function puts a mark for some \meta{class} at the current point.
% \begin{macrocode}
\cs_new_protected:Npn \mark_insert:nn #1#2
{
\seq_if_in:NnTF \g_@@_classes_seq {#1}
{
% \end{macrocode}
% We need to pass the evaluated argument into the mark but protected
% commands should not expand including those protected using the \cs{protect} approach of
% \LaTeXe{}. We also disable \cs{label} and the
% like.\footnote{Straight copy from \texttt{latex.ltx} but is this
% even correct? At least a label in a running header makes little
% sense if it get set several times! Maybe that needs looking at in
% the 2e kernel.}
%
% At this point the code eventually should get a public
% (and a kernel) hook instead of a set of hardwired settings.
% \begin{macrocode}
\group_begin:
% \end{macrocode}
% Within the group we alter some comments, e.g, \cs{label} or
% \cs{index}, to do the right at this point. This is done in the
% kernel hook \cs{@kernel@before@insertmark} which is followed by
% the public hook \hook{insertmark} that can be used by packages to
% augment or alter that setup as necessary.
% \begin{macrocode}
\@kernel@before@insertmark
\hook_use:n { insertmark }
\unrestored@protected@xdef \g_@@_tmp_tl {#2}
%<*trace>
\@@_debug:n{ \iow_term:x { Marks:~ set~#1~<-~
'\tl_to_str:V \g_@@_tmp_tl' ~ \msg_line_context: } }
%</trace>
\tex_marks:D \use:c { c_@@_class_ #1 _mark }
{
% \end{macrocode}
% Here is the trick to avoid truly empty marks: if the result from
% the above processing is empty we add something which eventually
% becomes empty, but not immediately; otherwise we just put
% \cs{g_@@_tmp_tl} in.
% \begin{macrocode}
\tl_if_empty:NTF \g_@@_tmp_tl
{ \exp_not:n { \prg_do_nothing: } }
{ \exp_not:o { \g_@@_tmp_tl } }
}
\group_end:
% \end{macrocode}
% A mark introduces a possible break point and in certain
% situations that should not happen in vertical mode in \LaTeX{}.
% This needs some cleanup \ldots.
% \begin{macrocode}
\if@nobreak\ifvmode\nobreak\fi\fi
}
% \end{macrocode}
% If the mark class was not known, raise an error.
% \begin{macrocode}
{
\msg_error:nnx { mark } { unknown-class }
{ \tl_to_str:n {#1} }
}
}
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}[int]{\@kernel@before@insertmark}
% \begin{macro}{insertmark}
% By default \cs{label}, \cs{index}, and \cs{glossary} do nothing
% when the mark is inserted.
% \begin{macrocode}
\cs_new:Npn \@kernel@before@insertmark {
\cs_set_eq:NN \label \scan_stop:
\cs_set_eq:NN \index \scan_stop:
\cs_set_eq:NN \glossary \scan_stop:
}
% \end{macrocode}
% The public hook to augment the setup.
% \begin{macrocode}
\hook_new:n {insertmark}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}[EXP]{\mark_use_top:nn, \mark_use_first:nn, \mark_use_last:nn}
%
% To retrieve the first, last or top region mark, we grab the
% appropriate value stored in the corresponding token list variable
% and pass its contents back. These functions should be used only
% in output routines after \cs{@@_update_structure:nn} has acted,
% otherwise their value will be wrong.
%
% If used with an unknown class or region they generate an error
% (fairly low-level because we are in an expandable context).
% \begin{macrocode}
\cs_new:Npn \mark_use_first:nn #1#2 { \exp_not:v { g_@@_#1_first_#2_tl } }
\cs_new:Npn \mark_use_last:nn #1#2 { \exp_not:v { g_@@_#1_last_#2_tl } }
\cs_new:Npn \mark_use_top:nn #1#2 { \exp_not:v { g_@@_#1_top_#2_tl } }
% \end{macrocode}
% \end{macro}
%
%
%
%
% \subsection{Comparing mark values}
%
%
%
% \begin{macro}[TF,EXP]{\mark_if_eq:nnnn,\mark_if_eq:nnnnnn}
% Test if in a given region (\verb=#1=) for a given class
% (\verb=#2=) the marks in position \verb=#3= and \verb=#4= (top,
% first, or last) are identical
% \begin{macrocode}
\prg_new_conditional:Npnn \mark_if_eq:nnnn #1#2#3#4 { T , F , TF }
{
\tl_if_eq:ccTF { g_@@_ #1 _#3_ #2 _tl }
{ g_@@_ #1 _#4_ #2 _tl }
\prg_return_true:
\prg_return_false:
}
% \end{macrocode}
% The fully general test (with two triplets of the form
% \meta{region}, \meta{class}, and \meta{position}) is this:
% \begin{macrocode}
\prg_new_conditional:Npnn \mark_if_eq:nnnnnn #1#2#3#4#5#6 { T , F , TF }
{
\tl_if_eq:ccTF { g_@@_ #1 _#3_ #2 _tl }
{ g_@@_ #4 _#6_ #5 _tl }
\prg_return_true:
\prg_return_false:
}
% \end{macrocode}
% \end{macro}
%
%
%
% \subsection{Messages}
%
% Mark errors are LaTeX kernel errors:
% \changes{v1.0d}{2022/06/01}{Marks are kernel errors}
% \begin{macrocode}
\prop_gput:Nnn \g_msg_module_type_prop { mark } { LaTeX }
% \end{macrocode}
%
% \begin{macrocode}
\msg_new:nnnn { mark } { class-already-defined }
{ Mark~class~'#1'~already~defined }
{
\c__msg_coding_error_text_tl
LaTeX~was~asked~to~define~a~new~mark~class~called~'#1':~
this~mark~class~already~exists.
\c__msg_return_text_tl
}
% \end{macrocode}
%
% \begin{macrocode}
\msg_new:nnnn { mark } { unknown-class }
{ Unknown~mark~class~'#1'. }
{
\c__msg_coding_error_text_tl
LaTeX~was~asked~to~manipulate~a~mark~of~class~'#1',~
but~this~class~of~marks~does~not~exist.
}
% \end{macrocode}
%
%
% \begin{macrocode}
\msg_new:nnnn { mark } { invalid-use }
{ Mark~region~'#1'~not ~usable }
{
\c__msg_coding_error_text_tl
The~region~'#1'~can~only~be~used~after~
all~columns~have~been~assembled.
\c__msg_return_text_tl
}
% \end{macrocode}
%
% \begin{macrocode}
\msg_new:nnnn { mark } { infinite-shrinkage }
{ Infinite~shrinkage~found~in~'#1'. }
{
\c__msg_coding_error_text_tl
The~mark~region~'#1'~contains~some~infinite~negative~glue~
allowing~it~to~shrink~to~an~arbitrary~size.~
This~makes~it~impossible~to~split~the~region~apart~to~
get~at~its~marks.~They~are~lost.
}
% \end{macrocode}
%
%
%
% \subsection{Debugging the mark structures}
%
% Code and commands in this section are not final, it needs more
% experimentation to see what kind of tracing information is going to
% be useful in practice. For now the tracing is mainly meant to be used
% for code testing and not so much for application testing.
%
% It is quite likely that the
% commands and the behavior of the tracing might change in the
% future once we gained some experience with it.
%
% \begin{macro}{\g_@@_debug_bool}
% Holds the current debugging state.
% \begin{macrocode}
\bool_new:N \g_@@_debug_bool
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\mark_debug_on:,\mark_debug_off:}
% \begin{macro}{\@@_debug:n}
% \begin{macro}{\@@_debug_gset:}
% Turns debugging on and off by redefining \cs{@@_debug:n}.
% \begin{macrocode}
\cs_new_eq:NN \@@_debug:n \use_none:n
\cs_new_protected:Npn \mark_debug_on:
{
\bool_gset_true:N \g_@@_debug_bool
\@@_debug_gset:
}
\cs_new_protected:Npn \mark_debug_off:
{
\bool_gset_false:N \g_@@_debug_bool
\@@_debug_gset:
}
\cs_new_protected:Npn \@@_debug_gset:
{
\cs_gset_protected:Npx \@@_debug:n ##1
{ \bool_if:NT \g_@@_debug_bool {##1} }
}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
%
%
% \begin{macro}{\DebugMarksOn,\DebugMarksOff}
% CamelCase commands for debugging.
% \begin{macrocode}
\cs_new_eq:NN \DebugMarksOn \mark_debug_on:
\cs_new_eq:NN \DebugMarksOff \mark_debug_off:
% \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\@@_class_status:nn}
% Shows the mark values across all regions for one mark class
% (\verb=#2=). The first argument gives some \meta{info} to help
% identifying where the command was called.
% \begin{macrocode}
%<*trace>
\cs_new_protected:Npn \@@_class_status:nn #1#2
{
\typeout{ Marks:~#2~ #1:}
\typeout{\@spaces page~ (current):
| \exp_not:v { g_@@_page_top_ #2 _tl }
| \exp_not:v { g_@@_page_first_ #2 _tl }
| \exp_not:v { g_@@_page_last_ #2 _tl } |}
\typeout{\@spaces page~ (previous):
| \exp_not:v { g_@@_previous-page_top_ #2 _tl }
| \exp_not:v { g_@@_previous-page_first_ #2 _tl }
| \exp_not:v { g_@@_previous-page_last_ #2 _tl } |}
\typeout{\@spaces column~ (previous):
| \exp_not:v { g_@@_previous-column_top_ #2 _tl }
| \exp_not:v { g_@@_previous-column_first_ #2 _tl }
| \exp_not:v { g_@@_previous-column_last_ #2 _tl } |}
\typeout{\@spaces column~ (current):
| \exp_not:v { g_@@_column_top_ #2 _tl }
| \exp_not:v { g_@@_column_first_ #2 _tl }
| \exp_not:v { g_@@_column_last_ #2 _tl } |}
\typeout{\@spaces column~ (first):
| \exp_not:v { g_@@_first-column_top_ #2 _tl }
| \exp_not:v { g_@@_first-column_first_ #2 _tl }
| \exp_not:v { g_@@_first-column_last_ #2 _tl } |}
\typeout{\@spaces column~ (second):
| \exp_not:v { g_@@_last-column_top_ #2 _tl }
| \exp_not:v { g_@@_last-column_first_ #2 _tl }
| \exp_not:v { g_@@_last-column_last_ #2 _tl } |}
}
% \end{macrocode}
% \end{macro}
%
%
%
%
% \begin{macro}{\@@_status:n}
% Show all mark class values across all regions.
% \begin{macrocode}
\cs_new_protected:Npn \@@_status:n #1
{
\seq_map_inline:Nn \g_@@_classes_seq
{ \@@_class_status:nn {#1} {##1} }
}
%</trace>
% \end{macrocode}
% \end{macro}
%
%
%
%
% \subsection{Designer-level interfaces}
%
%
% \begin{macro}{\NewMarkClass,\InsertMark}
% These two are identical to the L3 programming layer commands.
% \begin{macrocode}
\cs_new_eq:NN \NewMarkClass \mark_new_class:n
\@onlypreamble \NewMarkClass
% \end{macrocode}
%
% \begin{macrocode}
\cs_new_eq:NN \InsertMark \mark_insert:nn
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}[EXP]{\TopMark, \FirstMark, \LastMark}
% The following commands take an optional argument that defaults to
% page. There is no checking that the region is actually valid. If
% not there is simply an empty return.
% \begin{macrocode}
\NewExpandableDocumentCommand \FirstMark { O{page} m }
{ \mark_use_first:nn {#1}{#2} }
% \end{macrocode}
%
% \begin{macrocode}
\NewExpandableDocumentCommand \LastMark { O{page} m }
{ \mark_use_last:nn {#1}{#2} }
% \end{macrocode}
%
% \begin{macrocode}
\NewExpandableDocumentCommand \TopMark { O{page} m }
{ \mark_use_top:nn {#1}{#2} }
% \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}[EXP]{\IfMarksEqualTF}
% We only provide a CamelCase command for the case with one region
% (optional) and one class. One could think of also providing a
% version for the general case with several optional arguments, but
% use cases for this are most likely rare, so not done yet.
% \begin{macrocode}
\NewExpandableDocumentCommand \IfMarksEqualTF {O{page}mmm} {
\mark_if_eq:nnnnTF {#1}{#2}{#3}{#4}
}
% \end{macrocode}
% \end{macro}
%
%
%
%
% \section{\LaTeXe{} integration}
%
% \subsection{Core \LaTeXe{} integration}
%
% \begin{macro}{\@@_update_singlecol_structures:}
% This command updates the mark structures if we are producing a
% single column document.
% \begin{macrocode}
\cs_new_protected:Npn \@@_update_singlecol_structures: {
% \end{macrocode}
% First we update the \texttt{page} region (which also updates the
% \texttt{previous-page}.
%
% The \cs{@outputbox} is normally in \cs{vbox} in \LaTeX{} but we
% can't take that for granted (an \pkg{amsmath} test document
% changed it to an \cs{hbox} just to trip me up) so we are a little
% careful with unpack now.
% \begin{macrocode}
\box_if_vertical:NTF \@outputbox
{
\@@_update_structure:nn {page}
{ \vbox_unpack:N \@outputbox }
}
{
\@@_update_structure:nn {page}
{ \hbox_unpack:N \@outputbox }
}
% \end{macrocode}
% The we provide the necessary updates for the aliases.
% \begin{macrocode}
\@@_update_structure_alias:nn {previous-column}{previous-page}
\@@_update_structure_alias:nn {column}{page}
\@@_update_structure_alias:nn {first-column}{page}
\@@_update_structure_alias:nn {last-column}{page}
%<*trace>
% move this into status itself?
\@@_debug:n
{
\@@_status:n
{ in~ OR~ (
\legacy_if:nTF {@twoside}
{ twoside-
\int_if_odd:nTF \c@page
{ odd }{ even }
}
{ oneside }
)
}
}
%</trace>
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_update_dblcol_structures:}
% This commands handles the updates if we are doing two-column pages.
% \begin{macrocode}
\cs_new_protected:Npn \@@_update_dblcol_structures: {
% \end{macrocode}
% First we update the \texttt{column} and \texttt{previous-column}
% regions using the material assembled in \cs{@outputbox}.
% \begin{macrocode}
\box_if_vertical:NTF \@outputbox
{
\@@_update_structure:nn {column}
{ \vbox_unpack:N \@outputbox }
}
{
\@@_update_structure:nn {column}
{ \hbox_unpack:N \@outputbox }
}
% \end{macrocode}
% How we have to update the alias regions depends on whether or not
% \cs{@opcol} was called to process the first column or to produce
% the completed page
% \begin{macrocode}
\legacy_if:nTF {@firstcolumn}
{
% \end{macrocode}
% If we are processing the first column then \texttt{column} is our
% \texttt{first-column} and there is no \texttt{last-column} yet,
% so we make those an error.
% \begin{macrocode}
\@@_update_structure_alias:nn {first-column}{column}
\@@_update_structure_to_err:n {last-column}
}
{
% \end{macrocode}
% If we produce the completed page then the \texttt{first-column}
% is the same as the new \texttt{previous-column}. However, the
% structure should already be correct if you think about it
% (because is was set to \texttt{column} last time which is now the
% \texttt{previous-column}), thus there is no need to make an update.
% \begin{macrocode}
% \@@_update_structure_alias:nn {first-column}{previous-column}
% \end{macrocode}
% However, we now have a proper \texttt{last-column} so we assign that.
% \begin{macrocode}
\@@_update_structure_alias:nn {last-column}{column}
% \end{macrocode}
% What now remains doing is to update the \texttt{page} and
% \texttt{previous-page} regions. For this we have to copy the
% settings in \texttt{page} into \texttt{previous-page} and then
% update \texttt{page} such that the top and first marks are taken
% from the \texttt{first-column} region and the last marks are
% taken from the \texttt{last-column} region. All this has to be
% done for all mark classes so we loop over our sequence.
%
% Note that one loop is needed if we arrange the copy statements in
% a suitable way.
% \begin{macrocode}
\seq_map_inline:Nn \g_@@_classes_seq
{
\tl_gset_eq:cc { g_@@_previous-page_top_ ##1 _tl }
{ g_@@_page_top_ ##1 _tl }
\tl_gset_eq:cc { g_@@_previous-page_first_ ##1 _tl }
{ g_@@_page_first_ ##1 _tl }
\tl_gset_eq:cc { g_@@_previous-page_last_ ##1 _tl }
{ g_@@_page_last_ ##1 _tl }
% \end{macrocode}
% The \texttt{page} updates need to come after the corresponding
% updates for \texttt{previous-page} otherwise we loose the
% necessary value.
% \begin{macrocode}
\tl_gset_eq:cc { g_@@_page_top_ ##1 _tl }
{ g_@@_first-column_top_ ##1 _tl }
\tl_gset_eq:cc { g_@@_ page_first_ ##1 _tl }
{ g_@@_first-column_first_ ##1 _tl }
\tl_gset_eq:cc { g_@@_page_last_ ##1 _tl }
{ g_@@_last-column_last_ ##1 _tl }
}
}
%<*trace>
\@@_debug:n
{
\@@_status:n
{ in~ OR~ (
\legacy_if:nTF {@twoside}
{ twoside-
\int_if_odd:nTF \c@page
{ odd }{ even }
}
{ oneside }
\space
\legacy_if:nTF {@firstcolumn}
{ first~ }{ second~ }
column )
}
}
%</trace>
}
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%<@@=>
% \end{macrocode}
%
% \begin{macro}[int]{\@expl@@@mark@update@singlecol@structures@@,
% \@expl@@@mark@update@dblcol@structures@@}
% \begin{macrocode}
\cs_new_eq:NN \@expl@@@mark@update@singlecol@structures@@
\__mark_update_singlecol_structures:
\cs_new_eq:NN \@expl@@@mark@update@dblcol@structures@@
\__mark_update_dblcol_structures:
% \end{macrocode}
% \end{macro}
%
% \subsection{Other \LaTeXe{} output routines}
%
% This section will cover \pkg{multicol} and other packages altering
% or providing their own output routine. Not done yet.
%
%
%
%
% \begin{macrocode}
%<latexrelease>\IncludeInRelease{0000/00/00}{ltmarks}%
%<latexrelease> {Undo~Marks~handling}
%<latexrelease>
% \end{macrocode}
% We keep the interface commands around even if we roll back in
% case they are used in packages that don't roll back. Not likely
% to do a lot of good, but then there is not much we can do, but
% this at least then doesn't give errors.
% \begin{macrocode}
%<latexrelease>\DeclareRobustCommand \NewMarkClass[1]{}
%<latexrelease>\DeclareRobustCommand \InsertMark[2]{}
%<latexrelease>\RenewExpandableDocumentCommand \FirstMark { O{} m } { }
%<latexrelease>\RenewExpandableDocumentCommand \LastMark { O{} m } { }
%<latexrelease>\RenewExpandableDocumentCommand \TopMark { O{} m } { }
%<latexrelease>\RenewExpandableDocumentCommand \IfMarksEqualTF { O{} mmm }{ }
%<latexrelease>
% \end{macrocode}
% Same here, this avoided extra roll back code in the OR.
% \begin{macrocode}
%<latexrelease>\let \@expl@@@mark@update@singlecol@structures@@ \relax
%<latexrelease>\let \@expl@@@mark@update@dblcol@structures@@ \relax
%<latexrelease>
%<latexrelease>
%<latexrelease>\EndModuleRelease
% \end{macrocode}
%
% \begin{macrocode}
\ExplSyntaxOff
% \end{macrocode}
% \begin{macrocode}
%</2ekernel|latexrelease>
% \end{macrocode}
%
% Reset module prefix:
% \begin{macrocode}
%<@@=>
% \end{macrocode}
%
%
%
%
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\endinput
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
