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author | Karl Berry <karl@freefriends.org> | 2022-05-19 20:13:40 +0000 |
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committer | Karl Berry <karl@freefriends.org> | 2022-05-19 20:13:40 +0000 |
commit | 0068dc20e7132f24c1bb68957ef6ad5ea5b46157 (patch) | |
tree | 247f86a1a065910b2aabe033e4e10f5e62cbc5cf /Master/texmf-dist/source/latex-dev/base/ltmarks.dtx | |
parent | b48cdc7688e6483099499c0e3ec927b258e0f569 (diff) |
latex-dev (19may22)
git-svn-id: svn://tug.org/texlive/trunk@63339 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/texmf-dist/source/latex-dev/base/ltmarks.dtx')
-rw-r--r-- | Master/texmf-dist/source/latex-dev/base/ltmarks.dtx | 1602 |
1 files changed, 1602 insertions, 0 deletions
diff --git a/Master/texmf-dist/source/latex-dev/base/ltmarks.dtx b/Master/texmf-dist/source/latex-dev/base/ltmarks.dtx new file mode 100644 index 00000000000..e8971c9d6c5 --- /dev/null +++ b/Master/texmf-dist/source/latex-dev/base/ltmarks.dtx @@ -0,0 +1,1602 @@ +% \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{v1.0c} +\def\ltmarksdate{2022/05/06} +% \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 \cs{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 \cs{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). +% +% We therefore do an \tn{unskip} to get rid of that glue if present and +% also check if we have then a \cs{vbox} as the last item and if so +% unpack that too. 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 + \box_if_vertical:NT \l_@@_box + { \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 box +% is not totally empty (which it might have been from the start, or +% now), because \TeX{} does not report a badness for empty boxes +% which means out test would incorrectly conclude that we have +% infinite shrinking glue. A simple \tn{kern} is enough to avoid this. +% \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} +% +% \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 +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +% |