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diff --git a/Master/texmf-dist/source/latex/revtex/ltxgrid.dtx b/Master/texmf-dist/source/latex/revtex/ltxgrid.dtx new file mode 100644 index 00000000000..ab0209ed098 --- /dev/null +++ b/Master/texmf-dist/source/latex/revtex/ltxgrid.dtx @@ -0,0 +1,4815 @@ +% \iffalse ltxdoc klootch +% ltxgrid.dtx: package to change page grid, MVL. +% Copyright (c) 1999 Arthur Ogawa +% +% Disclaimer +% This file is distributed WITHOUT ANY WARRANTY; +% without even the implied warranty of +% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. +% ReadMe +% For the documentation and more detailed instructions for +% installation, typeset this document with \LaTeX. +% \fi +% \GetFileInfo{ltxgrid.dtx}\CheckSum{4234} +% +% \iffalse ltxdoc klootch +%<*ltxgrid> +%%% @LaTeX-file{ +%%% filename = "ltxgrid.dtx", +%%% version = "1.0rc5", +%%% date = "2001/07/26", +%%% time = "12:23:00 GMT+8", +%%% checksum = "4234", +%%% author = "Arthur Ogawa (mailto:ogawa@teleport.com), +%%% commissioned by the American Physical Society. +%%% ", +%%% copyright = "Copyright (C) 1999, 2000 Arthur Ogawa, +%%% distributed under the terms of the +%%% LaTeX Project Public License, see +%%% ftp://ctan.tug.org/macros/latex/base/lppl.txt +%%% ", +%%% address = "Arthur Ogawa, +%%% USA", +%%% telephone = "", +%%% FAX = "", +%%% email = "ogawa@teleport.com", +%%% codetable = "ISO/ASCII", +%%% keywords = "latex, page grid, main vertical list", +%%% supported = "yes", +%%% abstract = "package to change page grid, MVL", +%%% docstring = "The checksum field above generated by ltxdoc", +%%% } +%</ltxgrid> +% \fi +% +% \iffalse ltxdoc klootch +% The following references the \file{00readme.txt} file, +% which contains basic information about this package. +% The contents of this file are generated when +% you typeset the programmer's documentation. +% Search on "{filecontents*}{00readme.txt}" to locate it. +% \fi\input{00readme.txt}% +% +% \subsection{Bill of Materials} +% +% Following is a list of the files in this distribution arranged +% according to provenance. +% +% \subsubsection{Primary Source}% +% One single file generates all. +%\begin{verbatim} +%ltxgrid.dtx +%\end{verbatim} +% +% \subsubsection{Generated by \texttt{latex ltxgrid.dtx}}% +% Typesetting the source file under \LaTeX\ +% generates the readme and the installer. +%\begin{verbatim} +%00readme.txt ltxgrid.ins +%\end{verbatim} +% +% \subsubsection{Generated by \texttt{tex ltxgrid.ins}}% +% Typesetting the installer generates +% the package files. +%\begin{verbatim} +%ltxgrid.sty +%\end{verbatim} +% +% \subsubsection{Documentation}% +% The following are the online documentation: +% \begin{verbatim} +%ltxgrid.pdf +% \end{verbatim} +% +% \subsubsection{Auxiliary}% +% The following are auxiliary files generated +% in the course of running \LaTeX: +% \begin{verbatim} +%ltxgrid.aux ltxgrid.idx ltxgrid.ind ltxgrid.log ltxgrid.toc +% \end{verbatim} +% +% \section{Code common to all modules}% +% +% The following may look a bit klootchy, but we +% want to require only one place in this file +% where the version number is stated, +% and we also want to ensure that the version +% number is embedded into every generated file. +% +% Now we declare that +% these files can only be used with \LaTeXe. +% An appropriate message is displayed if +% a different \TeX{} format is used. +% \begin{macrocode} +%<*doc|ltxgrid> +\NeedsTeXFormat{LaTeX2e}[1995/12/01]% +%</doc|ltxgrid> +% \end{macrocode} +% As desired, the following modules all +% take common version information: +% \begin{macrocode} +%<ltxgrid>\ProvidesFile{ltxgrid.sty}% +%<*doc> +\expandafter\ProvidesFile\expandafter{\jobname.dtx}% +%</doc> +% \end{macrocode} +% +% The following line contains, for once and for all, +% the version and date information. +% By various means, this information is reproduced +% consistently in all generated files and in the +% typeset documentation. +% \begin{macrocode} +%<*doc|ltxgrid> + [2001/07/26 1.0rc5 page grid package]% \fileversion +%</doc|ltxgrid> +% \end{macrocode} +% +% +% \section{The driver module \texttt{doc}} +% +% This module, consisting of the present section, +% typesets the programmer's documentation, +% generating the \file{.ins} installer and \file{00readme.txt} as required. +% +% Because the only uncommented-out lines of code at the beginning of +% this file constitute the \file{doc} module itself, +% we can simply typeset the \file{.dtx} file directly, +% and there is thus rarely any need to +% generate the ``doc'' {\sc docstrip} module. +% Module delimiters are nonetheless required so that +% this code does not find its way into the other modules. +% +% The \enve{document} command concludes the typesetting run. +% +% \begin{macrocode} +%<*doc> +% \end{macrocode} +% +% \subsection{The Preamble} +% The programmers documentation is formatted +% with the \classname{ltxdoc} class with local customizations, +% and with the usual code line indexing. +% \begin{macrocode} +\documentclass{ltxdoc} +\RequirePackage{ltxdocext}% +\RequirePackage[colorlinks=true,linkcolor=blue]{hyperref}% +\ifx\package@font\@undefined\else + \expandafter\expandafter + \expandafter\RequirePackage + \expandafter\expandafter + \expandafter{% + \csname package@font\endcsname + }% +\fi +\CodelineIndex\EnableCrossrefs +% \end{macrocode} +% +% \subsubsection{Docstrip and info directives} +% We use so many {\sc docstrip} modules that we set the +% \texttt{StandardModuleDepth} counter to 1. +% \begin{macrocode} +\setcounter{StandardModuleDepth}{1} +% \end{macrocode} +% The following command retrieves the date and version information +% from this file. +% \begin{macrocode} +\expandafter\GetFileInfo\expandafter{\jobname.dtx}% +% \end{macrocode} +% +% +% \subsection{The installer file} +% +% The installer \file{ltxgrid.ins} appears here. +% If you have retrieved the standard distribution of this package, +% the installer file is already on your filesystem. +% If you are bootstrapping, +% the first typesetting of the \file{.dtx} file +% will cause the installer to be generated. +% +% The following modules are used to direct +% {\sc docstrip} in generating the external files: +% \begin{center} +% \begin{tabular}{lll} +% \textbf{Module}&\textbf{File}&\textbf{Description}\\ +% doc &\file{ltxgrid.drv}&driver for programmer's documentation\\ +% ltxgrid,ltxgrid-krn &\file{ltxgrid.sty}&this package\\ +% ltxgrid-krn& &the portion of this package suitable for inclusion within another package +% \end{tabular} +% \end{center} +% +% \begin{macrocode} +\begin{filecontents}{ltxgrid.ins} +%% This file will generate documentation and runtime files +%% from ltxgrid.dtx when run through LaTeX or TeX. +\input docstrip +\preamble + +This is a generated file; +altering it directly is inadvisable; +instead, modify the original source file. +See the URL in the file 00readme.txt. + +Copyright notice. + + These files are distributed + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + +\endpreamble +\keepsilent + \generate{% + \file{ltxgrid.drv}{\from{ltxgrid.dtx}{doc}}% + \file{ltxgrid.sty}{% + \from{ltxgrid.dtx}{ltxgrid,ltxgrid-krn}% + }% + }% +\ifToplevel{ +\Msg{***********************************************************} +\Msg{*} +\Msg{* To finish the installation, please move} +\Msg{* ltxgrid.sty} +\Msg{* into a directory searched by TeX;} +\Msg{* in a TDS-compliant installation:} +\Msg{* texmf/tex/macros/latex/ao/.} +\Msg{*} +\Msg{* To produce the documentation, + run ltxgrid.dtx through LaTeX.} +\Msg{*} +\Msg{* Happy TeXing} +\Msg{***********************************************************} +} +\endbatchfile +\end{filecontents} +% \end{macrocode} +% Note that, because all of the files generated by the installer +% are part of the standard distribution, it will +% be necessary to run the installer only when bootstrapping +% (or, of course, during development). +% Note, too, that it is rare to generate the \file{doc} +% module because it suffices to simply typeset the \file{.dtx} file itself. +% +% \subsection{The ``Read Me'' File} +% As promised above, here is the contents of the +% ``Read Me'' file. That file serves a double purpose, +% since it also constitutes the beginining of the +% programmer's documentation. What better thing, after +% all, to have appear at the beginning of the +% typeset documentation? +% +% A good discussion of how to write a ReadMe file can be found in +% Engst, Tonya, ``Writing a ReadMe File? Read This'' +% \emph{MacTech} October 1998, p. 58. +% +% Note the appearance of the +% \cmd\StopEventually\ command, which marks the +% dividing line between the user documentation +% and the programmer documentation. +% +% The usual user will not be asked to +% do a full build, not to speak +% of the bootstrap. +% Instructions for carrying these processes +% begin the programmer's manual. +% +% \begin{macrocode} +\begin{filecontents*}{00readme.txt} +\title{% + A \LaTeX\ Package for changing the page grid and MVL% + \thanks{% + This file has version number \fileversion, + last revised \filedate.% + % For version number and date, + % search on "\fileversion" in the .dtx file, + % or see the end of the 00readme.txt file. + }% +}% + +\author{% +Arthur Ogawa (\texttt{mailto:ogawa@teleport.com}), +\fileversion\\Copyright (C) 1999, 2000 Arthur Ogawa +}% +\maketitle + +This file embodies the \classname{ltxgrid} package, +the implementation and its user documentation. + +The distribution point for this work is +\url{ftp://ftp.teleport.com/users/ogawa/macros/latex/contrib/supported/ltxgrid...}, +which contains fully unpacked, prebuilt runtime files and documentation. + +The \classname{ltxgrid} package was commissioned by the American Physical Society +and is distributed under the terms of the \LaTeX\ Project Public License, +the same license under which all the portions of \LaTeX\ itself is distributed. +Please see \url{http://ctan.tug.org/macros/latex/base/lppl.txt} for details. + +To use this document class, you must have a working +\TeX\ installation equipped with \LaTeXe\ +and possibly pdftex and Adobe Acrobat Reader or equivalent. + +To install, retrieve the distribution, +unpack it into a directory on the target computer, +into a location in your filesystem where it will be found by \LaTeX; +in a TDS-compliant installation this would be: +\file{texmf/tex/macros/latex/ao/.} + +To use, read the user documentation \file{ltxgrid.pdf}. + +\tableofcontents + +\section{Processing Instructions} + +The package file \file{ltxgrid.sty} +is generated from this file, \file{ltxgrid.dtx}, +using the {\sc docstrip} facility of \LaTeX +via |tex ltxgrid.ins|. +The typeset documentation that you are now reading is generated from +the same file by typesetting it with \LaTeX\ or pdftex +via |latex ltxgrid.dtx| or |pdflatex ltxgrid.dtx|. + +\subsection{Build Instructions} + +You may bootstrap this suite of files solely from \file{ltxgrid.dtx}. +Prepare by installing \LaTeXe\ (and either tex or pdftex) on your computer, +then carry out the following steps: +\begin{enumerate} +\item +Within an otherwise empty directory, +typeset \file{ltxgrid.dtx} with \LaTeX\ or pdflatex; +you will obtain the typeset documentation you are now reading, +along with +the installer \file{ltxgrid.ins}, +and the file \file{00readme.txt}. + +Note: you will have to run \LaTeX\ twice, then \file{makeindex}, then +\LaTeX\ again in order to obtain a valid index and table of contents. +\item +Now typeset \file{ltxgrid.ins}, +thereby generating the package file \file{ltxgrid.sty}. +\item +Install \classname{ltxgrid.sty} +by moving it to a location +in your filesystem where they will be found by \LaTeX. +\end{enumerate} +\end{filecontents*} +% \end{macrocode} +% +% \subsection{The Document Body} +% +% Here is the document body, containing only a +% \cmd\DocInput\ directive---referring to this very file. +% This very cute self-reference is a common \classname{ltxdoc} idiom. +% \begin{macrocode} +\begin{document}% +\expandafter\DocInput\expandafter{\jobname.dtx}% +% ^^A\PrintChanges +\end{document} +% \end{macrocode} +% +% \begin{macrocode} +%</doc> +% \end{macrocode} +% +% \section{Using this package} +% Once this package is installed on your filesystem, you can employ it in +% adding functionality to \LaTeX\ by invoking it in your document or document class. +% +% \subsection{Invoking the package} +% In your document, you can simply call it up in your preamble: +% \begin{verbatim} +%\documentclass{book}% +%\usepackage{ltxgrid}% +%\begin{document} +%<your document here> +%\end{document} +% \end{verbatim} +% However, the preferred way is to invoke this package from within your +% customized document class: +% \begin{verbatim} +%\NeedsTeXFormat{LaTeX2e}[1995/12/01]% +%\ProvidesClass{myclass}% +%\LoadClass{book}% +%\RequirePackage{ltxgrid}% +%<class customization commands> +%\endinput +% \end{verbatim} +% +% Note that this package requires the features of the \classname{ltxutil} package, +% available at +% \url{ftp://ftp.teleport.com/users/ogawa/macros/latex/contrib/supported/ltxutil/}. +% +% Once loaded, the package gives you acccess to certain procedures, +% usually to be invoked by a \LaTeX\ command or environment, but not at the document level. +% +% \subsection{Changing the page grid}% +% This package provides two procedures, \cmd\onecolumngrid, \cmd\twocolumngrid, +% that change the page grid (it can be extended to more columns and to other page grids). +% +% They differ from standard \LaTeX's \cmd\onecolumn\ and \cmd\twocolumn\ commands in that +% they do not force a page break. Also, upon leaving a multiple-column grid, the columns are balanced. +% In other respects they work same. +% +% They differ from the grid-changing commands of Frank Mittelbach's \classname{multicol} package +% in that they allow floats of all types (single- and double column floats, that is) and +% preserve compatability with the \classname{longtable} package. +% +% These commands must be issued in vertical mode (conceivably via a \cmd\vadjust) such that +% they are ultimately present in the MVL, where they can do their work. +% Because they do not work in \LaTeX's left-right mode, they are unsuitable at the +% document level. +% Furthermore, packaging a grid command in a \cmd\vadjust, although possible, will probably +% not acheive satisfactory page layout. +% +% Page grid commands are not intended to be issued unnecessarily: only the first of +% two successive \cmd\onecolumngrid\ commands is effective; the second will be silently ignored. +% +% \DescribeMacro\onecolumngrid +% You command \LaTeX\ to return to the one-column grid with the +% \cmd\onecolumngrid\ command. If you are already in the one-column grid, this +% is a no-op. The one-column grid is considered special of all page grids, in that +% no portion of the page is held back (in \cmd\pagesofar); all items that might go +% on the current page (with the exception of floats and footnotes) are on the MVL. +% +% \DescribeMacro\twocolumngrid +% You command \LaTeX\ to return to the two-column grid with the +% \cmd\twocolumngrid\ command. If you are already in the two-column grid, this +% is a no-op. +% +% These two commands should be issued by a macro procedure that can ensure that +% \TeX\ is in outer vertical mode. +% +% \subsection{Changing the MVL}% +% +% This package also provides commands to modify the main vertical list (MVL) in a safe way. +% The scheme here is to structure, insofar possible, \TeX's MVL as follows: +%\begin{quotation} +%box or boxes\\ +%penalty\\ +%glue +%\end{quotation} +% This should be a familiar sequence. It is the prototype sequence for a vertical list, +% and is followed when \TeX\ breaks paragraphs into lines, and when \TeX\ generates +% a display math equation. +% +% If you (as a macro programmer) wish to modify the value of the penalty or glue item, +% you can use one of the MVL-altering commands to do so. Certain operations are implemented +% here; you can make up your own. +% +% Note that these commands must be issued in vertical mode, perhaps via a \cmd\vadjust\ or a \cmd\noalign. +% They can work directly if you are in inner mode (say within a parbox or a minipage). +% +% \DescribeMacro\removestuff +% You instruct \LaTeX\ to remove both the penalty and the glue item with this command. +% +% \DescribeMacro\addstuff +% You issue the \cmd\addstuff\arg{penalty}\arg{glue} command to add a penalty, glue, or both. +% If you do not wish to add one or the other, the corresponding argument should be nil. +% Note that the effect of \cmd\addstuff\ is to stack the penalties and glue items. +% Therefore, the lesser of the two penalties takes effect, +% and the two glue items add together. +% +% \cmd\addstuff\ is limited because once applied, it cannot be applied again with correct results. +% +% \DescribeMacro\replacestuff +% The \cmd\replacestuff\ command is syntactically the same as \cmd\addstuff, but works +% differently: the existing penalty and glue are replaced or modified. +% +% The specified penalty is not inserted if the existing penalty is greater than 10000 +% (that is, in case of a \cmd\nobreak), otherwise, the lower (non-zero) of the two penalties is inserted. +% +% If the specified glue has a larger natural component than the existing glue, we replace the glue. +% However, if the specified glue's natural component is negative, then the existing glue's natural component is +% changed by that amount. +% +% \cmd\replacestuff\ can be applied mutiple times bceause it retains the list structure in the canonical form. +% +% Note that we treat two penalties specially (as does \TeX): a penalty of 10000 is considered +% a garbage value, to be replaced if found. This is the signal value that \TeX\ inserts on +% the MVL replacing the penalty that caused the page break (if the page break occurred at a penalty). +% Also, a penalty of zero is indistinguishable from no penalty at all, so it will always +% be replaced by the given value. +% +% Therefore, it is highly recommended to never set any of \TeX's penalty parameters to +% zero (a value of, say, 1, is practically the same), nor should a skip parameter be set to zero +% (instead, use, say, 1sp). Also, to prevent a pagebreak, do not use a penalty of 10000, use, say +% 10001 instead. +% +% You can define your own construct that modifies the MVL: +% Define a command, say, \cmd\myadjust, as follows: +%\begin{verbatim} +%\def\myadjust#1{\noexpand\do@main@vlist{\noexpand\@myadjust{#1}}\@tempa}% +%\end{verbatim} +% that is, \cmd\myadjust\ invokes \cmd\do@main@vlist, passing it the procedure name +% \cmd\@myadjust\ along with the arguments thereof pre-expanded. +% Next, define the procedure \cmd\@myadjust: +%\begin{verbatim} +%\def\@myadjust#1{<meddle with the MVL>}% +%\end{verbatim} +% when \cmd\@myadjust\ executes, you will be in the output routine (in inner vertical mode) +% and the MVL will be that very vertical list. +% +% +% +% +% \section{Compatability with \LaTeX's Required Packages} +% Certain packages, usually ones written by members of the +% \LaTeX\ Project itself, have been designated ``required'' and +% are distributed as part of standard \LaTeX. +% These packages have been placed in a priviledged position +% vis \'a vis the \LaTeX\ kernel in that they override the definitions of certain kernel macros. +% +% Compatability between \classname{ltxgrid} and these packages is complicated +% by a number of factors. First is that \classname{ltxgrid} alters the meaning of some of the same +% kernel macros as certain of the ``required'' packages. +% Second is that fact that certain of the ``required'' packages of \LaTeX\ are incompatible with +% each other. +% +% Examples of the first kind are the \classname{ftnright}, \classname{multicol}, and \classname{longtable} +% packages. +% The \classname{ltxgrid} package is not compatible with \classname{multicol}, +% but if you are using \classname{ltxgrid}, you do not need to use \classname{ftnright} or \classname{multicol} +% anyway. The \classname{ltxgrid} package does however attempt to be compatible with \classname{longtable}. +% +% Among the ``required'' packages that are mutually incompatible are \classname{multicol} and \classname{longtable}, +% the incompatibility arising because both packages replace \LaTeX's output routine: +% if one package is active, the other must not be so. +% This state of affairs has remained essentially unchanged since the introduction of the two as \LaTeX2.09 packages in the late 1980s. +% +% The reason that \classname{ltxgrid} can remain compatible with \classname{longtable} is due to the +% introduction of a more modern architecture, the ``output routine dispatcher'', which allows all macro packages access to the +% safe processing environment of the output routine, on an equal footing. +% The relevant portions of the \classname{longtable} package are reimplemented in \classname{ltxgrid} +% to take advantage of this mechanism. +% +% Timing is critical: +% the \classname{ltxgrid} package will be incompatible with any package that +% redefines any of the kernel macros that \classname{ltxgrid} patches---if that +% package is loaded \emph{after} \classname{ltxgrid}. +% +% Hereinafter follows some notes on specific \LaTeX\ packages. +% +% \subsection{ftnright} +% Frank Mittelbach's \classname{ftnright} package effects a change to \LaTeX's +% \cmd\twocolumn\ mode such that footnotes are set at the bottom of the right-hand +% column instead of at the foot of each of the two columns. +% +% Note that it overwrites three \LaTeX\ kernel macros: \cmd\@outputdblcol, \cmd\@startcolumn, and \cmd\@makecol. +% Fortunately none of the three are patched by \classname{ltxgrid}, so that compatability +% is not excluded on this basis. +% +% At the same time, it changes the meaning of \cmd\footnotesize, the macro that is automatically +% invoked when setting a document's footnote into type. +% One might well argue that it is an error for the meaning of \cmd\footnotesize\ to be determined by +% a package such as \classname{ftnright}, that indeed such a choice should be made in the +% document class, or in a file such as \file{bk10.clo}. +% +% To avoid being tripped up by this misfeature in \classname{ftnright}, it is only necessary to +% reassert our meaning for \cmd\footnotesize\ later on, after \classname{ftnright} has been loaded. +% +% Note that \classname{ftnright} inserts code that demands that \LaTeX's flag \cmd\if@twocolumn\ +% is true, that is, it will complain if deployed in a \cmd\onecolumn\ document. +% It is therefore necessary for any other multicolumn package to assert that flag in order to +% avoid this package's complaint. It is an interesting question exactly why this package has +% this limitation. After all, a one-column page grid is just a degenerate case of the +% two column. +% +% \subsection{longtable} +% David Carlisle's \classname{longtable} package sets tables that can be so long as to break over pages. +% According to its author, it uses the same override of \LaTeX's output routine as +% Frank Mittelbach's \classname{multicol} package. By implication, then, it has a hard +% incompatability with the latter. +% +% The \classname{longtable} package also performs a check of whether the document is in +% \cmd\twocolumn\ mode, and declines to work if this is the case. It is not clear, however, +% that there is any true incompatability present if so. It's just that David did not see any reason +% anyone would want to set such long tables in a multicolumn document, hence the check. +% +% There does not appear to be any indication that \classname{longtable} would work less +% well under \classname{ltxgrid} than under standard \LaTeX's \cmd\twocolumn\ mode. +% Therefore, this \classname{ltxgrid} patches \classname{longtable} (if loaded) so as to provide +% compatability. In the course of which, \classname{longtable} becomes more robust +% (\classname{longtable} has mumerous bugs and incompatabilities of long standing, +% some of which are repaired by \classname{ltxgrid}). +% +% One problem remains, namely that, if a \env{longtable} environment breaks over columns +% and thereby inserts its special headers and footers at that break, and those columms are then +% balanced (due to a return to the one-column page grid), then those inserted rows +% will remain, and may no longer fall at the column break. This will, of course look +% wrong. +% +% The only way to fix this problem is to avoid doing column balancing in the way +% I have implemented here; such an enhancement to this package is possible. +% +% \subsection{multicol} +% Frank Mittelbach's \classname{multicol} package provides a page grid with many columns, +% albeit denies the placement of floats in individual columns. +% +% It esablishes its own \cmd\output\ routine, which is the reason it runs afoul of +% the \classname{longtable} package. On the other hand, \classname{ltxgrid} specifically +% allows for the case where a package installs its own \cmd\output\ routine, so +% there is no incompatability on that basis. +% +% Still, it is pointless to use \classname{multicol} if you are using \classname{ltxgrid}, +% since both packages provide multicolumn page layouts. +% Therefore, \classname{multicol} is not supported by \classname{ltxgrid}. +% +% \subsection{ltxgrid} +% It has been pointed out that one of the disadvantages of adopting the \classname{ltxgrid} package is that +% it does alter the \LaTeX\ kernel. +% Any package that itself alters the \LaTeX\ kernel may be incompatible with \classname{ltxgrid}, and new packages +% (destined perhaps to become part of the successor to \LaTeXe) may break \classname{ltxgrid}. +% +% The consequence is that packages introduced in future, and future changes to \LaTeX\ may be incompatible +% with \classname{ltxgrid}. +% This is, of course, true. +% The development plan for \classname{ltxgrid} is that when such packages and \LaTeX\ kernel changes come about, +% the burden will be on \classname{ltxgrid} to change in a way that provides for continued compatability with +% those packages and \LaTeX\ kernel changes. +% +% +% \section{How \classname{ltxgrid} places footnotes} +% +% In conventional multicolumn layouts, a footnote will appear at the bottom of the column in which it is called out. +% The \classname{ltxgrid} package implements this conventional layout choice by default. +% However, other choices are possible (a la \classname{ftnright}, whose compatability with \classname{ltxgrid} has not been tested). +% +% One unusual feature of \classname{ltxgrid}'s default implementation must be mentioned, though, +% namely the case in a two-column page grid, where a footnote is followed by a temporary change to the one-column page grid +% (e.g., for a wide equation). +% In such a case, the material above the wide material is split into two columns, and a footnote whose callout +% appears in the right-hand column will nonetheless be set at the base of the left column. +% +% This arrangement was chosen because it ensures that the footnotes at the bottom of any page will appear in +% numerical order. It can be argued that this choice is ``incorrect'', but be that as it may, +% the \classname{ltxgrid} package does not foreclose on other arrangements for the footnotes. +% The package can be adapted to accomodate any page design desired. +% +% \section{Limitations in \classname{ltxgrid}'s default column balancing method}% +% +% In a multicolumn page grid, when encountering a page that is not completely full, +% it is customary to set the material in balanced columns (typically with the last column no longer than any of the others). +% Such a case also crops up when temporarily interrupting the multicolumn grid to set material on the full width of the page: +% the material on the page above the break is customarily set in balanced columns. +% +% An awkward case arises when we have already set one or more complete columns of type before encountering the need to +% balance columns. In this subset of cases, the default in \classname{ltxgrid} is to +% do an operation I call ``re-balancing'': +% the material on the page so far is pasted back together into a single column, and new, balanced column breaks are +% calculated. +% +% This scheme typically works fine, but it has a significant vulnerability: +% any discardable items trimmed at the original column break is lost, never to be retrieved. +% Consequently, after re-balancing, an element like, say, a section head can fail to have the correct amount of whitespace above. +% +% This problem is due to an unfortunate optimization in \TeX, wherein a certain class of nodes is trimmed from the +% top of main vertical list upon returning from the output routine: +% any penalty, glue, or leader node falls in to this class of discardable nodes, +% and trimming proceeds until a non-discardable node (such as a box, or rule) is encountered. +% It gets better: a third class of nodes is transparent to this trimming process; +% they are neither discarded nor do they halt the process of trimming: +% mark nodes and all whatsits fall into this class of transparent nodes; +% they are quietly passed over during trimming. +% +% An alternative approach for \TeX\ to take would have been, +% rather than discarding the node entirely, to simply mark it as discarded. +% (Implementors of NTS, please note!) +% Then, upon shipping out, such nodes would not make it into the DVI. +% \TeX's optimization, driven by the small computer architectures current when it was developed, +% does save mem, but at the cost of revisiting page breaks in a reliable way. +% +% FIXME: how to fix a column break in the above case? Widetext? +% +%\StopEventually{} +% +% \section{Implementation of package} +% +% Special acknowledgment: this package uses concepts pioneered +% and first realized by William Baxter (mailto:web@superscript.com) +% in his SuperScript line of commercial typesetting tools, and +% which are used here with his permission. His thorough understanding +% of \TeX's output routine underpins the entire \classname{ltxgrid} +% package. +% +% \subsection{Beginning of the \file{ltxgrid} {\sc docstrip} module} +% Requires the underpinnings of the \classname{ltxkrnext} package. +% \begin{macrocode} +%<*ltxgrid> +\def\package@name{ltxgrid}% +\expandafter\PackageInfo\expandafter{\package@name}{% + Page grid for \protect\LaTeXe, + by A. Ogawa (ogawa@teleport.com)% +}% +\RequirePackage{ltxutil}% +%</ltxgrid> +% \end{macrocode} +% +% \subsection{Banner}% +% Credit where due. +% \begin{macrocode} +%<*ltxgrid-krn> +\typeout{% + ltxgrid: portions licensed from W. E. Baxter (web@superscript.com)% +}% +% \end{macrocode} +% +% \subsection{Sundry}% +% Here are assorted macro definitions. +% \begin{macro}{\lineloop} +% The document-level command \cmd\lineloop\ sets numbered lines until the +% specified count is reached. +% This command is mainly used to construct test documents. +% \begin{macrocode} +\newcounter{linecount} +\def\lineloop#1{% + \loop + \ifnum\c@linecount<#1\relax + \global\advance\c@linecount\@ne + \par + \hb@xt@\hsize{% + \ifnum\c@linecount<100 0\fi\ifnum\c@linecount<10 0\fi\number\c@linecount + \vrule depth2.5\p@ + \leaders\hrule\hfil + }% + \penalty\interlinepenalty + \repeat +}% +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Mark Components}% +% +% Override LaTeX's mark macros to allow more components. +% +% We remain bound by the weakness of LaTeX's scheme in that +% one cannot emulate the action of \TeX\ whereby +% material with marks can be inserted in the middle of +% a vertical list such that the marks are reliably calculated. +% If we did that, \cmd\@themark\ would no longer be utilized. +% +% A more robust scheme involves placing all marks (component and value) +% into a list (using global scoping, i.e., \cmd\gdef), +% and using \cmd\@@mark to place an index on that list into the MVL. +% Then, e.g., \cmd\@@botmark signifies the place where that list is to be cut, +% and the \cmd\botmark\ of any component is +% the value of the last element of the cut +% list having the given component. The \cmd\firstmark\ and \cmd\topmark\ +% can likewise be defined relative to \cmd\@@firstmark\ and \cmd\@@topmark, +% except in the latter case, we want the first following the cut instead of the last +% preceding the cut. +% +% The limitation of this scheme is its demands upon \TeX's mem. +% The list of marks would need to be trimmed back to, effectively, +% \cmd\topmark\ at the beginning of every page. +% +% This approach is not yet part of the extended LaTeX kernel. +% +% \begin{macro}{\@@mark} +% \begin{macro}{\@@topmark} +% \begin{macro}{\@@firstmark} +% \begin{macro}{\@@botmark} +% \begin{macro}{\@@splitfirstmark} +% \begin{macro}{\@@splitbotmark} +% Remember primitives under a new set of names. +% \begin{macrocode} +\let\@@mark\mark +\let\@@topmark\topmark +\let\@@firstmark\firstmark +\let\@@botmark\botmark +\let\@@splitfirstmark\splitfirstmark +\let\@@splitbotmark\splitbotmark +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \subsubsection{Procedures that expose the component data structure}% +% This portion of the code exposes the internal representation of +% the mark components. If we wish to add more components, we will have to revise +% these macro definitions: +% \cmd\@themark, +% \cmd\nul@mark, +% \cmd\set@mark@netw@, +% \cmd\set@marktw@, +% \cmd\set@markthr@@, +% \cmd\get@mark@@ne, +% \cmd\get@mark@tw@, +% \cmd\get@mark@thr@@, +% \cmd\get@mark@f@ur. +% +% \begin{macro}{\@themark} +%FIXME: is it safer to eliminate \cmd\@themark\ in favor of a message that evaluates \cmd\@@botmark? +% +% Note: these definitions expose the data structure of mark components. +% \begin{macrocode} +\def\@themark{{}{}{}{}}% +\def\nul@mark{{}{}{}{}\@@nul}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\set@mark@netw@} +% \begin{macro}{\set@marktw@} +% \begin{macro}{\set@markthr@@} +% These procedures insert the new value of a particular mark component into the given argument. +% They expose the data structure of mark components. +% +% \begin{macrocode} +\def\set@mark@netw@#1#2#3#4#5#6#7{\gdef#1{{#6}{#7}{#4}{#5}}\do@mark}% +\def\set@marktw@#1#2#3#4#5#6{\gdef#1{{#2}{#6}{#4}{#5}}\do@mark}% +\def\set@markthr@@#1#2#3#4#5#6{\gdef#1{{#2}{#3}{#6}{#5}}\do@mark}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\get@mark@@ne} +% \begin{macro}{\get@mark@tw@} +% \begin{macro}{\get@mark@thr@@} +% \begin{macro}{\get@mark@f@ur} +% These procedures retreive the value of a particular mark component. +% They expose the data structure of mark components. +% \begin{macrocode} +\def\get@mark@@ne#1#2#3#4#5\@@nul{#1}% +\def\get@mark@tw@#1#2#3#4#5\@@nul{#2}% +\def\get@mark@thr@@#1#2#3#4#5\@@nul{#3}% +\def\get@mark@f@ur#1#2#3#4#5\@@nul{#4}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsubsection{Procedures that do not expose the component data structure}% +% +% \begin{macro}{\mark@netw@} +% \begin{macro}{\marktw@} +% \begin{macro}{\markthr@@} +% These procedures insert the new value of a particular mark component into \cmd\@themark, +% then execute \cmd\do@mark. +% They constitute the implementation layer for mark components one, two, and three. +% An analogous procedure for component four could be defined; call it \cmd\markf@ur. +% +% \begin{macrocode} +\def\mark@netw@{\expandafter\set@mark@netw@\expandafter\@themark\@themark}% +\def\marktw@{\expandafter\set@marktw@\expandafter\@themark\@themark}% +\def\markthr@@{\expandafter\set@markthr@@\expandafter\@themark\@themark}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\do@mark} +% \begin{macro}{\do@@mark} +% Access procedures \cmd\mark (AKA \cmd\@@mark). +% The \cmd\do@mark\ procedure is used when a mark is being put down into the MVL; +% \cmd\do@@mark\ when this happens in the output routine. +% \begin{macrocode} +\def\do@mark{\do@@mark\@themark\nobreak@mark}% +\def\do@@mark#1{% + \begingroup + \let@mark + \@@mark{#1}% + \endgroup +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\let@mark} +% \begin{macro}{\nobreak@mark}% +% The procedure that makes \cmd\csname s robust within a mark. +% Use \cmd\appdef\ and \cmd\robust@\ to extend the list. +% \begin{macrocode} +\def\let@mark{% + \let\protect\@unexpandable@protect + \let\label\relax + \let\index\relax + \let\glossary\relax +}% +\def\nobreak@mark{% + \@if@sw\if@nobreak\fi{\@ifvmode{\nobreak}{}}{}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% +% \subsubsection{Using mark components}% +% +% These procedures use the component mark mechanism to implement +% a mark component that remembers the current environment (used in page makeup) +% and the the two mark components left over from the original \LaTeX. +% The fourth component is presently unused. +% +% \begin{macro}{\mark@envir} +% The third mark component's access procedures. +% The \cmd\mark@envir\ and \cmd\bot@envir\ commands are a good model of how to write +% access procedures for a new mark component. +% \begin{macrocode} +\def\mark@envir{\markthr@@}% +\def\bot@envir{% + \expandafter\expandafter + \expandafter\get@mark@thr@@ + \expandafter\@@botmark + \nul@mark +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\markboth} +% \begin{macro}{\markright} +% \begin{macro}{\leftmark} +% \begin{macro}{\rightmark} +% Set procedures for legacy components. +% \begin{macrocode} +\def\markboth{\mark@netw@}% +\def\markright{\marktw@}% +% \end{macrocode} +% +% Retrieval procedures for legacy mark components. +% The procedure for retrieving the first component from \cmd\botmark\ +% and the second component from \cmd\firstmark have names in \LaTeX; +% they are called, respectively, \cmd\leftmark\ and \cmd\rightmark. +% +% It is possible to retrieve the components of \cmd\topmark\ +% as well: use \cmd\saved@@topmark. +% \begin{macrocode} +\def\leftmark{% + \expandafter\expandafter + \expandafter\get@mark@@ne + \expandafter\saved@@botmark + \nul@mark +}% +\def\rightmark{% + \expandafter\expandafter + \expandafter\get@mark@tw@ + \expandafter\saved@@firstmark + \nul@mark +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% +% \subsection{Output Super-routine}% +% +% We want to change \LaTeX's output routine, but do not wish to remain vulnerable +% to interference from such ``required'' packages as +% \classname{multicol} (authored by Frank Mittelbach) +% and \classname{longtable} (authored by David P. Carlisle), which +% swap in their own output routines when the respective package is active. +% +% The better mechanism, used here, is due to William Baxter (web@superscript.com), +% who has allowed his several ideas to be used in this package. +% +% In what follows, we effectively wrap up the old \LaTeX\ output routine inside +% a new, more flexible ``super routine''. When the output routine is called, +% the ``super routine'' acts as a dispatcher. If the old routine is needed, it is called. +% +% If a package attempts to substitute in their own output routine, they will effectively +% be modifying a token register by the name of \cmd\output. +% The primitive \cmd\output\ is now known by a different name, which should no longer be +% necessary to use. +% +% Usage note: to make a visit to the output routine employing the dispatcher, enter +% with a value of \cmd\outputpenalty\ that corresponds to a macro. Defining as follows: +%\begin{verbatim} +%\@namedef{output@10000}{<your code here>}% +%\end{verbatim} +% by convention, your output routine should void out \cmd\box\cmd\@cclv. +% +% In rewriting \LaTeX's output dispatcher +% in a much simpler form, we also avoid the sin of multiple \cmd\shipout s +% within a single visit to the output routine. +% +% Conceptually, we divide visits to the output routine into two classes. +% The first involves natural page breaks +% (at a \cmd\newpage\ or when \cmd\pagetotal $>$ \cmd\pagegoal) +% and usually resulting in \cmd\box\cmd\@cclv\ either being shipped out or +% salted away (e.g., each column in a multicolumn layout). +% We might call this class the ``natural output routines''; the \cmd\outputpenalty\ +% will never be less than $-10000$. +% Furthermore, we ensure that \cmd\holdinginserts\ is cleared when +% calling such routines. +% +% The other class involves a forced visit to the output routine +% via a large negative penalty ($< -10000$). They do not generally +% result in a \cmd\shipout\ of \cmd\box\cmd\@cclv: they may be dead cycles. +% We provide a mechanism (call it a ``one-off'' output routine) that allows +% us to specify certain processing to be done when \TeX\ reaches +% the current position on the page. +% +% One-off output routines themselves fall into two divisions, ones +% that process \cmd\box\cmd\@cclv, and ones that work on the main vertical list (MVL). +% The former are typified by changes to the page grid, perhaps +% even column balancing. +% The latter involve the insertion of penalties or glue and the processing of floats. +% +% The natural output routine is a single procedure. We have not introduced multiple +% natural output routines based on the \cmd\outputpenalty\ because \TeX\ does not +% support such a thing: \TeX\ sometimes lays down a penalty whose value is the sum +% of other penalties. Because of this, we cannot depend on the value of \cmd\outputpenalty\ +% in such areas. +% +% We do introduce flexibility in the form of a mechanism for patching into the +% natural output routine. Three hooks are offered, allowing a procedure +% to prepare for the upcoming visit to the output routine, +% access to \cmd\box\cmd\@cclv, and after shipping out (or otherwise +% committing the material to the page). +% +% Environments, commands, and even packages can install their +% own procedures into these hooks. +% For instance, if the longtable package is loaded, it will install +% its procedures, but those procedures will punt if the page break +% being processed does not actually fall within a longtable environment. +% +% \begin{macro}{\primitive@output} +% Here we remember the \TeX\ primitive \cmd\output\ and its value, +% and then proceed to take over the \cmd\csname\ of \cmd\output, +% making it a \cmd\toks\ register and installing the old value of +% the output routine. +% \begin{macrocode} +\let\primitive@output\output +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\output} +% Grab the tokens in \cmd\the\cmd\output\ (but without the extra set of braces). +% The value of \cmd\toks@\ must remain untouched until loaded into the appropriate token +% register; this is done a few lines below. +% \begin{macrocode} +\long\def\@tempa#1\@@nil{#1}% +\toks@ +\expandafter\expandafter +\expandafter{% +\expandafter \@tempa + \the\output + \@@nil + }% +\newtoks\output +\output\expandafter{\the\toks@}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\dispatch@output} +% We now install our own output routine in place of the +% old one, which is still available as \cmd\the\cmd\output. +% +% The output routine is simply the procedure \cmd\dispatch@output. +% It either dispatches to a procedure based on a particular value of +% \cmd\outputpenalty\ or it executes \cmd\the\cmd\output\ tokens. +% \begin{macrocode} +\primitive@output{\dispatch@output}% +\def\dispatch@output{% + \let\par\@@par + \expandafter\let\expandafter\@tempa\csname output@\the\outputpenalty\endcsname + \outputdebug@sw{% + \saythe\badness + \saythe\outputpenalty + \saythe\holdinginserts + \say\thepagegrid + \saythe\pagegrid@col + \saythe\pagegrid@cur + %\say\bot@envir + \saythe\insertpenalties + %\say\@@topmark + %\say\saved@@topmark + %\say\@@firstmark + %\say\saved@@firstmark + \say\@@botmark + %\say\saved@@botmark + \saythe\pagegoal + \saythe\pagetotal + \saythe{\badness\@cclv}% + \expandafter\@ifx\expandafter{\csname output@-\the\execute@message@pen\endcsname\@tempa}{% + \say\@message@saved + }{% + \expandafter\say\csname output@\the\outputpenalty\endcsname + }% + \say\@toplist + \say\@botlist + \say\@dbltoplist + \say\@deferlist + {\tracingall\scrollmode + \showbox\@cclv + \showbox\@cclv@saved + \showbox\pagesofar + \showbox\footbox + \showbox\footins@saved + \showbox\footins + \showlists + }% + }{}% + \@ifnotrelax\@tempa{\@tempa}{\the\output}% +}% +\@ifxundefined{\outputdebug@sw}{% + \@booleanfalse\outputdebug@sw +}{}% +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Further thoughts about inserts} +% +% The only safe way to deal with inserts is to either set \cmd\holdininserts\ or +% to commit to using whatever insert comes your way: you cannot change your mind +% once you see a non-void \cmd\box\cmd\footins, say. +% +% Therefore all output routine processing must proceed with \cmd\holdinginserts\ set +% until you are sure of the material to be committed to the page. At that point, you +% can clear \cmd\holdinginserts, spew \cmd\box\cmd\@cclv, put down the appropriate penalty, +% and exit, with the knowledge that \TeX\ will re-find the same pagebreak, this time +% visiting the output routine with everything, including inserts, in their proper +% place. +% This technique applies to split elements (screens, longtable, index) as well as to +% manufactured pages (float pages and clearpage pages). +% +% Therefore, the output routine must not make assumptions about whether \cmd\holdinginserts\ +% should be cleared; instead this must be left to the one-off output routines or the natural output routine. +% +% If we are manufacturing pages (``float page processing''), and if \cmd\pagegoal\ is not equal to +% \cmd\vsize, then inserts are at hand, and our criterion should take into account the insert +% material, even though we cannot measure its height based on the size of \cmd\box\cmd\footins\ +% (because \cmd\holdinginserts\ is set, you see). +% +% It would be better to take the complement of \cmd\floatpagefraction\ and use that +% as a standard for the looseness of the page. Since \cmd\pagegoal\ reflects the inserted material, +% the criterion becomes the difference of the aggregate height of the floats and the \cmd\pagegoal\ +% versus this "page looseness" standard. +% +% As a check, consider what happens if we bail out: \cmd\@deferlist\ has never been touched, so it +% requires no attention. Also, \cmd\holdinginserts\ has never been cleared, so inserts require +% no attention. So we only have to ensure that marks are preserved, which is already taken +% care of by the message handler mechanism. +% +% If we are doing ordinary page cutting, then the scheme would be to detect whether we are within +% a screen (or longtable as may be), do the adjustment to the page height, and return, but this time +% with \cmd\holdinginserts\ cleared. Upon reentering the output routine, we may or may not be within +% the screen environment, but we are now sure to have a final page break, and we can commit this +% material (by shipping out or by saving it out as a full column). +% +% In the above, the first of the two visits to the output routine is a dead cycle and requires +% propagation of marks, but nothing else. +% +% The natural output routine +% +% Here is the portion of the output routine that fields cases not handled by +% the dispatcher. +% +% The default is to ship out a page and then look around for more material +% that might constitute a ``float page''. However, because \cmd\holdinginserts\ +% is normally set, this output routine must first have a dead cycle and +% come back again with \cmd\holdinginserts\ cleared. +% Then, after shipping out, it puts down a message that +% will manufacture zero or more float pages, finally terminating +% with a procedure that commits floats to a new unfinished page. +% +% To accomodate special processing, we execute hooks whose name is based +% on the value of the "envir" mark component. The default is "document", +% ensured by an initial mark of that value; the associated procedures +% are all nil. Any unknown envir value will "\cmd\relax\ out". +% +% The code \cmd\move@insert@sw\ tells whether we are on our first visit to +% the output routine (with \cmd\holdinginserts\ still set), or our second +% (with \cmd\holdinginserts\ cleared). The output routine will toggle the +% setting. +% +% The commands \cmd\hold@insertions\ and \cmd\move@insertions\ respectively +% clear and set the state of \cmd\move@insert@sw, so this procedure effectively +% clears \cmd\holdinginserts\ just long enough to pick up the insertions. +% Important: any output routine that clears \cmd\holdinginserts\ +% must guarentee that it is restored on the subsequent visit to the output routine. +% Or, to put it another way, if an output routine detects that \cmd\holdinginserts\ +% is cleared, it should take it upon itself to restore it before exiting. +% +% The branch with \cmd\holdinginserts\ set is executed first; the other +% branch follows on practically immediately thereafter. In the first branch, +% we simply execute the appropriate hook and then execute a dead cycle. +% +% In the branch with \cmd\holdinginserts\ cleared, the procedure +% builds up the current column, which is now complete, with \cmd\@makecol, then +% dispatches to the shipout routine associated with the current page grid, \cmd\output@column@. +% At the end, it triggers the execution of an output routine to prepare the next column (or page). +% +% \subsection{Natural output routine}% +% +% \begin{macro}{\output} +% Here is what has become of the output routine of \LaTeX. +% It is of necessity divided into phases, \cmd\output@holding\ is executed upon first encountering the natural page-breaking point, while inserts are being held. +% The second phase, \cmd\output@moving, is set in motion by the first: here the same material (in most cases) will be processed with \cmd\holdinginserts\ cleared. +% +% \begin{macrocode} +\output={\toggle@insert\output@holding\output@moving}% +% \end{macrocode} +% +% The procedure \cmd\output@holding\ +% is our first cycle through the output routine; \cmd\holdinginserts\ is still set. +% We give the current environment a heads up +% (it is through this means that \classname{longtable} sets its running header and footer), +% then we execute a dead cycle, which should propagate marks. +% +% One corner case that can crop up is the presence of a single unbreakable chunk whose size is larger +% than \cmd\vsize. +% Doing a dead cycle under such circumstances will not find the same breakpoint as this time +% (remember we threw in a \cmd\mark\ node). +% Instead, we attempt to remove the excess height of the material, so we can continue to propagate marks. +% +% The corner case is at hand if the natural size of \cmd\box\cmd\@cclv\ exceeds \cmd\pagegoal\ and +% the contents cannot be shrunk to fit. +% +% \begin{macrocode} +\def\output@holding{% + \csname output@init@\bot@envir\endcsname +%\vbadness\@M +%\vfuzz\maxdimen + \@if@exceed@pagegoal{\unvcopy\@cclv}{% + \setbox\z@\vbox{\unvcopy\@cclv}% + \outputdebug@sw{{\tracingall\scrollmode\showbox\z@}}{}% + \dimen@\ht\@cclv\advance\dimen@-\ht\z@ + \dead@cycle@repair\dimen@ + }{% + \dead@cycle + }% +}% +\def\@if@exceed@pagegoal#1{% + \begingroup + \setbox\z@\vbox{#1}% + \dimen@\ht\z@\advance\dimen@\dp\z@ + \outputdebug@sw{\saythe\dimen@}{}% + \@ifdim{\dimen@>\pagegoal}{% + \setbox\z@\vbox{\@@mark{}\unvbox\z@}% + \splittopskip\topskip + \splitmaxdepth\maxdepth + \vbadness\@M + \vfuzz\maxdimen + \setbox\tw@\vsplit\z@ to\pagegoal + \outputdebug@sw{{\tracingall\scrollmode\showbox\tw@\showbox\z@}}{}% + \setbox\tw@\vbox{\unvbox\tw@}% + \@ifdim{\ht\tw@=\z@}{% + \ltxgrid@info{Found overly large chunk while preparing to move insertions. Attempting repairs}% + \aftergroup\true@sw + }{% + \aftergroup\false@sw + }% + }{% + \aftergroup\false@sw + }% + \endgroup +}% +% \end{macrocode} +% +% The procedure \cmd\output@moving\ +% is our second cycle through the output routine; \cmd\holdinginserts\ is now cleared, +% and \cmd\insert s will have been split off into their respective box registers, like \cmd\footins. +% +% \begin{enumerate} +% \item +% Set the values of \cmd\topmark\ and \cmd\firstmark. +% \item +% If we got here because of a \cmd\clearpage\ command, remove the protection box that this mechanism has left on the MVL. +% \item +% If the contents of \cmd\box\cmd\@cclv\ are non-trivial, commit it to the current page or ship it out as the case may call for. +% \item +% If not, discard it (we are at the end of \cmd\clearpage\ processing). +% \item +% Set various values, including the available space for setting type on the next column (\cmd\@colroom). +% \end{enumerate} +% +% The processing for a non-trivial \cmd\box\cmd\@cclv\ are: +% \begin{enumerate} +% \item +% Execute the head procedure for the current environment. +% \item +% Make up a column and ship it out (or commit it to the current page) via a procedure keyed to the current page grid. +% \item +% Put down an interrupt for \cmd\do@startcolumn@pen: this will force a visit to the output routine for the +% purpose of committing floats to the next column. +% \item +% Possibly put down an interrupt to continue \cmd\clearpage\ proccessing. +% \item +% Execute the tail procedure for the current environment. +% \end{enumerate} +% +% +% The processing for a trivial \cmd\box\cmd\@cclv\ are: +% \begin{enumerate} +% \item +% Void out \cmd\box\cmd\@cclv\ and give appropriate warning messages and diagnostics. +%% \item +%% Put down the same interrupts as for the non-trivial case above. +% \end{enumerate} +% +% \begin{macrocode} +\def\output@moving{% + \set@top@firstmark + \@ifnum{\outputpenalty=\do@newpage@pen}{% + \setbox\@cclv\vbox{% + \unvbox\@cclv + \setbox\z@\lastbox + \@ifdim{\ht\z@=\ht\@protection@box}{\box\lastbox}{\unskip}% + }% + }{}% + \@cclv@nontrivial@sw{% + \csname output@prep@\bot@envir \endcsname + \@makecol\csname output@column@\thepagegrid\endcsname + \protect@penalty\do@startcolumn@pen + \clearpage@sw{% + \protect@penalty\do@endpage@pen + }{}% + \csname output@post@\bot@envir \endcsname + }{% + {\setbox\z@\box\@cclv}% + }% + \set@colroom + \global\@mparbottom\z@ + \global\@textfloatsheight\z@ %FIXME: this legacy LaTeX variable is set, but never queried! +}% +% \end{macrocode} +% +% The procedure \cmd\@cclv@nontrivial@sw\ determines if this visit to \cmd\output@moving\ +% is a trivial one, which happens at the end of \cmd\clearpage\ processing and under some pathological circumstances. +% It emits a Boolean, so it is syntactically like \cmd\true@sw, albeit does not execute solely via expansion. +% +% Note: the case where \cmd\box\cmd\@cclv\ is void comes up at the very beginning of the job, when +% typesetting a (full-page-width) title block in a two-column layout. +% +% Note: the code that removes the last box and skip from the output is intended to detect the case +% where the output has whatit nodes followed by topskip and a protection box. +% This is what happens under normal circumstances at the end of \cmd\clearpage\ processing. +% \begin{macrocode} +\def\@cclv@nontrivial@sw{% + \@ifx@empty\@toplist{% + \@ifx@empty\@botlist{% + \@ifvoid\footins{% + \@ifvoid\@cclv{% + \false@sw + }{% + \setbox\z@\vbox{\unvcopy\@cclv}% + \@ifdim{\ht\z@=\topskip}{% + \setbox\z@\vbox{% + \unvbox\z@ + \setbox\z@\lastbox\dimen@\lastskip\unskip + \@ifdim{\ht\z@=\ht\@protection@box}{% + \advance\dimen@\ht\z@ + \@ifdim{\dimen@=\topskip}{% + \aftergroup\true@sw + }{% + \aftergroup\false@sw + }% + }{% + \aftergroup\false@sw + }% + }% + {% + \false@sw % Normal for \clearpage + }{% + \true@sw + }% + }{% + \@ifdim{\ht\z@=\z@}{% + \ltxgrid@info{Found trivial column. Discarding it}% + \outputdebug@sw{{\tracingall\scrollmode\showbox\@cclv}}{}% + \false@sw + }{% + \true@sw + }% + }% + }% + }{% + \true@sw + }% + }{% + \true@sw + }% + }{% + \true@sw + }% +}% +% \end{macrocode} +% +% +% \end{macro} +% +% \begin{macro}{\protect@penalty} +% The procedure \cmd\protect@penalty\ is the utility procedure for invoking a +% one-off output routine. Such a routine can expect to find the protection box +% above it in \cmd\box\cmd\@cclv: it should remove that box. +% +% Note that \cmd\execute@message\ does the same thing as \cmd\protect@penalty, but +% in a slightly different way. +% +% We create a specially formulated box that will be universally used when a protection box is needed. +% In this way, we can always recognize when \cmd\box\cmd\@cclv\ is trivial: +% it will consist of whatsits followed by \cmd\topskip\ glue and the \cmd\@protection@box. +% \begin{macrocode} +\def\protect@penalty#1{\protection@box\penalty-#1\relax}% +\newbox\@protection@box +\setbox\@protection@box\vbox to1986sp{\vfil}% +\def\protection@box{\nointerlineskip\copy\@protection@box}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\dead@cycle} +% \begin{macro}{\dead@cycle@repair} +% The procedure \cmd\dead@cycle\ is defined separately as a utility which can be used by +% any output processing routine to emulate what takes place in the standard output routine. +% +% Here, we have entered the output routine with \cmd\holdinginserts\ enabled, which means that we +% are not yet ready to ship out material, because the \cmd\insert\ registers are being held. +% We want to clear \cmd\holdinginserts\ and come back here with the same page break as before, whereupon +% we may properly proceed with page makeup. +% +% To do this, we +% propagate marks, then spew the contents of \cmd\box\cmd\@cclv\ followed by the +% original output penalty that landed us here (but only if it is not 10000, +% the flag value for a pagebreak not at a penalty). +% +% However, the natural output routine should do this only if \cmd\box\cmd\@cclv\ is nontrivial. +% A pathological case exists wherein a box of height greater than \cmd\textheight\ would cause an infinite loop involving the output routine. +% The procedure \cmd\dead@cycle@repair, attempts to catch this case and avoid the loop. +% +% The test of the height of \cmd\box\cmd\@cclv\ is not the correct one, because this test will run afoul in +% the case where \cmd\box\cmd\@cclv\ contains nothing but an \cmd\insert\ node. What to do? +% +% It is possible that the pathological case can be detected by looking at \cmd\pagetotal. If that quantity is +% zero, then \cmd\box\cmd\@cclv\ really is trivial. +% +% In the procedure \cmd\dead@cycle@repair, if \cmd\box\cmd\@cclv\ is nontrivial, we execute \cmd\dead@cycle, +% otherwise it contains nothing but a mark, so we dispense with propagating marks +% and we simply spew out \cmd\box\cmd\@cclv\ without an accompanying mark. +% This has the effect of failing to propagate marks, but this problem is preferrable to the infinite loop, +% which in principle could crash even a robust operating system by filling up the file system. +% +% If a document has such a large chunk, it should be fixed, so we give a message in the log. +% +% You ask, ``In what way does this infinite loop come about?'' Good question! +% +% The setup is a chunk in the MVL that is taller than \cmd\textheight. +% (Yes, it's that simple.) +% As soon as the previous page ships out, the MVL will contain a mark (propagated from the previous page) followed +% by that large chunk (call it the `big bad box', albeit does not need to be a single box). +% The next visit to the output routine will be a natural page break, but +% \TeX\ will select the juncture between the mark and the big bad box as the least-cost page break. +% Unless the test in \cmd\dead@cycle\ is done, the cycle is perpetuated when the macro +% reinserts the mark. +% +% The crux matter is achieving, in a robust way, the goal of going from a \cmd\holdinginserts\ state to one +% where the insertions are moving. +% +% \begin{macrocode} +\def\dead@cycle@repair#1{% + \expandafter\do@@mark + \expandafter{% + \@@botmark + }% + \unvbox\@cclv + \nointerlineskip + \vbox to#1{\vss}% + \@ifnum{\outputpenalty<\@M}{\penalty\outputpenalty}{}% +}% +\def\dead@cycle@repair@protected#1{% + \expandafter\do@@mark + \expandafter{% + \@@botmark + }% + \begingroup + \unvbox\@cclv + \setbox\z@\lastbox % Remove protection box + \nointerlineskip + \advance#1-\ht\@protection@box + \vbox to#1{\vss}% + \protection@box % Reinsert protection box + \@ifnum{\outputpenalty<\@M}{\penalty\outputpenalty}{}% + \endgroup +}% +\def\dead@cycle{% + \expandafter\do@@mark + \expandafter{% + \@@botmark + }% + \unvbox\@cclv + \@ifnum{\outputpenalty<\@M}{\penalty\outputpenalty}{}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\output@init@document} +% \begin{macro}{\output@prep@document} +% \begin{macro}{\output@post@document} +% The default processing simply provides for insertion of held-over footnotes. +% At a natural page break, we are either at the bottom of a column or at the bottom +% of a page. In either case, the \cmd\output@init@\ processing adjusts for the height +% of the held-over footnotes and bails out. +% Upon our return, at \cmd\output@prep@\ time, the page break will accomodate the material; +% it is now actually inserted by concatenating it with the contents of \cmd\footins. +% The default processing for \cmd\output@post@\ is nil. +% \begin{macrocode} +\def\output@init@document{% + \@ifvoid\footbox{}{% + \global\advance\vsize-\ht\footbox + \global\advance\vsize-\dp\footbox + }% +}% +\def\output@prep@document{% + \@ifvoid\footbox{}{% +% {\tracingall\scrollmode\showbox\footbox\showbox\footins}% + \setbox\footins\vbox{\unvbox\footbox\unvbox\footins}% + }% +}% +\def\output@post@document{}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@opcol} +% The standard \LaTeX\ procedure \cmd\@opcol\ is now completely obsoleted. +% \begin{macrocode} +\let\@opcol\@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@makecol} +% The procedure \cmd\@makecol\ packages up a page along with all its insertions and floats. +% Therefore it is essential that it be executed with \cmd\holdininserts\ cleared. +% +% Note that there is a corner case when in a multi-column grid, where the change back to +% one-column grid occurs just after a complete page ships out. We want to detect when +% \cmd\@cclv\ contains nothing but a \cmd\mark, but this is a \TeX\ impossibility. +% +% Note on \cmd\@kludgeins: we have removed this mechanism from \LaTeX, because the implementation +% of \cmd\enlargethispage\ no longer requires it. +% Here, for consistency sake, we remove \cmd\@makespecialcolbox. +% \begin{macrocode} +\def\@makecol{% + \setbox\@outputbox\vbox{% + \boxmaxdepth\@maxdepth + \@tempdima\dp\@cclv + \unvbox\@cclv + \vskip-\@tempdima + }% + \xdef\@freelist{\@freelist\@midlist}\global\let\@midlist\@empty + \@combinefloats + \@combineinserts\@outputbox\footins +%\@ifvbox\@kludgeins{% +% \@makespecialcolbox +%}{% + \set@adj@colht\dimen@ + \count@\vbadness + \vbadness\@M + \setbox\@outputbox\vbox to\dimen@{% + \@texttop + \dimen@\dp\@outputbox + \unvbox\@outputbox + \vskip-\dimen@ + \@textbottom + }% + \vbadness\count@ +%}% + \global\maxdepth\@maxdepth +}% +\let\@makespecialcolbox\@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@combineinserts} +% We split out the procedure to add the \cmd\footins\ insertions to the packaged-up page. +% Any other non-trivial insertions should also be dealt with at this time. +% \begin{macrocode} +\def\@combineinserts#1#2{% + \setbox#1\vbox{% + \unvbox#1% +% {\tracingall\scrollmode\showbox#2}% + \vbox{% + \@ifvoid#2{}{% + \vskip\skip\footins + \color@begingroup + \normalcolor + \footnoterule + \nointerlineskip + \box#2% + \color@endgroup + }{}% + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@floatplacement} +% In standard \LaTeX, someone (DPC?) makes the assumption that \cmd\@fpmin\ can be assigned +% locally. This is no longer true now that we ship no more than one page per visit to the output routine. +% We apply a bandaid. +% \begin{macrocode} +\appdef\@floatplacement{% + \global\@fpmin\@fpmin +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\pagebreak@pen} +% While we are in the way of registering certain penalty values, +% let us register the smallest one that will force a visit to the output routine. +% However, this penalty will not have an assciated macro: we wish to execute the +% natural output routine instead. +% +% Note that this penalty is invoked by \cmd\clearpage\ and \cmd\newpage. +% \begin{macrocode} +\mathchardef\pagebreak@pen=\@M +\expandafter\let\csname output@-\the\pagebreak@pen\endcsname\relax +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Float placement}% +% +% \begin{macro}{\do@startcolumn@pen} +% The procedure \cmd\do@startcolumn@pen\ is executed as a one-off output routine +% just after a page is shipped out (or, in a multicolumn page grid, a column is salted away). +% +% Its job is to either generate a ``float page'' (in reality a column) for shipping out, +% or to commit deferred floats to the fresh column, concluding with a dead cycle. +% In the former case, we accomodate split footnotes and other insertions (by comparing \cmd\vsize\ and \cmd\pagegoal): +% the floats are spewed onto the page, whereupon \LaTeX's output routine will place the footnotes and ship out, +% iterating the process once again. +% +% Note that when this procedure is invoked, \cmd\box\cmd\@cclv\ still has within it the protection box, so we +% start by removing it. Note also that if there was a split insertion held over from the previous page, the +% insert node will be present in \cmd\box\cmd\@cclv, \emph{prior to} the protection box. For this reason, we cannot +% just throw away that box, as we might be tempted to do. +% +% FIXME: where else do we possibly inappropriately discard \cmd\box\cmd\@cclv? +% +% Note that, because a column or page page had previously just been completed, +% we can assume that there is nothing of importance on the page, +% and because no message is being passed, we can preserve marks in a simple way. +% +% A Note on terminology: +% In a single-column page grid, you might expect that we would execute the procedure \cmd\do@startpage. +% But this is not so. +% \LaTeX\ has a confustion of long standing, +% in which the procedures that handle full-page width floats in a two-column page grid all have in their names +% the string `dbl', which erroneously suggests having something to do with ``double''. It does not: +% when you see `dbl', think ``full page width''. +% \begin{macrocode} +\mathchardef\do@startcolumn@pen=10005 +\@namedef{output@-\the\do@startcolumn@pen}{\do@startcolumn}% +\def\do@startcolumn{% + \setbox\@cclv\vbox{\unvbox\@cclv\setbox\z@\lastbox\unskip}% + \clearpage@sw{\@clearfloatplacement}{\@floatplacement}% + \set@colroom + \@booleanfalse\pfloat@avail@sw + \begingroup + \@colht\@colroom + \@booleanfalse\float@avail@sw + \@tryfcolumn\test@colfloat + \float@avail@sw{\aftergroup\@booleantrue\aftergroup\pfloat@avail@sw}{}% + \endgroup + \fcolmade@sw{% + \setbox\@cclv\vbox{\unvbox\@outputbox\unvbox\@cclv}% +% \csname float@column@\thepagegrid\endcsname +% \csname output@column@\thepagegrid\endcsname + \outputpenalty-\pagebreak@pen % ask for a return visit, this time with insertions and all. + \dead@cycle + }{% + \begingroup + \let\@elt\@scolelt + \let\reserved@b\@deferlist\global\let\@deferlist\@empty\reserved@b + \endgroup + \clearpage@sw{% + \outputpenalty\@M + }{% + \outputpenalty\do@newpage@pen + }% + \dead@cycle + }% + \check@deferlist@stuck\do@startcolumn + \set@vsize +}% +\def\@scolelt#1{\def\@currbox{#1}\@addtonextcol}% +\def\test@colfloat#1{% + \csname @floatselect@sw@\thepagegrid\endcsname#1{}{\@testtrue}% + \@if@sw\if@test\fi{}{\aftergroup\@booleantrue\aftergroup\float@avail@sw}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@addtonextcol} +% We must adjust \cmd\@addtonextcol\ to take held-over inserts into account. +% Now that all deferred floats are queued up together (in order), we must have a way of +% differentiating them; this is done by the page grid-dependent procedure \cmd\@floatselect@sw@. +% \begin{macrocode} +\def\@addtonextcol{% + \begingroup + \@insertfalse + \@setfloattypecounts + \csname @floatselect@sw@\thepagegrid\endcsname\@currbox{% + \@ifnum{\@fpstype=8 }{}{% + \@ifnum{\@fpstype=24 }{}{% + \@flsettextmin + \@reqcolroom \ht\@currbox + \advance \@reqcolroom \@textmin + \advance \@reqcolroom \vsize % take into account split insertions + \advance \@reqcolroom -\pagegoal + \@ifdim{\@colroom>\@reqcolroom}{% + \@flsetnum \@colnum + \@ifnum{\@colnum>\z@}{% + \@bitor\@currtype\@deferlist + \@if@sw\if@test\fi{}{% + \@addtotoporbot + }% + }{}% + }{}% + }% + }% + }{}% + \@if@sw\if@insert\fi{}{% + \@cons\@deferlist\@currbox + }% + \endgroup +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\do@startpage@pen} +% \begin{macro}{\forcefloats@sw} +% \begin{macro}{\@sdblcolelt} +% \begin{macro}{\test@dblfloat} +% \begin{macro}{\@if@notdblfloat} +% Similar to \cmd\do@startcolumn, +% the procedure \cmd\do@startpage\ starts up a new page (not column) in a multi-column page grid. +% It is invoked after a page is shipped out in a multi-column page grid, and +% it commits full-page-width floats to the fresh page, possibly resulting in a float page. +% In implementation, it is similar to \cmd\do@startcolumn, except that +% it commits effectively via \cmd\@addtodblcol\ instead of \cmd\@addtonextcol. +% Note that this procedure will inevitably be followed by \cmd\do@startcolumn. +% +% Some details of the procedure: +% +% We begin by removing the protection box from \cmd\box\cmd\@cclv, then setting the values of the +% float placement parameters appropriately, and resetting \cmd\@colht, \cmd\@colroom, and \cmd\vsize\ to base values. +% +% Next we attempt to compose a float page, a page consisting entirely of floats. If successful, +% we ship out the float page and lay down an interrupt that will send us back here for another try. +% +% If no float page is formed, we attempt to commit full-page-width floats to the text page, and return with a dead cycle. +% We are now ready to compose columns of text. +% +% Note that all floats (both column floats and full-page-width floats) move through a single queue. +% To differentiate between the two, the width of the float is compared to \cmd\textwidth. +% This comparison is encapsulated in the macro \cmd\@if@notdblfloat, which should be used whenever +% such a determination must be made. This procedure returns a Boolean. +% \begin{macrocode} +\mathchardef\do@startpage@pen=10006 +\@namedef{output@-\the\do@startpage@pen}{\do@startpage}% +\def\do@startpage{% + \setbox\@cclv\vbox{\unvbox\@cclv\setbox\z@\lastbox\unskip}% + \clearpage@sw{\@clearfloatplacement}{\@dblfloatplacement}% + \set@colht + \@booleanfalse\pfloat@avail@sw + \begingroup + \@booleanfalse\float@avail@sw + \@tryfcolumn\test@dblfloat + \float@avail@sw{\aftergroup\@booleantrue\aftergroup\pfloat@avail@sw}{}% + \endgroup + \fcolmade@sw{% + \global\setbox\pagesofar\vbox{\unvbox\pagesofar\unvbox\@outputbox}% + \@combinepage + \@combinedblfloats + \@outputpage + \global\pagegrid@cur\@ne + \protect@penalty\do@startpage@pen + }{% + \begingroup + \@booleanfalse\float@avail@sw + \let\@elt\@sdblcolelt + \let\reserved@b\@deferlist\global\let\@deferlist\@empty\reserved@b + \endgroup + \@ifdim{\@colht=\textheight}{% No luck... + \pfloat@avail@sw{% ...but a float *was* available! + \forcefloats@sw{% + \ltxgrid@warn{Forced dequeueing of floats stalled}% + }{% + \ltxgrid@warn{Dequeueing of floats stalled}% + }% + }{}% + }{}% + \outputpenalty\@M + \dead@cycle + }% + \check@deferlist@stuck\do@startpage + \set@colht +%\set@colroom +}% +\def\@sdblcolelt#1{\def\@currbox{#1}\@addtodblcol}% +\def\test@dblfloat#1{% + \@if@notdblfloat{#1}{\@testtrue}{}% + \@if@sw\if@test\fi{}{\aftergroup\@booleantrue\aftergroup\float@avail@sw}% +}% +\def\@if@notdblfloat#1{\@ifdim{\wd#1<\textwidth}}% +\@booleanfalse\forcefloats@sw +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@addtodblcol} +% +% The procedure \cmd\@addtodblcol\ is called into play at the beginning of each fresh page +% and operates on each deferred float, in the hopes of placing one or more such floats +% at the top of the current page. +% +% We alter the procedure of standard \LaTeX\ by putting failed floats into +% \cmd\@deferlist\ instead of \cmd\@dbldeferlist. Having done so, we must have a means +% of differentiating full-page-width floats from column-width floats. +% We assume that the latter will always be narrower than \cmd\textwidth. +% +% In aid of detecting a stalled float flushing process, we set a Boolean if we encounter +% a qualified full-page-width float here. Any that qualify but fail the rest of the tests +% might still pass when reconsidered on an otherwise blank page. +% \begin{macrocode} +\def\@addtodblcol{% + \begingroup + \@if@notdblfloat{\@currbox}{% + \false@sw + }{% + \@setfloattypecounts + \@getfpsbit \tw@ + \@bitor \@currtype \@deferlist + \@if@sw\if@test\fi{% + \false@sw + }{% + \@ifodd\@tempcnta{% + \aftergroup\@booleantrue\aftergroup\float@avail@sw + \@flsetnum \@dbltopnum + \@ifnum{\@dbltopnum>\z@}{% + \@ifdim{\@dbltoproom>\ht\@currbox}{% + \true@sw + }{% + \@ifnum{\@fpstype<\sixt@@n}{% + \begingroup + \advance \@dbltoproom \@textmin + \@ifdim{\@dbltoproom>\ht\@currbox}{% + \endgroup\true@sw + }{% + \endgroup\false@sw + }% + }{% + \false@sw + }% + }% + }{% + \false@sw + }% + }{% + \false@sw + }% + }% + }% + {% + \@tempdima -\ht\@currbox + \advance\@tempdima + -\@ifx{\@dbltoplist\@empty}{\dbltextfloatsep}{\dblfloatsep}% + \global \advance \@dbltoproom \@tempdima + \global \advance \@colht \@tempdima + \global \advance \@dbltopnum \m@ne + \@cons \@dbltoplist \@currbox + }{% + \@cons \@deferlist \@currbox + }% + \endgroup +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@tryfcolumn} +% \begin{macro}{\@wtryfc} +% \begin{macro}{\@xtryfc} +% \begin{macro}{\@ztryfc} +% Whenever a page is shipped out, \LaTeX\ automatically tries out a float column: +% a page containing nothing but floats (and, as we have added here, split footnotes). +% +% The following four procedures employ certain macros to communicate between each other: +% +% \cmd\fcolmade@sw, a boolean, says whether we were successful in making a float column. +% +% \cmd\if@test, a \cmd\newif\ switch, says a float has failed some test. +% +% \cmd\@deferlist, is the input to the process, a list, of deferred floats. +% +% \cmd\@trylist, a list, stores the deferred floats to be tried out on the float column. +% +% \cmd\@failedlist, a list of floats that have failed the selection for the float column. +% +% \cmd\@flfail, a list of floats that have failed the second selection for the float column. +% +% \cmd\@flsucceed, a list, the floats that have been successfully placed on the float column. +% +% \cmd\@freelist, a list, receives any freed floats. +% +% \cmd\@colht, a dimen, the available space for the column, including column floats and insertions (footnotes). +% +% \cmd\@fpmin, a dimen, the required minimum height for the float column. +% +% \cmd\@outputbox, a box, the output of the process. +% +% \cmd\@fptop, \cmd\@fpsep, \cmd\@fpbot, glue, placed above, between, and below floats on the float column. +% +% \cmd\@currtype, a count, used temporarily for the float's bits. +% +% \cmd\@tempcnta, a count, used temporarily for the float's bits. +% +% In \cmd\@tryfcolumn, we alter the criterion for a float page, because if footnotes are present at this point +% (presumably due to a split insertion) then \cmd\@fpmin is no longer the right threshold to apply. +% +% Note that we have changed \cmd\@tryfcolumn, \cmd\@xtryfc, and \cmd\@ztryfc\ syntactically so that the procedure +% to test for the float's being a column float versus a full-page-width float is passed in as an +% argument. +% +% \begin{macrocode} +\def\@tryfcolumn#1{% + \global\@booleanfalse\fcolmade@sw + \@ifx@empty\@deferlist{}{% + \global\let\@trylist\@deferlist + \global\let\@failedlist\@empty + \begingroup + \dimen@\vsize\advance\dimen@-\pagegoal\@ifdim{\dimen@>\z@}{% + \advance\@fpmin-\dimen@ + }{}% + \def\@elt{\@xtryfc#1}\@trylist + \endgroup + \fcolmade@sw{% + \global\setbox\@outputbox\vbox{\vskip \@fptop}% + \let \@elt \@wtryfc \@flsucceed + \global\setbox\@outputbox\vbox{\unvbox\@outputbox + \unskip \vskip \@fpbot + }% + \let \@elt \relax + \xdef\@deferlist{\@failedlist\@flfail}% + \xdef\@freelist{\@freelist\@flsucceed}% + }{}% + }% +}% +\def\@wtryfc #1{% + \global\setbox\@outputbox\vbox{\unvbox\@outputbox + \box #1\vskip\@fpsep + }% +}% +\def\@xtryfc#1#2{% + \@next\reserved@a\@trylist{}{}% trim \@trylist. Ugly! + \@currtype \count #2% + \divide\@currtype\@xxxii\multiply\@currtype\@xxxii + \@bitor \@currtype \@failedlist + \@testfp #2% + #1#2% + \@ifdim{\ht #2>\@colht }{\@testtrue}{}% + \@if@sw\if@test\fi{% + \@cons\@failedlist #2% + }{% + \begingroup + \gdef\@flsucceed{\@elt #2}% + \global\let\@flfail\@empty + \@tempdima\ht #2% + \def \@elt {\@ztryfc#1}\@trylist + \@ifdim{\@tempdima >\@fpmin}{% + \global\@booleantrue\fcolmade@sw + }{% + \@cons\@failedlist #2% + }% + \endgroup + \fcolmade@sw{% + \let \@elt \@gobble + }{}% + }% +}% +\def\@ztryfc #1#2{% + \@tempcnta \count#2% + \divide\@tempcnta\@xxxii\multiply\@tempcnta\@xxxii + \@bitor \@tempcnta {\@failedlist \@flfail}% + \@testfp #2% + #1#2% + \@tempdimb\@tempdima + \advance\@tempdimb \ht#2\advance\@tempdimb\@fpsep + \@ifdim{\@tempdimb >\@colht}{% + \@testtrue + }{}% + \@if@sw\if@test\fi{% + \@cons\@flfail #2% + }{% + \@cons\@flsucceed #2% + \@tempdima\@tempdimb + }% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsection{Clearing pages}% +% +% Clearing the page is an elaboration of ending the page: it entails flushing all floats. +% +% This package might make number of float flushing algorithms available, +% a very simple one that does not try to produce excellent pages, +% another that tries to make the best use of space, +% and a more complex one that tries to balance columns. +% +% At the beginning of the page-clearing process, by definition all of the paragraph text involved is on the MVL and all floats have been encountered. +% There may be material in \cmd\pagesofar, and (in a multi-column page grid) any number of columns of the page have been composed. +% Also, there might be footnote material saved up in \cmd\footbox. +% +% Because we did not want to perform multiple \cmd\shipout s per visit to the output routine, +% our multi-column page makeup will not compose multiple columns per visit. +% This implementation detail may not require alteration, but it is not a limitation that is truly necessary: +% it is only multiple \cmd\shipout s per visit that must be avoided. +% +% The crux matter is how to continue with flushing floats even after the material in the MVL is exhausted. +% At that point, we must, upon completion of the output routine, +% insert into the MVL an interrupt that triggers the next step in the processing. +% +% Therefore, after processing a \cmd\do@startcolumn\ interrupt, we must somehow force the completion of that column. +% This could be done by inserting a \cmd\do@newpage@pen\ interrupt. +% +% And after processing a \cmd\do@startpage@pen\ interrupt, that results in \cmd\@dbltopinsert s, +% we must ensure that the multiple columns on the page get completed, so that the page itself finally gets shipped out. +% This part will proceed automatically given that \cmd\do@startcolumn\ processing completes successfully. +% +% The process will not be complete until all deferred floats have been placed and shipped out, and all saved-up footnotes have been inserted. +% +% Full-page-width floats can get out of order of column floats. This problem can be remedied by holding them all in the same list. +% We therefore stop using \cmd\@dbldeferlist\ entirely, and all of the procedures that formerly used it have been rewritten to +% use \cmd\@deferlist\ instead. When traversing the list, we apply a selector on the given box that determines whether it is a column-width or page-width float. +% This selector is different depending on the page grid. +% +% When the \cmd\@deferlist\ is processed (by any means), we have to take care of the case where a float of one category is passed over but we are looking for a float of the other category. +% Here, we must terminate processing, to avoid disordering the floats. This we do by the usual means. +% +% The system has a Boolean that says we are clearing pages: \cmd\clearpage@sw; if it is true, +% then at the tail of \cmd\do@startcolumn\ processing, we should put down a (\cmd\vfil?) \cmd\do@newpage@pen\ interrupt. +% This is because the MVL is now empty, so we have to force the columns to complete. +% +% One potential very pathological case would be where there is one or more deferred floats that never successfully get placed: +% placing floats has stalled, and we will ship out blank pages indefinitely. How to detect this case? +% +% First, \cmd\do@startpage\ will evidently be stalled if the following are all true: +% a) \cmd\@tryfcolumn\ and \cmd\@sdblcolelt\ both fail, +% b) there are deferred floats available for page placement, and +% c) the \cmd\@colht=\cmd\textheight, that is, the full page height is available for placement of column floats. +% +% Second, \cmd\do@startcolumn\ will evidently be stalled if the following are all true: +% a) tryfcolumn fails, +% b) there are deferred floats available for column placement, and +% a) the \cmd\@colroom=\cmd\textheight, that is, the full page height is available for placement of column floats. +% +% +% \begin{macro}{\cleardoublepage} +% \begin{macro}{\clearpage} +% \begin{macro}{\newpage} +% \begin{macro}{\newpage@prep} +% The function of \cmd\clearpage\ is to end the current page with \cmd\newpage\ and then +% ship out additional pages until (\footins) inserts and (deferred) floats are exhausted. +% +% The method involves setting the float placement parameters to completely permissive values +% and kicking out the current page (using a non-discardable penalty). +% A possibly short page will be shipped out, followed +% by any number of float pages. However these float pages, because using permissive float placement, +% will exhaust all inserts and deferred floats. +% +% Bug Note: in the code for \cmd\clearpage, the first penalty we output is an unprotected \cmd\pagebreak@pen. +% I tried using a protected \cmd\do@newpage@pen, but that gave rise to a corner case where a blank page +% was output. +% +% At present, the \cmd\clearpage\ procedure does the same as \cmd\newpage, +% except that \cmd\clearpage@sw\ is turned on, +% and the (discardable) \cmd\newpage\ is inevitably followed by the same procedures +% that are executed if a page is shipped out. +% +% FIXME: it seems that better than \cmd\pagebreak@pen\ would be an unprotected penalty of a special value that would +% entail output routine processing consisting of the following steps: +% 3) \cmd\unvbox\cmd\@cclv, +% 1) set \cmd\clearpage@sw\ to \cmd\true@sw, +% 2) put down a protected \cmd\do@startcolumn@pen, +% 4) take a dead cycle. +% +% The effect would be to liberalize float placement options for the current column as well as further columns that may be output as part of \cmd\clearpage\ processing. +% Of course, it would still be necessary to set \cmd\clearpage@sw\ again via an interrupt. +% +% An optimization might be to clear \cmd\clearpage@sw\ as part of the same interrupt, +% but that would actually not work properly, because it is necessary for \cmd\do@endpage\ to +% possibly invoke furhter visits to the output routine before clearpage processing ceases. +% \begin{macrocode} +\def\newpage@prep{% + \if@noskipsec + \ifx \@nodocument\relax + \leavevmode + \global \@noskipsecfalse + \fi + \fi + \if@inlabel + \leavevmode + \global \@inlabelfalse + \fi + \if@nobreak \@nobreakfalse \everypar{}\fi + \par +}% +\def \newpage {% + \newpage@prep + \do@output@MVL{% + \vfil + \penalty-\pagebreak@pen + }% +}% +\def\clearpage{% + \newpage@prep + \do@output@MVL{% + \vfil + \penalty-\pagebreak@pen + \global\@booleantrue\clearpage@sw + \protect@penalty\do@startcolumn@pen + \protect@penalty\do@endpage@pen + }% + \do@output@MVL{% + \global\@booleanfalse\clearpage@sw + }% +}% +\def\cleardoublepage{% + \clearpage + \@if@sw\if@twoside\fi{% + \@ifodd\c@page{}{% + \null\clearpage + }% + }{}% +}% +\@booleanfalse\clearpage@sw +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\do@endpage@pen} +% The penalty \cmd\do@endpage@pen\ simply dispatches to the page grid procedure that forces an end page. +% That procedure should test whether there is anything to ship out (say committed floats), then act accordingly. +% Note that as part of this work, it should \cmd\unvbox\cmd\@cclv, which has been left boxed up so it can be +% measured. +% \begin{macrocode} +\mathchardef\do@endpage@pen=10007 +\@namedef{output@-\the\do@endpage@pen}{% + \csname end@column@\thepagegrid\endcsname +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\do@newpage@pen} +% The penalty \cmd\do@newpage@pen\ allows a ``non-discardable \cmd\newpage'' command: +% a \cmd\newpage\ command that will not disappear at a pagebreak. +% This visit to the output routine will not be dispatched to an interrupt, +% rather the natural output routine will be executed, where it +% will remove the protection box. +% +% Call this routine by executing \cmd\protect@penalty\cmd\do@newpage@pen. +% \begin{macrocode} +\mathchardef\do@newpage@pen=10001 +\expandafter\let\csname output@-\the\do@newpage@pen\endcsname\relax +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@clearfloatplacement} +% The procedure \cmd\@clearfloatplacement\ sets all of the float placement parameters +% to completely permissive values. The standard values appear as comments. +% \begin{macrocode} +\def\@clearfloatplacement{% + \global\@topnum \maxdimen % \c@topnumber + \global\@toproom \maxdimen % \topfraction\@colht + \global\@botnum \maxdimen % \c@bottomnumber + \global\@botroom \maxdimen % \bottomfraction\@colht + \global\@colnum \maxdimen % \c@totalnumber +%\global\@fpmin \z@ % \floatpagefraction\@colht + \global\@dbltopnum \maxdimen % \c@dbltopnumber + \global\@dbltoproom \maxdimen % \dbltopfraction\@colht + \global\@textmin \z@ % \@colht\advance \@textmin -\@dbltoproom + \global\@fpmin \z@ % \dblfloatpagefraction\textheight + \let\@testfp\@gobble + \appdef\@setfloattypecounts{\@fpstype16\advance\@fpstype\m@ne}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@doclearpage} +% The \cmd\@doclearpage\ procedure is now obsoleted, as is \cmd\@makefcolumn, which it invoked. +% \begin{macrocode} +\let\@doclearpage\@undefined +\let\@makefcolumn\@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\clr@top@firstmark} +% \begin{macro}{\set@top@firstmark} +% \begin{macro}{\@outputpage} +% We want accurate values of \cmd\topmark\ and \cmd\firstmark, but we must deal with +% the fact that there are many different ways of contributing material +% to the page. Only upon the first contribution to the page is the value of \cmd\topmark\ +% accurate. However, with \cmd\firstmark\ we must potentially examine each contribution +% because the first mark on the page may happen to fall in the last piece of material contributed. +% +% To begin, we define the procedure that initializes the macros to appropriate flag values. +% \begin{macrocode} +\def\clr@top@firstmark{% + \global\let\saved@@topmark\@undefined + \global\let\saved@@firstmark\@empty + \global\let\saved@@botmark\@empty +}% +\clr@top@firstmark +% \end{macrocode} +% +% Note that the flag value for \cmd\saved@@topmark\ is \cmd\@undefined, just as one would +% expect. But that for \cmd\saved@@firstmark\ and \cmd\saved@@botmark\ is \cmd\@empty. +% +% Next, we define procedure \cmd\set@top@firstmark; it will be exercised everywhere material is contributed, +% capturing the mark values if appropriate. +% \begin{macrocode} +\def\set@top@firstmark{% + \@ifxundefined\saved@@topmark{\expandafter\gdef\expandafter\saved@@topmark\expandafter{\@@topmark}}{}% + \@if@empty\saved@@firstmark{\expandafter\gdef\expandafter\saved@@firstmark\expandafter{\@@firstmark}}{}% + \@if@empty\@@botmark{}{\expandafter\gdef\expandafter\saved@@botmark\expandafter{\@@botmark}}% +}% +% \end{macrocode} +% When should \cmd\set@top@firstmark\ be called? +% A good candidate for a universal procedure for handling contributed material is +% the natural output routine; are any other calls needed? +% +% Yes, in \cmd\save@column\ we must execute \cmd\set@top@firstmark\ because we are about to +% save away \cmd\box\cmd\@cclv, and we will never see its marks again (unless it is unboxed into the MVL), +% because \TeX\ lets one access a box's marks only within an output routine that has put that box into \cmd\box\cmd\@cclv. +% +% As soon as a page is shipped out, we initialize the two macros that +% hold the values of \cmd\topmark\ and \cmd\firstmark, respectively. +% \LaTeX\ has exactly one procedure \cmd\@outputpage\ that does \cmd\shipout, +% which is as it should be: we tailpatch it, and the job is done. +% \begin{macrocode} +\appdef\@outputpage{% + \clr@top@firstmark +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsection{Other interfaces to \LaTeX}% +% +% \begin{macro}{\@float} +% \begin{macro}{\@dblfloat} +% \begin{macro}{\@yfloat} +% \begin{macro}{\fps@} +% \begin{macro}{\fpsd@} +% The \LaTeX\ kernel procedures \cmd\@float\ and \cmd\@dblfloat\ are treated on an equal footing. +% Each now takes environment-specific float placement defaults. +% If none are defined for the calling environment, we apply a default. +% +% A parameter is passed that will set the width of text within the float, normally \cmd\columnwidth, +% and in the "dbl" version, \cmd\textwidth. However, an environment such as \env{turnpage} +% may change the meanings of these macros to allow turnpage floats. +% +% \begin{macrocode} +\def\@float#1{% + \@ifnextchar[{%}]{%Brace-matching klootch + \@yfloat\width@float{#1}% + }{% + \@ifxundefined@cs{fps@#1}{% + \edef\reserved@a{\noexpand\@yfloat\noexpand\width@float{#1}[\csname fps@\endcsname]}\reserved@a + }{% + \edef\reserved@a{\noexpand\@yfloat\noexpand\width@float{#1}[\csname fps@#1\endcsname]}\reserved@a + }% + }% +}% +\def\@dblfloat#1{% + \@ifnum{\pagegrid@col=\@ne}{% + \@float{#1}% + }{% + \@ifnextchar[{%}]{%Brace-matching klootch + \@yfloat\widthd@float{#1}% + }{% + \@ifxundefined@cs{fpsd@#1}{% + \edef\reserved@a{\noexpand\@yfloat\noexpand\widthd@float{#1}[\csname fpsd@\endcsname]}\reserved@a + }{% + \edef\reserved@a{\noexpand\@yfloat\noexpand\widthd@float{#1}[\csname fpsd@#1\endcsname]}\reserved@a + }% + }% + }% +}% +\def\@yfloat#1#2[#3]{% + \@xfloat{#2}[#3]% + \hsize#1\linewidth\hsize + \minipagefootnote@init +}% +\def\fps@{tbp}% +\def\fpsd@{tp}% +\def\width@float{\columnwidth}% +\def\widthd@float{\textwidth}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\end@float} +% \begin{macro}{\end@dblfloat} +% \begin{macro}{\end@@float} +% \begin{macro}{\check@currbox@count} +% \begin{macro}{\minipagefootnote@init} +% \begin{macro}{\minipagefootnote@here} +% \LaTeX\ kernel procedures \cmd\end@float\ and \cmd\end@dblfloat\ +% have been changed to work alike; in particular, floats of both classes +% are deferred into the same queue. +% This measure ensures that they will be placed in their original order, +% an aspect in which \LaTeX\ is broken. +% +% Note: when retrieving floats from the queues, we can differentiate those of the two categories +% by the width of the box. +% +% Floats are processed via an output routine message, and are checked for +% sanity in re the float placement options. In the case of full-page-width floats, +% we ensure that the h and b float placement options are never asserted, because they +% make no sense. +% +% Note that if we get to the end of the float box and still have pending +% footnotes, we put then out. +% +% LaTeX Bug note: if a user types \cmd\begin{table*}[h], the float will never succeed in being placed! +% we try to catch such cases. +% +% Note that the macro \cmd\check@currbox@count\ trys to catch cases where the float placement options +% are such that the float can never be placed. +% \begin{macrocode} +\def\end@float{% + \end@@float{% + \check@currbox@count + }% +}% +\def\end@dblfloat{% + \@ifnum{\pagegrid@col=\@ne}{% + \end@float + }{% + \end@@float{% + \@boxfpsbit\@currbox{1}\@ifodd\@tempcnta{\global\advance\count\@currbox\m@ne}{}% + \@boxfpsbit\@currbox{4}\@ifodd\@tempcnta{\global\advance\count\@currbox-4\relax}{}% + \global\wd\@currbox\textwidth % Klootch + \check@currbox@count + }% + }% +}% +\def\end@@float#1{% + \minipagefootnote@here +%\minipagefootnotes + \@endfloatbox + #1% + \@ifnum{\@floatpenalty <\z@}{% + \@largefloatcheck + \@cons\@currlist\@currbox + \@ifnum{\@floatpenalty <-\@Mii}{% + \do@output@cclv{\@add@float}% + }{% + \vadjust{\do@output@cclv{\@add@float}}% + \@Esphack + }% + }{}% +}% +\def\check@currbox@count{% + \@ifnum{\count\@currbox>\z@}{% + \count@\count\@currbox\divide\count@\sixt@@n\multiply\count@\sixt@@n + \@tempcnta\count\@currbox\advance\@tempcnta-\count@ + \@ifnum{\@tempcnta=\z@}{% + \ltxgrid@warn{Float cannot be placed}% + }{}% + }{% + % Is a \marginpar + }% +}% +\providecommand\minipagefootnote@init{}% +\providecommand\minipagefootnote@here{}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@specialoutput} +% The \cmd\@add@float\ procedure used to reside in standard \LaTeX's \cmd\@specialoutput, +% which is no more. +% +% Historical Note: \cmd\@specialoutput\ and Lamport's method of an output routine dispatcher +% is the genesis of our more powerful and refined way of using \TeX's output routine to +% safely accomplish page makeup tasks. To it and to him we owe acknowledgement and thanks. +% \begin{macrocode} +\let\@specialoutput\@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@add@float} +% In the following, we do not need to execute \cmd\@reinserts, which was wrong anyway, as you cannot +% reliably recover insertions when they split (unless you have a way of reinserting the captured insertion +% ahead of the split-off part). +% +% Now that full-page-width floats are being processed the same as column floats, we +% have to nip in here and cause them always to be deferred. +% +% At the very end, the \cmd\vsize\ is adjusted for any newly committed float. +% \begin{macrocode} +\def\@add@float{% + \@pageht\ht\@cclv\@pagedp\dp\@cclv + \unvbox\@cclv + \@next\@currbox\@currlist{% + \csname @floatselect@sw@\thepagegrid\endcsname\@currbox{% + \@ifnum{\count\@currbox>\z@}{% + \advance \@pageht \@pagedp + \advance \@pageht \vsize \advance \@pageht -\pagegoal % do not assume \holdinginserts is cleared! +% \@ifvbox\@kludgeins{% +% \@ifdim{\wd\@kludgeins=\z@}{% +% \advance \@pageht \ht\@kludgeins +% }{}% +% }{}% +% \@reinserts + \@addtocurcol % Commit an h float + }{% +% \@reinserts + \@addmarginpar + }% + }{% + \@resethfps + \@cons\@deferlist\@currbox + }% + }{\@latexbug}% + \@ifnum{\outputpenalty<\z@}{% + \@if@sw\if@nobreak\fi{% + \nobreak + }{% + \addpenalty \interlinepenalty + }% + }{}% + \set@vsize +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@reinserts} +% The \cmd\@reinserts\ procedure of standard \LaTeX\ is now obsoleted. +% \begin{macrocode} +\let\@reinserts\@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@addtocurcol} +% We modify the \cmd\@addtocurcol\ procedure of standard \LaTeX\ +% so that a float placed ``here'' may break over pages. +% \begin{macrocode} +\def \@addtocurcol {% + \@insertfalse + \@setfloattypecounts + \ifnum \@fpstype=8 + \else + \ifnum \@fpstype=24 + \else + \@flsettextmin + \advance \@textmin \@textfloatsheight + \@reqcolroom \@pageht + \ifdim \@textmin>\@reqcolroom + \@reqcolroom \@textmin + \fi + \advance \@reqcolroom \ht\@currbox + \ifdim \@colroom>\@reqcolroom + \@flsetnum \@colnum + \ifnum \@colnum>\z@ + \@bitor\@currtype\@deferlist + \if@test + \else + \@bitor\@currtype\@botlist + \if@test + \@addtobot + \else + \ifodd \count\@currbox + \advance \@reqcolroom \intextsep + \ifdim \@colroom>\@reqcolroom + \global \advance \@colnum \m@ne + \global \advance \@textfloatsheight \ht\@currbox + \global \advance \@textfloatsheight 2\intextsep + \@cons \@midlist \@currbox + \if@nobreak + \nobreak + \@nobreakfalse + \everypar{}% + \else + \addpenalty \interlinepenalty + \fi + \vskip \intextsep + \unvbox\@currbox %AO + \penalty\interlinepenalty + \vskip\intextsep + \ifnum\outputpenalty <-\@Mii \vskip -\parskip\fi + \outputpenalty \z@ + \@inserttrue + \fi + \fi + \if@insert + \else + \@addtotoporbot + \fi + \fi + \fi + \fi + \fi + \fi + \fi + \if@insert + \else + \@resethfps + \@cons\@deferlist\@currbox + \fi +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\if@twocolumn} +% The \cmd\newif\ switch \cmd\if@twocolumn\ is entirely unused. However its access words are invoked by +% \LaTeX's \cmd\document\ procedure, so we de-fang it. +% \begin{macrocode} +\@twocolumnfalse +\let\@twocolumntrue\@twocolumnfalse +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@addmarginpar} +% The procedure \cmd\@addmarginpar\ used to access \cmd\if@twocolumn, but that switch is not reliable; +% the better way is to use \cmd\thepagegrid. We establish a convention for a page-grid-oriented +% procedure, e.g., \cmd\@addmarginpar@one, that emits a boolean, telling this procedure +% whether to set the marginpar on the left or right. +% \begin{macrocode} +\def\@addmarginpar{% + \@next\@marbox\@currlist{% + \@cons\@freelist\@marbox\@cons\@freelist\@currbox + }\@latexbug + \setbox\@marbox\hb@xt@\columnwidth{% + \csname @addmarginpar@\thepagegrid\endcsname{% + \hskip-\marginparsep\hskip-\marginparwidth + \box\@currbox + }{% + \hskip\columnwidth\hskip\marginparsep + \box\@marbox + }% + \hss + }% + \setbox\z@\box\@currbox + \@tempdima\@mparbottom + \advance\@tempdima -\@pageht + \advance\@tempdima\ht\@marbox + \@ifdim{\@tempdima >\z@}{% + \@latex@warning@no@line {Marginpar on page \thepage\space moved}% + }{% + \@tempdima\z@ + }% + \global\@mparbottom\@pageht + \global\advance\@mparbottom\@tempdima + \global\advance\@mparbottom\dp\@marbox + \global\advance\@mparbottom\marginparpush + \advance\@tempdima -\ht\@marbox + \global\setbox \@marbox + \vbox {\vskip \@tempdima + \box \@marbox}% + \global \ht\@marbox \z@ + \global \dp\@marbox \z@ + \kern -\@pagedp + \nointerlineskip + \box\@marbox + \nointerlineskip + \hbox{\vrule \@height\z@ \@width\z@ \@depth\@pagedp}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{environment}{turnpage} +% Any float (viz., \env{figure} or \env{table}) within the scope of this environment +% will be a turnpage float: It will be assumed to occupy an entire page (constitute a float page), +% the width will be \cmd\textheight, the height \cmd\textwidth, and the entire float will be presented +% rotated 90 degrees. +% +% The implementation requires the services of the \cmd\rotatebox\ command, so we supply a dummy definition +% that explains things to the user. +% \begin{macrocode} +\newenvironment{turnpage}{% + \def\width@float{\textheight}% + \def\widthd@float{\textheight}% + \appdef\@endfloatbox{% + \@ifxundefined\@currbox{% + \ltxgrid@warn{Cannot rotate! Not a float}% + }{% + \setbox\@currbox\vbox to\textwidth{\vfil\unvbox\@currbox\vfil}% + \global\setbox\@currbox\vbox{\rotatebox{90}{\box\@currbox}}% + }% + }% +}{% +}% +\def\rotatebox@dummy#1#2{% + \ltxgrid@warn{You must load the graphics or graphicx package in order to use the turnpage environment}% + #2% +}% +\AtBeginDocument{% + \@ifxundefined\rotatebox{\let\rotatebox\rotatebox@dummy}{}% +}% +% \end{macrocode} +% \end{environment} +% +% +% \subsection{One-off output routines} +% +% These procedures are executed in lieu of \cmd\the\cmd\output\ when the output penalty has the associated flag value. +% +% \begin{macro}{output@-1073741824} +% The first one-off output routine handles the end of the job, wherein +% \LaTeX\ executes \cmd\@@end, and breaks to the output with a penalty of +% $"40000000 = 2^{32}/4$. We simply discard \cmd\box\cmd\@cclv\ and leave. +% This means that \LaTeX\ is obligated to do \cmd\clearpage\ as part of +% its \enve{document} processing, otherwise material will be lost. +% \begin{macrocode} +\@namedef{output@-1073741824}{%"40000000 + \deadcycles\z@ +%\showbox\@cclv + \setbox\z@\box\@cclv +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\save@column@pen} +% The one-off output routine associated with \cmd\penalty\cmd\save@column@pen\ +% will be called within a sequence of three such routines by \cmd\execute@message +% or its companion routine \cmd\execute@message@insert. +% This procedure must save away any the current page and preserve marks. +% \begin{macrocode} +\mathchardef\save@column@pen=10016 +\@namedef{output@-\the\save@column@pen}{\save@column}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@cclv@saved} +% We take over the \cmd\@holdpg\ box register. Hereafter, +% we no longer use the \cmd\@holdpg\ box register, so let the world know. +% This should decisively break packages that assume standard \LaTeX. +% Breaking decisively is preferred to quietly proceeding erroneously. +% \begin{macrocode} +\let \@cclv@saved \@holdpg +\let \@holdpg \@undefined +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\save@column} +% The procedure \cmd\save@column\ does the actual work of saving away the material +% on the page. It is invoked both by \cmd\save@column@pen\ and by \cmd\save@column@insert@pen. +% We save \cmd\box\cmd\@cclv\ and the primitive \cmd\@@topmark. +% \begin{macrocode} +\def\save@column{% + \@ifvoid\@cclv@saved{% + \set@top@firstmark + \global\@topmark@saved\expandafter{\@@topmark}% + }{}% + \global\setbox\@cclv@saved\vbox{% + \@ifvoid\@cclv@saved{}{% + \unvbox\@cclv@saved + \marry@baselines + }% + \unvbox\@cclv + \lose@breaks + \setbox\z@\lastbox + }% +}% +\newtoks\@topmark@saved +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\prep@cclv} +% The procedure \cmd\prep@cclv\ is used by message handlers to set up their environment +% to ape that of the usual output routine, with the boxed-up page in \cmd\box\cmd\@cclv. +% Here, we retrieve the material from \cmd\@cclv@saved, where it was saved away by +% the one-off output routine associated with \cmd\save@column@pen. +% \begin{macrocode} +\def\prep@cclv{% + \setbox\z@\box\@cclv + \setbox\@cclv\box\@cclv@saved + \vbadness\@M +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\save@column@insert@pen} +% The one-off output routine associated with \cmd\penalty\cmd\save@column@insert@pen\ +% is similar to that of \cmd\save@column@pen\ augmented with the processing of insertions. +% It is called by \cmd\execute@message@insert\ (i.e., at a grid change) +% and saves away the current page and preserves marks. +% In addition, it saves away any insertions that fall on the current page. +% As with the regular output routine, it executes in two phases, +% first with \cmd\holdinginserts\ set, then with it cleared. +% \begin{macrocode} +\mathchardef\save@column@insert@pen=10017 +\@namedef{output@-\the\save@column@insert@pen}{\toggle@insert\savecolumn@holding\savecolumn@moving}% +% \end{macrocode} +% The procedure \cmd\savecolumn@holding\ is the first phase of saving a column with its inserts. +% This phase must detect and remedy the one circumstance that will confound our efforts to propagate marks. +% It is similar to \cmd\output@holding, except that we have to deal with the protection box, which must +% remain, because the messaging mechanism is being used. +% +% If it appears that we have the pathological ``Big Bad Box'' case at hand, we use the \cmd\dead@cycle@repair@protected\ +% procedure instead of \cmd\dead@cycle\ to do our dead cycle. +% \begin{macrocode} +\def\savecolumn@holding{% + \@if@exceed@pagegoal{\unvcopy\@cclv\setbox\z@\lastbox}{% + \setbox\z@\vbox{\unvcopy\@cclv\setbox\z@\lastbox}% + \outputdebug@sw{{\tracingall\scrollmode\showbox\z@}}{}% + \dimen@\ht\@cclv\advance\dimen@-\ht\z@ + \dead@cycle@repair@protected\dimen@ + }{% + \dead@cycle + }% +}% +% \end{macrocode} +% The procedure \cmd\save@column@moving\ is the second phase of saving a column with its inserts. +% Now that \cmd\holdinginserts\ is cleared, we can look in the various \cmd\insert\ registers for +% our inserts (at present there is only one, \cmd\footins). +% if anything is there, we save it away and ask for another cycle (because it may have split). +% +% Note that the message that is about to be executed had better deal properly with the contents of +% the \cmd\footins@saved\ box. +% \begin{macrocode} +\def\savecolumn@moving{% + \@cclv@nontrivial@sw{% + \save@column + }{% + {\setbox\z@\box\@cclv}% + }% + \@ifvoid\footins{}{% + \outputdebug@sw{{\tracingall\scrollmode\showbox\footins}}{}% + \global\setbox\footins@saved\vbox{\unvbox\footins@saved\marry@baselines\unvbox\footins}% + \protect@penalty\save@column@insert@pen + }% +}% +\newbox\footins@saved +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\save@message@pen} +% The one-off output routine associated with \cmd\penalty\cmd\save@message@pen\ +% saves away the message that has been passed. +% This procedure is penultimate in a sequence of one-off output routine calls; +% earlier ones have saved away the MVL and preserved marks, the last executes the message. +% +% Note that we are passing tokens to \TeX's primitive \cmd\mark\ mechanism, so we must ensure +% that they are not inappropriately expanded. We use the same mechanism for all such cases, +% namely \cmd\let@mark. +% +% Note: we expect that \cmd\box\cmd\@cclv's contents are well known: +% \cmd\topskip, protection box, and a \cmd\mark, the latter havin the +% message. +% But if we came here via \cmd\penalty 10017, there might be an \cmd\insert\ node here as well, because +% a footnote split. +% Because this procedure simply voids out \cmd\box\cmd\@cclv, such material would be lost. +% Perhaps we can repair things by manipulating the \cmd\insert \ mechanism temporarily. +% \begin{macrocode} +\mathchardef\save@message@pen=10018 +\@namedef{output@-\the\save@message@pen}{\save@message}% +\def\save@message{% + \setbox\z@\box\@cclv %FIXME: what if \box\@cclv is not empty? + \toks@\expandafter{\@@firstmark}% + \expandafter\gdef\expandafter\@message@saved\expandafter{\the\toks@}% + \expandafter\do@@mark\expandafter{\the\@topmark@saved}% +}% +\gdef\@message@saved{}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\execute@message@pen} +% The one-off output routine associated with \cmd\execute@message@pen\ +% simply executes the given message. It is last in a sequence of one-off output routine calls; +% earlier ones have saved all that require saving. +% \begin{macrocode} +\mathchardef\execute@message@pen=10019 +\@namedef{output@-\the\execute@message@pen}{\@message@saved}% +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Output messages} +% +% Message handlers are procedures that execute output messages, tokens that are passed to +% the output routine for execution in an environment appropriate to page makeup. +% +% How it works. We put down three large negative penalties, each of which will be handled by +% the output dispatcher (not the output routine), each penalty being protected by +% a removable, non-discardable item (i.e., a box). +% Either three or four invocations of one-off output routines are involved per message. +% +% We make the last of the three protection boxes have a depth equal to the value of \cmd\prevdepth\ +% that was current when the procedure is called. This effectively restores \cmd\prevdepth. +% +% In each case, the one-off output routine will remove the extraneous box we have inserted. +% And the second and third one-off routines will simply void \cmd\box\cmd\@cclv, because its contents +% are entirely artificial. +% +% FIXME: not so! If \cmd\holdinginserts\ is cleared, that box may have an insert node; it must be preserved, too. +% +% The first routine saves away the current column contents and remembers the \cmd\topmark\ for later +% use. There is a variant routine that first clears \cmd\holdinginserts, so that the message can +% handle any inserts present in the boxed-up page; this of course entails yet another +% visit to the output routine. +% +% The penultimate routine saves away the tokens transmitted in via the \cmd\@@mark: the argument of +% the macro. These tokens are of course the very thing we wish to execute within the safety +% of the output routine. It also puts down a mark containing the \cmd\topmark\ tokens saved +% by the first routine. By this means, the mark, which we have clobbered, is restored. +% +% The last routine simply executes the given tokens. +% In the course of doing this, it must take care of \cmd\box\cmd\@cclv, either by shipping it out, +% or by \cmd\unvbox ing it onto the MVL. +% +% \begin{macro}{\execute@message} +% The procedure \cmd\execute@message\ simply calls the utility procedure \cmd\@execute@message\ +% with a penalty value for the standard treatment. +% \begin{macrocode} +\def\execute@message{% + \@execute@message\save@column@pen %Implicit #2 +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\execute@message@insert} +% The procedure \cmd\execute@message@insert\ is like \cmd\execute@message\ in all respects +% except that the penalty value is \cmd\save@column@insert@pen, which arranges for the +% message handler involved to deal with the page's insertions. +% At the same time, we prepare the \cmd\footins\ box so that these insertions can be dealt with. +% +% Note: +% If more insertions are added to \LaTeX\ (presumably via \cmd\newinsert), then they +% must be dealt with in a way entirely analogous to \cmd\footins. +% \begin{macrocode} +\def\execute@message@insert#1{% + \@execute@message\save@column@insert@pen{\setbox\footins\box\footins@saved#1}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@execute@message} +% The utility procedure \cmd\@execute@message\ is called by \cmd\execute@message\ and \cmd\execute@message@insert. +% We prepare by creating a \cmd\vbox\ containing all the needed nodes and proceed by simply +% \cmd\unvbox ing that box onto the MVL. +% We ensure that \cmd\box\cmd\@cclv\ is properly set up for the output message handler +% by always inserting \cmd\prep@cclv\ in advance of the argument. +% +% Note that each one-off output routine is invoked effectively the same as +% \cmd\protect@penalty, except that the second invocation involves an additional +% \cmd\mark\ node, and the third a specially prepared protection box. +% +% Note also that \TeX's primitive \cmd\mark\ is called here without any expansion protection. +% This is the only place where it is called that way, but it's OK because those tokens +% have have been pre-expanded by procedures that call \cmd\execute@message. +% FIXME: all procedures calling \cmd\execute@message\ must pre-expand their tokens! +% \begin{macrocode} +\long\def\@execute@message#1#2{% + \begingroup + \dimen@\prevdepth\@ifdim{\dimen@<\z@}{\dimen@\z@}{}% + \setbox\z@\vbox{% + \protect@penalty#1% + \protection@box + \toks@{\prep@cclv#2}% + \@@mark{\the\toks@}% + \penalty-\save@message@pen +% \hbox{\vrule\@height\z@\@width\z@\@depth\dimen@}% + \setbox\z@\null\dp\z@\dimen@\ht\z@-\dimen@ + \nointerlineskip\box\z@ + \penalty-\execute@message@pen + }\unvbox\z@ + \endgroup +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\do@output@cclv} +% The procedure \cmd\do@output@cclv\ provides access to message handlers at their simplest. +% The message will execute in the usual environment of the output routine, with +% the boxed-up page in \cmd\box\cmd\@cclv, and we assume that \cmd\holdinginserts\ remains set. +% This procedure must be invoked within main vertical mode; +% it is the obligation of the macro writer to ensure that this is the case. +% \begin{macrocode} +\def\do@output@cclv{\execute@message}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\do@output@MVL} +% The procedure \cmd\do@output@MVL, like \cmd\do@output@cclv, is an interface for messages, +% but provides two additional services: the command may also be invoked in horizontal mode, and +% the message handler will execute with the MVL unboxed. +% \begin{macrocode} +\def\do@output@MVL#1{% + \@ifvmode{% + \begingroup\execute@message{\unvbox\@cclv#1}\endgroup + }{% + \@ifhmode{% + \vadjust{\execute@message{\unvbox\@cclv#1}}% + }{% + \@latexerr{\string\do@output@MVL\space cannot be executed in this mode!}\@eha + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\lose@breaks} +% The purpose of this procedure is to get rid of all the extraneous +% \cmd\penalty\cmd\@M\ nodes that tend to build up in the MVL. +% \begin{macrocode} +\def\lose@breaks{% + \loopwhile{% + \count@\lastpenalty + \@ifnum{\count@=\@M}{% 10000 is a TeX magic number! + \unpenalty\true@sw + }{% + \false@sw + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\removestuff} +% \cmd\removestuff\ is a document-level command that removes the bottom skip glue item +% from the MVL. +% \begin{macrocode} +\def\removestuff{\do@output@MVL{\unskip\unpenalty}}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\removephantombox} +% The procedure \cmd\removephantombox\ is a special-purpose message handler exclusively for +% preventing incorrect spacing above display math. It must be issued in +% horizontal mode within the phantom paragraph generated when display math starts up in +% vertical mode. +% \begin{macrocode} +\def\removephantombox{% + \vadjust{% + \execute@message{% + \unvbox\@cclv + \setbox\z@\lastbox + \unskip + \unskip + \unpenalty + \penalty\predisplaypenalty + \vskip\abovedisplayskip + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\addstuff} +% \cmd\addstuff\ is a document-level command that adds penalty, glue, or both to the +% MVL. The penalty and glue items are rearranged so that all penalties nodes precede all the glue nodes, +% which is the canonical arrangement. +% \begin{macrocode} +\def\addstuff#1#2{\edef\@tempa{\noexpand\do@output@MVL{\noexpand\@addstuff{#1}{#2}}}\@tempa}% +\def\@addstuff#1#2{% + \skip@\lastskip\unskip + \count@\lastpenalty\unpenalty + \@if@empty{#1}{}{\penalty#1\relax}% + \@ifnum{\count@=\z@}{}{\penalty\count@}% + \vskip\skip@ + \@if@empty{#2}{}{\vskip#2\relax}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\replacestuff} +% \cmd\replacestuff\ is a document-level command similar to \cmd\addstuff; +% but it replaces penalty, glue, or both in the MVL. +% The penalty and glue items are rearranged so that all penalties nodes precede all the glue nodes, +% which is the canonical arrangement. +% \begin{macrocode} +\def\replacestuff#1#2{\edef\@tempa{\noexpand\do@output@MVL{\noexpand\@replacestuff{#1}{#2}}}\@tempa}% +\def\@replacestuff#1#2{% + \skip@\lastskip\unskip + \count@\lastpenalty\unpenalty + \@if@empty{#1}{}{% + \@ifnum{\count@>\@M}{}{% + \@ifnum{\count@=\z@}{\count@=#1\relax}{% + \@ifnum{\count@<#1\relax}{}{% + \count@=#1\relax + }% + }% + }% + }% + \@ifnum{\count@=\z@}{}{\penalty\count@}% + \@if@empty{#2}{}{% + \@tempskipa#2\relax + \@ifdim{\z@>\@tempskipa}{% + \advance\skip@-\@tempskipa + }{% + \@ifdim{\skip@>\@tempskipa}{}{% + \skip@\@tempskipa + }% + }% + }% + \vskip\skip@ +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\move@insertions} +% \begin{macro}{\hold@insertions} +% \begin{macro}{\move@insert@sw} +% In order to avoid bolluxing up \cmd\insert\ registers by our one-off +% output routines, we set \cmd\holdinginserts\ to zero by default and only +% clear it (briefly) while we handle cases where we want inserts to show up. +% \begin{macrocode} +\def\move@insertions{\global\holdinginserts\z@}% +\def\hold@insertions{\global\holdinginserts\@ne}% +\hold@insertions +\def\move@insert@sw{\@ifnum{\holdinginserts=\z@}}% +\def\toggle@insert#1#2{% + \@ifnum{\holdinginserts=\z@}{\hold@insertions#2}{\move@insertions#1}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsection{Messages to alter the page grid}% +% +% Here is the implementation of the grid-switching procedures. +% We perform two checks when changing the page grid; first to ensure that +% the target page grid is known (defensive programming), second to ensure that +% the switch is a non-trivial one. The latter check must be performed within +% the safety of the output routine, so requires using an output message. +% Thus, a grid change requires two messages, for a total of six visits to the output routine. +% +% \begin{macro}{\do@columngrid} +% Utility procedure \cmd\do@columngrid\ changes the page grid. +% Note that this command forces an end to the current paragraph. This is necessary, because +% a page grid change makes no sense unless we can alter the \cmd\hsize\ before commencing to +% typeset the following paragraph. So the command should never be executed in horizontal mode +% anyway. +% \begin{macrocode} +\def\do@columngrid#1#2{% + \par + \expandafter\let\expandafter\@tempa\csname open@column@#1\endcsname + \@ifx{\relax\@tempa}{% + \ltxgrid@warn{Unknown page grid #1. No action taken}% + }{% + \do@output@MVL{\start@column{#1}{#2}}% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\start@column} +% Procedure \cmd\start@column\ lays down the interrupts to switch the page grid. +% If the change to the page grid would have been trivial, it bails out. +% It seems a reasonable tradeoff of processing versus security: once we commit +% to changing the page grid, we clear \cmd\holdinginserts, so there is no turning back. +% +% Note that the second argument to the macro allows us to pass an argument to the +% page grid that is starting up. This can be handy, because a single procedure can +% handle multiple page grids, differing only by the value of a parameter. +% +% FIXME: this means that you cannot switch between mlt page grids in a single step. +% But do we want to do this, at all, at all? +% \begin{macrocode} +\def\start@column#1#2{% + \def\@tempa{#1}\@ifx{\@tempa\thepagegrid}{% + \ltxgrid@info{Already in page grid \thepagegrid. No action taken}% + }{% + \expandafter\execute@message@insert + \expandafter{% + \csname shut@column@\thepagegrid\expandafter\endcsname + \csname open@column@#1\endcsname{#2}% + \set@vsize + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\thepagegrid} +% The macro \cmd\thepagegrid\ tracks what kind of page grid we are in. +% +% Note: Access \cmd\thepagegrid\ only within the safety of the output routine. +% +% Warning: The page grid should be changed only within the safety of the output routine. +% People who write multicol page grid mechanisms appear not to understand the matter, so they +% should particularly heed this warning. Think about it: obviously Lamport did so, which is why +% his \cmd\twocolumn\ command forced a pagebreak, which is limiting, but safe. +% \begin{macrocode} +\def\thepagegrid{one}% +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Application Note: implementing a page grid} +% +% If you want to create a new page grid for \LaTeX, +% you must define five procedures with specific names: +% \cmd\open@column@ name, \cmd\shut@column@ name, \cmd\end@column@ name, +% \cmd\output@column@ name, and \cmd\@addmarginpar@ name, where ``name'' is the +% name of your page grid. +% +% The procedure \cmd\open@column@ name starts the new page grid. It should define \cmd\thepagegrid, +% deal with \cmd\box\cmd\pagesofar\ and \cmd\box\cmd\footbox\ (perhaps by leaving them alone), +% and it should set the values of \LaTeX's page layout parameters for the column size and height. +% +% The procedure \cmd\shut@column@ name should expect to be called with \cmd\holdinginserts\ +% cleared (it can assume that \cmd\holdinginserts\ will automatically be restored). +% It should properly deal with insertions (like footnotes); calling \cmd\@makecol\ +% is a good way to do this. It should know that the page grid is being terminated +% in the middle of a page, so it should make arrangements to carry the footnotes down to the +% bottom of the column or page, and it should possibly salt away the material for later +% incorporation into the page. The box registers \cmd\footbox\ and \cmd\pagesofar\ are customarily used +% for this purpose. +% +% The procedure \cmd\end@column@ name should kick out a possibly short page containing all the +% floats committed to the page. It will be invoked during \cmd\clearpage\ processing. +% After that, it should \cmd\unvbox\cmd\@cclv. +% +% The procedure \cmd\output@column@ name should ship out or commit the current \cmd\@outputbox. +% In a one-column layout, you ship out; in a multicolumn layout, you commit the box as the contents +% of a particular column, and if that column is the last, you ship out. +% +% The procedure \cmd\@addmarginpar@ name should return a boolean (either \cmd\true@sw\ or \cmd\false@sw\ or an equivalent) +% to tell the marginpar mechanism to place the marginal material to the right or left, respectively. +% +% You can use the existing page grids ``one'' and ``mlt'' as a point of departure for creating others. +% The former can be the basis for, say, a single-column page grid with a side column. +% +% \begin{macro}{\pagesofar} +% \begin{macro}{\footbox} +% \begin{macrocode} +\newbox\pagesofar +\newbox\footbox +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% +% \subsubsection{One-column page grid} +% +% \begin{macro}{\onecolumngrid} +% \begin{macro}{\open@column@one} +% \begin{macro}{\shut@column@one} +% \begin{macro}{\float@column@one} +% \begin{macro}{\end@column@one} +% \begin{macro}{\output@column@one} +% \begin{macro}{\@addmarginpar@one} +% Here are all the procedures necessary for the standard page grid named ``one'': +% a single column layout. It is, of course, \LaTeX's familiar \cmd\onecolumn\ layout. +% We begin with the procedure exposed to the style writer. +% This is, however, not a \LaTeX\ command; users should not change the page grid. +% \begin{macrocode} +\newcommand\onecolumngrid{\do@columngrid{one}{\@ne}}% +% \end{macrocode} +% +% Note that a document class that issues the command \cmd\onecolumn\ will break. This includes +% \LaTeX's standard classes.dtx-based classes: if your class descends from one of these, you +% must expunge it of all such commands. +% \begin{macrocode} +\let\onecolumn\@undefined +% \end{macrocode} +% +% The procedure \cmd\open@column@one\ takes advantage of the special nature of the one-column +% page grid to deal with \cmd\box\cmd\pagesofar, therefore it must also reset \cmd\@colroom. +% \begin{macrocode} +\def\open@column@one#1{% + \unvbox\pagesofar + \gdef\thepagegrid{one}% + \global\pagegrid@col#1% + \global\pagegrid@cur\@ne + \set@colht +%\set@colroom + \set@column@hsize\pagegrid@col +}% +% \end{macrocode} +% +% The procedure \cmd\shut@column@one\ saves away the one-column material into the box register \cmd\pagesofar. +% Because it is called from a message handler, we are assured that marks are properly taken care of. +% \begin{macrocode} +\def\shut@column@one{% + \@makecol + \global\setbox\pagesofar\vbox{\unvbox\@outputbox\recover@footins}% + \set@colht +%\set@colroom +}% +% \end{macrocode} +% +% The procedure \cmd\float@column@one\ takes care of a float column that has been built by \cmd\@tryfcolumn, +% in the single-column page grid. +% \begin{macrocode} +\def\float@column@one{% + \@makecol + \@outputpage +}% +% \end{macrocode} +% +% The procedure \cmd\end@column@one\ is executed at the end of \cmd\clearpage\ processing, +% if we were in a one-column page grid, once all permissive float pages have been shipped out. +% At this point, one could perhaps +% assume that nothing more need be done, but let us anyway test for committed floats and force a shipout. +% +% FIXME: this procedure does the same as \cmd\end@column@mlt +% (except for the test of \cmd\@ifx@empty\cmd\@dbltoplist): +% the two could almost be the same procedure. +% +% I have changed this procedure to avoid the testing it once did: it simply puts down interrupts, +% upon which it relies to correctly do what \cmd\clearpage\ requires. +% \begin{macrocode} +\def\end@column@one{% + \unvbox\@cclv\setbox\z@\lastbox + \protect@penalty\do@newpage@pen +}% +% \end{macrocode} +% +% The procedure \cmd\output@column@one\ is dispatched from the output routine when +% we have completed a page (that is, a column in a one-column page grid). +% It ships out the page using the \cmd\@outputpage\ of standard \LaTeX, +% which has been retained (it is needed also in \cmd\output@column@mlt, +% and in any case should remain as the sole procedure in \LaTeX\ where \cmd\shipout\ is performed). +% It will be followed up with an output routine message to prepare a new column. +% \begin{macrocode} +\def\output@column@one{% + \@outputpage +}% +% \end{macrocode} +% +% The following procedure determines which side of the page a marginpar will appear. +% It reproduces the behavior of standard \LaTeX. +% \begin{macrocode} +\def\@addmarginpar@one{% + \@if@sw\if@mparswitch\fi{% + \@ifodd\c@page{\false@sw}{\true@sw}% + }{\false@sw}{% + \@if@sw\if@reversemargin\fi{\false@sw}{\true@sw}% + }{% + \@if@sw\if@reversemargin\fi{\true@sw}{\false@sw}% + }% +}% +% \end{macrocode} +% +% The following procedure yields a Boolean value; it determines whether a float in the deferred queue +% is appropriate for placing. In the one-column grid, all floats are so. +% \begin{macrocode} +\def\@floatselect@sw@one#1{\true@sw}% +% \end{macrocode} +% +% \begin{macrocode} +\def\onecolumngrid@push{% + \do@output@MVL{% + \@ifnum{\pagegrid@col=\@ne}{% + \global\let\restorecolumngrid\@empty + }{% + \xdef\restorecolumngrid{% + \noexpand\start@column{\thepagegrid}{\the\pagegrid@col}% + }% + \start@column{one}{\@ne}% + }% + }% +}% +\def\onecolumngrid@pop{% + \do@output@MVL{\restorecolumngrid}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsubsection{Two-column page grid} +% +% \begin{macro}{\twocolumngrid} +% \begin{macro}{\open@column@mlt} +% \begin{macro}{\shut@column@mlt} +% \begin{macro}{\end@column@mlt} +% \begin{macro}{\output@column@mlt} +% \begin{macro}{\@addmarginpar@mlt} +% Here are all the procedures necessary for the standard page grid named ``mlt'': +% the multi-column page grid. With an argument of "2", it is, +% of course, \LaTeX's familiar \cmd\twocolumn\ layout. +% +% We start with the procedure to switch to the two-column page grid. +% \begin{macrocode} +\newcommand\twocolumngrid{\do@columngrid{mlt}{\tw@}}% +% \end{macrocode} +% +% The corresponding command of \LaTeX\ is obsolete. +% \begin{macrocode} +\let\twocolumn\@undefined +% \end{macrocode} +% +% Of course, \cmd\@topnewpage\ is also obsolete. Just do +%\begin{quote} +% \cmd\clearpage\cmd\onecolumngrid<vertical mode material>\cmd\twocolumngrid. +%\end{quote} +% \begin{macrocode} +\let\@topnewpage\@undefined +% \end{macrocode} +% +% If your document class descends from one of \LaTeX's standard classes.dtx-derived +% classes, it will break. You must expunge from it all such commands. +% +% \begin{macrocode} +\def\open@column@mlt#1{% + \gdef\thepagegrid{mlt}% + \global\pagegrid@col#1% + \global\pagegrid@cur\@ne + \set@column@hsize\pagegrid@col + \set@colht +%\set@colroom +}% +% \end{macrocode} +% +% The procedure \cmd\shut@column@mlt\ ends the current column, balances the columns, and +% salts away all in \cmd\pagesofar. Because it is called in a message handler, +% we are assured that marks are handled properly. +% Attention: because this procedure balances columns, all footnotes are +% held aside in \cmd\footbox\ for placement at the bottom of the page. +% +% Bug note: the last macro executed by this procedure is \cmd\set@colht, but had been erroneously \cmd\set@colroom. +% I now believe that the latter should be changed pretty much everywhere to the former. +% \begin{macrocode} +\def\shut@column@mlt{% + \@cclv@nontrivial@sw{% + \@makecol + \@ifnum{\pagegrid@cur<\pagegrid@col}{% + \expandafter\global\expandafter\setbox\csname col@\the\pagegrid@cur\endcsname\box\@outputbox + \global\advance\pagegrid@cur\@ne + }{}% + }{% + {\setbox\z@\box\@cclv}% + }% + \@ifnum{\pagegrid@cur>\@ne}{% + \csname balance@\the\pagegrid@col\endcsname + \grid@column{}% + \@combinepage + \@combinedblfloats + \global\setbox\pagesofar\box\@outputbox + }{}% + \set@colht +}% +% \end{macrocode} +% +% The procedure \cmd\float@column@mlt\ takes care of a float page that has been built by \cmd\@tryfcolumn, +% in the multi-column page grid. +% \begin{macrocode} +\def\float@column@mlt{% + \@combinepage + \@combinedblfloats + \@outputpage + \global\pagegrid@cur\@ne + \protect@penalty\do@startpage@pen +}% +% \end{macrocode} +% +% The procedure \cmd\end@column@mlt\ is executed at the end of \cmd\clearpage\ processing, +% if we were in a multi-column page grid, once all permissive float pages have been shipped out. +% If no floats are committed and if no columns are yet filled, we have nothing to do. +% Otherwise, we kick out a column and try again. +% +% Note that in our code to kick out a column, we must deal properly with the case where the column +% is trivial: it will have nothing but \cmd\topskip\ glue plus a protection box. We substitute an ordinary +% \cmd\null\ for the protection box. +% +% \begin{macrocode} +\def\end@column@mlt{% + \@ifx@empty\@toplist{% + \@ifx@empty\@botlist{% + \@ifx@empty\@dbltoplist{% + \@ifx@empty\@deferlist{% + \@ifnum{\pagegrid@cur=\@ne}{% + \false@sw + }{% + \true@sw + }% + }{% + \true@sw + }% + }{% + \true@sw + }% + }{% + \true@sw + }% + }{% + \true@sw + }% + % true = kick out a column and try again + {% + \@cclv@nontrivial@sw{% + \unvbox\@cclv\setbox\z@\lastbox + }{% + \unvbox\@cclv\setbox\z@\lastbox\unskip\null + }% + \protect@penalty\do@newpage@pen + \protect@penalty\do@endpage@pen + }{% + \unvbox\@cclv\setbox\z@\lastbox + }% +}% +% \end{macrocode} +% The procedure \cmd\output@column@mlt (cf. \cmd\output@column@one) +% is dispatched from the output routine when +% we have completed a column in a multi-column page grid). +% (It replaces the \cmd\@outputdblcol\ of standard \LaTeX.) +% If a complete set of columns is at hand, it ships out the page and +% lays down an interrupt for \cmd\do@startpage@pen, which will commit the +% full-page-width floats to the next page. +% Like \cmd\output@column@mlt, this is followed by +% an output routine message to prepare a new column. +% \begin{macrocode} +\def\output@column@mlt{% + \@ifnum{\pagegrid@cur<\pagegrid@col}{% + \expandafter\global\expandafter\setbox\csname col@\the\pagegrid@cur\endcsname\box\@outputbox + \global\advance\pagegrid@cur\@ne + }{% + \set@adj@colht\dimen@ +% \advance\dimen@-\topskip + \grid@column{}%{\dimen@}% + \@combinepage + \@combinedblfloats + \@outputpage + \global\pagegrid@cur\@ne + \protect@penalty\do@startpage@pen + }% +}% +% \end{macrocode} +% The procedure \cmd\output@column@mlt\ obsoletes \LaTeX's \cmd\@outputdblcol +% \begin{macrocode} +\let\@outputdblcol\@undefined +% \end{macrocode} +% +% The following procedure yields a Boolean value; it determines whether a float in the deferred queue +% is appropriate for placement in the column. In the multi-column grid, only those narrower than \cmd\textwidth\ are so. +% \begin{macrocode} +\def\@floatselect@sw@mlt#1{\@if@notdblfloat{#1}}% +% \end{macrocode} +% +% The following procedure determines which side of the page a marginpar will appear. +% It reproduces the behavior of standard \LaTeX. +% \begin{macrocode} +\def\@addmarginpar@mlt{% emits a boolean + \@ifnum{\pagegrid@cur=\@ne}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsubsection{Page grid utility procedures} +% +% \begin{macro}{\pagegrid@cur} +% \begin{macro}{\pagegrid@col} +% \begin{macro}{\col@} +% \begin{macro}{\pagegrid@init} +% We take over \LaTeX's \cmd\col@number\ and \cmd\@leftcolumn, which are obsolete. +% We create two counters to hold the columns in the page grid and the current column within. +% We also create the first of a set of box registers to hold the committted columns. +% \begin{macrocode} +\let\pagegrid@cur\col@number +\let\col@number\@undefined +\newcount\pagegrid@col +\pagegrid@cur\@ne +\expandafter\let\csname col@\the\pagegrid@cur\endcsname\@leftcolumn +\let\@leftcolumn\@undefined +% \end{macrocode} +% +% The default is for maximum two columns. +% If your class will require more columns, assign that number to \cmd\pagegrid@col\ +% before \envb{document} time. +% \begin{macrocode} +\pagegrid@col\tw@ +% \end{macrocode} +% +% The procedure \cmd\pagegrid@init\ exercises \cmd\newbox\ sufficiently to create the +% boxes for holding the columns in the page grid. +% \begin{macrocode} +\def\pagegrid@init{% + \advance\pagegrid@cur\@ne + \@ifnum{\pagegrid@cur<\pagegrid@col}{% + \csname newbox\expandafter\endcsname\csname col@\the\pagegrid@cur\endcsname + \pagegrid@init + }{% + }% +}% +\appdef\class@documenthook{% + \pagegrid@init +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\grid@column} +% The procedure \cmd\grid@column\ knows how to lay up the columns in a multi-column page grid. +% It uses utility procedures \cmd\append@column\ and \cmd\box@column. +% +% \begin{macrocode} +\def\grid@column#1{% + \global\setbox\@outputbox\vbox{% + \hb@xt@\textwidth{% + \vrule\@height\z@\@width\z@\@if@empty{#1}{}{\@depth#1}% + \pagegrid@cur\@ne + \append@column + \box@column\@outputbox + }% + \vskip\z@skip % FIXME: page depth! + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\append@column} +% \begin{macro}{\box@column} +% \begin{macro}{\marry@baselines} +% The procedure \cmd\append@column\ appends columns for \cmd\grid@column, +% \cmd\box@column\ builds the columns for \cmd\append@column, +% and \cmd\marry@baselines\ pastes vertical things back together. +% \changes{v4.0rc1}{2001/06/18} +% {Introoduce \cs{marry@height} } +% +% Note that \cmd\box@column\ makes an attempt to prevent excessive \cmd\topskip\ +% or \cmd\baselineskip\ glue +% from being applied by \TeX\ when \cmd\@outputbox\ is contributed to the MVL. +% If this is not done, it is possible to get into an infinite loop in the corner case, +% wherein the page grid is changed to one column and the balanced-up columns are +% already sufficient to fill the page. +% +% Note (AO 0920): I have changed the dimension involved with \cmd\box@column\ from +% \cmd\vsize\ to \cmd\textheight, because the former is certainly not the correct value +% to use: it will change if floats have been placed in the last column of the page. +% I believe \cmd\textheight\ is the correct parameter to use here. +% +% A REVTeX4 beta user, Sergey Strelkov (strelkov@maik.rssi.ru), wants the option +% of ragged-bottom columns. Implementing this feature properly means reboxing the +% columns to their natural height only if \cmd\raggedcolumn@sw\ is true. +% Otherwise, they get reboxed to their common height (\cmd\@colht?). +% +% Note that the default has hereby changed from ragged to flush. +% It's not clear that anyone but Sergey will notice. +% +% The macro \cmd\marry@skip\ addresses (in a limited way) +% the fact that neither the value of \cmd\baselineskip\ nor that of \cmd\topskip\ +% can be relied upon for the purpose of marrying the baselines of two split columns. +% (Because there might have been a local change to their values at the point where +% the output routine got triggered.) +% +% For best results, your document class should call for grid changes only when in basal text +% settings. The \cmd\marry@baselines\ procedure will use the values appropriate to that point +% when attempting to put the columns back together. +% +% In any case, we are not attempting to solve the more general problem of how to marry baselines +% where the leading can change arbitrarily within the galley or where glue could have been trimmed +% at a page top. +% \begin{macrocode} +\def\append@column{% + \@ifnum{\pagegrid@cur<\pagegrid@col}{% + \expandafter\box@column\csname col@\the\pagegrid@cur\endcsname + \hfil + \vrule \@width\columnseprule + \hfil + \advance\pagegrid@cur\@ne + \append@column + }{% + }% +}% +\def\box@column#1{% + \raise\topskip + \hb@xt@\columnwidth{% + \dimen@\ht#1\@ifdim{\dimen@>\@colht}{\dimen@\@colht}{}% +% \advance\dimen@-\topskip + \count@\vbadness\vbadness\@M + \dimen@ii\vfuzz\vfuzz\maxdimen + \outputdebug@sw{\saythe\@colht\saythe\dimen@}{}% + \vtop to\dimen@ +% \@ifdim{\ht#1>\textheight}{to\textheight}{}% + {\hrule\@height\z@ + \unvbox#1% + \raggedcolumn@skip + }% + \vfuzz\dimen@ii + \vbadness\count@ + \hss + }% +}% +\def\marry@baselines{% +%{\tracingall\scrollmode\showlists}% +%\skip@\baselineskip\advance\skip@-\topskip %FIXME: cannot assume \baselineskip nor \topskip + \vskip\marry@skip\relax +}% +\gdef\marry@skip{\z@skip}% +\def\set@marry@skip{% + \begingroup + \skip@\baselineskip\advance\skip@-\topskip + \@ifdim{\skip@>\z@}{% + \xdef\marry@skip{\the\skip@}% + }{}% + \endgroup +}% +\AtBeginDocument{% + \@ifxundefined\raggedcolumn@sw{\@booleanfalse\raggedcolumn@sw}{}% +}% +\def\raggedcolumn@skip{% + \vskip\z@\raggedcolumn@sw{\@plus.0001fil\@minus.0001fil}{}\relax +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@combinepage} +% The procedure \cmd\@combinepage\ prepends the stored page to \cmd\@outputbox. +% \begin{macrocode} +\def\@combinepage{% + \@ifvoid\pagesofar{}{% + \setbox\@outputbox\vbox{% + \unvbox\pagesofar + \marry@baselines + \unvbox\@outputbox + }% + }% + \@ifvoid\footbox{}{% + \setbox\@outputbox\vbox{% + \unvbox\@outputbox + \marry@baselines + \unvbox\footbox + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@combinedblfloats} +% We modify \LaTeX's \cmd\@combinedblfloats\ to be more appropriate for incremental page building: +% we \cmd\unvbox\ the \cmd\@outputbox. +% \begin{macrocode} +\def\@combinedblfloats{% + \@ifx@empty\@dbltoplist{}{% + \setbox\@tempboxa\vbox{}% + \let\@elt\@comdblflelt\@dbltoplist + \let\@elt\relax\xdef\@freelist{\@freelist\@dbltoplist}% + \global\let\@dbltoplist\@empty + \setbox\@outputbox\vbox{% + %\boxmaxdepth\maxdepth %% probably not needed, CAR + \unvbox\@tempboxa\unskip + \@ifnum{\@dbltopnum>\m@ne}{\dblfigrule}{}%FIXME: how is \@dbltopnum maintained? + \vskip\dbltextfloatsep + \unvbox\@outputbox + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\set@column@hsize}% +% The procedure \cmd\set@column@hsize\ takes care of setting up the horizontal dimensions +% for the current page grid. The present routine will certainly not be adequate for more +% complex page layouts (e.g., with a side column), but works for the common ones. +% \changes{v4.0rc1}{2001/06/18} +% {Introoduce \cs{set@marry@height} } +% \begin{macrocode} +\def\set@column@hsize#1{% + \pagegrid@col#1% + \global\columnwidth\textwidth + \global\advance\columnwidth\columnsep + \global\divide\columnwidth\pagegrid@col + \global\advance\columnwidth-\columnsep + \global\hsize\columnwidth + \global\linewidth\columnwidth + \skip@\baselineskip\advance\skip@-\topskip + \@ifnum{\pagegrid@col>\@ne}{\set@marry@skip}{}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\set@colht}% +% \begin{macro}{\set@colroom}% +% \begin{macro}{\set@vsize}% +% \begin{macro}{\set@adj@colht}% +% The story of \cmd\textheight, \cmd\@colht, \cmd\@colroom, and \cmd\vsize. +% +% \cmd\textheight---height of the text column. Not a running parameter, however, each time a page is +% shipped out, the \cmd\textheight\ could in principle be altered. This must be done before +% +% \cmd\@colht---\cmd\textheight\ minus the height of any full-page-width floats. The latter are committed +% only just after shipping out, and only if we are in a multicolumn page grid. +% Therefore, \cmd\@colht\ should be set after a \cmd\shipout\ (by \cmd\@outputpage) and +% will be adjusted when full-page-width floats are committed to the fresh page by \cmd\do@startpage. +% +% \cmd\@colroom---\cmd\@colht\ (adjusted by \cmd\pagesofar) minus the height of any column-width floats. +% The latter are committed anywhere on the page, at which point \cmd\@colroom\ must be adjusted. +% Therefore, \cmd\@colroom\ should be set (by \cmd\set@colroom) whenever a column is prepared (by ). +%FIXME: committed (by \cmd\output@column@) and +% will be adjusted (by \cmd\@add@float\ or \cmd\do@startcolumn) whenever a float is committted to the column. +% +% \cmd\vsize---\cmd\@colroom. +% Therefore, \cmd\vsize\ should be set (by \cmd\set@vsize) whenever +% the \cmd\@colroom\ is set (by \cmd\set@colroom) or adjusted (by \cmd\@add@float\ or \cmd\do@startcolumn) +%FIXME: or when the \cmd\pagesofar\ box is changed (after invoking \cmd\open@column@). +% +% Question: what if there are committed floats? Footnotes? +% Answer: full-page-width floats are only committed at top, and they are already reckoned with in \cmd\@colht. +% Column-width committed floats are incorporated by \cmd\@makecol; footnotes need help. +% +% Note: FIXME: adjusting for \cmd\pagesofar\ is done at not quite the right time. I need to reexamine \cmd\set@colht, +% because \cmd\@dbltoplist\ and \cmd\pagesofar\ really should be on the same footing. +% Perhaps \cmd\@colht\ and \cmd\@colroom\ should both deal with their respective ``lists'' in the same way? +% +% These concerns will be particularly germane if we ever extend this package to deal with full-page-width floats +% placed at the bottom of the page, or committed on the same page as called out. +% +% It occurs to me that we should ditch \cmd\set@colroom\ and only ever execute \cmd\set@colht, which sets \cmd\@colroom\ as a side effect. +% If so, we can make \cmd\@colht\ take \cmd\pagesofar\ into account, as it should. Then \cmd\@colht\ will return to its +% original significance as the value that \cmd\@colroom\ is set to after a column is committed. +% +% On the other hand, why not simply forget all this caching and (re-)calculate \cmd\vsize\ as late as possible? +% Paticularly, \cmd\@colht\ is an artifact of the old way of doing things, where once it was set, it would never change. +% +% \begin{macrocode} +\def\set@colht{% + \set@adj@textheight\@colht + \global\let\enlarge@colroom\@empty + \set@colroom +}% +\def\set@adj@textheight#1{% + #1\textheight + \def\@elt{\adj@page#1}% + \@booleantrue\firsttime@sw\@dbltoplist + \let\@elt\relax +%\@ifvoid\pagesofar{}{% +% \advance#1-\ht\pagesofar\advance#1-\dp\pagesofar +%}% + \global#1#1\relax + \outputdebug@sw{\saythe#1}{}% +}% +\def\set@colroom{% + \set@adj@colht\@colroom + \@if@empty\enlarge@colroom{}{% + \global\advance\@colroom\enlarge@colroom\relax + }% + \outputdebug@sw{\saythe\@colroom}{}% + \@ifdim{\@colroom>\topskip}{}{% + \ltxgrid@info{Not enough room: \string\@colroom=\the\@colroom; increasing to \the\topskip}% + \@colroom\topskip + }% + \global\@colroom\@colroom + \set@vsize +}% +% +\def\set@vsize{% + \global\vsize\@colroom + \outputdebug@sw{\saythe\vsize}{}% +}% +% +\def\set@adj@colht#1{% + #1\@colht + \@ifvoid\pagesofar{}{% + \advance#1-\ht\pagesofar\advance#1-\dp\pagesofar + }% + \@ifvoid\footbox{}{% + \advance#1-\ht\footbox\advance#1-\dp\footbox + }% + \def\@elt{\adj@column#1}% + \@booleantrue\firsttime@sw\@toplist + \@booleantrue\firsttime@sw\@botlist + \let\@elt\relax + \outputdebug@sw{\saythe#1}{}% +}% +\def\adj@column#1#2{% + \advance#1-\ht#2% + \advance#1-\firsttime@sw{\textfloatsep\@booleanfalse\firsttime@sw}{\floatsep}% +}% +\def\adj@page#1#2{% + \advance#1-\ht#2% + \advance#1-\firsttime@sw{\dbltextfloatsep\@booleanfalse\firsttime@sw}{\dblfloatsep}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@outputpage}% +% At the tail of \cmd\@outputpage, we set \cmd\@colht\ and the float placement parameters +% (this is the one point where it is appropriate to set \cmd\@colht). +% At \cmd\do@startpage\ time, we adjust \cmd\@colht's value to reflect committed +% full-page-width floats. +% +% Note: with a correctly written output routine, a call to \cmd\@outputpage\ will inevitably be +% followed by a call to \cmd\do@startpage, so these procedure calls would be unneeded. +% \begin{macrocode} +\appdef\@outputpage{% + \set@colht % FIXME: needed? + \@floatplacement % FIXME: needed? + \@dblfloatplacement % FIXME: needed? +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{balance@2} +% We define procedures for balancing columns in a multicolumn layout. +% For now, we define only one: a procedure for the two-column grid. +% All others will simply \cmd\relax\ out. +% \begin{macrocode} +\@namedef{balance@2}{% + \expandafter\balance@two\csname col@1\endcsname\@outputbox + % Avoid a bug by preventing a restore when leaving this group + \global\setbox\csname col@1\endcsname\box\csname col@1\endcsname + \@ifvoid\footbox{}{% + \global\setbox\footbox\vbox{% + \setbox\z@\box\@tempboxa + \let\recover@footins\relax + \balance@two\footbox\@tempboxa + \hb@xt@\textwidth{\box\footbox\hfil\box\@tempboxa}% + }% + }% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\balance@two} +% The procedure \cmd\balance@two\ takes two columns and balances them; in the process it removes +% any footnotes that may be present to a place of safety, for later placement at the foot of the +% shipped-out page. +% The box register \cmd\box\cmd\@ne\ is the aggregate of all columns. +% The box register \cmd\box\cmd \z@\ is the last column. +% The box register \cmd\box\cmd\tw@\ is the first column. +% The \cmd\dimen\ register \cmd\dimen@\ is the trial value to balance to, +% initially half the height of \cmd\box\cmd\@ne. +% The \cmd\dimen\ register \cmd\dimen@i\ is the increment for the next trial; +% its initial value is equal to the initial value of \cmd\dimen@. +% The \cmd\dimen\ register \cmd\dimen@ii\ is the difference of the heights of the two columns. +% +% The procedure uses a binary search for that value of \cmd\dimen@\ which is stable to within .5\cmd\p@\ and which +% makes the last column be shorter than the others. +% +% This procedure can be extended to multiple columns simply by changing it to execute \cmd\vsplit\ multiple +% times (one less than the total number of columns in the page layout) and to calculating \cmd\dimen@ii\ +% to be the difference of the heights of last column and the \cmd\dimen@. +% Upon termination of the search, one would excute the \cmd\vsplit s once again, this time +% using the actual \cmd\col@\ box registers to store the +% balanced columns, thereby clobbering their former contents. +% +% Bug Note: +% as originally written, this macro had a bug, which is well worth avoiding under similar circumstances anywhere. +% So, learn from the mistakes of others, as they say. +% In trying to remove the depth of the boxes created via \cmd\vsplit\ within the \cmd\loopwhile\ control, +% I originally coded +% \cmd\unvbox +% \cmd\z@\ +% \cmd\setbox +% \cmd\z@ +% \cmd\lastbox\ +% \cmd\dimen@ +% \cmd\dp +% \cmd\z@\ +% \cmd\box +% \cmd\z@\ +% \cmd\vskip-% +% \cmd\dimen@. +% The error here is that the shift of the last box in the vertical list will be lost in the process. +% Simply put, \cmd\setbox\cmd\z@\cmd\lastbox\ fails to retain the shift of the box node in the vertical list, +% and when it is put down again via \cmd\box\cmd\z@, it will no longer have the correct shift. +% +% This bug affected things placed in the MVL with \cmd\moveleft, \cmd\moveright, \cmd\parshape, and +% \cmd\hangindent, as well as things shifted by \TeX's primitive mechanisms. +% +% A superior strategy for removing the depth of the last line of the list is more expensive, but safer: +% make a separate copy of the list, measure the depth of the last box as above, but then discard +% the list, retaining only the value of the dimension. +% +% Note that this procedure will not work if the material within is excessively chunky. +% A particular failure mode exists where none of the material is allocated to the last (right) column. +% We detect this case and revert to unbalanced columns. +% +% Another failure mode is where a large chunk occurs at the beginning of the composite box. +% In this case, the left column may fill up even when \cmd\dimen@\ is very small. +% If this configuration leaves the left column longer than the right, then we are done, +% but \cmd\dimen@\ by no means represents the height of either finished box. +% +% Therefore the last step in the process is to rebox the two columns to a common height determined +% independently of the balancing process. +% +% The dimension involved is checked against the current \cmd\@colroom\ to guard against the case where +% excessive material happens to fall in either column. +% \begin{macrocode} +\def\balance@two#1#2{% + \outputdebug@sw{{\tracingall\scrollmode\showbox#1\showbox#2}}{}% + \setbox\@ne\vbox{% + \@ifvoid#1{}{% + \unvcopy#1\recover@footins + \@ifvoid#2{}{\marry@baselines}% + }% + \@ifvoid#2{}{% + \unvcopy#2\recover@footins + }% + }% + \dimen@\ht\@ne\divide\dimen@\tw@ + \dimen@i\dimen@ + \vbadness\@M + \vfuzz\maxdimen + \loopwhile{% + \dimen@i=.5\dimen@i + \outputdebug@sw{\saythe\dimen@\saythe\dimen@i\saythe\dimen@ii}{}% + \setbox\z@\copy\@ne\setbox\tw@\vsplit\z@ to\dimen@ + \setbox\z@ \vbox{% + \unvcopy\z@ + \setbox\z@\vbox{\unvbox\z@ \setbox\z@\lastbox\aftergroup\vskip\aftergroup-\expandafter}\the\dp\z@\relax + }% + \setbox\tw@\vbox{% + \unvcopy\tw@ + \setbox\z@\vbox{\unvbox\tw@\setbox\z@\lastbox\aftergroup\vskip\aftergroup-\expandafter}\the\dp\z@\relax + }% + \dimen@ii\ht\tw@\advance\dimen@ii-\ht\z@ + \@ifdim{\dimen@i>.5\p@}{% + \advance\dimen@\@ifdim{\dimen@ii<\z@}{}{-}\dimen@i + \true@sw + }{% + \@ifdim{\dimen@ii<\z@}{% + \advance\dimen@\tw@\dimen@i + \true@sw + }{% + \false@sw + }% + }% + }% + \outputdebug@sw{\saythe\dimen@\saythe\dimen@i\saythe\dimen@ii}{}% + \@ifdim{\ht\z@=\z@}{% + \@ifdim{\ht\tw@=\z@}{% + \true@sw + }{% + \false@sw + }% + }{% + \true@sw + }% + {% + }{% + \ltxgrid@info{Unsatifactorily balanced columns: giving up}% + \setbox\tw@\box#1% + \setbox\z@ \box#2% + }% + \setbox\tw@\vbox{\unvbox\tw@\vskip\z@skip}% + \setbox\z@ \vbox{\unvbox\z@ \vskip\z@skip}% + \set@colroom + \dimen@\ht\z@\@ifdim{\dimen@<\ht\tw@}{\dimen@\ht\tw@}{}% + \@ifdim{\dimen@>\@colroom}{\dimen@\@colroom}{}% + \outputdebug@sw{\saythe{\ht\z@}\saythe{\ht\tw@}\saythe\@colroom\saythe\dimen@}{}% + \setbox#1\vbox to\dimen@{\unvbox\tw@\unskip\raggedcolumn@skip}% + \setbox#2\vbox to\dimen@{\unvbox\z@ \unskip\raggedcolumn@skip}% + \outputdebug@sw{{\tracingall\scrollmode\showbox#1\showbox#2}}{}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\recover@footins} +% The procedure \cmd\recover@footins\ is the utility procedure for recovering the footnotes +% from the bottom of a column. It is used when the page grid is changed, so that footnotes can be +% set at the bottom of the shipped out page. +% \begin{macrocode} +\def\recover@footins{% + \skip\z@ \lastskip\unskip + \skip\@ne\lastskip\unskip + \setbox\z@\lastbox + \@ifvbox\z@{% + \setbox\z@\vbox{% + \unvbox\z@ + \setbox\z@\lastbox +% \outputdebug@sw{{\tracingall\showbox\lastbox}}{}% + \@ifvoid\z@{}{% + \global\setbox\footbox\vbox{% + \unvbox\footbox + \@ifvbox\z@{% + \unvbox\z@ + }{% + \box\z@ + }% + }% + }% + }% + }{}% + \outputdebug@sw{{\tracingall\scrollmode\showbox\footbox}}{}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\@begindocumenthook} +% Initialization: +% we initialize to the page grid named ``one''. +% If the class decides to initially set type in a different grid, it +% should execute these same commands, but changing the first to the appropriate procedure. +% +% Note that the point where this sequence is executed would be an excellent place to arrange for +% floats to be committed to the first page of a document. +% That is, we execute \cmd\do@startpage, which triggers \cmd\do@startcolumn. +% +% FIXME: it should be the job of the page grid to determine the procedure to execute at +% the start of the job. Make this a hook. +% \begin{macrocode} +\prepdef\@begindocumenthook{% + \open@column@one\@ne + \set@colht + \@floatplacement + \@dblfloatplacement +}% +% \end{macrocode} +% \end{macro} +% +% Comment: our technique of balancing columns is severely limited, because it cannot properly work +% with \env{longtable}, which places material at the bottom and top of the column break. +% +% The proper way to handle a grid change in the middle of the page is to accumulate all the material for +% an entire article (or chapter) and then assemble finished pages therefrom. This approach is fundamentally +% superior for complex layouts: it corresponds to real-world workflows. +% Such a scheme is an excellent subject for another \LaTeX\ package. +% +% +% \subsection{Patches for the longtable package}% +% +% \LaTeX's ``required'' package \classname{longtable} (written by David P. Carlilsle), +% which is part of /latex/required/tools, is incmpatible with both +% \LaTeX's ``required'' package \classname{multicol} and with +% \LaTeX's native \cmd\twocolumn\ capability. There is no essential reason +% for this incompatability, aside from implementation details, and the +% \classname{ltxgrid} package gives us the ability to lift them. +% +% Only four of \classname{longtable}'s procedures require rewriting: +% \cmd\longtable, +% \cmd\endlongtable, +% \cmd\LT@start, and +% \cmd\LT@end@hd@ft. +% The procedure \cmd\switch@longtable\ checks against their expected meanings +% and, if all is as expected, applies the patches. +% In the process, we simplify things considerably and also make them more +% secure. +% +% Why does \classname{longtable} need to access the output routine, anyway? +% What it comes down to, is what happens when a pagebreak falls within a +% long table. If this happens, we would like to append a row at the bottom of +% the broken table and add a row at the top of the next page. +% +% These things can be accomodated easily by the \classname{ltxgrid} output +% routine hooks. +% +% +% \begin{macro}{\longtable} +% \begin{macrocode} +\def\longtable@longtable{% + \par + \ifx\multicols\@undefined\else\ifnum\col@number>\@ne\@twocolumntrue\fi\fi + \if@twocolumn\LT@err{longtable not in 1-column mode}\@ehc\fi + \begingroup + \@ifnextchar[\LT@array{\LT@array[x]}% +}% +\def\longtable@new{% + \par + \@ifnextchar[\LT@array{\LT@array[x]}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\endlongtable} +% \begin{macrocode} +\def\endlongtable@longtable{% + \crcr + \noalign{% + \let\LT@entry\LT@entry@chop + \xdef\LT@save@row{\LT@save@row}}% + \LT@echunk + \LT@start + \unvbox\z@ + \LT@get@widths + \if@filesw + {\let\LT@entry\LT@entry@write\immediate\write\@auxout{% + \gdef\expandafter\noexpand + \csname LT@\romannumeral\c@LT@tables\endcsname + {\LT@save@row}}}% + \fi + \ifx\LT@save@row\LT@@save@row + \else + \LT@warn{Column \@width s have changed\MessageBreak + in table \thetable}% + \LT@final@warn + \fi + \endgraf\penalty -\LT@end@pen + \endgroup + \global\@mparbottom\z@ + \pagegoal\vsize + \endgraf\penalty\z@\addvspace\LTpost + \ifvoid\footins\else\insert\footins{}\fi +}% +\def\endlongtable@new{% + \crcr + \noalign{% + \let\LT@entry\LT@entry@chop + \xdef\LT@save@row{\LT@save@row}% + }% + \LT@echunk + \LT@start + \unvbox\z@ + \LT@get@widths + \@if@sw\if@filesw\fi{% + {% + \let\LT@entry\LT@entry@write + \immediate\write\@auxout{% + \gdef\expandafter\noexpand\csname LT@\romannumeral\c@LT@tables\endcsname + {\LT@save@row}% + }% + }% + }{}% + \@ifx\LT@save@row\LT@@save@row{}{% + \LT@warn{% + Column \@width s have changed\MessageBreak in table \thetable + }\LT@final@warn + }% + \endgraf + \nobreak + \box\@ifvoid\LT@lastfoot{\LT@foot}{\LT@lastfoot}% + \global\@mparbottom\z@ + \endgraf + \LT@post +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\LT@start} +% \begin{macrocode} +\def\LT@start@longtable{% + \let\LT@start\endgraf + \endgraf + \penalty\z@ + \vskip\LTpre + \dimen@\pagetotal + \advance\dimen@ \ht\ifvoid\LT@firsthead\LT@head\else\LT@firsthead\fi + \advance\dimen@ \dp\ifvoid\LT@firsthead\LT@head\else\LT@firsthead\fi + \advance\dimen@ \ht\LT@foot + \dimen@ii\vfuzz\vfuzz\maxdimen + \setbox\tw@\copy\z@ + \setbox\tw@\vsplit\tw@ to \ht\@arstrutbox + \setbox\tw@\vbox{\unvbox\tw@}% + \vfuzz\dimen@ii + \advance\dimen@ \ht + \ifdim\ht\@arstrutbox>\ht\tw@\@arstrutbox\else\tw@\fi + \advance\dimen@\dp + \ifdim\dp\@arstrutbox>\dp\tw@\@arstrutbox\else\tw@\fi + \advance\dimen@ -\pagegoal + \ifdim \dimen@>\z@\vfil\break\fi + \global\@colroom\@colht + \ifvoid\LT@foot\else + \advance\vsize-\ht\LT@foot + \global\advance\@colroom-\ht\LT@foot + \dimen@\pagegoal\advance\dimen@-\ht\LT@foot\pagegoal\dimen@ + \maxdepth\z@ + \fi + \ifvoid\LT@firsthead\copy\LT@head\else\box\LT@firsthead\fi + \output{\LT@output}% +}% +\def\LT@start@new{% + \let\LT@start\endgraf + \endgraf + \markthr@@{}% + \LT@pre + \@ifvoid\LT@firsthead{\LT@top}{\box\LT@firsthead\nobreak}% + \mark@envir{longtable}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\LT@end} +% \begin{macrocode} +\def\LT@end@hd@ft@longtable#1{% + \LT@echunk + \ifx\LT@start\endgraf + \LT@err{Longtable head or foot not at start of table}{Increase LTchunksize}% + \fi + \setbox#1\box\z@ + \LT@get@widths\LT@bchunk +}% +\def\LT@end@hd@ft@new#1{% + \LT@echunk + \@ifx{\LT@start\endgraf}{% + \LT@err{Longtable head or foot not at start of table}{Increase LTchunksize}% + }% + \global\setbox#1\box\z@ + \LT@get@widths + \LT@bchunk +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\LT@array} +% \begin{macrocode} +\def\LT@array@longtable[#1]#2{% + \refstepcounter{table}\stepcounter{LT@tables}% + \if l#1% + \LTleft\z@ \LTright\fill + \else\if r#1% + \LTleft\fill \LTright\z@ + \else\if c#1% + \LTleft\fill \LTright\fill + \fi\fi\fi + \let\LT@mcol\multicolumn + \let\LT@@tabarray\@tabarray + \let\LT@@hl\hline + \def\@tabarray{% + \let\hline\LT@@hl + \LT@@tabarray}% + \let\\\LT@tabularcr\let\tabularnewline\\% + \def\newpage{\noalign{\break}}% + \def\pagebreak{\noalign{\ifnum`}=0\fi\@testopt{\LT@no@pgbk-}4}% + \def\nopagebreak{\noalign{\ifnum`}=0\fi\@testopt\LT@no@pgbk4}% + \let\hline\LT@hline \let\kill\LT@kill\let\caption\LT@caption + \@tempdima\ht\strutbox + \let\@endpbox\LT@endpbox + \ifx\extrarowheight\@undefined + \let\@acol\@tabacol + \let\@classz\@tabclassz \let\@classiv\@tabclassiv + \def\@startpbox{\vtop\LT@startpbox}% + \let\@@startpbox\@startpbox + \let\@@endpbox\@endpbox + \let\LT@LL@FM@cr\@tabularcr + \else + \advance\@tempdima\extrarowheight + \col@sep\tabcolsep + \let\@startpbox\LT@startpbox\let\LT@LL@FM@cr\@arraycr + \fi + \setbox\@arstrutbox\hbox{\vrule + \@height \arraystretch \@tempdima + \@depth \arraystretch \dp \strutbox + \@width \z@}% + \let\@sharp##\let\protect\relax + \begingroup + \@mkpream{#2}% + \xdef\LT@bchunk{% + \global\advance\c@LT@chunks\@ne + \global\LT@rows\z@\setbox\z@\vbox\bgroup + \LT@setprevdepth + \tabskip\LTleft\halign to\hsize\bgroup + \tabskip\z@ \@arstrut \@preamble \tabskip\LTright \cr}% + \endgroup + \expandafter\LT@nofcols\LT@bchunk&\LT@nofcols + \LT@make@row + \m@th\let\par\@empty + \everycr{}\lineskip\z@\baselineskip\z@ + \LT@bchunk +}% +\def\LT@LR@l{\LTleft\z@ \LTright\fill}% +\def\LT@LR@r{\LTleft\fill \LTright\z@ }% +\def\LT@LR@c{\LTleft\fill \LTright\fill}% +\def\LT@array@new[#1]#2{% + \refstepcounter{table}\stepcounter{LT@tables}% + \table@hook + \LTleft\fill \LTright\fill + \csname LT@LR@#1\endcsname + \let\LT@mcol\multicolumn + \let\LT@@hl\hline + \prepdef\@tabarray{\let\hline\LT@@hl}% + \let\\\LT@tabularcr + \let\tabularnewline\\% + \def\newpage{\noalign{\break}}% + \def\pagebreak{\noalign{\ifnum`}=0\fi\@testopt{\LT@no@pgbk-}4}% + \def\nopagebreak{\noalign{\ifnum`}=0\fi\@testopt\LT@no@pgbk4}% + \let\hline\LT@hline + \let\kill\LT@kill + \let\caption\LT@caption + \@tempdima\ht\strutbox + \let\@endpbox\LT@endpbox + \@ifxundefined\extrarowheight{% + \let\@acol\@tabacol + \let\@classz\@tabclassz + \let\@classiv\@tabclassiv + \def\@startpbox{\vtop\LT@startpbox}% + \let\@@startpbox\@startpbox + \let\@@endpbox\@endpbox + \let\LT@LL@FM@cr\@tabularcr + }{% + \advance\@tempdima\extrarowheight + \col@sep\tabcolsep + \let\@startpbox\LT@startpbox + \let\LT@LL@FM@cr\@arraycr + }% +% + \let\@acoll\@tabacoll + \let\@acolr\@tabacolr + \let\@acol\@tabacol +% + \setbox\@arstrutbox\hbox{% + \vrule + \@height \arraystretch \@tempdima + \@depth \arraystretch \dp \strutbox + \@width \z@ + }% + \let\@sharp##% + \let\protect\relax + \begingroup + \@mkpream{#2}% + \@mkpream@relax + \edef\@preamble{\@preamble}% + \prepdef\@preamble{% + \global\advance\c@LT@chunks\@ne + \global\LT@rows\z@ + \setbox\z@\vbox\bgroup + \LT@setprevdepth + \tabskip\LTleft + \halign to\hsize\bgroup + \tabskip\z@ + \@arstrut + }% + \appdef\@preamble{% + \tabskip\LTright + \cr + }% + \global\let\LT@bchunk\@preamble + \endgroup + \expandafter\LT@nofcols\LT@bchunk&\LT@nofcols + \LT@make@row + \m@th + \let\par\@empty + \everycr{}% + \lineskip\z@ + \baselineskip\z@ + \LT@bchunk +}% +\appdef\table@hook{}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\switch@longtable} +% +% Here is the switch from standard \classname{longtable} to the new, \classname{ltxgrid}-compatible values. +% +% At this point, we extend \env{longtable} with a \env{longtable*} form, which signifies that we want to +% use the full page width for setting the table. +% You can think this way: \env{longtable*} is to \env{longtable} as \env{table*} is to \env{table}. +% +%FIXME: the following is no longer true: +%% Note that it is not enough to define the environment itself; we also have to create the corresponding +%% \cmd\output\ routine procedures, which provide for continued footers and headers +%% (the very feature of \env{longtable} requiring support in the output routine). +% +%% This same consideration would arise in defining any syntactic extension to \env{longtable}, because +%% the environment name itself is exposed in the output routine. +% +% \begin{macrocode} +\def\switch@longtable{% + \@ifpackageloaded{longtable}{% + \@ifx{\longtable\longtable@longtable}{% + \@ifx{\endlongtable\endlongtable@longtable}{% + \@ifx{\LT@start\LT@start@longtable}{% + \@ifx{\LT@end@hd@ft\LT@end@hd@ft@longtable}{% + \@ifx{\LT@array\LT@array@longtable}{% + \true@sw + }{\false@sw}% + }{\false@sw}% + }{\false@sw}% + }{\false@sw}% + }{\false@sw}% + {% + \class@info{Patching longtable package}% + }{% + \class@info{Patching unrecognized longtable package. (Proceeding with fingers crossed)}% + }% + \let\longtable\longtable@new + \let\endlongtable\endlongtable@new + \let\LT@start\LT@start@new + \let\LT@end@hd@ft\LT@end@hd@ft@new + \let\LT@array\LT@array@new + \newenvironment{longtable*}{% + \onecolumngrid@push + \longtable + }{% + \endlongtable + \onecolumngrid@pop + }% +% \expandafter\let\csname output@init@longtable*\endcsname\output@init@longtable +% \expandafter\let\csname output@prep@longtable*\endcsname\output@prep@longtable +% \expandafter\let\csname output@post@longtable*\endcsname\output@post@longtable + }{}% +}% +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\LT@pre} +% \begin{macro}{\LT@bot} +% \begin{macro}{\LT@top} +% \begin{macro}{\LT@post} +% \begin{macro}{\LT@adj} +% Note that at the end of the longtable environment, we reestablish the \cmd\mark@envir\ of the +% containing environment. We have left \cmd\curr@envir\ alone, so this will work. +% \begin{macrocode} +\def\LT@pre{\penalty\z@\vskip\LTpre}% +\def\LT@bot{\nobreak\copy\LT@foot\vfil}% +\def\LT@top{\copy\LT@head\nobreak}% +\def\LT@post{\penalty\z@\addvspace\LTpost\mark@envir{\curr@envir}}% +\def\LT@adj{% + \setbox\z@\vbox{\null}\dimen@-\ht\z@ + \setbox\z@\vbox{\unvbox\z@\LT@bot}\advance\dimen@\ht\z@ + \global\advance\vsize-\dimen@ +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% \begin{macro}{output@init} +% \begin{macro}{output@prep} +% \begin{macro}{output@post} +% \begin{macrocode} +\def\output@init@longtable{\LT@adj}% +\def\output@prep@longtable{\setbox\@cclv\vbox{\unvbox\@cclv\LT@bot}}% +\def\output@post@longtable{\LT@top}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsection{Patches for index processing}% +% +% Another feature that uses the output routine hooks occurs within +% an index, where one wishes to apply a ``continue head'' when a +% column breaks within a primary index entry. +% Some book designs call for the continue head to only be applied +% at a turnpage break. +% +% In any case, it is easy enough for \cmd\output@post@theindex\ +% to do this in conjunction with component marks. +% Only the bare outlines are shown here. +% +% \begin{macro}{\output@init} +% \begin{macro}{\output@prep} +% \begin{macro}{\output@post} +% \begin{macrocode} +\let\output@init@theindex\@empty +\let\output@prep@theindex\@empty +\def\output@post@theindex{% + \@ifodd\c@page{}{% + \@ifnum{\pagegrid@cur=\@ne}{% we have the leftmost column of a verso page + % insert the current top-level continued head + }% + }% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \subsection{Checking the auxiliary file}% +% +% We relegate the checking of the auxiliary file to the output routine. +% This task must wait until the last page is shipped out, because otherwise +% the stream might get closed before the last page is shipped out. +% Obviously, we must use \cmd\do@output@MVL\ for the job. +% +% \begin{macro}{\check@aux} +% \begin{macrocode} +\def\check@aux{\do@output@MVL{\do@check@aux}}% +% \end{macrocode} +% \end{macro} +% +% +% +% \subsection{Dealing with stuck floats and stalled float dequeueing}% +% +% \LaTeX's float placement mechanism is fundamentally flawed, as evidenced by +% its warning message ``too many unprocessed floats'', which users understandably find frustrating. +% The \classname{ltxgrid} package provides tools for ameliorating the situation somewhat. +% +% Two cases require detection and rectification: +% \begin{enumerate} +% \item +% A float is ``stuck'' in the \cmd\@deferlist: for whatever reason, the float fails to be committed, +% even at the start of a fresh page. +% Once this condition prevails, following floats can never be committed, subsequently all of \LaTeX's +% float registers are used up. +% +% If this condition is detected, we reconsider float dequeueing under permissive (\cmd\clearpage-style) processing. +% +% \item +% The \cmd\@freelist\ is exhausted: +% a large concentration of floats, say, uses up all of \LaTeX's float registers all at once. +% This condition commonly occurs when the user collects floats at the end of the document, for some reason. +% +% When a float is encountered, \LaTeX\ uses a float register (allocated from a pool of free registers) to contain it until it can be placed. +% However, no further action is taken until the pagebuilder is visited, so floats can accumulate. +% Also, even after the pagebuilder is visited, deferred floats can accumulate, and these are not committed +% until a column (or page) of text is completed. +% +% Once the last free float register is used, action should be taken that will commit some of the deferred floats, +% even if this might require ending the page right where we are (resulting in a short page). +% +% Perhaps, committed floats should be stored using some mechanism other than a list, as is currently done. +% A feasible alternative storage method would be to use a \cmd\box\ register in place of +% \cmd\@toplist, +% \cmd\@botlist, and +% \cmd\@dbltoplist. +% This is probably just fine, since such committed floats are not reconsidered (I think). +% +% \end{enumerate} +% +% The emergency processing implemented here immediately ends the current page and begins to output float pages under (\cmd\clearpage-style) rules. +% It proceeds until all deferred floats have been flushed. +% +% Users should expect non-optimal page makeup under these circumstances. +% +% Note that there is a weakness in our approach that we have not attempted to repair: if floats are being +% added as part of a paragraph, we will not be able to take these remedial steps until the paragraph ends. +% This means that the approach implemented here cannot fix all \LaTeX\ documents. Users can still construct +% documents that exhaust \LaTeX's pool of float registers! +% +% \begin{macro}{\check@deferlist@stuck} +% \begin{macro}{\@outputpage} +% We detect the case where, at the start of a fresh page, there are deferred floats, but none are +% committed. We memorize the \cmd\@deferlist\ at \cmd\shipout\ time, then examine it at the point where +% our efforts to commit floats to the new page are complete. +% If it has not changed, the first float must be stuck, and we +% attempt to fix things via \cmd\force@deferlist@stuck. +% +% This simple approach is comp[letely effective in for typical documents. +% +% Note that we try to avoid an infinite loop by examining the value of \cmd\clearpage@sw: +% if we come here with that boolean true, we are in a loop. +% \begin{macrocode} +\def\check@deferlist@stuck#1{% + \@ifx{\@deferlist@postshipout\@empty}{}{% + \@ifx{\@deferlist@postshipout\@deferlist}{% + \@fltstk + \clearpage@sw{% + \ltxgrid@warn{Deferred float stuck during \string\clearpage\space processing}% + }{% + \force@deferlist@stuck#1% + }% + }{% + %Successfully committed float(s) + }% + \global\let\@deferlist@postshipout\@empty + }% +}% +\def\@fltstk{% + \@latex@warning{A float is stuck (cannot be placed without \string\clearpage)}% +}% +\appdef\@outputpage{% + \global\let\@deferlist@postshipout\@deferlist +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\@next} +% \begin{macro}{\@xnext} +% We rewrite the \LaTeX\ kernel macros that dequeue float registers from, e.g., \cmd\@deferlist, +% providing a test for the condition where the pool of free registers is about to underflow. +% +% In this case, we attempt to fix things via \cmd\force@deferlist@empty. +% \begin{macrocode} +\def\@next#1#2{% + \@ifx{#2\@empty}{\false@sw}{% + \expandafter\@xnext#2\@@#1#2% + \true@sw + }% +}% +\def\@xnext\@elt#1#2\@@#3#4{% + \def#3{#1}% + \gdef#4{#2}% + \def\@tempa{#4}\def\@tempb{\@freelist}% + \@ifx{\@tempa\@tempb}{% + \@ifx{#4\@empty}{% + \force@deferlist@empty%{Float register pool exhausted}% + }{}% + }{}% +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\force@deferlist@stuck} +% \begin{macro}{\force@deferlist@empty} +% \begin{macro}{\force@deferlist@sw} +% \begin{macro}{\do@forcecolumn@pen} +% \begin{macro}{\do@forcecolumn} +% The procedure \cmd\force@deferlist@empty\ is an attempt to rectify a situation where \LaTeX's float placement mechanism +% may fail (``too many unprocessed floats''). +% +% We put down interrupts that call for the float placement to be redone, but under permissive conditions, +% just the same as if \cmd\clearpage\ had been invoked. +% +% Note that the attempt to rectify the error is contingent on the setting of \cmd\force@deferlist@sw, +% default false. A document class using this package that wishes to enable this error recovery mechanism should +% set this boolean to true. +% +% The interrupt \cmd\do@forcecolumn@pen, which invokes the procedure \cmd\do@forcecolumn, +% does the same as \cmd\do@startcolumn, except under permissive conditions: +% we are trying to empty out the float registers completely. +% +% In order to properly with the case where there is material in \cmd\box\cmd\@cclv, +% \cmd\@toplist, \cmd\@botlist, \cmd\@dbltoplist, etc, +% we do what amounts to \cmd\newpage\ to get things rolling. +% +% In \cmd\force@deferlist@stuck, we take advantage of already being in the output routine: +% simply reinvoke \cmd\do@startcolumn\ under permissive conditions. +% +% \begin{macrocode} +\def\force@deferlist@stuck#1{% + \force@deferlist@sw{% + \@booleantrue\clearpage@sw + \@booleantrue\forcefloats@sw + #1% + }{% + }% +}% +\def\force@deferlist@empty{% + \force@deferlist@sw{% +% \ltxgrid@info{#1, attempting rectification}% + \penalty-\pagebreak@pen + \protect@penalty\do@forcecolumn@pen + }{% +% \ltxgrid@info{#1}% + }% +}% +\@booleanfalse\force@deferlist@sw +\mathchardef\do@forcecolumn@pen=10009 +\@namedef{output@-\the\do@forcecolumn@pen}{\do@forcecolumn}% +\def\do@forcecolumn{% + \@booleantrue\clearpage@sw + \@booleantrue\forcefloats@sw +%\unvbox\@cclv +%\vfil +%\penalty-\pagebreak@pen + \do@startcolumn +}% +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% A more thorough revision of \LaTeX's float placement mechanism would involve substituting a single \cmd\box\ +% register for the \cmd\@deferlist. This way, \LaTeX's ability to have latent floats would be limited by +% box memory alone. +% +% Because only the \cmd\box\ and \cmd\count\ components of the float box register are actually used by \LaTeX, +% our scheme can be accomplished if we can find a way to encode the information held in the \cmd\count\ component. +% +% A first-in, first-out mechanism exists, wherein a box-penalty pair is dequeued by \cmd\lastbox\cmd\lastpenalty\cmd\unpenalty\ and enqueued +% by \cmd\setbox\cmd\foo=\cmd\hbox\cmd\bgroup\cmd\penalty\cmd\floatpenalty\cmd\box\cmd\floatbox\cmd\unhbox\cmd\foo\cmd\egroup. +% +% Note that this scheme is made possible by our change to \LaTeX's float placement mechanism, +% wherein we consolidated the two \cmd\@deferlist s into one. +% +% \section{Support for legacy \LaTeX\ commands} +% +% We provide support for the \cmd\enlargethispage\ command. +% +% Note: using a command of this sort is questionable. +% Instead, people should enlarge the entire spread. +% +% Timing Note: In a multicolumn page grid, the user should issue the \cmd\enlargethispage\ command +% while the first column of the page is being typeset. +% We provide a helpful message if the timing is wrong. +% +% This code can serve as a model for introducing commands that need to execute within the safety of the output routine. +% We ensure that the arguments are fully expanded, then execute \cmd\do@output@MVL\ to cause an output procedure, +% \cmd\@@enlargethispage, to execute. When it does execute, the MVL will be exposed. +% +% The \cmd\@@enlargethispage\ procedure simply adjusts the vertical dimensions of the page. +% The adjustment will persist until the column is committed, at which point the page dimension +% will revert to its standard value. +% \begin{macrocode} +\def\enlargethispage{% + \@ifstar{% + \@enlargethispage{}% + }{% + \@enlargethispage{}% + }% +}% +\def\@enlargethispage#1#2{% + \begingroup + \dimen@#2\relax + \edef\@tempa{#1}% + \edef\@tempa{\noexpand\@@enlargethispage{\@tempa}{\the\dimen@}}% + \expandafter\do@output@MVL\expandafter{\@tempa}% + \endgroup +}% +\def\@@enlargethispage#1#2{% + \def\@tempa{one}% + \@ifx{\thepagegrid\@tempa}{% + \true@sw + }{% + \def\@tempa{mlt}% + \@ifx{\thepagegrid\@tempa}{% + \@ifnum{\pagegrid@cur=\@ne}{% OK to adjust this page + \gdef\enlarge@colroom{#2}% + \true@sw + }{% Can only adjust this column; give up + \ltxgrid@warn{Too late to enlarge this page; move the command to the first column.}% + \false@sw + }% + }{% Unknown page grid + \ltxgrid@warn{Unable to enlarge a page of this kind.}% + \false@sw + }% + }% + {% + \class@info{Enlarging page \thepage\space by #2}% + \global\advance\@colroom#2\relax + \set@vsize + }{% + % Could not adjust this page + }% +}% +\let\enlarge@colroom\@empty +% \end{macrocode} +% The \cmd\@kludgeins\ insert register is now unneeded. +% Ensure that packages using this mechanism break (preferrable to subtle bugs). +% \begin{macrocode} +\let\@kludgeins\@undefined +% \end{macrocode} +% +% \subsubsection{Building the page for shipout} +% +% \begin{macro}{\@outputpage} +% The procedures that build \cmd\@outputbox\ just before a page is shipped out by \cmd\@outputpage\ are: +% \cmd\@makecol, +% \cmd\@combinepage, and +% \cmd\@combinedblfloats. +% We headpatch \cmd\@outputpage\ to make the \cmd\@outputbox\ be of fixed height. +% \begin{macrocode} +\@booleantrue\textheight@sw +\prepdef\@outputpage{% + \textheight@sw{% + \count@\vbadness\vbadness\@M + \dimen@\vfuzz\vfuzz\maxdimen + \setbox\@outputbox\vbox to\textheight{\unvbox\@outputbox}% + \vfuzz\dimen@ + \vbadness\count@ + }{}% +}% +% \end{macrocode} +% \end{macro} +% +% \subsubsection{Warning message} +% +% \begin{macro}{\ltxgrid@info} +% \begin{macro}{\ltxgrid@warn} +% Something has happened that the user might be interested in. +% Print a message to the log, but only if the user selected the verbose option. +% \begin{macrocode} +\def\ltxgrid@info{% + \ltxgrid@info@sw{\class@info}{\@gobble}% +}% +\@booleanfalse\ltxgrid@info@sw +\def\ltxgrid@warn{% + \ltxgrid@warn@sw{\class@warn}{\@gobble}% +}% +\@booleantrue\ltxgrid@warn@sw +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \section{End of the \file{ltxgrid} {\sc docstrip} module} +% Here ends the module. +% \begin{macrocode} +%</ltxgrid-krn> +% \end{macrocode} +% +% \Finale +% %Here ends the programmer's documentation. +% \endinput +% +\endinput +%%EOF |