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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /macros/latex/contrib/showlabels/showlabels.dtx
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+% \iffalse % meta-comment
+%
+%% This is the showlabels package
+%%
+%%%% Copyright 1999, 2001-09, 2013-16, Norman Gray
+%%
+%% This work may be distributed and/or modified under the
+%% conditions of the LaTeX Project Public Licence, either version 1.3
+%% of this licence or (at your option) any later version.
+%% The latest version of this licence is in
+%% http://www.latex-project.org/lppl.txt
+%% and version 1.3 or later is part of all distributions of LaTeX
+%% version 2005/12/01 or later.
+%%
+%% This work has the LPPL maintenance status `maintained'.
+%%
+%% The Current Maintainer of this work is Norman Gray <http://nxg.me.uk>
+%%
+%% This work consists of the files showlabels.dtx and showlabels.ins,
+%% and the derived file showlabels.sty.
+
+%%%% File: showlabels.dtx
+%%%% Source: 95a544e6b41b, 2016-06-09T16:51:03+01:00
+
+\def\filename{showlabels}
+\def\fileversion{1.8}
+\def\filedate{2016/06/09}
+\def\docdate{2016 June 9}
+\def\filemaintainer{norman@astro.gla.ac.uk}
+% This is revision 95a544e6b41b, 2016-06-09T16:51:03+01:00.
+%<+package>\NeedsTeXFormat{LaTeX2e}
+%<+package>\ProvidesPackage{showlabels}[\filedate\space v\fileversion]
+%<+package>\typeout{Package: `showlabels' v\fileversion\space<\filedate>}
+%
+%<*driver>
+\documentclass{ltxdoc}
+\EnableCrossrefs
+% \end{macrocode}
+% Some commonly used abbreviations for option names, filenames,
+% counters and packages.
+% \begin{macrocode}
+\newcommand\Lopt[1]{\textsf{#1}} % package options
+\newcommand\file[1]{\texttt{#1}} % filename
+%\newcommand\Lcount[1]{\textsl{\small#1}}
+\newcommand\Lenv[1]{\textsl{\{#1\}}}
+\newcommand\Lpackage[1]{\textsf{\{#1\}}} % packages
+%% \url macro (url.sty does this better, but we don't want extra dependencies)
+\def\setpathdots{\discretionary{.}{}{.}}
+\def\setpathslash{\discretionary{/}{}{/}}
+{\catcode`\.=\active
+ \catcode`\/=\active
+ \gdef\pathcats{%
+ \catcode`\%=12 \catcode`\~=12
+ \catcode`\.=\active \let.\setpathdots
+ \catcode`\/=\active \let/\setpathslash
+ \catcode`\#=12 \catcode`\_=12}%
+ }
+\def\setpath#1{\ttfamily <\nobreak #1\nobreak>\endgroup}
+\def\url{\begingroup\pathcats\setpath}
+\begin{document}
+% \OnlyDescription
+\DocInput{showlabels.dtx}
+\PrintIndex
+\end{document}
+%</driver>
+%
+% \fi
+%
+%
+% \title{The \texttt{\filename} package}
+% \author{Norman Gray\\|norman@astro.gla.ac.uk|}
+% \date{Version \fileversion, \docdate}
+%
+% \maketitle
+%
+% This package helps you keep track of all the labels you define, by
+% putting the name of new labels into the margin whenever the
+% |\label| command is used.
+%
+% You can do the same thing for other commands (see below).
+% The only one for which this is \emph{obviously} useful is the
+% |\cite| command, but it is also reasonable to do it with, for example,
+% the |\ref| or |\begin| commands.
+%
+% Invoke this package with the command |\usepackage{showlabels}| in
+% the preamble, and you may give the following options:
+% \begin{quotation}
+% \begin{tabular}{lp{25em}}
+% \Lopt{outer} & [default] all notes are placed in the text's outer
+% margin\\
+% \Lopt{inner} & \dots inner margin\\
+% \Lopt{left} & \dots left margin\\
+% \Lopt{right} & \dots right margin\\
+% \Lopt{marginal} & [default] put notes in the margin\\
+% \Lopt{inline} & put notes inline, as much as possible, and ignore
+% any of the margin-placement options above \\
+% \Lopt{nolabel} & do not insert a marginal note for |\label| commands
+% (see command |\showlabels| below)\\
+% \Lopt{draft} & [default] does nothing, partner of\dots\\
+% \Lopt{final} & turns off all the package's functionality
+% \end{tabular}
+% \end{quotation}
+% If you don't use the \Lopt{twoside} option,
+% then all pages are `right-hand' pages, and the `outer margin' is the
+% right hand one.
+%
+% The package will also work in the presence of the \Lopt{twocolumn}
+% option. In this case, the options \Lopt{inner}, \Lopt{outer},
+% \Lopt{left} and \Lopt{right} will be ignored, and the label will be
+% placed in the nearer margin.
+%
+% Finally, we have the options \Lopt{final} and \Lopt{draft}. The option
+% \Lopt{final} turns off all the functionality of this package. This
+% is included so that if that
+% option is given globally in the |\documentclass| declaration then this
+% package does respect it. The \Lopt{draft} option does nothing, and therefore
+% simply continues the default behaviour of this package; it is here
+% to partner the \Lopt{final} option.
+%
+% \DescribeMacro{\showlabels}
+% If you wish the package to do its magic with the command |\foo|
+% (most typically |\cite|), then give the command |\showlabels{foo}|.
+% The default behaviour of the package is to give the command
+% |\showlabels{label}| internally; if you don't want this to happen --
+% perhaps because you \emph{only} want |\cite| commands highlighted --
+% then give the option \Lopt{nolabel} to the |\usepackage| command:
+% |\usepackage[nolabel]{showlabels}|.
+%
+% By default, the package displays labels in the margin of the
+% document, but as an alternative, labels can be kept inline as much
+% as possible; this is much more legible when there are multiple
+% labels on a single line. To select this, give the option
+% \Lopt{inline}, and to select the default behaviour, use
+% \Lopt{marginal}.
+%
+% \DescribeMacro{\showlabelsinline}
+% It is sometimes convenient (for example when a document encounters a
+% situation which this package mishandles) to force inline labels
+% temporarily, within a block or environment. Use the
+% |\showlabelsinline| macro to do that.
+%
+% \subsection*{Formatting}
+%
+% If you want to change the font the labels appear in, redefine the
+% |\showlabelfont| command, which by default expands to
+% |\small\ttfamily|. For example, to have labels in a slanted font,
+% and green, you could include the definition
+% \begin{quote}
+% |\renewcommand{\showlabelfont}{\small\slshape\color{green}}|
+% \end{quote}
+% in the preamble of your document, as long as you have loaded the
+% \Lpackage{color} package.
+%
+% Alternatively, the |\showlabels| command has an optional argument containing
+% formatting commands, which allows you to format |\cite| labels, for
+% example, differently from |\label|. Thus:
+% \begin{quote}
+% |\showlabels[\color{green}]{cite}|
+% \end{quote}
+%
+% If, finally, you want complete control over the labels, you can
+% instead override |\showlabelsetlabel|, which initially expands to
+% just |\showlabelfont #1|. You can use this mechanism to get a
+% variety of effects. For example, if you say
+% \begin{quote}
+% |\usepackage{showlabels,rotating}|\\
+% |\renewcommand{\showlabelsetlabel}[1]|\\
+% \null\qquad |{\begin{turn}{60}\showlabelfont #1\end{turn}}|\\
+% \end{quote}
+% then you end up with your labels at a jaunty angle in the margin.
+% Finally, you can change the definition of the
+% |\showlabelrefline| rule from its default,
+% in order to change how the inline rule (see below) is displayed.
+% For example, defining this to be
+% |\color{red}\hrule width 0.1em height 1.5ex depth 0pt |
+% produces a fattish red line, and defining it to be
+% |\hrule width 0pt height 1.5ex depth 0pt|
+% suppresses the line but still positions the text between the lines.
+%
+% \subsection*{Compatibility with other packages, and other problems}
+%
+% The \Lpackage{showlabels} package works by redefining the |\label|
+% command, along with a few internal \LaTeX\ commands. All the other commands it
+% defines are `hidden' by prefixing them with `\texttt{SL@}', with
+% the exception of the user commands |\showlabelfont| and
+% |\showlabelsetlabel|. Each of
+% the three redefined commands carefully includes its previous
+% definition. The \Lpackage{showlabels} package should therefore come
+% \emph{last} of the packages you include using |\usepackage|.
+%
+% In version 1.1, the package was modified to conform to the slightly
+% different mechanism that \texttt{amsmath} uses to produce equation
+% numbers. Do note that the
+% |\usepackage{showlabels}| command \emph{must} appear after the
+% |\usepackage{amsmath}| if it is to detect that you are using the
+% \Lpackage{amsmath} package\footnote{Note that AMS-\LaTeX\ and the
+% \texttt{amstex} package have been declared `obsolete' in favour of
+% the \texttt{amsmath} package. This package now claims conformance
+% with the \texttt{amsmath} package alone, though it will probably
+% work with older versions in fact.}.
+%
+% In version 1.3e, the package became compatible with the
+% \Lpackage{hyperref} package in particular, and in general with other
+% packages which themselves modify the |\label| command. This will
+% work, however, only if the \Lpackage{showlabels} package is loaded
+% after other packages which do this. Notwithstanding Sebastian
+% Rahtz's excellent general advice on this, \Lpackage{showlabels} should
+% be loaded after \Lpackage{hyperref}.
+%
+% In version 1.7, the package became compatible with the
+% equation-numbering mechanism of the \Lpackage{IEEEtrantools}
+% package. As with \Lpackage{amsmath}, this involves a certain amount
+% of special-casing.
+%
+% For reasonably obvious reasons, this package will not work at all
+% well with the \Lpackage{multicol} package, and for possibly less obvious
+% reasons, it won't work with the \Lopt{leqno} option either (at some point
+% it should be modified to at least recognise and warn of the conflict in
+% either case, though it's not obvious to me how to do that). The
+% package \emph{should} now work with \Lpackage{wrapfig}, though I'm not
+% sure that I've exhausted that package's various clevernesses, and
+% there might be some spacing and layout bugs which manifest
+% themselves in that context. Please report them; in the mean time,
+% using option \Lopt{inline} should act as a workaround for any that
+% appear.
+%
+% When labels appear in the margins, they sometimes appear on the
+% `wrong' side in \Lopt{twoside} mode. This is a fairly inevitable
+% side-effect of the way that \TeX\ builds pages, and a specific
+% symptom of the general problem described in
+% \url{http://www.tex.ac.uk/cgi-bin/texfaq2html?label=oddpage}.
+% As that answer suggests, there are bear-traps involved in the
+% standard solutions. Now, showlabels is (a)~permanently teetering
+% on the edge of clashing with everything else that messes around with
+% labels, and (b)~a draft-only package rather than anything that
+% would appear in a final document. (a)~means that I'm rather nervous
+% about putting too much cleverness in there, and incidentally shy of
+% putting any dependencies on other packages; (b)~means that I feel it
+% doesn't really matter enough to be worth removing robustness. So
+% I'm afraid I don't plan to change this, and I simply put up with the
+% occasional slip. Again the \Lopt{inline} option is a possible
+% workaround.
+%
+% The package might still work with \LaTeX2.09, but that's neither
+% supported, nor even still tested.
+%
+% This software is copyright, 1999, 2001--09, 2013--16 Norman Gray.
+% It is released under the terms of the LaTeX Project Public Licence.
+% See the copyright declaration at the top of file \texttt{showlabels.dtx},
+% and the file \texttt{lppl.txt}, for the licence conditions.
+%
+% The canonical home page of the package is
+% \url{http://purl.org/nxg/dist/showlabels}, and it is on CTAN at
+% \url{https://www.ctan.org/pkg/showlabels}. The source is in
+% a repository at Bitbucket: \url{https://bitbucket.org/nxg/showlabels/}.
+%
+% \subsection*{Other packages}
+%
+% The \Lpackage{showlabels} package has a large overlap in
+% functionality with David Carlisle's \Lpackage{showkeys}, although
+% the latter will only handle |\label| and |\cite| keys. If
+% \Lpackage{showlabels} fails in some particular situation, you might
+% want to try using \Lpackage{showkeys}, but please do mention the
+% problem, either by email to me, or via the Bitbucket issues list.
+%
+% \subsection*{History and Credits}
+%
+% I've received bug reports, fixes, or implementable suggestions from many
+% people, including
+% Andreas Balser,
+% bartgol (on Stackexchange),
+% Francesco Biccari,
+% Francis M. C. Ching,
+% Sven de Vries,
+% A L Dukeman,
+% Michael Friendly,
+% Guillermo Garza,
+% Tino G\"ortem\"oller,
+% Lester L. Helms,
+% Boris Kheyfets,
+% Hagen Kleinert,
+% David R. Leal Valmana,
+% Olivier Michel,
+% Enno Nagel,
+% Sungmo Park,
+% Ignacy Sawicki,
+% Andrei Shelankov,
+% Patrick Sibille,
+% `Stirling' (on Stackexchange),
+% Mariano Su\'arez-Alvarez,
+% Ji\v ri Vesely,
+% Elmar Walhorn,
+% Alex Watson,
+% Ben William Carabelli,
+% Roland Winkler.
+% Many thanks to all. If I've missed your name out of this list
+% (or indeed if I've alphabetised you incorrectly),
+% please accept my apologies, and do let me know.
+%
+% The package was originally released by me on 1991 September 21, under the name
+% \texttt{labels.sty}.
+% On 1992 January 29, Darrel Hankerson
+% \url{hank@ducvax.auburn.edu}, made the update to NFSS, and
+% changed the name to `showlabel.sty'.
+%
+%
+% \StopEventually{}
+%
+% \section{Implementation}
+% \begin{macrocode}
+%<*package>
+% \end{macrocode}%
+% \iffalse
+% Update history:
+% October 94: Norman Gray (norman@astro.gla.ac.uk). Modified to be a
+% \LaTeX2e package.
+% 29-Jan-92 Darrel Hankerson (hank@ducvax.auburn.edu)
+% Update to NFSS. Change name to `showlabel.sty'. Substitute
+% \nintt -> \small\tt
+% \sevit -> \scriptsize\it
+% 21-Sep-91 Norman Gray no_gray@vax.acs.open.ac.uk
+% Original release of labels.sty
+% \fi
+%
+% Before we do anything else, find out if we're using \Lpackage{amsmath}\dots.
+% Note that, since these additions appeared, AMS-\LaTeX\ and the
+% \texttt{amstex} package seem to have been declared `obsolete'. This
+% package now claims conformance with the \texttt{amsmath} package.
+% \begin{macrocode}
+\newif\ifSL@AMS
+\@ifundefined{maketag@@@}
+ \SL@AMSfalse
+ {\SL@AMStrue\typeout{with amsmath equation tags}}
+% \end{macrocode}
+%
+% The command which sets equation text is |\SL@eqntext|, which tests
+% whether the content should be inline or not.
+% \begin{macrocode}
+\def\SL@eqntext{%
+ \ifSL@labelsinline
+ \let\@tempa\SL@interlinetextleft
+ \else
+ \let\@tempa\SL@eqnlrtext
+ \fi
+ \@tempa
+}
+% \end{macrocode}
+%
+% The |\SL@wrap@labeller| macro wraps the given macro in such a way
+% that we display the label.
+% \begin{macrocode}
+\def\SL@wrap@labeller#1{%
+ \expandafter\let\csname SL@orig@#1\expandafter\endcsname\csname #1\endcsname
+ \expandafter\def\csname #1\endcsname{%
+ \csname SL@orig@#1\endcsname
+ \ifx\SL@labelname\relax
+ % do nothing
+ \else
+ \SL@eqntext{\SL@labelname}%
+ \fi
+ \global\let\SL@labelname\relax}}
+% \end{macrocode}
+%
+% \begin{macro}{\@eqnnum}
+% This replacement for |\@eqnnum| will produce a note, sticking
+% into the margin beside the equation number, showing the equation's label.
+% |\SL@labelname| is initialised to |\relax|, redefined within the
+% |\label| macro, and reset to |\relax| here. If it's already equal
+% to |\relax| here, the equation number hasn't been labelled, and so
+% we avoid putting anything in the margin. In the \Lpackage{amsmath} case
+% we instead redefine |\maketag@@@|.
+%
+% First, deal with the case where the document uses the
+% \Lpackage{amsmath} macros.
+% \begin{macrocode}
+\ifSL@AMS
+% \end{macrocode}
+%
+% \Lpackage{amsmath} redefines |\label| to set the macro |\df@label|,
+% and then uses |\maketag@@@{\df@label}| or |\tagform@| to form tags
+% (ie, equation labels) in equations. So we hook into \emph{both} of
+% these macros. If the |\df@label| is
+% empty (almost certainly because the user has used the
+% \Lenv{eqnarray} environment within \Lpackage{amsmath}), then fall back
+% on the |\SL@labelname| contents instead.
+% \iffalse See tests t2, t11 and t18. \fi
+% We must make sure to leave |\SL@labelname| equal to |\relax| at the
+% end of this macro, otherwise a |{eqnarray}| followed by an (AMSTeX)
+% |\eqref| can end up with the wrong label being referred to by the
+% |\maketag@@@| within |\eqref| (or something like that).
+%
+% The test here must be |\ifx\SL@labelname\relax| with
+% |\global\let\SL@labelname\relax|, not |\expandafter\ifx\SL@...| and
+% |\global\def\SL@labelname{\relax}| (as it once was), since the
+% latter evaluates to true when |\SL@...| is |\relax| \emph{and} when
+% |\SL@...| starts with two identical characters, which is wrong (it
+% took embarrassingly many goes to get this right). The following is
+% similar to the effect of |\SL@wrap@labeller|, but is not quite identical,
+% because (a) |\maketag@@@| and |\tagform@| take an argument,
+% and (b) we also have to check |\df@label|.
+% \begin{macrocode}
+ \def\SL@setlabel@ams{%
+ \ifx\df@label\@empty
+ \ifx\SL@labelname\relax
+ % do nothing
+ \else
+ \SL@eqntext{\SL@labelname}%
+ \fi
+ \else
+ \SL@eqntext{\df@label}%
+ \fi
+ \global\let\SL@labelname\relax
+ }
+ \let\SL@orig@maketag@@@=\maketag@@@
+ \def\SL@maketag@@@#1{%
+ \SL@orig@maketag@@@{#1}%
+ \SL@setlabel@ams
+ }
+ \let\SL@orig@tagform@\tagform@
+ \def\SL@tagform@#1{%
+ \SL@orig@tagform@{#1}%
+ \SL@setlabel@ams
+ }
+\else
+% \end{macrocode}
+%
+% Next, deal with the `normal' case, without \Lpackage{amsmath}.
+% Package \Lpackage{amsmath} redefines |\@eqnnum| in terms of
+% |\maketag@@@|, so we should avoid doing this in the
+% non-\Lpackage{amsmath} case.
+% \begin{macrocode}
+ %% \let\SL@eqnnum=\@eqnnum
+ %% \def\@eqnnum{%
+ %% \SL@eqnnum
+ %% \ifx\SL@labelname\relax
+ %% % do nothing
+ %% \else
+ %% \SL@eqntext{\SL@labelname}%
+ %% \fi
+ %% \global\let\SL@labelname\relax
+ %% }
+ \SL@wrap@labeller{@eqnnum}
+\fi
+% \end{macrocode}
+% \end{macro}
+% And initialise the value of |\SL@labelname| to |\relax|, so that
+% |\@eqnnum| starts off behaving the right way.
+% \begin{macrocode}
+\global\let\SL@labelname\relax
+% \end{macrocode}
+%
+% Labels are printed with the font specified by |\showlabelfont|, which
+% can be overridden within the document:
+% Define this using |\ttfamily|, unless we're still using \LaTeX 2.09
+% (surprising it still works!), in which case stick with |\tt|.
+% \begin{macrocode}
+\@ifundefined{ttfamily}
+ {\providecommand{\showlabelfont}{\small\tt}}
+ {\providecommand{\showlabelfont}{\small\ttfamily}}
+% \end{macrocode}
+%
+% If you want slightly more general control over the labels, you can
+% instead override |\showlabelsetlabel|.
+% \begin{macrocode}
+\providecommand{\showlabelsetlabel}[1]{{\normalfont\showlabelfont\SL@fmt@ #1}}
+% \end{macrocode}
+%
+% For the benefit of |\SL@prlabelname|, define |\SL@gobblethree| to do nothing
+% other than eat three tokens.
+% \begin{macrocode}
+\def\SL@gobblethree#1#2#3{}
+% \end{macrocode}
+%
+% \begin{macro}{\SL@prlabelname}
+% Expansion is label name with all catcodes `other' (Appendix~D trickery
+% abounds!). Use |\r@#1|, rather then just |\#1| to avoid defining any new
+% control sequences.
+% \begin{macrocode}
+\def\SL@prlabelname#1{%
+\expandafter\expandafter\expandafter\SL@gobblethree
+ \expandafter\string\csname r@#1\endcsname}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\showlabels}
+% Define the |\showlabels| command which allows us to redefine
+% commands which are to have their arguments highlighted.
+% That is, |\showlabels{foo}| means that the command |\foo{bar}| will
+% write `bar' in the margin, as well as executing whatever |\foo| does
+% normally.
+%
+% The net result of all this is that a |\showlabels{foo}| command
+% arranges things so that, after |\begin{document}|, |\foo{bar}| expands into
+% |\SL@setlabel{bar}\SL@origfoo{bar}|.
+%
+% First, define a command |\SL@initfoo|, which, when executed, will
+% save the current (at that time) behaviour of the command |\foo| as
+% |\@SL@origfoo|, and then set |\foo| to be equivalent to |\SL@foo|,
+% which does the magic; we will
+% shortly give this command to |\AtBeginDocument|, so that it is
+% switched on at the correct time, when other packages have done
+% \emph{their} redefinitions of |\foo| (this makes it compatible with
+% the \Lpackage{hyperref} package, which does its own wholesale redefinitions of
+% things like |\label|). Below, the locution
+% |\the\@temptokena| causes the token contents of |\@temptokena| to be
+% included unexpanded in the definition, despite the |\edef|.
+%
+% If the optional argument is present, then use this as per-command
+% formatting, so that, for example |\cite| instances may be formatted
+% distinctively from |\label|.
+% \begin{macrocode}
+\def\showlabels{\@ifnextchar[\showlabels@{\showlabels@[]}}
+\def\showlabels@[#1]#2{%
+ \@temptokena=\expandafter{\csname #2\endcsname}
+ \def\@tempa{#1}%
+ \ifx\@tempa\@empty
+ \expandafter\let\csname SL@fmt@#2\endcsname\relax
+ \else
+ \expandafter\def\csname SL@fmt@#2\endcsname{#1}%
+ \fi
+ \expandafter\edef\csname SL@init@#2\endcsname{%
+ \let\csname SL@orig#2\endcsname\the\@temptokena
+ \let\the\@temptokena\csname SL@#2\endcsname}
+ \AtBeginDocument{\csname SL@init@#2\endcsname}%
+% \end{macrocode}
+% \emph{Now} define |\SL@foo| -- it must be undefined when we define
+% |\SL@initfoo| above, so that it isn't expanded in the |\edef|.
+% \begin{macrocode}
+ \expandafter\def\csname SL@#2\endcsname{%
+ \expandafter\let\expandafter\SL@fmt@\csname SL@fmt@#2\endcsname
+ \SL@showlabels{#2}}
+}
+% \end{macrocode}
+%
+% We need a default definition of |\SL@fmt@| for the cases (some
+% equation formatting) where we don't get to the formatting via this
+% mechanism.
+% \begin{macrocode}
+\let\SL@fmt@\relax
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\SL@showlabels}
+% Now we get to the command which does the main processing. The
+% |\SL@showlabels| command calls |\SL@setlabel| to format the label
+% (putting it in the margin, for example), then calls the original
+% |\foo| command (namely |\SL@origfoo|) with the original argument.
+%
+% The command takes a single argument, namely the name of the command
+% being wrapped (for example, `label'). We set |\@tempa| to be the
+% original version of that command (stored in |\SL@orig#1|), and then
+% take one of two similar paths, depending on whether the command has
+% an optional argument or not.
+%
+% We have to be somewhat careful about the positioning of the
+% |\@bsphack| and |\@esphack| commands. The |\@esphack| command should
+% \emph{not} come after the call to |\SL@origfoo|, since that would
+% confuse things terribly if that command took any other arguments, or
+% otherwise messed with the token stream (there's actually no problem
+% in the most common case where we're replacing |\label|, and calling
+% |\SL@origlabel|, but there are problems when we try to replace
+% |\begin| or |\ref| in this way). Instead, adapt the contents
+% of |\@esphack|, but instead of calling |\ignorespaces| when
+% |\@savsk| is positive, add an |\hskip| of 1~scaled point (equal to
+% $1/65536\mathrm{pt}=5.363\times10^{-9}\mathrm{m}$). This will be
+% invisible, but it \emph{is} greater than zero, so that if
+% |\SL@origfoo| itself uses a |\@bsphack|\dots|\@esphack| pair then
+% the saved |\@savsk| will be positive, and that future |\@esphack|
+% will correctly invoke |\ignorespaces|; that pair will also pick up
+% the |\spacefactor| we restore here. The net result is that the
+% |\SL@setlabel| is invisible, and |\SL@origfoo| is able to make
+% itself invisible, too. Command sequence |\SL@setlabel| is what does
+% the work -- this is |\let| equal to either |\SL@margtext| or
+% |\SL@inlinetext| below.
+%
+% We must declare |\SL@showlabels| to be a robust command, or else we
+% get confusing expansion problems when, for example, we do
+% |\showlabels{ref}| and use |\ref| in a caption (see test case t3).
+% We actually handle three distinct cases here, for |\foo{label}|,
+% |\foo[opt]{label}| and |\foo*{label}| (the last is to handle the
+% \Lpackage{hyperref} package's |\ref*{label}| variant; see test case t14).
+% \begin{macrocode}
+\DeclareRobustCommand\SL@showlabels[1]{%
+ \expandafter\let\expandafter\SL@orig@@next\csname SL@orig#1\endcsname
+ \@ifstar
+ {\SL@showlabelsplainstar}
+ {\@ifnextchar[
+ {\SL@showlabelsopt}
+ {\SL@showlabelsplain}}
+}
+\def\SL@showlabelsopt[#1]#2{%
+ \@bsphack
+ \SL@setlabel{#2}\relax
+ \ifhmode \spacefactor\@savsf \ifdim\@savsk>\z@ \hskip1sp \fi\fi
+ \SL@orig@@next[#1]{#2}%
+}
+\def\SL@showlabelsplain#1{%
+ \@bsphack
+ \SL@setlabel{#1}\relax
+ \ifhmode \spacefactor\@savsf \ifdim\@savsk>\z@ \hskip1sp \fi\fi
+ \SL@orig@@next{#1}%
+}
+\def\SL@showlabelsplainstar#1{%
+ \@bsphack
+ \SL@setlabel{#1}\relax
+ \ifhmode \spacefactor\@savsf \ifdim\@savsk>\z@ \hskip1sp \fi\fi
+ \SL@orig@@next*{#1}%
+}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@makecaption}
+% The |\@makecaption| command needs special treatment. The
+% |\SL@margtext| command doesn't work in figure captions, so we need
+% to force the layout commands to use |\SL@inlinetext| instead, for
+% all label types, and irrespective of whether we're using the
+% \Lopt{inline} option. The code here is independent of that in
+% |\showlabels|, but imitates it, for consistency.
+% \begin{macrocode}
+\def\SL@initmakecaption{%
+ \let\SL@origmakecaption\@makecaption
+ \def\@makecaption##1##2{{%
+ \let\SL@setlabel\SL@inlinetext
+ \SL@origmakecaption{##1}{##2}}}}
+\AtBeginDocument{\SL@initmakecaption}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\SL@margtext}
+% This is the central bit of this package, used by |\SL@showlabels|.
+% The argument is the argument of the |\foo| command which we're
+% processing (for example, the argument to a |\label| command).
+%
+% Depending on the mode, put the
+% current label name in the margin in one of a variety of ways.
+% \begin{macrocode}
+\def\SL@margtext#1{%
+% \end{macrocode}
+%
+% There are three cases here:
+% \begin{enumerate}
+% \item We are in maths mode, setting an equation.
+% \item We are not in maths mode but we \emph{are} within a display
+% (this can happen in, for example, the \Lenv{cases} environment from
+% the \Lpackage{cases} package).
+% \item We are in text.
+% \end{enumerate}
+%
+% Case 1:
+% In maths mode, produce a label name alongside the equation number.
+% Save the label name in |\SL@labelname|, so we can use it later
+% (this is redundant in most \Lpackage{amsmath} contexts, because that
+% style generally saves this in |\df@label|, but sometimes -- for
+% example when using the traditional \Lenv{eqnarray} environment
+% within \Lpackage{amsart} -- |\df@label| can end up unset).
+% \begin{macrocode}
+ \ifmmode
+ \xdef\SL@labelname{\SL@prlabelname{#1}}%
+% \end{macrocode}
+%
+% Case 2:
+% Check if we're within a display equation,
+% and if so act as if we are in maths mode (ie, as above).
+% Note: most contexts which match case~1 would also be caught by this
+% test, since |\label| is used almost exclusively within displays,
+% but it seems clearer to separate the two cases explicitly, as well
+% as probably dealing better with cases where the package is used for
+% non-|\label| commands.
+% \begin{macrocode}
+ \else\ifdim\displaywidth>0pt
+ \xdef\SL@labelname{\SL@prlabelname{#1}}%
+% \end{macrocode}
+%
+% Case 3:
+% Otherwise, create a box with zero height and depth, and the same width
+% as the page. Put all this in braces, to contain the setting of
+% |\box\@tempboxa| (which probably shouldn't be necessary). The box
+% here we set to be the width of |\hsize|. This is \emph{probably}
+% best, though there's always the worry that |\linewidth| would be the
+% more \LaTeX-ish thing to do -- using |\columnwidth| is almost
+% certainly wrong, since |\linewidth| can sometimes be changed without
+% |\columnwidth| changing with it (for example, in package
+% \Lpackage{wrapfig}), causing \Lpackage{showlabels} to fail badly.
+% \begin{macrocode}
+ \else
+ \setbox\@tempboxa=\vbox to 0pt{%
+ \vss
+ \hbox to \hsize{\SL@lrtext{#1}}}%
+ \dp\@tempboxa\z@
+% \end{macrocode}
+% Attach this box below the last one, using |\nointerlineskip| if we're in
+% vertical mode, or |\vadjust| otherwise. We need to save and restore
+% the value of |\prevdepth| (which has the sentinel value -1000pt if we're
+% adding this box at the beginning of a vertical list, and
+% |\nointerlineskip| sets |\prevdepth| to this same value). If we don't
+% do this, we get extra (`interline') vertical space added in this
+% case (it might be thought smart to use |\marginpar| here, and so
+% avoid some of this nonsense, but that's not possible since this
+% might be called within boxes, which |\marginpar| objects to).
+% \begin{macrocode}
+ \ifvmode
+ \@tempdima=\prevdepth
+ \nointerlineskip\box\@tempboxa\nobreak
+ \prevdepth=\@tempdima
+ \else
+ \vadjust{\box\@tempboxa\nobreak}%
+ \fi
+% \end{macrocode}
+% That's it. Finish off the sequence of cases.
+% \begin{macrocode}
+ \fi\fi
+}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\SL@inlinetext}
+% This is an alternative way of formatting the label, which puts it
+% inline as much as possible, and avoids straying into the margins.
+% We just use the same mechanism as for |\SL@margtext|, but do the
+% inline-or-not testing there.
+% \begin{macrocode}
+\def\SL@inlinetext#1{%
+ \SL@interlinetextright{\SL@prlabelname{#1}}%
+}
+% \end{macrocode}
+% In vmode, put the label between lines. Set the box depth to zero to
+% make sure that descenders don't mess up the spacing.
+% \begin{macrocode}
+\def\SL@interlinetextleft{\SL@setlefttrue\SL@interlinetext}
+\def\SL@interlinetextright{\SL@setleftfalse\SL@interlinetext}
+\def\SL@interlinetext#1{%
+ \setbox\@tempboxa=\hbox{\showlabelsetlabel{\SL@prlabelname{#1}}}\dp\@tempboxa\z@
+ \ifvmode
+ \nointerlineskip\vbox to 0pt{\vss
+ \hbox to \columnwidth{\hss \box\@tempboxa}}%
+% \end{macrocode}
+% And in horizontal mode, squeeze it between the lines, at the current point,
+% carefully taking up no space.
+% \begin{macrocode}
+ \else
+ \ifSL@setleft
+ \hbox to 0pt{%
+ \hss
+ \vbox to 0pt{\vss
+ \hbox to 0pt{\hss\box\@tempboxa}%
+ \showlabelrefline
+ }}%
+ \else
+ \hbox to 0pt{%
+ \vbox to 0pt{\vss
+ \box\@tempboxa
+ \showlabelrefline
+ }\hss}%
+ \fi
+ \penalty10000
+ \fi
+}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\showlabelrefline}
+% Set a short line which indicates the point where a label is
+% attached, when producing inline labels. This additionally positions
+% the label up above the line.
+% \begin{macrocode}
+\def\showlabelrefline{\hrule width 0.05em height 1.5ex depth 0pt }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\SL@margintext}
+% Set the actual text of the label. Use |\SL@prlabelname| here: without
+% this, a label command given outside of an equation or a |\caption|
+% will appear wrongly if the label has things like underscores within it.
+% \begin{macrocode}
+\def\SL@margintext#1{{\showlabelsetlabel{\{\SL@prlabelname{#1}\}}}}
+% \end{macrocode}
+% \end{macro}
+%
+% But where is the marginal text actually set? It can be in the left
+% margin, the right one, or can alternate. |\SL@lrtext|, used in the
+% |\vbox| above, is set, under the control of |\SL@labelposition| below, to
+% one of |\SL@lefttext|, |\SL@righttext| or |\SL@alternatetext|.
+% \begin{macro}{\SL@righttext}
+% \begin{macro}{\SL@lefttext}
+% \begin{macrocode}
+\def\SL@righttext#1{\hfill\rlap{\quad\SL@margintext{#1}}}
+\def\SL@lefttext #1{\llap{\SL@margintext{#1}\quad}\hfill}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\SL@setLR}
+% Define a switch which allows us to state whether we've decided to
+% set a particular label to the left or the right, and a macro
+% |\SL@setLR| to set it. After |\SL@setLR|, |\ifSL@setleft| is true
+% if a label should be set to the left, and is false if it should go
+% to the right.
+% \begin{macrocode}
+\newif\ifSL@setleft
+\def\SL@setLR{%
+ \ifcase\SL@labelposition
+ % 0=outer margin
+ \ifodd\c@page
+ \SL@setleftfalse
+ \else
+ \SL@setlefttrue
+ \fi
+ \or
+ % 1=inner margin
+ \ifodd\c@page
+ \SL@setlefttrue
+ \else
+ \SL@setleftfalse
+ \fi
+ \or
+ % 2=left margin
+ \SL@setlefttrue
+ \or
+ % 3=right margin
+ \SL@setleftfalse
+ \else
+ \SL@canthappen{Impossible labelposition \the\SL@labelposition}
+ \SL@labelposition=3 % put everything in the right-margin for now
+ \SL@setleftfalse
+ \fi
+}
+% \end{macrocode}
+% \end{macro}
+%
+% The code for |\SL@alternatetext| doesn't work perfectly, as it
+% sometimes manages to get things on the wrong side of the text near the
+% top of a new page. This is a venial slip, however, as this package
+% should never be used in a final version.
+% \begin{macro}{\SL@alternatetext}
+% \begin{macrocode}
+\def\SL@alternatetext{%
+ \SL@setLR
+ \ifSL@setleft
+ \let\SL@next\SL@lefttext
+ \else
+ \let\SL@next\SL@righttext
+ \fi
+ \SL@next
+}
+% \end{macrocode}
+% \end{macro}
+% The case where the \Lopt{twocolumn} option is set is slightly different.
+% There we have to switch between placing the note in the left and right
+% margins, depending on whether we're setting the first or second column.
+% This macro, and |\SL@eqntwocoltext| below, uses the switch
+% |\if@firstcolumn| to decide whether it's in the first or the second
+% column of the text (I suppose it'll get terribly confused if we use
+% \file{multicol.sty} along with this). This is defined and maintained in
+% the base file \file{ltoutput.dtx}. It's not part of the defined
+% interface, however (there doesn't seem to be one, grump), so I don't
+% suppose we should really rely on it. There isn't an option, however.
+% \begin{macro}{\SL@twocoltext}
+% \begin{macrocode}
+\def\SL@twocoltext{%
+ \if@firstcolumn
+ \let\SL@next\SL@lefttext
+ \else
+ \let\SL@next\SL@righttext
+ \fi
+ \SL@next}
+% \end{macrocode}
+% \end{macro}
+%
+% We have very similar things for equations, except that they are set in
+% place, rather than within a zero depth box. This code \emph{assumes} that
+% equation numbers are going to be on the right hand side of the page. It
+% should probably check for the existence of the \Lopt{leqno} option (how?).
+% \begin{macro}{\SL@eqnrighttext}
+% \begin{macro}{\SL@eqnlefttext}
+% \begin{macrocode}
+\def\SL@eqnrighttext#1{\rlap{\quad\SL@margintext{#1}}}
+\def\SL@eqnlefttext #1{\hbox to 0pt{\kern -\columnwidth
+ \llap{\SL@margintext{#1}\quad}\hss}}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% Now do the analogues for the equation numbers, in the case of the
+% alternate page selection\dots
+% \begin{macro}{\SL@eqnalternatetext}
+% \begin{macrocode}
+\def\SL@eqnalternatetext{%
+ \SL@setLR
+ \ifSL@setleft
+ \let\SL@next\SL@eqnlefttext
+ \else
+ \let\SL@next\SL@eqnrighttext
+ \fi
+ \SL@next
+}
+% \end{macrocode}
+% \end{macro}
+% \dots and the twocolumn option
+% \begin{macro}{\SL@eqntwocoltext}
+% \begin{macrocode}
+\def\SL@eqntwocoltext{%
+ \if@firstcolumn
+ \let\SL@next\SL@eqnlefttext
+ \else
+ \let\SL@next\SL@eqnrighttext
+ \fi
+ \SL@next}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\SL@canthappen}
+% Issues a |\PackageError| command, and solicits bug reports.
+% \begin{macrocode}
+\def\SL@canthappen#1{%
+ \PackageError{showlabels}{#1}
+ {This shouldn't happen -- the package showlabels has a bug.
+ \MessageBreak
+ Please report this, if possible with a sample document which
+ \MessageBreak
+ demonstrates the problem, to \filemaintainer. Thanks.}}
+% \end{macrocode}
+% \end{macro}
+%
+% To control the positioning of labels, set the |\SL@labelposition|
+% switch, which can take values 0, 1, 2, 3, meaning outer, inner,
+% left, right margin respectively.
+% \begin{macrocode}
+\newcount\SL@labelposition
+\SL@labelposition=0
+% \end{macrocode}
+%
+% We select between the various possibilities using the \Lopt{outer} and
+% \Lopt{inner} options and, implicitly, the \Lopt{twoside} option.
+% \begin{macrocode}
+\DeclareOption{outer}{\SL@labelposition=0}
+\DeclareOption{inner}{\SL@labelposition=1}
+\DeclareOption{left}{\SL@labelposition=2}
+\DeclareOption{right}{\SL@labelposition=3}
+% \end{macrocode}
+%
+% Labels can be set either in the margins or inline, by switching
+% between definitions of |\SL@setlabel|.
+% \begin{macrocode}
+\newif\ifSL@labelsinline
+\SL@labelsinlinefalse
+\DeclareOption{marginal}{\SL@labelsinlinefalse}
+\DeclareOption{inline}{\SL@labelsinlinetrue}
+% \end{macrocode}
+% \begin{macro}{\SL@setlabel}
+%
+% Macro |\SL@setlabel| is where we switch between inline and marginal labels.
+% \begin{macrocode}
+\def\SL@setlabel{%
+ \ifSL@labelsinline
+ \let\@tempa\SL@inlinetext
+ \else
+ \let\@tempa\SL@margtext
+ \fi
+ \@tempa
+}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\showlabelsinline}
+% It is sometimes convenient (for example when a document encounters a
+% situation which this package mishandles) to force inline labels
+% temporarily, within a block or environment. Use this macro to do
+% that.
+% \begin{macrocode}
+\def\showlabelsinline{\SL@labelsinlinetrue}
+% \end{macrocode}
+% \end{macro}
+% By default, we run |\showlabels{label}|. The option \Lopt{nolabel}
+% turns this off.
+% \begin{macrocode}
+\newif\ifSL@labellabel
+\SL@labellabeltrue
+\DeclareOption{nolabel}{\SL@labellabelfalse}
+% \end{macrocode}
+%
+% Define the options \Lopt{final} and \Lopt{draft}. The option
+% \Lopt{final} turns off all the functionality of this package by
+% disabling the command |\showlabels|, including the implicit
+% |\showlabels| command which the package issues as long as the
+% \Lopt{nolabel} option has not been given. This is included so that if that
+% option is given in the |\documentclass| declaration then this
+% package does respect it. \Lopt{draft} does nothing, and therefore
+% simply continues the default behaviour of this package; it is here
+% purely to partner the \Lopt{final} option.
+% \begin{macrocode}
+\DeclareOption{final}{\let\showlabels\@gobble}
+\DeclareOption{draft}{}
+% \end{macrocode}
+%
+% Process any options that have been set.
+% \begin{macrocode}
+\ProcessOptions
+% \end{macrocode}
+% and use the values of |\SL@labelposition| and |if@twoside| which may have
+% been set by those options, to set |\SL@lrtext| to be the
+% appropriate control sequence. The presence of the \Lopt{twocolumn} option
+% means that we ignore the \Lopt{inner} and \Lopt{outer} options.
+% \begin{macrocode}
+\if@twocolumn
+ \let\SL@lrtext\SL@twocoltext
+ \let\SL@eqnlrtext\SL@eqntwocoltext
+\else
+ \ifcase\SL@labelposition
+ % 0=outer margin
+ \if@twoside
+ \let\SL@lrtext\SL@alternatetext
+ \let\SL@eqnlrtext\SL@eqnalternatetext
+ \else
+ \let\SL@lrtext\SL@righttext
+ \let\SL@eqnlrtext\SL@eqnrighttext
+ \fi
+ \or
+ % 1=inner margin
+ \if@twoside
+ \let\SL@lrtext\SL@alternatetext
+ \let\SL@eqnlrtext\SL@eqnalternatetext
+ \else
+ \let\SL@lrtext\SL@lefttext
+ \let\SL@eqnlrtext\SL@eqnlefttext
+ \fi
+ \or
+ % 2=left margin
+ \let\SL@lrtext\SL@lefttext
+ \let\SL@eqnlrtext\SL@eqnlefttext
+ \or
+ % 3=right margin
+ \let\SL@lrtext\SL@righttext
+ \let\SL@eqnlrtext\SL@eqnrighttext
+ \else
+ \SL@canthappen{Impossible labelposition \the\SL@labelposition}
+ \SL@labelposition=3 % put everything in the right-margin for now
+ \let\SL@lrtext\SL@righttext
+ \let\SL@eqnlrtext\SL@eqnrighttext
+ \fi
+\fi
+% \end{macrocode}
+%
+% Finally, label all the |\label| commands
+% (default behaviour),
+% unless this has been suppressed through the \Lopt{nolabel} option.
+% \begin{macrocode}
+\ifSL@labellabel
+ \showlabels{label}
+ \ifSL@AMS
+ \ifx\showlabels\@gobble
+ % do nothing -- we're in [final] mode (see test case t13)
+ \else
+ \AtBeginDocument{%
+ \let\maketag@@@\SL@maketag@@@
+ \let\tagform@\SL@tagform@}
+ \fi
+ \fi
+ \@ifundefined{theIEEEsubequationdis}\relax % and \theequationdis
+ {\SL@wrap@labeller{theIEEEsubequationdis}
+ \SL@wrap@labeller{theequationdis}}
+\fi
+% \end{macrocode}
+%
+% That's us.
+%
+% \begin{macrocode}
+%</package>
+% \end{macrocode}
+%
+% \Finale
+\endinput