path: root/Master/texmf-dist/source/latex/labelcas/labelcas.dtx

% \iffalse meta-comment
%
% Copyright (C) 2006 by Ulrich Diez <ulrich.diez@alumni.uni-tuebingen.de>
%
% This Work may be distributed and/or modified under the conditions of
% the LaTeX Project Public License, either version 1.3 of this license
% or (at your option) any later version.  The latest version of this
% license is in:
%
%    http://www.latex-project.org/lppl.txt
%
% and version 1.3 or later is part of all distributions of LaTeX version
% 2003/12/01 or later.
%
% This Work has the LPPL maintenance status `author-maintained'.
%
% The Current Maintainer of this work is Ulrich Diez.
%
% This Work consists of the files labelcas.dtx, labelcas.ins, README and
% the derived files labelcas.sty and labelcas.pdf.
%
% \fi
%
% \iffalse
%<labelcas>\NeedsTeXFormat{LaTeX2e}
%<labelcas>\ProvidesPackage{labelcas}
%<labelcas>   [2006/08/14 v1.12 check label-existence and fork accordingly]
%<*driver>
\documentclass[a4paper]{ltxdoc}
\makeatletter
\@ifdefinable\saved@wrindex{\global\let\saved@wrindex\@wrindex}
\makeatother
\usepackage[colorlinks, linkcolor=linkcolour, urlcolor=linkcolour
%, draft%
]{hyperref}
\usepackage{color}
\definecolor{linkcolour}{cmyk}{0.64,0,0.95,0.40}% <-Olive Green
\usepackage[DefineLabelcase]{labelcas}
\EnableCrossrefs
\CodelineIndex
\RecordChanges
%\OnlyDescription
\pagestyle{plain}%
\setlength{\textheight}{52\baselineskip}
\setlength{\topmargin}{\paperheight}
\addtolength{\topmargin}{-\textheight}
\setlength{\topmargin}{.5\topmargin}
\addtolength{\topmargin}{-1in}
\addtolength{\topmargin}{-\voffset}
\addtolength{\topmargin}{-\headheight}
\addtolength{\topmargin}{-\headsep}
\setlength{\footskip}{\paperheight}
\addtolength{\footskip}{-\textheight}
\setlength{\footskip}{.15\footskip}
\addtolength{\footskip}{\baselineskip}
\makeatletter
\@settopoint{\textheight}
\@settopoint{\topmargin}
\@settopoint{\footskip}
\makeatother
\begin{document}
  \DocInput{labelcas.dtx}
\end{document}
%</driver>
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% \makeatother
%
% \changes{v1.0}{2006/01/04}%
%         {Initial public release.\suppresspage}
% \changes{v1.01}{2006/01/06}%
%         {Fixed documentation-inaccuracies.\suppresspage}
% \changes{v1.02}{2006/01/29}%
%         {Fixed documentation-inaccuracies.\suppresspage}
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% \changes{v1.08}{2006/07/10}%
%         {DefineLabelcase-option declared within group for
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%
% \GetFileInfo{labelcas.sty}
% \filedatetodate
% \title{&
%   The \textsf{\mbox{labelcas}} package&
%   \thanks{&
%     \vtop{\noindent This document corresponds to
%       \mbox{\textsf{labelcas}~\fileversion}, dated \filedate.\newline
%       Usage and distribution under \textsf{\mbox{LPPL}}-conditions. See
%       \hyperref[sec6]{\emph{\ref*{sec6}~\nolinknameref{sec6}}} for more
%       details.&
%     }&
%   }&
% }&
% \author{Ulrich Diez}&
% \maketitle
%
% \begin{abstract}
% \noindent This \LaTeXe-package provides macros |\eachlabelcase| and
% |\lotlabelcase| as a means of forking depending on whether specific
% labels are defined in the current document.
% \end{abstract}
%
% \tableofcontents
%
% \newpage
% \section{Introduction}\label{sec1}
%
% The package's name \textsf{\mbox{labelcas}} is an eight-letter
% abbreviation for the phrases ``label'' and ``case''.
%
% There are rare occasions where the author of a document would like to
% have detected whether specific labels are defined/in use within the
% document so that proper forking/referencing can take place.
% This package provides the macros |\eachlabelcase| and |\lotlabelcase|
% which might facilitate this task.
%
% A mechanism for branching depending on whether referencing-labels exist,
% might be handy, e.g., when extracting a ``snippet'' from a large
% document: In case that within the snippet a label/document-part is
% referenced which is outside the snippet's scope, ugly `{\makeatletter
% \nfss@text{\reset@font\bfseries??}}' will intersperse the resulting
% output-file and warnings about undefined references will accumulate
% within the log-file.
%
% By testing the label's existence, you can catch up the error and either
% change the way of referencing (e.g., refer to the snippet's bibliography
% instead) or completely suppress referencing for those cases. (By using
% \textsf{\mbox{David Carlisle's}} \textsf{xr}- or
% \textsf{\mbox{xr-hyper}}-package, you can make available labels of the
% large document to the snippet also. A label not defined in the snippet
% can be picked up from the large document\dots)
%
% \subsection{Space notation}
%
% When listing some piece of \TeX-source-code, you may need to visibly
% distinguish word-separation from single space-characters. The symbol
% \verb*+ + is chosen whenever it is important to give a visible
% impression of a space-character in a (possibly ASCII-encoded) \TeX-&
% input-file. {\verb*+ +}\nobreak\(_{x}\) does not represent a character
% of an input-file but a token which occurs after tokenizing the input.
% The token's category-code is \(x\), the character-number usually is
% \(32\), which is the ASCII-number of the space-character.
%
% \section{Package-loading}\label{sec2}
%
% The package is to be loaded in the document-preamble by |\usepackage|.
% \medskip
%
% |\usepackage{labelcas}|~~~or
%
% |\usepackage[DefineLabelcase]{labelcas}|.
% \medskip
%
% The only package-option is |DefineLabelcase|. Its usage is described in
% section~\hyperref[sec4]{\emph{\ref*{sec4}~\nolinknameref{sec4}}}.
%
% \newpage
% \section{The macros}\label{sec3}
%
% \subsection{Basic usage}\label{sec3-1}
%
% \DescribeMacro{\eachlabelcase}
% The macro |\eachlabelcase| iterates on a comma-separated list of
% ``argument-triplets'', whereby each triplet specifies:~~\nobreak
% {&
%   \makeatletter
%   \setbox\@tempboxa\hbox{3. Action if the label is undefined.}&
%   \@tempdima\dp\@tempboxa
%   \vtop{&
%     \noindent
%     1. a label,\\
%     2. action if the label is defined,\\
%     3. action if the label is undefined.&
%   }&
%   \par\prevdepth\@tempdima
% }&
% \noindent
% During the iteration, an ``action-queue'' is gathered up from these
% specifications. After iterating, the ``action-queue'' will be executed.
% You can also specify a new macro-name within an optional argument. If
% you do so, the ``action-queue'' will not be executed but the macro will
% be defined to perform the actions specified in the queue:
% \bigskip
%
% \noindent
% {&
%   \footnotesize
%   |\eachlabelcase[|\emph{\textbackslash macro}|]{|~~~\nobreak
%   \vtop{&
%     \noindent
%     \marg{label 1}\marg{action if label 1 defined}&
%     \marg{action if label 1 undefined}|,|\\
%     \marg{label 2}\marg{action if label 2 defined}&
%     \marg{action if label 2 undefined}| ,|\\
%     \hspace*{.275\hsize}\texttt{\dots}\\
%     \marg{label n}\marg{action if label n defined}&
%     \marg{action if label n undefined}\ \ \ |}|&
%   }&
% }&
% \bigskip
%
% \noindent Space-tokens which might surround the comma-separated triplets
%  will be gobbled.
% \medskip
%
% \noindent
% \DescribeMacro{\lotlabelcase}
% The macro |\lotlabelcase| iterates on a comma-separated list of label-&
% names and tests for each name if the corresponding label is defined.
% Within the arguments you can specify actions for the cases:~~\nobreak
% {&
%   \makeatletter
%   \setbox\@tempboxa\hbox{4. the list does not contain any label.}&
%   \@tempdima\dp\@tempboxa
%   \vtop{&
%     \noindent
%     1. all labels are defined,\\
%     2. none of the labels is defined,\\
%     3. some labels are defined/some are undefined,\\
%     4. the list does not contain any label.&
%   }&
%   \par\prevdepth\@tempdima
% }&
% \noindent
% Like in |\eachlabelcase|, you can also specify a new macro-name within
% an optional argument. If you do so, the action will not be executed but
% the macro will be defined to perform the action:
% \bigskip
%
% \noindent
% {&
%   \footnotesize
%   |\lotlabelcase[|\emph{\textbackslash macro}|]|\nobreak
%   \vtop{&
%     \noindent
%     |{|\meta{label 1}|,|\meta{label 2}|,|\texttt{\dots}&
%     |,|\meta{label n}|}|\\
%     \marg{actions if all labels are defined}\\
%     \marg{actions if all labels are undefined}\\
%     \marg{actions if some labels are defined and
%           some labels are undefined}\\
%     \marg{actions if list is empty}&
%   }&
% }&
% \bigskip
%
% \noindent Space-tokens which might surround the label-names will be
% gobbled. One level of braces will also be gobbled so that you can also
% test for labels the names of which start or end by a space or contain
% some comma.
%
% \subsubsection{Possible problems}\label{sec3-1-1}
%
% \begin{itemize}
% \item Testing for labels which are \textbf{not definable} according to
%       the syntax-rules will lead to \TeX-internal error-messages and
%       deliver unexpected/unwanted results!
% \item ``Label- and referencing management'' in \LaTeXe\ is done by
%       means of the aux-file, the content of  which is gathered and
%       corrected during several \LaTeX-runs, and which does not yet
%       exist in the first run. So, in the first run, all labels from the
%       current document are undefined---when applying |\...labelcase| to
%       labels of the current document, it will in any case take at least
%       two \LaTeX-runs until everything matches out correctly.
% \item It was mentioned that, in the macros |\eachlabelcase| and
%       |\lotlabelcase|, space-tokens which surround the argument-&
%       triplets/label-names, will be gobbled. There are situations where
%       the category-code of the input-character \verb*+ + is changed---&
%       e.g., due to a preceding |\obeyspaces| or when using some package
%       where the encoding of \TeX-input-files is played around with.
%       In such cases, the input-character \verb*+ + does not get
%       tokenized as space-token any more but as some \verb*+ +\nobreak&
%       \(_{\neq10}\)-token, so that in such cases, triplets/labels in
%       these macros may, in the input-file, not be surrounded by
%       \verb*+ +\nobreak-\nobreak characters.\\
%       If you want to have these \verb*+ +\nobreak\(_{\neq10}\)-tokens
%       gobbled anyway, you can easily achieve this by defining another
%       set of these macros where the appropriate token, e.g.,
%       \verb*+ +\nobreak\(_{13}\)~(active-space) instead of
%       \verb*+ +\nobreak\(_{10}\)~(space-token), is taken into account.
%       How this is done, is described in
%       section~\hyperref[sec4]{\emph{\ref*{sec4}~\nolinknameref{sec4}}}.
% \item In the very unlikely case{\makeatletter\footnote{The case is very
%       unlikely because it is a convention in \LaTeXe\ to leave
%       {\verbatim@font\string\@nil} undefined. If labels are defined in
%       terms of macros, these macros are to expand to something that can
%       be evaluated by a {\verbatim@font\string\csname\dots\string&
%       \endcsname}-construct. If they are to expand to something, they
%       must be defined\dots}} that you wish |\lotlabelcase| (or variants
%       thereof\thinspace\footnote{\(\rightarrow\)&
%       \hyperref[sec4]{\emph{\ref*{sec4}~\nolinknameref{sec4}}}.})&
%       to scan for the label |\@nil|, |\@nil|
%       has to be put in  braces and/or has to be surrounded by space-&
%       tokens. This is because the internal iterator-macros terminate on
%       |\@nil|.
% \item Internally token-registers are used and temporary-macros get
%       defined. So the macros |\eachlabelcase| and |\lotlabelcase| (and
%       all variants&
%       \addtocounter{footnote}{-1}\addtocounter{Hfootnote}{-1}&
%       \footnotemark) are not ``full-expandable''. This means, |\edef| or
%       |\write| or control-sequences the like which evaluate their
%       arguments fully, cannot be applied to them.\footnote{In any case it
%       cannot be ensured that all arguments supplied are
%       ``full-expandable''\dots} Therefore they are declared robust.
% \item |\lotlabelcase| and |\eachlabelcase| can be nested. Inner
%       instances will be gathered into the action-queues of outer
%       instances.
% \item If the optional argument for defining a \meta{macro} rather than
%       having the action(s) executed immediately, is used, \meta{macro}
%       will only be defined within the group where the |\...labelcase|-&
%       command occurred.\\
%       |\@ifdefinable| is involved into the assignment-process, so that
%       an ``already-defined''-error is forced whenever an existing macro
%       is about to be overridden.\\
%       If you need it global, you can achieve this---after having
%       \meta{macro} defined---by something like
%       |\global\let\macro=\macro|.\\
%       If you need a ``long''-macro, you can achieve this---after having
%       \meta{macro} defined---by something like:\\
%       |\expandafter\renewcommand\expandafter\macro\expandafter{\macro}|&
%       .\\
%       But think about it. These macros don't take arguments!
% \item If you use the arguments of |\lotlabelcase|/|\eachlabelcase| for
%       defining other referencing-labels, things can easily get very
%       confusing\dots
% \end{itemize}
%
% \newpage
% \subsubsection{Examples}\label{sec3-1-2}
% \smallskip
%
% Within this document, only the labels |sec1|, |sec2|, |sec3|, |sec4|,
% |sec5| and |sec6| are defined.\bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\lotlabelcase{sec1, sec2 , {sec3} ,sec4}|\\
%   |             {All labels are defined.}|\\
%   |             {None of the labels is defined.}|\\
%   |             {Some labels are defined, some not.}|\\
%   |             {The list is empty.}|\medskip\\
%   yields:
%   \lotlabelcase{sec1, sec2 , {sec3} ,sec4}
%                {All labels are defined.}
%                {None of the labels is defined.}
%                {Some labels are defined, some not.}
%                {The list is empty.}&
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\lotlabelcase{sec1, sec2 , UNDEFINED ,sec3}|\\
%   |             {All labels are defined.}|\\
%   |             {None of the labels is defined.}|\\
%   |             {Some labels are defined, some not.}|\\
%   |             {The list is empty.}|\medskip\\
%   yields:
%   \lotlabelcase{sec1, sec2 , UNDEFINED ,sec3}
%                {All labels are defined.}
%                {None of the labels is defined.}
%                {Some labels are defined, some not.}
%                {The list is empty.}&
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\lotlabelcase{UNDEF1, UNDEF2 , {UNDEF3} ,UNDEF4}|\\
%   |             {All labels are defined.}|\\
%   |             {None of the labels is defined.}|\\
%   |             {Some labels are defined, some not.}|\\
%   |             {The list is empty.}|\medskip\\
%   yields:
%   \lotlabelcase{UNDEF1, UNDEF2 , {UNDEF2-1} ,UNDEF2-2}
%                {All labels are defined.}
%                {None of the labels is defined.}
%                {Some labels are defined, some not.}
%                {The list is empty.}&
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\lotlabelcase{ ,,  ,}|\\
%   |             {All labels are defined.}|\\
%   |             {None of the labels is defined.}|\\
%   |             {Some labels are defined, some not.}|\\
%   |             {The list is empty.}|\medskip\\
%   yields:
%   \lotlabelcase{ ,,  ,}
%                {All labels are defined.}
%                {None of the labels is defined.}
%                {Some labels are defined, some not.}
%                {The list is empty.}&
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\lotlabelcase[\test]{sec1, sec2 , UNDEFINED ,sec3}|\\
%   |                    {All labels are defined.}|\\
%   |                    {None of the labels is defined.}|\\
%   |                    {Some labels are defined, some not.}|\\
%   |                    {The list is empty.}|\medskip\\
%   defines: |\test|:{
%   \lotlabelcase[\test]{sec1, sec2 , UNDEFINED ,sec3}
%                       {All labels are defined.}
%                       {None of the labels is defined.}
%                       {Some labels are defined, some not.}
%                       {The list is empty.}&
%   {\makeatletter\verbatim@font\meaning\test}}
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\eachlabelcase{ {sec1}{sec1 defined/}{sec1 undefined/},|\\
%   |                {sec2}{sec2 defined/}{sec2 undefined/} ,|\\
%   |                {UNDEF}{UNDEF defined/}{UNDEF undefined/} ,|\\
%   |                {sec3}{sec3 defined.}{sec3 undefined.}  }|&
%   \medskip\\
%   yields:
%   \eachlabelcase{ {sec1}{sec1 defined/}{sec1 undefined/},
%                   {sec2}{sec2 defined/}{sec2 undefined/} ,
%                   {UNDEF}{UNDEF defined/}{UNDEF undefined/} ,
%                   {sec3}{sec3 defined.}{sec3 undefined.}  }&
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\eachlabelcase[\test]{ {sec1}{sec1 defined/}{sec1 undefined/},|\\
%   |                       {sec2}{sec2 defined/}{sec2 undefined/} ,|\\
%   |                       {UNDEF}{UNDEF defined/}{UNDEF undefined/} ,|&
%   \\
%   |                       {sec3}{sec3 defined.}{sec3 undefined.}  }|&
%   \medskip\\
%   {&
%      \eachlabelcase[\test]{ {sec1}{sec1 defined/}{sec1 undefined/},
%                             {sec2}{sec2 defined/}{sec2 undefined/} ,
%                             {UNDEF}{UNDEF defined/}{UNDEF undefined/} ,
%                             {sec3}{sec3 defined.}{sec3 undefined.}  }&
%      defines: |\test|:
%
%     \hskip\leftmargini
%     \vtop{{\makeatletter\verbatim@font\meaning\test}}&
%   }&
% \end{minipage}
%
% \newpage
% \subsection{&
%   \texorpdfstring
%   {&
%     Advanced usage (brace-matching, {\ttfamily\selectfont\Outif&
%     \dots\thinspace}, defining macros)&
%   }&
%   {&
%     Advanced usage (brace-matching, {\textbackslash if\dots}, defining
%     macros)&
%   }&
% }
%
% \begin{itemize}
%   \item Braces within the arguments/comma-separated items must be
%         balanced.
%   \item Within the ``action-parts'' of |\eachlabelcase|'s argument-&
%         triplets from which the action-queue is formed, balancing
%         {\makeatletter\verbatim@font\mbox{\string\if\dots\string\else
%         \dots\string\fi}}-constructs is not required. But ensured must
%         be, that in the resulting action-queue everything is balanced
%         correctly in any case.
%         \bigskip
%
%         \noindent
%         \begin{minipage}{\linewidth}
%           \noindent
%           |\eachlabelcase{  {sec1}     {\if aa}       {\if ab},|\\
%           |                 {sec2}  {a is a\else}   {a is b\else} ,|\\
%           |                 {sec3}{a is not a\fi.}{a is not b\fi.}   }|&
%           \smallskip\\
%           is gathered to: |\if aaa is a\else a is not a\fi.|\\
%           Executing the queue yields:
%           \eachlabelcase{ {sec1}    {\if aa}       {\if aa},
%                           {sec2}  {a is a\else}   {a is b\else} ,
%                           {sec3}{a is not a\fi.}{a is not b\fi.},   }&
%         \end{minipage}
%         \bigskip
%
%         \noindent
%         \begin{minipage}{\linewidth}
%           \noindent
%           |\eachlabelcase{  {sec1}     {\if aa}       {\if ab},|\\
%           |                 {UNDEF}  {a is a\else}  {a is b\else} ,|\\
%           |                 {sec3} {a is not a\fi.}{a is not b\fi.}   }|&
%           \smallskip\\
%           is gathered to: |\if aaa is b\else a is not a\fi.|\\
%           Executing the queue yields:
%           \eachlabelcase{ {sec1}     {\if aa}       {\if aa},
%                           {UNDEF}  {a is a\else}  {a is b\else} ,
%                           {sec3} {a is not a\fi.}{a is not b\fi.},   }&
%         \end{minipage}
%         \medskip
%
%         When trying such obscure things, you must be aware that brace/&
%         group-nesting is independent from conditional-nesting! You might
%         easily end up with a ``forgotten-endgroup''-error or some
%         ``extra |\else|\dots''-error when placing such things into other
%         {\makeatletter\verbatim@font\mbox{\string\if\dots\string\else
%         \dots\string\fi}}-constructs!
%
%   \item If you wish to use the arguments/comma-separated items for
%         defining macros, no extra |#|-level is needed as everything is
%         accumulated within/pro\-ces\-sed by means of token-registers.
%         \bigskip
%
%         \noindent
%         \begin{minipage}{\linewidth}
%           \noindent
%           |\eachlabelcase{ {sec1}{\def\testA#1#2#3}{\def\testB#1#2#3},|\\
%           |                {sec2}   {{#1,#2,#3}}      {{#3,#2,#1}}     }|&
%           \smallskip\\
%           is gathered to: |\def\testA#1#2#3{#1,#2,#3}|~~~.\\
%           Executing the queue defines:&
%           {&
%             \eachlabelcase{ {sec1}{\def\testA#1#2#3}{\def\testB#1#2#3},
%                             {sec2}   {{#1,#2,#3}}     {{#3,#2,#1}}   }
%             \vtop{&
%               |\testA|: {\makeatletter\verbatim@font\meaning\testA}\\
%               |\testB|: {\makeatletter\verbatim@font\meaning\testB}~~~.&
%             }&
%           }&
%         \end{minipage}
%         \bigskip
%
%         \noindent
%         \begin{minipage}{\linewidth}
%           |\eachlabelcase{ {sec1}{\def\testA#1#2#3}{\def\testB#1#2#3},|\\
%           |               {UNDEF}   {{#1,#2,#3}}      {{#3,#2,#1}}     }|&
%           \smallskip\\
%           is gathered to: |\def\testA#1#2#3{#3,#2,#1}|~~~.\\
%           Executing the queue defines:&
%           {&
%             \eachlabelcase{ {sec1}{\def\testA#1#2#3}{\def\testB#1#2#3},
%                          {UNDEF}   {{#1,#2,#3}}     {{#3,#2,#1}}   }
%             \vtop{&
%               |\testA|: {\makeatletter\verbatim@font\meaning\testA}\\
%               |\testB|: {\makeatletter\verbatim@font\meaning\testB}~~~.&
%             }&
%           }&
%         \end{minipage}
%         \medskip
% \end{itemize}
%
% \newpage
% \section{&
%   \texorpdfstring
%   {Package option---Different spaces, different se\-pa\-ra\-tors}&
%   {Package option\textemdash Different spaces, different separators}&
% }&
% \label{sec4}
%
% Above was said that space-tokens (\verb*+ +\nobreak\(_{10}\)-tokens)
% which surround the comma-list-arguments of |\eachlabelcase| and
% |\lotlabelcase| are gobbled.
%
% There are circumstances where the category-code which gets assigned to
% the input-character \verb*+ + during the tokenizing-process is changed,
% and thus the gobbling-mechanism is broken for these input-characters.
% E.g., due to a preceding |\obeyspaces| or when using some package where
% the encoding of \TeX-input-files is played around with.
% This is because space-gobbling internally is implemented by means of
% macros with \verb*+ +\nobreak\(_{10}\)-token-delimited arguments.
%
% In normal circumstances, \verb*+ +\nobreak-characters in the input-file
% which trail a control-word do not get tokenized when \TeX\ ``reads'' an
% input. So it's kind of a problem to get space-tokens right behind the
% name of a control-word, e.g., as first items of the parameter-text when
% defining macros. A space within braces \verb*+{ }+ does get tokenized as
% it is not preceded by a control-word, but by a brace-character. So a
% solution to the problem is: Define a macro which takes an (en-braced)
% argument and use this macro for defining the desired control-word
% whereby the argument is placed right behind the name of the control-&
% word which is about to be defined. (Henceforth the term \emph{definer&
% -macro} is applied in order to call special attention to the fact that
% defining other control-sequences is the only purpose of such a macro.)
% A \verb*+ + as the definer-macro's argument gets tokenized while this
% argument is used as the first item of the desired control-word's
% parameter-text \(\rightarrow\) the first item of the desired control-&
% word's parameter-text will be a space-token.
%
% \DescribeMacro{\DefineLabelcase}
% In case of the \textsf{\mbox{labelcas}}-package, the problem of getting
% space-tokens as delimiters right behind control-words, is also solved by
% implementing such a definer-macro. It is called |\DefineLabelcase| and
% used for defining both the user-level-macros |\eachlabelcase| and
% |\lotlabelcase| and the internal-macros |\lc@iterate|,
% |\lc@remtrailspace| and |\lc@remleadspace|.
% Usually it is discarded/destroyed when defining these macros has taken
% place. But you can specify the package-option |DefineLabelcase|. When
% you do so, |\DefineLabelcase| does not get destroyed, and you can use it
% for creating ``new variants'' of |\eachlabelcase| and |\lotlabelcase|
% plus internals while specifying proper space-tokens and separators.
% |\DefineLabelcase| takes four mandatory arguments:
% \bigskip
%
% \noindent
% |\DefineLabelcase|\marg{space}\marg{delimiter}\marg{prefix}&
% \marg{global-indicator}
%
% \begin{description}
% \item[\textnormal{\meta{space}}] specifies the argument-surrounding
%      token that is to be removed. Usually surrounding space-tokens
%      shall be discarded. Usually:~\verb*+ +\nobreak\(_{10}\)~(space).
% \item[\textnormal{\meta{delimiter}}] specifies the delimiter/separator.
%      Usually the argument-triplets or label-lists are comma-separated.
%      Usually:~\verb*+,+\nobreak\(_{12}\)~(comma).
% \item[\textnormal{\meta{prefix}}] specifies the macro-name-prefix. You
%      cannot assign the same name at the same time to different
%      control-sequences. Therefore, when creating new variants of
%      |\eachlabelcase| and |\lotlabelcase|, you have to specify a prefix
%      which gets inserted at the beginning of the macro-name. E.g.,
%      specifying the prefix |FOO| leads to defining the macro-set:\\
%      |\FOOeachlabelcase|\MacroIndexEntry{\<prefix!>eachlabelcase},
%      |\FOOlotlabelcase|\MacroIndexEntry{\<prefix!>lotlabelcase}
%      (user-macros) and\\
%      |\FOOlc@iterate|\MacroIndexEntry{\<prefix!>lc@iterate},
%      |\FOOlc@remtrailspace|\MacroIndexEntry{\<prefix!>lc@remtrailspace},
%      |\FOOlc@remleadspace|\MacroIndexEntry{\<prefix!>lc@remleadspace}
%      (internal).\\
%      The original versions are just called |\eachlabelcase|,
%      |\lotlabelcase|, |\lc@iterate|\dots (without a prefix in the
%      macro-name). Usually:~(empty).
% \item[\textnormal{\meta{global-indicator}:}] In case that this argument
%      contains only the token |\global|, defining the new macro-set takes
%      place in terms of |\global|. Otherwise the scope is restricted to
%      the current grouping-level. Usually:~\verb*+\global+.
% \end{description}
%
% Don't try weird things like specifying the same token both for
% \meta{space} and \meta{delimiter}, or leaving any of those empty, or
% specifying any of those to |\@nil| (,~which is reserved for terminating
% the recursion)---unless you like error-messages! Please only specify
% tokens which may be used for separating parameters from each other
% within the parameter-text of a definition! Also please specify the
% \meta{prefix} only in terms of letter-character-tokens! \textbf{There is
% no extra error-checking implemented on these things!}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\begingroup|\\
%   |\obeyspaces|\\
%   |\endlinechar=-1\relax%|\\
%   \verb*|\DefineLabelcase{ }{/}{SPACEOBEYED}{local}%|\\
%   \verb*|\SPACEOBEYEDlotlabelcase[\test]{sec1/ sec2   /   UNDEF     /sec3}%|\\
%   \verb*|{All   labels   are   defined.}%|\\
%   \verb*|{None   of   the   labels   is   defined.}%|\\
%   \verb*|{Some   labels   are   defined,   some not.}%|\\
%   \verb*|{The   list   is   empty.}%|\\
%   |\global\let\test\test%|\\
%   |\endgroup|\medskip\\
%   defines: |\test|:
%\begingroup
%\obeyspaces
%\endlinechar=-1\relax&
%\DefineLabelcase{ }{/}{SPACEOBEYED}{local}&
%\SPACEOBEYEDlotlabelcase[\test]{sec1/ sec2   /   UNDEF     /sec3}&
%{All   labels   are   defined.}&
%{None   of   the   labels   is   defined.}&
%{Some   labels   are   defined,   some not.}&
%{The   list   is   empty.}&
%\global\let\test\test&
%\endgroup
%   {&
%     \makeatletter
%     \def\spacereplace#1 #2\@nil{&
%       #1&
%       \def\@tempa{#2}&
%       \ifx\@tempa\@empty
%         \expandafter\@gobble
%       \else
%         \expandafter\@firstofone
%       \fi
%       {\char32\spacereplace#2\@nil}&
%     }&
%     \verbatim@font
%     \expandafter\expandafter
%     \expandafter\spacereplace
%     \expandafter\meaning
%     \expandafter\test
%     \space\@nil
%   }&
%   \global\let\test\undefined
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\begingroup|\\
%   |\endlinechar=-1\relax|\\
%   |\DefineLabelcase{-}{/}{BAR}{local}%|\\
%   |\BARlotlabelcase[\test]{sec1/-sec2----/--%|\\
%   |                              ---/sec3}%|\\
%   |{All   labels   are   defined.}%|\\
%   |{None   of   the   labels   is   defined.}%|\\
%   |{Some   labels   are   defined,   some not.}%|\\
%   |{The   list   is   empty.}%|\\
%   |\global\let\test\test|\\
%   |\endgroup|\medskip\\
%   defines: |\test|:
%   \begingroup
%     \endlinechar=-1\relax
%     \DefineLabelcase{-}{/}{BAR}{local}&
%     \BARlotlabelcase[\test]{sec1/-sec2----/--&
%                                   ---/sec3}&
%                            {All   labels   are   defined.}&
%                            {None   of   the   labels   is   defined.}&
%                            {Some   labels   are   defined,   some not.}&
%                            {The   list   is   empty.}&
%     \global\let\test\test
%   \endgroup
%   {\makeatletter\verbatim@font\meaning\test}&
%   \global\let\test\undefined
% \end{minipage}
% \bigskip
%
% \noindent
% \begin{minipage}{\linewidth}
%   \noindent
%   |\begingroup|\\
%   |\endlinechar=-1\relax|\\
%   |\DefineLabelcase{.}{/}{DOT}{local}%|\\
%   |\DOTeachlabelcase{.{sec1}..{sec1 defined/}{sec1 undefined/}/%|\\
%   |..................{sec2}...{sec2 defined/}...{sec2 undefined/}./..%|\\
%   |..................{UNDEF}{UNDEF defined/}...{UNDEF undefined/}./%|\\
%   |..................{sec3}{sec3 defined.}{sec3 undefined.}..}|\\
%   |\endgroup|\medskip\\
%   yields:
%   \begingroup
%     \endlinechar=-1\relax
%     \DefineLabelcase{.}{/}{DOT}{local}&
%     \DOTeachlabelcase{.{sec1}..{sec1 defined/}{sec1 undefined/}/&
%...................{sec2}...{sec2 defined/}...{sec2 undefined/}./..&
%...................{UNDEF}{UNDEF defined/}...{UNDEF undefined/}./&
%...................{sec3}{sec3 defined.}{sec3 undefined.}..}&
%   \endgroup
% \end{minipage}
%
% \newpage
% \section{Thanks, Acknowledgements}\label{sec5}
% \begin{itemize}
% \item Many thanks to all who encouraged me in making the attempt of
%       getting things in this package less error-prone.
% \item Thanks to everybody who took the macro-writing challenges
%       presented in the \textsf{\mbox{INFO-\TeX}-`Around the bend'}-&
%       department which was initiated back in the early 90's by
%       \textsf{\mbox{Michael Downes}} and regularly took place under his
%       guidance. His summaries of the solutions are archived and online
%       available at \href{http://www.tug.org/tex-archive/info/aro-bend/}&
%       {\textsf{http://www.tug.org/tex-archive/info/aro-bend/}}. The
%       information therein helps a great deal in understanding \TeX\ in
%       general and in learning about basic problem-solving-strategies---&
%       e.g., the removal of leading- and trailing spaces from an (almost)
%       arbitrary token-sequence (exercise.015/answer.015).
% \item Thanks to everybody who provides valuable information at the
%       \TeX-news-groups and mailing-lists. I received great help
%       especially at \textsf{\mbox{comp.text.tex}}, where my---often
%       trivial---questions were answered patiently again and again.
% \item Thanks to the \LaTeX-package authors, not only for providing means
%       of achieving special typesetting-goals, but also for hereby
%       delivering informative programming-examples.
%       \textsf{\mbox{labelcas}} actually was inspired by
%       \textsf{\mbox{David Carlisle's}} \textsf{xr}- and
%       \textsf{\mbox{xr-hyper}}-packages which make available the labels
%       of other \LaTeX-documents to the current one.
% \end{itemize}
%
% \section{Legal Notes}\label{sec6}
%
% \textsf{\mbox{labelcas}}---Copyright (C) 2006 by \mbox{Ulrich Diez}
% (\href{mailto:ulrich.diez@alumni.uni-tuebingen.de}&
%       {\textsf{ulrich.diez@alumni.uni-tuebingen.de}})
% \medskip
%
% \textsf{\mbox{labelcas}} may be distributed and/or modified under the
% conditions of the \textsf{\LaTeX\ Project Public Licence (LPPL)}, either
% version 1.3 of this license or (at your option) any later version.&
% \footnote{The latest version of this license is in
% \href{http://www.latex-project.org/lppl.txt}&
%      {\textsf{http://www.latex-project.org/lppl.txt}}
% and version 1.3 or later is part of all distributions of \LaTeX\ version
% 2003/12/01 or later.}
% The author and Current Maintainer of this Work is \mbox{Ulrich Diez}.
% This Work has the LPPL maintenance status `author-maintained' and
% consists of the files \textsf{\mbox{labelcas.dtx}},
% \textsf{\mbox{labelcas.ins}}, \textsf{\mbox{README}} and the derived
% files \textsf{\mbox{labelcas.sty}} and \textsf{\mbox{labelcas.pdf}}.
% \medskip
%
% Usage of the \textsf{\mbox{labelcas}}-package is at your own risk. There
% is no warranty---neither for the documentation nor for any other part of
% the \textsf{\mbox{labelcas}}-package. If something breaks, you usually
% may keep the pieces.
%
% \StopEventually{&
%   \let\PrintChanges\relax
%   \PrintIndex
% }
%
% \newpage
% \section{Implementation}
%
% \subsection{A note about removing leading and trailing spaces}
%
% The matter of removing trailing spaces from an (almost) arbitrary
% token-sequence is elaborated in detail by \textsf{\mbox{Michael Downes},
% `Around the Bend \#15, answers'}, a summary of internet-discussion which
% took place under his guidance primarily at the \textsf{\mbox{INFO-\TeX}
% list}, but also at \textsf{\mbox{comp.text.tex}} (usenet) and via
% private e-mail; December 1993. Online archived at
% \href{http://www.tug.org/tex-archive/info/aro-bend/answer.015}&
%      {\textsf{http://www.tug.org/tex-archive/info/aro-bend/answer.015}}.
%
% One basic approach suggested therein is using \TeX's scanning of
% delimited parameters in order to detect and discard the ending space of
% an argument:
% \begin{quote}
%   \dots scan for a pair of tokens: a space-token and some well-chosen
%   bizarre token that can't possibly occur in the scanned text. If you
%   put the bizarre token at the end of the text, and if the text has a
%   trailing space, then \TeX's delimiter matching will match at that
%   point and not before, because the earlier occurrences of space don't
%   have the requisite other member of the pair.
%
%   Next consider the possibility that the trailing space is absent:
%   \TeX\ will keep on scanning ahead for the pair \meta{space}&
%   \meta{bizarre} until either it finds them or it decides to give up and
%   signal a `Runaway argument?' error. So you must add a stop pair to
%   catch the runaway argument possibility: a second instance of the
%   bizarre token, preceded by a space. If \TeX\ doesn't find a match at
%   the first bizarre token, it will at the second one.
% \end{quote}
%
% (Look up the macros |\KV@@sp@def|, |\KV@@sp@b|, |\KV@@sp@c| and
% |\KV@@sp@d| in \textsf{\mbox{David Carlisle's} \mbox{keyval}-package}
% for an interesting variation on this approach.)
% \medskip
%
% When scanning for parameters ~~~|##1|\meta{space}\meta{bizarre}|##2|&
% \meta{B1}~~~ the sequence:
% \\
% \meta{stuff where to remove trail-space}\meta{bizarre}\meta{space}&
% \meta{bizarre}\meta{B1}&
% \\
% , you can fork two cases:
% \begin{enumerate}
%   \parskip=0ex\relax
%   \item Trailing-space:\\
%         |##1|=\meta{stuff where to remove trail-space}, but with removed
%         space. (And possibly one removed brace-level!)\\
%         |##2| = \meta{space}\meta{bizarre}.
%   \item No trailing-space:\\
%         |##1|=\meta{stuff where to remove trail-space}\meta{bizarre}.\\
%         |##2| is empty.
% \end{enumerate}
%
% So forking can be implemented depending on the emptiness of |##2|.
%
% You can easily prevent the brace-removal in the first case, e.g., by
% adding (and later removing) something (e.g., a space-token) in front of
% the \meta{stuff where to remove trail-space}.
%
% You can choose \meta{B1}=\meta{bizarre}\meta{space}.
% \medskip
%
% \textsf{`Around the Bend \#15, answers'} also presents a similar way for
% the removal of leading spaces from an (almost) arbitrary token-sequence:
% \begin{quote}
%   The latter method is perhaps most straightforwardly done as a mirror-&
%   image of the method for removing a trailing space: make the delimiter
%   \meta{bizarre}\meta{space}, and call the macro [\dots] by putting
%   \meta{bizarre} before the scanned text and a stop pair \meta{bizarre}&
%   \meta{space} after it, in case a leading space is not present
% \end{quote}
%
% When scanning for parameters ~~~|##1|\meta{bizarre}\meta{space}|##2|&
% \meta{B2}~~~ the sequence:
% \\
% \meta{bizarre}\meta{stuff where to remove lead-space}\meta{bizarre}&
% \meta{space}\meta{B2}&
% \\
% , you can fork two cases:
% \begin{enumerate}\parskip=0ex\relax
%   \item Leading space:\\
%         |##1|= is empty.\\
%         |##2| = \meta{stuff where to remove lead-space}\meta{bizarre}&
%                 \meta{space} (but with a leading-space removed from
%                 \meta{stuff where to remove lead-space}).
%   \item No leading space:\\
%         |##1|=\meta{bizarre}\meta{stuff where to remove lead-space}.\\
%         |##2| is empty.
% \end{enumerate}
%
% Thus forking can be implemented depending on the emptiness of either of
% the two arguments.
%
% You can choose \meta{B2}=\meta{bizarre}\meta{bizarre}.
%
% \subsection{Flow of work}
%
% \begin{sloppypar}
% Both |\|\meta{prefix}|eachlabelcase| and |\|\meta{prefix}|lotlabelcase|
% iterate on (e.g., comma-) separated lists:
% \settowidth\labelwidth{5.}&
% \leftmargini=\labelwidth\relax
% \advance\leftmargini\labelsep\relax
% \advance\leftmargini\parindent\relax
% \begin{enumerate}
%   \parskip=0ex\relax\itemsep=.25\baselineskip\relax
% \item The list is passed as an argument to the user-macro.
% \item The list is passed from the user-macro to
%       |\|\meta{prefix}|lc@iterate|\MacroIndexEntry{\<prefix!>lc@iterate}
%       whereby a leading \meta{space} is added for brace-removal-&
%       protection.
% \item |\|\meta{prefix}|lc@iterate|\MacroIndexEntry{\<prefix!>lc@iterate}
%       recursively iterates on the list-items until the item
%      \meta{space}|\@nil| occurs:&
% {\def\labelenumii{\theenumii)}&
%  \settowidth\labelwidth{a)}&
%  \leftmarginii=\labelwidth\relax
%  \advance\leftmarginii\labelsep\relax
% \begin{enumerate}
%   \parskip=0ex\relax\itemsep=0ex\relax
%   \makeatletter\@topsep=0ex\relax\makeatother
%   \item The item will be passed to |\|\meta{prefix}|lc@remtrailspace|&
%         \MacroIndexEntry{\<prefix!>lc@remtrailspace}. Here trailing
%         \meta{space} is removed recursively. If after removing
%         trailing-space the result is empty, you can conclude that
%         everything (incl the previously inserted ``brace-removal-&
%         protection-\meta{space}'' was removed as either the item was
%         empty or consisted of a sequence of \meta{space}. If the
%         result does not imply an empty item, it will be passed to
%   \item |\|\meta{prefix}|lc@remleadspace|&
%         \MacroIndexEntry{\<prefix!>lc@remleadspace} where leading
%         \meta{space} (also the previously inserted one) is removed
%         recursively. After that |\|\meta{prefix}|lc@remleadspace|&
%         \MacroIndexEntry{\<prefix!>lc@remleadspace} passes the item to
%         the macro
%   \item |\@tempa| for further processing. |\@tempa| at this stage will
%         be locally defined within the user-macro. |\@tempa| initiates
%         the actual work which (hopefully!) results in adding the
%         appropriate action-sequence to the queue which is represented by
%         |\@temptokena|.
%   \item Before processing the next item in the next iteration-round, a
%         leading \meta{space} for brace-removal-protection will be added
%         in front of the remaining list by |\|\meta{prefix}|lc@iterate|&
%         \MacroIndexEntry{\<prefix!>lc@iterate}.
% \end{enumerate}\unskip}&
% \item After iterating the list within the user-macro, the routine
%       |\lc@macrodefiner|\MacroIndexEntry{\lc@macrodefiner} will check
%       for the user-macro's optional argument and, in case that it is
%       present, modify the action-queue-register, so that, when
%       ``flushing'' it, a macro will be produced instead of queue-&
%       execution.
% \item The final step within the user-macro is ``flushing'' the action-&
%       queue-register.
% \end{enumerate}
% \end{sloppypar}
%
% \newpage
% \subsection{Code}
%
% \begin{macro}{\DefineLabelcase}
%   |\DefineLabelcase| is used for providing parameters during the
%   definition of the macros~\nobreak
%   {&
%     \makeatletter
%     \setbox\@tempboxa\hbox{|\|\meta{prefix}|lc@remleadspace|
%                            (internal).}&
%     \@tempdima\dp\@tempboxa
%     \vtop{&
%       \noindent
%       |\|\meta{prefix}|eachlabelcase|,
%       |\|\meta{prefix}|lotlabelcase| (user),\\
%       |\|\meta{prefix}|lc@iterate|,
%       |\|\meta{prefix}|lc@remtrailspace|,\\
%       |\|\meta{prefix}|lc@remleadspace| (internal).&
%     }&
%     \par\prevdepth\@tempdima
%   }&
%   \noindent
%   Parameters are:
%   |#1|\(=\)\meta{space}; |#2|\(=\)\meta{delimiter};
%   |#3|\(=\)\meta{prefix}; |#4|\(=\)\meta{global-indicator}.
%
%   Defining of |\DefineLabelcase| takes place within a group, so that
%   after closing the group it gets discarded. Package-options will also
%   be evaluated within that group, right after defining
%   |\DefineLabelcase|. By the option |DefineLabelcase|,
%   |\DefineLabelcase| can be ``globalized'' before closing the group:
% \iffalse
%<*labelcas>
% \fi
%    \begin{macrocode}
\begingroup
\DeclareOption{DefineLabelcase}%
              {\global\let\DefineLabelcase\DefineLabelcase}%
\newcommand\DefineLabelcase[4]{%
%    \end{macrocode}
% \end{macro}
% \def\pref{prefix}
% \begin{macro}{lc@remtrailspace}
% \Patchsavedatmacroname
% \changes{v1.01}{2006/01/06}{\meta{B1}\ChgEq\meta{bizarre}\nobreak
%   \meta{space}.}
% \changes{v1.03}{2006/02/21}{Chan\-ged forking-mechanism to \string
%   \verb+\string\@firstoftwo+/\string\verb+\string\@secondoftwo+.}
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+ instead
%   of \string\verb*+\string\newcommand+.}
% \changes{v1.10}{2006/07/21}{Empty-argument-check added.}
%   It is assured that \meta{delimiter} does not occur in the top-level of
%   the \meta{stuff where to remove trail-space}, for \meta{delimiter} is
%   used in the list for separating the single items of \meta{stuff where
%   to remove trail-space} from each other. Therefore you can choose
%   \meta{bizarre}=\meta{delimiter} and \meta{B1}=\meta{bizarre}&
%   \meta{space}=\meta{delimiter}\meta{space}:
%    \begin{macrocode}
  \expandafter\@ifdefinable\csname#3lc@remtrailspace\endcsname{%
    \expandafter\long
    \expandafter\def
    \csname#3lc@remtrailspace\endcsname##1#1#2##2#2#1{%
%    \end{macrocode}
%   \InsertPrefixedUsageToIndex{prefix}{lc@remtrailspace}&
%   Above was said that forking can take place depending on emptiness of
%   the second argument. The arguments come from the items of the comma-&
%   separated list---thus they might contain macro-definitions and/or
%   unbalanced {\makeatletter\verbatim@font\mbox{\string\if\dots\string
%   \else\dots\string\fi}}-constructs. So put the second argument into a
%   macro |\@tempa| by means of a token-register in order to prevent
%   errors related to parameter-numbering:
%    \begin{macrocode}
      \begingroup
      \toks@{##2}%
      \edef\@tempa{\the\toks@}%
%    \end{macrocode}
%   When forking takes place, the content of the arguments might---when
%   placed into the corresponding |\if|- or |\else|-branches directly---&
%   erroneously match up those constructs. In order to prevent this, the
%   action related to the different branches is handled by means of
%   |\@firstoftwo| and |\@secondoftwo| which get expanded when
%   ``choosing the forking-route'' is already accomplished:
%    \begin{macrocode}
      \expandafter\endgroup
      \ifx\@tempa\@empty
        \expandafter\@firstoftwo
      \else
        \expandafter\@secondoftwo
      \fi
%    \end{macrocode}
%   The appropriate action in case of no more trailing \meta{space} is
%   checking if the item is not empty and if so, initiating the removal
%   of leading \meta{space}. In this case |##1| is terminated by
%   \meta{bizarre}. If the item is empty, the leading \meta{space}
%   inserted by the iterator for brace-protection is also removed so that
%   |##1| equals \meta{bizarre}. If the item is not empty, start leading-&
%   \meta{space}-removal, but add only \meta{space}\meta{B2} at the end
%   instead of \meta{bizarre}\meta{space}\meta{B2}---above was said that
%   \meta{B2}=\meta{bizarre}\meta{bizarre}=&
%   \meta{delimiter}\meta{delimiter} in |\|\meta{prefix}|lc@remleadspace|:
%    \begin{macrocode}
      {%
        {\toks@{##1}\edef\@tempa{\the\toks@}%
         \toks@{#2}\edef\@tempb{\the\toks@}%
         \expandafter}%
        \ifx\@tempa\@tempb
          \expandafter\@gobble
        \else
          \expandafter\@firstofone
        \fi
        {\csname#3lc@remleadspace\endcsname#2##1#1#2#2}%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%    \begin{macrocode}
      }%
%    \end{macrocode}
%   The appropriate action in case of trailing \meta{space} is checking
%   and possibly removing more thereof:
%    \begin{macrocode}
      {\csname#3lc@remtrailspace\endcsname##1#2#1#2#2#1}%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remtrailspace}&
%    \begin{macrocode}
    }%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{lc@remleadspace}
% \Patchsavedatmacroname
% \changes{v1.01}{2006/01/06}{\meta{B2}\ChgEq\meta{bizarre}\meta{bizarre}.}
% \changes{v1.03}{2006/02/21}{Chan\-ged forking-mechanism to
%   \string\verb+\string\@firstoftwo+/\string\verb+\string\@secondoftwo+.}
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+
%   instead of \string\verb*+\string\newcommand+.}
%   |\|\meta{prefix}|lc@remleadspace| is similar to
%   |\|\meta{prefix}|lc@remtrailspace|, but with \meta{B2}=\meta{bizarre}&
%   \meta{bizarre}=\meta{delimiter}\meta{delimiter}:
%    \begin{macrocode}
  \expandafter\@ifdefinable\csname#3lc@remleadspace\endcsname{%
    \expandafter\long
    \expandafter\def
    \csname#3lc@remleadspace\endcsname##1#2#1##2#2#2{%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%   Above was said that forking can take place e.g., depending on
%   emptiness of the first argument. Arguments still come from the list-&
%   items, so let's use token-registers for the same reasons as in
%   |\|\meta{prefix}|lc@remtrailspace|:
%    \begin{macrocode}
      \begingroup
      \toks@{##1}%
      \edef\@tempa{\the\toks@}%
%    \end{macrocode}
%   The single list-items might still contain macro-definitions, |\if|-&
%   forking and the like, therefore again choose the forking-route in
%   terms of |\@firstoftwo| and |\@secondoftwo|:
%    \begin{macrocode}
      \expandafter\endgroup
      \ifx\@tempa\@empty
        \expandafter\@firstoftwo
      \else
        \expandafter\@secondoftwo
      \fi
%    \end{macrocode}
%   The appropriate action in case of leading \meta{space} is checking
%   and possibly removing more thereof:
%    \begin{macrocode}
      {\csname#3lc@remleadspace\endcsname#2##2#2#2}%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%   In case of no more leading \meta{space}, the actual work, which is
%   defined in user-macro's |\@tempa|, can be done:
%    \begin{macrocode}
      {\@tempa##1#2}%
    }%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{lc@iterate}
% \Patchsavedatmacroname
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+
%   instead of \string\verb*+\string\newcommand+.}
% \changes{v1.07}{2006/04/27}{Define \string\verb*+\string\@tempa+
%   in terms of \string\verb*+\string\long+.}
% \changes{v1.08}{2006/07/10}{Chan\-ged forking-mechanism to
%   \string\verb+\string\@firstoftwo+/\string\verb+\string\@secondoftwo+.}
% \changes{v1.09}{2006/07/16}{Chan\-ged forking-mechanism so that
%   two temporary macros suffice.}
% \changes{v1.10}{2006/07/21}{Empty-argument-check removed.}
%   |\|\meta{prefix}|lc@iterate| iterates on arguments which are
%   delimited by \meta{delimiter}.
%    \begin{macrocode}
  \expandafter\@ifdefinable\csname#3lc@iterate\endcsname{%
    \expandafter\long
    \expandafter\def
    \csname#3lc@iterate\endcsname##1#2{%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%   Make locally available the arguments as macros:\\
%   |\@tempa|\(=\)current argument\\
%   |\@tempb|\(=\)recursion-stop-item:
%    \begin{macrocode}
      \begingroup
      \toks@{##1}%
      \edef\@tempa{\the\toks@}%
      \toks@{#1\@nil}%
      \edef\@tempb{\the\toks@}%
%    \end{macrocode}
%   End the group and test if the current argument equals the
%   recursion-stop-item:
%    \begin{macrocode}
      \expandafter\endgroup\ifx\@tempa\@tempb
        \expandafter\@gobble
      \else
        \expandafter\@firstofone
      \fi
%    \end{macrocode}
%   If not: Start trailing-space-removal\dots, then continue iterating the
%   list and hereby add a preceding \meta{space} to the next item for
%   brace-protection during trailing-\meta{space}-removal in the next run:
%    \begin{macrocode}
      {%
        \csname#3lc@remtrailspace\endcsname##1#2#1#2#2#1%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remtrailspace}&
%    \begin{macrocode}
        \csname#3lc@iterate\endcsname#1%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%    \begin{macrocode}
      }%
    }%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{eachlabelcase}
% \Patchsavedatmacroname
% \changes{v1.03}{2006/02/21}{Chan\-ged forking-mechanism to
%   \string\verb+\string\@firstoftwo+/\string\verb+\string\@secondoftwo+.}
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+
%    instead of \string\verb*+\string\newcommand+.}
%   |\|\meta{prefix}|eachlabelcase|'s optional argument is the possibly-&
%   to-be-defined control-sequence. The mandatory-argument contains the
%   argument-triplet-list.
%    \begin{macrocode}
  \expandafter\@ifdefinable\csname#3eachlabelcase\endcsname{%
    \expandafter\DeclareRobustCommand
    \csname#3eachlabelcase\endcsname[2][]{%
%    \end{macrocode}
%   \InsertPrefixedUsageToIndex{prefix}{eachlabelcase}&
%   Locally define |\@tempa|---it is called by
%   |\|\meta{prefix}|lc@remleadspace| for working on a list-item when all
%   surrounding \meta{space} has been removed:
%    \begin{macrocode}
      {%
%    \end{macrocode}
%   The stuff that results from \meta{space}-removing is surrounded by
%   \meta{delimiter}. It cannot be processed at this place, as first the
%   triplet needs to be split into its components by |\@tempb|:
%    \begin{macrocode}
        \long\def\@tempa#2####1#2{%
          \@tempb####1#2#1#2#2%
        }%
%    \end{macrocode}
%   |\@tempb| is used for splitting the triplet and removing \meta{space}
%   between the triplet's components. In this process it redefines itself
%   several times. In case that no label is defined the name thereof
%   corresponds to the first component, add the third  component to
%   |\@temptokena|, otherwise add the second:
%    \begin{macrocode}
        \long\def\@tempb####1{%
          \begingroup
          \long\def\@tempb########1########2########3{%
            \expandafter\expandafter
            \expandafter\endgroup
            \expandafter\ifx
            \csname r@########1\endcsname\relax
              \expandafter\@firstoftwo
            \else
              \expandafter\@secondoftwo
            \fi
            {\@temptokena\expandafter{\the\@temptokena########3}}%
            {\@temptokena\expandafter{\the\@temptokena########2}}%
          }%
          \begingroup
          \toks@{}%
          \long\def\@tempb########1{%
            \long\def\@tempa#2################1#2{%
              \toks@\expandafter{\the\toks@{################1}}%
              \expandafter\endgroup\expandafter\@tempb\the\toks@
            }%
            \toks@\expandafter{\the\toks@{########1}}%
            \csname#3lc@remleadspace\endcsname#2%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%    \begin{macrocode}
          }%
          \toks@{{####1}}\csname#3lc@remleadspace\endcsname#2%
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%    \begin{macrocode}
        }%
%    \end{macrocode}
%   Let's clear the register where the action-queue is accumulated:
%    \begin{macrocode}
        \@temptokena{}%
%    \end{macrocode}
%   Let's iterate on the list:
%    \begin{macrocode}
        \csname#3lc@iterate\endcsname#1##2#2\@nil#2%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%   In case that the optional argument is specified, the routine
%   |\lc@macrodefiner| will modify the register to define a macro:
%    \begin{macrocode}
        \lc@macrodefiner{##1}%
%    \end{macrocode}
%   Close the group and ``flush'' the register:
%    \begin{macrocode}
      \expandafter}\the\@temptokena
    }%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{lotlabelcase}
% \Patchsavedatmacroname
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+
%    instead of \string\verb*+\string\newcommand+.}
%   |\|\meta{prefix}|lotlabelcase|'s optional argument is the possibly-&
%   to-be-defined control-sequence. The five mandatory-arguments contain
%   the label-list and the actions that shall take place in the cases: All
%   of the labels are defined~/ none are defined~/ just some are defined~/
%   list is empty:
%    \begin{macrocode}
  \expandafter\@ifdefinable\csname#3lotlabelcase\endcsname{%
    \expandafter\DeclareRobustCommand
    \csname#3lotlabelcase\endcsname[6][]{%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lotlabelcase}&
%   Locally define |\@tempa|---it is called by
%   |\|\meta{prefix}|lc@remleadspace| for working on a list-item when all
%   surrounding \meta{space} has been removed:
%    \begin{macrocode}
      {%
        \long\def\@tempa#2####1#2{%
%    \end{macrocode}
%   The list item is a label. In case that it is undefined, have the
%   helper-macro |\@tempb| defined/switched to |\relax|, otherwise do the
%   same but use |\@tempc| instead:
%    \begin{macrocode}
          {\expandafter\expandafter\expandafter}\expandafter
          \ifx\csname r@####1\endcsname\relax
            \let\@tempb\relax
          \else
            \let\@tempc\relax
          \fi
        }%
%    \end{macrocode}
%   Define |\@tempb| and |\@tempc| to empty. They may be ``switched'' to
%   |\relax| when |\@tempa| is called during iteration.
%    \begin{macrocode}
        \def\@tempb{}%
        \def\@tempc{}%
%    \end{macrocode}
%   Let's iterate on the list:
%    \begin{macrocode}
        \csname#3lc@iterate\endcsname#1##2#2\@nil#2%
%    \end{macrocode}
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%   Assign the register according to the label-defining-cases which are
%   now represented by the definitions of |\@tempb| and |\@tempc| which
%   are defined either |\relax| or |empty|:
%    \begin{macrocode}
        \ifx\@tempb\@empty
          \ifx\@tempc\@empty
            \@temptokena{##6}%
          \else
            \@temptokena{##3}%
          \fi
        \else
          \ifx\@tempc\@empty
            \@temptokena{##4}%
          \else
            \@temptokena{##5}%
          \fi
        \fi
%    \end{macrocode}
%   In case that the optional argument is specified, the routine
%   |\lc@macrodefiner| will modify the register to define a macro:
%    \begin{macrocode}
        \lc@macrodefiner{##1}%
%    \end{macrocode}
%   Close the group and ``flush'' the register:
%    \begin{macrocode}
      \expandafter}\the\@temptokena
    }%
  }%
%    \end{macrocode}
% \end{macro}
% If the \meta{global-indicator}-argument equals |\global|, the above
% definitions need to be made |\global|:
%    \begin{macrocode}
  {\toks@{#4}\edef\@tempa{\the\toks@}\def\@tempb{\global}\expandafter}%
  \ifx\@tempa\@tempb
    \expandafter\global\expandafter\let
      \csname#3lc@remtrailspace\expandafter\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remtrailspace}&
%    \begin{macrocode}
      \csname#3lc@remtrailspace\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remtrailspace}&
%    \begin{macrocode}
    \expandafter\global\expandafter\let
      \csname#3lc@remleadspace\expandafter\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%    \begin{macrocode}
      \csname#3lc@remleadspace\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@remleadspace}&
%    \begin{macrocode}
    \expandafter\global\expandafter\let
      \csname#3lc@iterate\expandafter\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%    \begin{macrocode}
      \csname#3lc@iterate\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lc@iterate}&
%    \begin{macrocode}
    \expandafter\global\expandafter\let
      \csname#3eachlabelcase\expandafter\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{eachlabelcase}&
%    \begin{macrocode}
      \csname#3eachlabelcase\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{eachlabelcase}&
%    \begin{macrocode}
    \expandafter\global\expandafter\let
      \csname#3lotlabelase\expandafter\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lotlabelcase}&
%    \begin{macrocode}
      \csname#3lotlabelcase\endcsname
%    \end{macrocode}
%    \compensategap
%    \InsertPrefixedUsageToIndex{prefix}{lotlabelcase}&
%    \begin{macrocode}
  \fi
%    \end{macrocode}
% Now the definition of |\DefineLabelcase| is complete:
%    \begin{macrocode}
}%
%    \end{macrocode}
% Remember that a group was started for performing |\DefineLabelcase|'s
% definition and that |\DefineLabelcase| will be gone when that group gets
% closed---unless some ``globalizing'' takes place before. So this is the
% time for checking if |\DefineLabelcase| shall be available to the user
% and in this case for making it global:
%    \begin{macrocode}
\ProcessOptions\relax
%    \end{macrocode}
% Now the group which was started for defining |\DefineLabelcase| can be
% closed---right after using it for defining the basic-usage-macros:
%    \begin{macrocode*}
\expandafter\endgroup\DefineLabelcase{ }{,}{}{\global}%
%    \end{macrocode*}
% \let\pref\empty
% \begin{macro}{\lc@macrodefiner}
% \changes{v1.06}{2006/04/20}{\string\verb*+\string\@ifdefinable+
%    instead of \string\verb*+\string\newcommand+.}
% \changes{v1.11}{2006/08/04}{Unnecessary
%   \string\verb*+\string\expandafter+ removed.}
%   There is still the routine left which is applied by the user-macros
%   for having the action-queue-register modified, so that when
%   ``flushing'' it, a macro will be produced instead of queue-execution.
%   |\lc@macrodefiner| takes as its argument the optional argument of a
%   user-macro. In case that the argument is not empty, the action-queue-&
%   register is modified, so that ``flushing'' it yields the attempt of
%   defining a macro from the argument which expands to the former content
%   of the register:
%    \begin{macrocode}
\newcommand\lc@macrodefiner[1]{%
  {\def\@tempa{#1}\expandafter}%
  \ifx\@tempa\@empty
  \else
    \@temptokena\expandafter{%
                \expandafter\begingroup
                \expandafter\toks@
                \expandafter\expandafter
                \expandafter            {%
                \expandafter\expandafter
                \expandafter            \@temptokena
                \expandafter\expandafter
                \expandafter            {%
                \expandafter\the
                \expandafter\@temptokena
                \expandafter}%
                \expandafter}%
                \expandafter\@temptokena
                \expandafter{%
                \expandafter\@temptokena
                \expandafter{%
                \the\@temptokena}%
                \@ifdefinable#1{\edef#1{\the\@temptokena}}}%
                \expandafter\endgroup
                \the\expandafter\@temptokena
                \the\toks@
    }%
  \fi
}%
%    \end{macrocode}
% \end{macro}
% \iffalse
%</labelcas>
% \fi
% \newpage\anglechange\PrintChanges
% \Finale
\endinput