doc/sod.sty: Report errors for undeclared description categories.

[sod] / doc / sod.sty

%%% -*-latex-*-
%%%
%%% Styles and other hacking for the Sod manual
%%%
%%% (c) 2015 Straylight/Edgeware
%%%

%%%----- Licensing notice ---------------------------------------------------
%%%
%%% This file is part of the Sensible Object Design, an object system for C.
%%%
%%% SOD is free software; you can redistribute it and/or modify
%%% it under the terms of the GNU General Public License as published by
%%% the Free Software Foundation; either version 2 of the License, or
%%% (at your option) any later version.
%%%
%%% SOD is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%%% GNU General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License
%%% along with SOD; if not, write to the Free Software Foundation,
%%% Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

\ProvidesPackage{sod}

%%%--------------------------------------------------------------------------
%%% Basic style things.

%% More reference types.
\defxref{p}{part}

%% A gadget to include in `\xref': call as
%%
%%      \xref[\instead{THING}]{LABEL}
%%
%% to replace the usual `section' or whatever with THING.
\def\instead#1#2{#1}

%% Other languages with special typesetting.
\def\Cplusplus{C\kern-\p@++}
\def\Csharp{C\#}

%% Special maths notation.
\def\chain#1#2{\mathsf{ch}_{#1}(#2)}
\def\chainhead#1#2{\mathsf{hd}_{#1}(#2)}
\def\chaintail#1#2{\mathsf{tl}_{#1}(#2)}

%% Other mathematical tweaks.
\let\implies\Rightarrow
\let\epsilon\varepsilon

%% A table heading cell.  Clone and hack \multicolumn.
\def\thd{\omit\@ifnextchar[\thd@{\thd@[l]}}
\def\thd@[#1]#2{%
  \begingroup
    \tab@multicol \tab@initread \let\tab@looped\tab@err@multi
    \tab@preamble{}\def\tab@midtext{\bfseries#2}\tab@readpreamble{#1}%
    \the\tab@preamble
  \endgroup \ignorespaces
}

%% Unix manpage references.
\def\man#1#2{\textbf{#1}(#2)}

%% Listings don't need to be small.
\let\listingsize\relax

%% Notes for later.
\def\fixme#1{\leavevmode\marginpar{FIXME}\index{FIXME}[FIXME: #1]}

%% Diagram settings.
\tikzset{
  every picture/.style={>=stealth, thick},
  lit/.style={font=\sffamily},
  dashed/.style={dash pattern=on 2.19pt off 2.19pt}
}

%% Metavariables are italics without decoration.
\def\syntleft{\normalfont\itshape}
\let\syntright\empty

%% Literal code is in sans face.
\def\codeface{\upshape\sffamily}
\DeclareRobustCommand\code[1]{%
  \ifmmode\hbox\else\leavevmode\fi%
  {\normalfont\codeface\/#1\/}%
}
\def\ulitleft{\normalfont\codeface}
\let\ulitright\empty
\def\lit@i#1#2#3{\ifmmode\leavevmode\hbox\fi{#1{#3\/}#2}}

%% Conditionally enter maths mode.  Can't use \ensuremath here because we
%% aren't necessarily sure where the maths will actually end.
\let\m@maybe@end\relax
\def\m@maybe{\ifmmode\else$\let\m@maybe@end$\fi}

%% Standard syntax shortcuts.
\atdef <#1>{\synt{#1}\@scripts}
\atdef "#1"{\lit*{#1}\@scripts}
\atdef `#1'{\lit{#1}\@scripts}
\atdef |#1|{\lit*{#1}\@scripts}

%% A handy abbreviation; `\\' itself is too good to steal.
\atdef \\{\textbackslash}

%% Intercept grammar typesetting and replace the vertical bar with the
%% maths-font version.
\let\@@syn@shorts\syn@shorts
\def\syn@shorts{\def\textbar{\hbox{$|$}}\@@syn@shorts}

%% Collect super- and subscripts.  (Note that underscores are active for the
%% most part.)  When we're done, end maths mode if we entered it
%% conditionally.
\def\@scripts{\futurelet\@ch\@scripts@i}
\begingroup\lccode`\~=`\_\lowercase{\endgroup
\def\@scripts@i{\if1\ifx\@ch~1\else\ifx\@ch_1\else\ifx\@ch^1\else0\fi\fi\fi%
  \expandafter\@scripts@ii\else\expandafter\m@maybe@end\fi}}
\def\@scripts@ii#1#2{\m@maybe#1{#2}\@scripts}

%% Doubling characters, maybe.  Either way, chain onto \@scripts.
\def\dbl@maybe#1{\let\@tempa#1\futurelet\@ch\dbl@maybe@i}
\def\dbl@maybe@i{\m@maybe\ifx\@ch\@tempa\@tempa\!\@tempa%
  \expandafter\@firstoftwo\expandafter\@scripts%
  \else\@tempa\expandafter\@scripts\fi}

%% Lookahead without eating spaces.
\def\@ifnextchar@preserve#1#2#3{%
  \let\want@= #1\def\@tempa{#2}\def\@tempb{#3}%
  \futurelet\nch@\@ifnch@p%
}
\def\@ifnch@p{%
  \ifx\want@\nch@\expandafter\@tempa\else\expandafter\@tempb\fi}

%% Extra syntax for Lisp templates.  These produce the maths-font versions of
%% characters, which should contrast well against the sans face used for
%% literals.
\atdef [{\dbl@maybe[}
\atdef ]{\dbl@maybe]}
\atdef {{\m@maybe\{\@scripts}
\atdef }{\m@maybe\}\@scripts}
\atdef ({\m@maybe(\@scripts}
\atdef ){\m@maybe)\@scripts}
\atdef !{\m@maybe|\@scripts}

\def\returns{\m@maybe\longrightarrow\m@maybe@end\hspace{0.5em}\ignorespaces}
\def\nlret{\\\hspace{4em}\returns}
\atdef >{\leavevmode\unskip\hspace{0.5em}\returns}

%% Extra syntax for common tokens.
\atdef ~{\textasciitilde}
\atdef -{\leavevmode\hbox\bgroup\futurelet\ch@\@dash}
\def\@dash{%
  \ifx\ch@>%
    --\raisebox{.4pt}{>}%
    \def\next@{\@firstoftwo{\egroup\penalty200\relax}}%
  \else\ifx\ch@-%
    --\,%
    \def\next@{\@firstoftwo{\futurelet\ch@\@dash}}%
  \else%
    --%
    \let\next@\egroup%
  \fi\fi
  \next@%
}

%% Comment setting.
\def\comment#1{\mbox{\normalfont\itshape\/#1\/}}
\atdef /*#1*/{/*\comment{#1}*/}
\def\@semis;{\@ifnextchar@preserve;{;\@semis}\@semicomment}
\def\@semicomment#1\\{\comment{#1}\\}
\atdef ;{;\@semis;}

%% Put a chunk of text in a box.
\newenvironment{boxy}[1][\q@]{%
  \savenotes%
  \dimen@\linewidth\advance\dimen@-1.2pt\advance\dimen@-2ex%
  \medskip%
  \vbox\bgroup\hrule\hbox\bgroup\vrule%
  \vbox\bgroup\vskip1ex\hbox\bgroup\hskip1ex\minipage\dimen@%
  \def\@temp{#1}\ifx\@temp\q@\else\leavevmode{\headfam\bfseries#1\quad}\fi%
}{%
  \endminipage\hskip1ex\egroup\vskip1ex\egroup%
  \vrule\egroup\hrule\egroup%
  \medskip%
  \spewnotes%
}

%%%--------------------------------------------------------------------------
%%% Environment for setting programs.

%% Save `\kill' so that `longtable' won't clobber it.
\let\prog@@kill\kill

%% Main guts of `prog' and `nprog'.
\def\@prog{%
  \let\prog@@cr\@tabcr%
  \let\@tabcr\@progcr%
  \let\kill\prog@@kill%
  \codeface%
  \tabbing%
}

%% Newlines: called by `\\' within a `prog'.
%%
%% \\           newline without following break
%% \\[SKIP]     newline /with/ break and vertical glue
%% \\*[SKIP]    newline without break, with optional glue
%% \\+          newline with break and a vertical gap
%% \\-          newline without break, with a tiny gap
\def\@progcr{\futurelet\@tempa\@progcr@i}
\def\@progcr@i{%
  \ifx\@tempa\@sptoken\let\next@\@progcr@sp\else
  \if1\ifx\@tempa[1\else
      \ifx\@tempa*1\else
      0\fi\fi
    \let\next@\prog@@cr\else
  \if1\ifx\@tempa+1\else
      \ifx\@tempa-1\else
      0\fi\fi
    \let\next@\@progcr@ii\else
  \let\next@\@progcr@a\fi\fi\fi
  \next@}
\def\@progcr@a{\prog@@cr*{}\ignorespaces}
\def\@progcr@ii#1{\csname @progcr@#1\endcsname\ignorespaces}
\@namedef{@progcr@+}{\prog@@cr[\medskipamount]}
\@namedef{@progcr@-}{\prog@@cr*[\jot]}
{\def\:{\gdef\@progcr@sp}\: {\@progcr}} % \@progcr@sp eats space and recurses

%% Set a program in `codeface', with implicit tabbing and other toys.
%% Newlines are explicit, because otherwise I need comments in weird places
%% to make the vertical spacing come out properly.  You can write
%% `\obeylines' if you really want to.
\def\prog{\quote\@prog}
\def\endprog{\endtabbing\endquote}

%% Like `prog', but without indenting the code.  Use this within environments
%% which already set their contents out from the body text in some
%% distinctive way.
\let\nprog\@prog
\let\endnprog\endtabbing

%% Indent the following material.  Cancel using `\-'.
\def\ind{\quad\=\+\kill}

%% Show a backslash by the right-hand margin; for multiline macros etc.
\def\macsl{\`\textbackslash\hskip\leftmargin}

%% \maplist{THING}{{ITEM}...}: Invoke THING{ITEM} for each ITEM in turn.
\def\maplist#1#2{\map@i{#1}#2\q@}
\def\map@i#1{\def\next@{\map@ii{#1}}\futurelet\ch@\next@}
\def\map@ii#1{\ifx\ch@\q@\expandafter\@gobble%
  \else\def\next@{\map@iii{#1}}\expandafter\next@\fi}
\def\map@iii#1#2{#1{#2}\map@i{#1}}

%% \crossproduct{THING}{{LIST}...} where each LIST is {ITEM}...
%% For each possible way of selecting one ITEM from each LIST, in order,
%% invoke THING{{ITEM}...}
\toksdef\cprod@new=0
\toksdef\cprod@old=2
\toksdef\cprod@head=4
\toksdef\cprod@tail=6
\def\crossproduct#1#2{%
  \cprod@new{{}}%
  \maplist{\cprod@f{#1}}{#2}%
  \cprod@head{#1}%
  \edef\next@{\noexpand\maplist{\the\cprod@head}{\the\cprod@new}}
  \next@%
}
\def\cprod@f#1#2{%
  \cprod@old\cprod@new\cprod@new{}%
  \maplist\cprod@g{#2}%
}
\def\cprod@g#1{%
  \cprod@head{#1}%
  \expandafter\maplist\expandafter\cprod@h\expandafter{\the\cprod@old}%
}
\def\cprod@h#1{%
  \cprod@tail{#1}%
  \cprod@new\expandafter{\the\expandafter\cprod@new\expandafter{%
      \the\expandafter\cprod@tail\the\cprod@head}}%
}

%%%--------------------------------------------------------------------------
%%% Machinery for describing functions, etc.

%% \definedescribecategory{CAT}[KIND]{NAME}
%%
%% Define a category of things to document.  CAT is a short label identifying
%% the category to `\describe', `\descref', and friends.  The NAME is the
%% text to show in the description headline; it is a macro body which is
%% passed an argument `#1' that applies a modifier to some portion of the
%% text.
%%
%% The KIND allows additional arguments to be collected, included in label
%% strings, and mentioned in the index.  The default is `plain'.
\def\definedescribecategory#1{%
  \@ifnextchar[{\def@desc{#1}}{\def@desc{#1}[plain]}}
\def\def@desc#1[#2]#3{\@namedef{cat!#1}##1{#3}\@namedef{catsw!#1}{#2}}

%% \describecategoryname[MOD]{CAT}
%%
%% Typeset the category name for CAT, modified by MOD.
\def\describecategoryname{\@ifnextchar[\@descname@i{\@descname@i[]}}
\def\@descname@i[#1]#2{%
  \expandafter\let\expandafter\@tempa\csname cat!#2\endcsname%
  \expandafter\let\expandafter\@tempb\csname modcat/#1\endcsname%
  \ifx\@tempa\relax\PackageError{sod}{unknown description category `#2'}%
    {I don't know what `#2' means as a thing you might try to\MessageBreak
     document.  Maybe you mistyped it, or forgot to say\MessageBreak
     `\protect\definedescribecategory' for it.  For now I'm going\MessageBreak
     just use the literal string `#2' and hope that doesn't look\MessageBreak
     too terrible.}%
    \@tempb{#2}%
  \else\@tempa\@tempb\fi}

%% Call a modifier method.
\def\@mod@dispatch#1#2{\csname #1/#2\endcsname}

%% Call a description method given the category.
\def\@desc@dispatch#1#2{%
  \csname #1/%
    \expandafter\ifx\csname catsw!#2\endcsname\relax plain%
    \else \csname catsw!#2\endcsname \fi%
  \endcsname%
}

%% Modifier methods for the default `plain' modifier.
\@namedef{modcat/plain}#1{#1}
\@namedef{modlabel/plain}#1{#1}
\@namedef{modindex/plain}#1{#1@\noexpand\code{#1}}

%% Modifier methods for `setf'.  The name text prefixes the relevant word
%% with `setf-'.
\@namedef{modcat/setf}#1{\code{setf}-#1}
\@namedef{modlabel/setf}#1{setf/#1}
\@namedef{modindex/setf}#1{#1@\noexpand\code{#1}}

%% Modifier methods for words with *earmuffs*.  Sort into the index without
%% the earmuffs.
\@namedef{modcat/muffs}#1{#1}
\@namedef{modlabel/muffs}#1{#1}
\@namedef{modindex/muffs}#1{\@unmuff#1@\noexpand\code{#1}}
\def\@unmuff*#1*{#1}

%% Modifier methods for :keywords.  Sort into the index without the `:'.
\@namedef{modcat/kwd}#1{#1}
\@namedef{modlabel/kwd}#1{#1}
\@namedef{modindex/kwd}#1{\@gobble#1@\noexpand\code{#1}}

%% Category-kind methods for plain categories.
\@namedef{descargs/plain}#1{#1{}}
\@namedef{desclabel/plain}#1#2#3{#2:\@mod@dispatch{modlabel}{#1}{#3}}
\@namedef{descindex/plain}#1#2#3{%
  \@mod@dispatch{modindex}{#1}{#3}!%
  \protect\describecategoryname[#1]{#2}%
}

%% Category-kind methods for `method' categories.  Collect an extra argument
%% listing the specializers: include them in the label, and typeset them in
%% the index.
\def\fmtspecs#1#2{%
  \if!#2!\else\count@\z@\toks@{}#1\fmtspecs@i#2,\q@,\fi}
\def\fmtspecs@i#1,{%
  \def\@tempa{#1}%
  \ifx\@tempa\q@%
    \ifcase\count@(no args?!)%
    \or% nothin' doin
    \or \space and %
    \else, and %
    \fi%
    \the\toks@%
  \else%
    \ifnum\count@>\@ne, \fi%
    \the\toks@%
    \toks@{\code{#1}}\advance\count@\@ne%
    \expandafter\fmtspecs@i%
  \fi%
}
\@namedef{descargs/method}#1#2{#1{{#2}}}
\@namedef{desclabel/method}#1#2#3#4%
  {#2:\@mod@dispatch{modlabel}{#1}{#4}(#3)}
\@namedef{descindex/method}#1#2#3#4{%
  \@mod@dispatch{modindex}{#1}{#4}!%
  \protect\describecategoryname[#1]{#2}%
  \protect\fmtspecs{ specialized at }{#3}%
}

%% Some magic strings.
\def\q@{\q@}
\def\@setf{setf}
\def\@starstar{**}

%% \parse@dhd{NEXT}[MOD]{CAT}{...}...[NAME]{SYNOPSIS}
%%
%% Parse the arguments for a description header, and call
%%
%%      NEXT{MOD}{CAT}{{...}...}{NAME}{SYNOPSIS}
%%
%% Here, {...}... represents the additional category-kind arguments.  See
%% `describe' for what all of this means.
\def\parse@dhd#1{%  {NEXT}
  \@ifnextchar[{\parse@dhd@a{#1}}{\parse@dhd@c{#1}}}
\def\parse@dhd@a#1[#2]#3{%  {NEXT}[MOD]{CAT}
  \@desc@dispatch{descargs}{#3}{\parse@dhd@ab{#1}{#2}{#3}}}
\def\parse@dhd@ab#1#2#3#4{%  {NEXT}{MOD}{CAT}{{...}...}
  \@ifnextchar[{\parse@dhd@ac{#1}{#2}{#3}{#4}}{\parse@dhd@ad{#1}{#2}{#3}{#4}}}
\def\parse@dhd@ac#1#2#3#4[#5]#6{%  {NEXT}{MOD}{CAT}{{...}...}[NAME]{SYNOPSIS}
  #1{#2}{#3}{#4}{#5}{#6}}
\def\parse@dhd@ad#1#2#3#4#5{%  {NEXT}{MOD}{CAT}{{...}...}{NAME [ARGS...]}
  \parse@dhd@ae{#1}{#2}{#3}{#4}{#5}#5 \q@}
\def\parse@dhd@ae#1#2#3#4#5#6 #7\q@{%
  % {NEXT}{MOD}{CAT}{{...}...}{SYNSOPSIS}NAME [ARGS...]\q@
  #1{#2}{#3}{#4}{#6}{#5}}

\def\parse@dhd@c#1#2{%  {NEXT}{CAT}
  \@desc@dispatch{descargs}{#2}{\parse@dhd@cb{#1}{#2}}}
\def\parse@dhd@cb#1#2#3{%  {NEXT}{CAT}{{...}...}
  \@ifnextchar[{\parse@dhd@cc{#1}{#2}{#3}}{\parse@dhd@cd{#1}{#2}{#3}}}
\def\parse@dhd@cc#1#2#3[#4]#5{%  {NEXT}{CAT}{{...}...}[NAME]{SYNOPSIS}
  #1{plain}{#2}{#3}{#4}{#5}}
\def\parse@dhd@cd#1#2#3#4{%  {NEXT}{CAT}{{...}...}{SYNOPSIS}
  \parse@dhd@ce{#1}{#2}{#3}{#4}#4 \q@}
\def\parse@dhd@ce#1#2#3#4#5 #6\q@{%
  % {NEXT}{CAT}{{...}...}{SYNOPSIS}NAME [ARGS...]\q@
  \def\temp@{#5}%
  \ifx\@setf\temp@\def\next@{\parse@dhd@csetf{#1}{#2}{#3}{#4}#6 \q@}%
  \else\def\temp@##1##2*##3\q@{\def\temp@{##1##3}}\temp@#5*\q@%
    \ifx\temp@\@starstar\def\next@{#1{muffs}{#2}{#3}{#5}{#4}}%
    \else\def\temp@##1##2\q@{\def\temp@{##1}}\temp@#5\q@%
      \if:\temp@\def\next@{#1{kwd}{#2}{#3}{#5}{#4}}%
      \else\def\next@{#1{plain}{#2}{#3}{#5}{#4}}\fi\fi\fi%
  \next@%
}
\def\parse@dhd@csetf#1#2#3#4(#5 #6\q@{%
  % {NEXT}{CAT}{{...}...}{SYNOPSIS}(NAME [ARGS...])\q@
  #1{setf}{#2}{#3}{#5}{#4}}

%% \dhead[MOD]{CAT}{...}...[NAME]{SYNOPSIS}
%% \dhead*[MOD]{CAT}{...}...[NAME]{SYNOPSIS}
%%
%% Typeset a description head.  Use this within the first argument of
%% `describe*'; see `describe' for the details.
%%
%% With `*', don't set labels or add items to the index.
\newif\if@dheadfirst
\newif\if@dheadindex
\def\dhead{\@ifstar%
  {\parse@dhd{\global\@dheadindexfalse\dhead@}}%
  {\parse@dhd{\global\@dheadindextrue\dhead@}}}
\def\dhead@#1#2#3#4#5{%  {MOD}{CAT}{{...}...}{NAME}{SYNOPSIS}
  \if@dheadfirst\global\@dheadfirstfalse\else\relax\\*[\smallskipamount]\fi%
  \if@dheadindex%
    \phantomsection%
    {\let\protect\@empty\let\@uscore\relax%
     \edef\temp@{\@desc@dispatch{desclabel}{#2}{#1}{#2}#3{#4}}%
     \def\@uscore{_\@gobble}\expandafter\message\expandafter{\temp@}%
     \def\@uscore{-\@gobble}\expandafter\label\expandafter{\temp@}}%
    {\begingroup\lccode`\~=`\_\lowercase{\endgroup\def~{_}}%
     \protected@edef\@tempa##1{%
       \noexpand\index{\@desc@dispatch{descindex}{#2}{#1}{#2}#3{#4}##1}}%
     \toks@\expandafter{\@tempa{|)}}%
     \toks\tw@\expandafter{\after@desc}%
     \xdef\after@desc{\the\toks\tw@\the\toks@}%
     \@tempa{|(}}%
  \fi%
  \rlap{\hb@xt@\linewidth{\hfil\normalfont\bfseries
      [\describecategoryname[#1]{#2}]}}%
  #5%
}

%% Main guts of a description environment.  The argument here typesets the
%% header line(s).
\def\desc@begin#1{%
  \let\saved@after@desc\after@desc%
  \gdef\after@desc{}%
  \normalfont%
  \if@nobreak\else\par\goodbreak\fi%
  \global\@dheadfirsttrue%
  \begingroup%
    \let\@endparenv\relax%
    \clubpenalty\@M \widowpenalty\@M \interlinepenalty50%
    \@prog#1\endtabbing%
  \endgroup%
  \penalty\@M\@afterheading%
  \list{}{\rightmargin\z@\topsep\z@}\item%
}
\def\desc@end{\endlist\after@desc\global\let\after@desc\saved@after@desc}

%% \begin{describe}[MOD]{CAT}{...}...[NAME]{SYNOPSIS}
%%   ...
%% \end{describe}
%%
%% Describe some kind of program object.  The CAT names the category of thing
%% being described -- this will be shown in the header, and index.  The
%% SYNOPSIS is an implicit `prog' environment in which invoking the thing can
%% be summarized.
%%
%% The {...}... are any additional arguments required by the category's kind
%% (e.g., method specializers).
%%
%% The NAME is the name of the thing, which ends up in the index and
%% cross-reference label.  If omitted, it defaults to the first word of the
%% SYNOPSIS, except that there are some special cases.
%%
%% The MOD is the modifier to apply.  If omitted, it will usually default to
%% `plain', but in the absence of a NAME, some kinds of synopses are
%% recognized specially:
%%
%%   * `setf (NAME ...) ...': selects NAME, and defaults MOD to `setf'.
%%
%%   * `*NAME*': defaults MOD to `muffs'.
%%
%%   * `:NAME': defaults MOD to `kwd'.
\def\describe{\parse@dhd\desc@}
\def\desc@#1#2#3#4#5{%
  \global\@dheadindextrue%
  \desc@begin{\dhead@{#1}{#2}{#3}{#4}{#5}}%
}
\let\enddescribe\desc@end

%% \begin{describe*}
%%     {\dhead[MOD]{CAT}{...}...[NAME]{SYNOPSIS}
%%      ...}
%%   ...
%% \end{describe*}
%%
%% This is the fancy form of `describe' for describing several different
%% things at once.
\@namedef{describe*}#1{\desc@begin{#1}}
\expandafter\let\csname enddescribe*\endcsname\desc@end

%% \parse@dlbl{NEXT}[MOD]{CAT}{...}...{LABEL}
%%
%% Parse a description label, and call
%%
%%      NEXT{MOD}{CAT}{{...}...}{LABEL}
%%
%% This handles defaulting the MOD correctly, based on the LABEL text.  See
%% `\descref' for the details.
\def\parse@dlbl#1{\@ifnextchar[{\parse@dlbl@a{#1}}{\parse@dlbl@c{#1}}}
\def\parse@dlbl@a#1[#2]#3{\@desc@dispatch{descargs}{#3}{#1{#2}{#3}}}
\def\parse@dlbl@c#1#2%
  {\@desc@dispatch{descargs}{#2}{\parse@dlbl@cb{#1}{#2}}}
\def\parse@dlbl@cb#1#2#3#4{%
  \def\temp@##1##2*##3\q@{\def\temp@{##1##3}}\temp@#4*\q@%
    \ifx\temp@\@starstar\def\next@{#1{muffs}{#2}{#3}{#4}}%
    \else\def\temp@##1##2\q@{\def\temp@{##1}}\temp@#4\q@%
      \if:\temp@\def\next@{#1{kwd}{#2}{#3}{#4}}
      \else\def\next@{#1{plain}{#2}{#3}{#4}}\fi\fi%
  \next@%
}

%% \descref[MOD]{CAT}{...}...{LABEL}[TEXT]
%% \descref*[MOD]{CAT}{...}...{LABEL}
%%
%% Typesets a cross-reference to a described thing.  The CAT names the
%% category of thing being described, and the LABEL names the specific thing.
%%
%% The {...}... are any additional arguments required by the category's kind
%% (e.g., method specializers).
%%
%% The MOD is the modifier to apply, similar (but subtly different from) to
%% the `describe' environment.  If omitted, it will usually default to
%% `plain', but in the absence of a NAME, some kinds of synopses are
%% recognized specially:
%%
%%   * `*NAME*': defaults MOD to `muffs'.
%%
%%   * `:NAME': defaults MOD to `kwd'.
%%
%% (`setf' is /not/ specially detected here.  Write an explicit `setf'
%% modifier if necessary, because it's no more typing.)
%%
%% Usually a page-number cross-reference is included, so as to help readers
%% of a dead-tree copy; this is suppressed by the `*' version.
\def\descref{\@ifstar%
  {\parse@dlbl{\descref@i\relax\@gobble\relax}}%
  {\parse@dlbl{\descref@i{ (}\autopageref)}}}
\def\descref@i#1#2#3#4#5#6#7{\@ifnextchar@preserve[%
  % {PGA}{PGB}{PGC}{MOD}{CAT}{{...}...}{LABEL}
  {\descref@ii{#1}{#2}{#3}{#4}{#5}{#6}{#7}}%
  {\descref@iii{#1}{#2}{#3}{#4}{#5}{#6}{#7}{}}}
\def\descref@ii#1#2#3#4#5#6#7[#8]%
  % {PGA}{PGB}{PGC}{MOD}{CAT}{{...}...}{LABEL}[AFTER]
  {\descref@iii{#1}{#2}{#3}{#4}{#5}{#6}{#7}{ #8}}
\def\descref@iii#1#2#3#4#5#6#7#8{%
  % {PGA}{PGB}{PGC}{MOD}{CAT}{{...}...}{LABEL}{AFTER}
  \begingroup%
    \let\protect\@empty\def\@uscore{-\@gobble}%
    \edef\temp@{\@desc@dispatch{desclabel}{#5}{#4}{#5}#6{#7}}%
    \edef\next@##1##2##3{\endgroup%
      \noexpand\hyperref[\temp@]{##1}##2{\temp@}##3}%
  \next@{\code{#7}}{#8#1#2}{#3}%
}

%% \descindex[MOD]{CAT}{...}...{LABEL}[SUFFIX]
%%
%% Set a label and index entry here, as if for a description.  The CAT names
%% the category of thing being described, and the LABEL names the specific
%% thing, as for `\descref'.  The {...}... are any additional arguments
%% required by the category's kind (e.g., method specializers).  The MOD is
%% the modifier to apply; see `\descref' for the details.
%%
%% The SUFFIX is appended to the index-entry text; by default it is empty.
%% Useful values are `|(' and `|)' to set ranges.
\def\descindex{\parse@dlbl\descindex@i}
\def\descindex@i#1#2#3#4{\@ifnextchar[%
  {\descindex@ii{#1}{#2}{#3}{#4}}%
  {\descindex@ii{#1}{#2}{#3}{#4}[]}}
\def\descindex@ii#1#2#3#4[#5]{%
  {\begingroup\lccode`\~=`\_\lowercase{\endgroup\def~{_}}%
   \protected@edef\@tempa{%
     \noexpand\index{\@desc@dispatch{descindex}{#2}{#1}{#2}#3{#4}#5}}%
   \@tempa}%
}

%% \desclabel[MOD]{CAT}{...}...{LABEL}[INDEX-SUFFIX]
%%
%% Set a label and index entry here, as if for a description.  The CAT names
%% the category of thing being described, and the LABEL names the specific
%% thing, as for `\descref'.  The {...}... are any additional arguments
%% required by the category's kind (e.g., method specializers).  The MOD is
%% the modifier to apply; see `\descref' for the details.
%%
%% This will also add an index entry, as for `\descindex'; the INDEX-SUFFIX
%% argument has the same effect as its SUFFIX argument.
\def\desclabel{\parse@dlbl\desclabel@i}
\def\desclabel@i#1#2#3#4{%
  \begingroup%
    \let\protect\@empty\def\@uscore{-\@gobble}%
    \edef\@tempa{\@desc@dispatch{desclabel}{#2}{#1}{#2}#3{#4}}%
    \phantomsection\label{\@tempa}%
  \endgroup%
  \descindex@i{#1}{#2}{#3}{#4}%
}

%% Description categories.
\definedescribecategory{sym}{symbol}
\definedescribecategory{fun}{#1{function}}
\definedescribecategory{gf}{generic #1{function}}
\definedescribecategory{msg}{message}
\definedescribecategory{var}{variable}
\definedescribecategory{modvar}{module variable}
\definedescribecategory{const}{constant}
\definedescribecategory{meth}[method]{primary #1{method}}
\definedescribecategory{ar-meth}[method]{\code{:around} #1{method}}
\definedescribecategory{be-meth}[method]{\code{:before} #1{method}}
\definedescribecategory{af-meth}[method]{\code{:after} #1{method}}
\definedescribecategory{cls}{class}
\definedescribecategory{rst}{restart}
\definedescribecategory{ty}{type}
\definedescribecategory{mac}{#1{macro}}
\definedescribecategory{feat}{feature macro}
\definedescribecategory{lmac}{local #1{macro}}
\definedescribecategory{parse}{parser spec}
\definedescribecategory{parseform}{parser form}
\definedescribecategory{opt}{option handler}
\definedescribecategory{optmac}{option macro}
\definedescribecategory{plug}{pluggable parser}

%%%----- That's all, folks --------------------------------------------------
\endinput