X-Git-Url: https://git.distorted.org.uk/~mdw/mdwtools/blobdiff_plain/3d509049d0984b7c233e73557369fb952a10e7af..9cb5c64cc696cd59cf723021386b254ab8de5b13:/mdwref.dtx

diff --git a/mdwref.dtx b/mdwref.dtx
index 10134d3..1a40fb3 100644
--- a/mdwref.dtx
+++ b/mdwref.dtx
@@ -27,7 +27,7 @@
 %<+package>                [2020/09/06 1.14.0 Cross-referencing]
 % \end{meta-comment}
 %
-% ^^A\CheckSum{96}
+% \CheckSum{131}
 %% \CharacterTable
 %%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
 %%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
@@ -95,18 +95,6 @@
 %\newcommand{\Xref}[1]{\xref[\toupper]{#1}}
 % \end{listing}
 %
-% \DescribeMacro\formatxref
-% The reference itself is typeset by calling
-% \syntax{"\\formatxref{"<mangle>"}{"<string>"}{"<label>"}"}, which can do as
-% it pleases: the \<mangle> token is from the |\xref| invocation; the
-% \<string> is category of thing being referred to (as established by
-% |\defxref| below); and \<label> is the label, again from |\xref| .  The
-% default behaviour is to print
-% \syntax{<mangle>"{"<string>"}~\\ref{"<label>"}"}, but this can be
-% overridden.
-% (Not quite true: in fact, the default does something better if
-% \package{hyperref} is detected, but the idea is basically the same.)
-%
 % All that remains is to define the strings to be typeset for various kinds
 % of labels.
 % \DescribeMacro\defxref
@@ -119,15 +107,59 @@
 % \]]
 % \end{grammar}
 % The \<prefix> is what you put on the front of your labels; the \<string> is
-% the string to be typeset by |\xref|.
+% the string to be typeset by |\xref|.  Such references are typeset using
+% |\formatxref|, described below.
+%
+% For references that don't fit into this pattern, there's a more complex
+% definition syntax using |\defxref*|:
+% \begin{grammar}
+% <definition> ::= \[[
+% "\\defxref*"
+% "{" <prefix> "}"
+% "{" <expansion> "}"
+% \]]
+% \end{grammar}
+% The \<expansion> is given four arguments.
+% \begin{itemize}
+% \item |#1| is the name of a macro which should be given two arguments,
+%   respectively the reference name and the body of the hyperlink to
+%   generate.
+% \item |#2| is the name of a macro to apply to the reference name to typeset
+%   the actual reference.
+% \item |#3| is the \<mangle> token, or |\relax|.
+% \item |#4| is the reference name itself.
+% \end{itemize}
+%
+% \DescribeMacro\formatxref
+% Simple references are typeset by calling
+% \syntax{"\\formatxref{"<mangle>"}{"<string>"}{"<label>"}"}, which can do as
+% it pleases: the \<mangle> token is from the |\xref| invocation; the
+% \<string> is category of thing being referred to (as established by
+% |\defxref| below); and \<label> is the label, again from |\xref| .  The
+% default behaviour is to print
+% \syntax{<mangle>"{"<string>"}~\\ref{"<label>"}"}, but this can be
+% overridden.
+% (Not quite true: in fact, the default does something better if
+% \package{hyperref} is detected, but the idea is basically the same.)
 %
 % A number of useful prefixes are already defined, following my usual
 % preferences; they're shown in \xref{tab:defs}.
 % \begin{table}
-%   \def\i#1#2{\texttt{#1}&\texttt{#2}\\}
 %   \begin{tabular}[C]{ll} \hlx*{hv}
 %   \textbf{Prefix} & \textbf{Text} \\ \hlx{vhv}
-%   \csname xref@defs\endcsname
+%     \texttt{ch}       & chapter $n$                                   \\
+%     \texttt{app}      & appendix $n$                                  \\
+%     \texttt{sec}      & section $n$                                   \\
+%     \texttt{def}      & definition $n$                                \\
+%     \texttt{th}       & theorem $n$                                   \\
+%     \texttt{lem}      & lemma $n$                                     \\
+%     \texttt{prop}     & proposition $n$                               \\
+%     \texttt{cor}      & corollary $n$                                 \\
+%     \texttt{fig}      & figure $n$                                    \\
+%     \texttt{tab}      & table $n$                                     \\
+%     \texttt{eq}       & ($n$)                                         \\
+%     \texttt{i}        & item $n$                                      \\
+%     \texttt{ex}       & exercise $n$                                  \\
 %   \hlx*{vh}\end{tabular}
 %   \caption{Predefined reference prefixes}
 %   \label{tab:defs}
@@ -147,28 +179,37 @@
 %
 % \begin{macro}{\defxref}
 % Defining prefixes is easy.  We store the text for each prefix in a macro
-% called \syntax{"\\xref$"<prefix>}.  The only catch is that, for the
-% purposes of generating \xref{tab:defs}, we maintain a list of the prefixes
-% which have been defined so far, but this is fairly easy.
+% called \syntax{"\\xref$"<prefix>}, which takes two arguments: a \<mangle>
+% token (or |\relax|), and the reference name.
 %    \begin{macrocode}
-\def\defxref#1#2{%
-  \toks@\expandafter{\xref@defs\i{#1}{#2}}\xdef\xref@defs{\the\toks@}%
-  \expandafter\def\csname xref$#1\endcsname{#2}%
+\def\defxref{\@ifstar\defxref@raw\defxref@cooked}
+\def\defxref@cooked#1#2%
+  {\expandafter\def\csname xref$#1\endcsname##1##2{\formatxref{##1}{#2}{##2}}}
+\def\defxref@raw#1#2{%
+  \expandafter\edef\csname xref$#1\endcsname
+    {\noexpand\xrefdispatch\expandafter\noexpand\csname xref$$#1\endcsname}%
+  \expandafter\def\csname xref$$#1\endcsname##1##2##3##4{#2}%
 }
 %    \end{macrocode}
-% The list is obviously empty initially.
+% \end{macro}
+%
+% \begin{macro}{\xrefdispatch}
 %    \begin{macrocode}
-\gdef\xref@defs{}
+\def\xref@hyper#1{\hyperref[#1]}
+\def\xrefdispatch#1{%
+  \ifx\hyperref\@@undefined \def\@tempa{#1\@gobble\ref}%
+  \else \def\@tempa{#1\xref@hyper{\ref*}}%
+  \fi \@tempa%
+}
 %    \end{macrocode}
 % \end{macro}
 %
 % \begin{macro}{\formatxref}
 % Output a cross-reference in the right way.
 %    \begin{macrocode}
-\def\formatxref#1#2#3{%
-  \ifx\hyperref\@@undefined #1{#2}~\ref{#3}%
-  \else \hyperref[#3]{#1{#2}~\ref*{#3}}\fi%
-}
+\def\formatxref{\xrefdispatch\xref@formatsimple}
+\def\xref@formatsimple#1#2#3#4#5{#1{#5}{#3{#4}~#2{#5}}}
+\def\xref@fallback#1{\formatxref\relax{?\texttt{#1}}{#1}}
 %    \end{macrocode}
 % \end{macro}
 %
@@ -176,7 +217,7 @@
 % We're meant to typeset a reference.  The first job is to see whether
 % there's an optional argument.  If so, grab it; otherwise |\relax| will do.
 %    \begin{macrocode}
-\def\xref{\@ifnextchar[\xref@{\xref@[\relax]}}
+\DeclareRobustCommand\xref{\@ifnextchar[\xref@{\xref@[\relax]}}
 \def\xref@[#1]#2{\xref@@{#1}#2:\q@delim:\q@delim:\q@delim\q@delim}
 %    \end{macrocode}
 % Right; now we abuse \TeX's argument parser to pick apart the reference
@@ -192,14 +233,17 @@
   \def\@tempa{#2}\def\@tempb{#3}%
   \ifx\@tempb\q@delim%
     \PackageError{xref}{Bad ref syntax}%
+      {A reference name doesn't contain a `:'-delimited prefix.  Did you %
+       mean to use plain \string\ref here?}%
+     \xref@fallback{#2}%
   \else%
     \expandafter\let\expandafter\@tempa\csname xref$#2\endcsname%
     \ifx\@tempa\relax%
       \PackageError{xref}{Unknown ref kind `#2'}%
-    \else%
-      \toks@\expandafter{\@tempa}%
-      \edef\next@##1{##1{\the\toks@}}%
-      \next@{\formatxref{#1}}{#2:#3}%
+        {The ref name's prefix `#2' is unknown: either it's been mistyped %
+         or there's a missing \string\defxref somewhere.}%
+     \xref@fallback{#2:#3}%
+    \else \@tempa{#1}{#2:#3}%
     \fi%
   \fi%
 }
@@ -234,7 +278,7 @@
 \defxref{cor}{corollary}
 \defxref{fig}{figure}
 \defxref{tab}{table}
-\defxref{eq}{equation}
+\defxref*{eq}{#1{#4}{(#2{#4})}}
 \defxref{i}{item}
 \defxref{ex}{exercise}
 %    \end{macrocode}