Subject: RefTeX: Regexp for parsing labels in optional arguments

From: Arash Esbati <[email-masked]>
Date: Sat, 07 Jul 2018 23:11:26 +0200

Hi all,

please consider the following example:

--8<---------------cut here---------------start------------->8---
\documentclass{article}
\usepackage{listings}
\begin{document}

\begin{lstlisting}[
caption={Some caption},
label=lst:1]
Some code
\end{lstlisting}

\begin{lstlisting}[
caption={Some caption},
label=lst:2
]
Some code
\end{lstlisting}

\begin{lstlisting}[
caption = {Some caption},
label   = lst:3                   ]
Some code
\end{lstlisting}

\ref{lst:1}, \ref{lst:2
}, \ref{lst:3                   }

\ref{lst:1}, \ref{lst:2}, \ref{lst:3}

\end{document}
--8<---------------cut here---------------end--------------->8---

With RefTeX active, it fails to parse the labels defined in optional
arguments correctly (see the first set of \ref commands).  It is due to
the regex defined in `reftex-label-regexps' in `reftex-vars.el' which
expects one of ],} directly after the label.  With the following patch,
it parses the labels correctly:

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/textmodes/reftex-vars.el b/lisp/textmodes/reftex-vars.el
index 11dbb8d..66d800d 100644
--- a/lisp/textmodes/reftex-vars.el
+++ b/lisp/textmodes/reftex-vars.el
@@ -895,7 +895,7 @@ DOWNCASE    t:   Downcase words before using them."
       "\\\\label{\\(?1:[^}]*\\)}"
       ;; keyvals [..., label = {foo}, ...] forms used by ctable,
       ;; listings, minted, ...
-      "\\[[^][]\\{0,2000\\}\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^],}]+\\)}?")
+      "\\[[^][]\\{0,2000\\}\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^], \t\n\r%}]+\\)}?")
     "List of regexps matching \\label definitions.
 The default value matches usual \\label{...} definitions and
 keyval style [..., label = {...}, ...] label definitions.  It is
 --8<---------------cut here---------------end--------------->8---

Any suggestion if I'm missing a character?  My next step would be to add
the same regexp to `LaTeX-auto-label-regexp-list' in order to make
AUCTeX also capable of this feature.  Any comments welcome.

Best, Arash