latex: code blocks linebreaks easier customized

Via re-definable ``\sphinxbreaksbeforelist`` and ``\sphinxbreaksafterlist``,
latex user can specify (using ``'preamble'`` key for example) if broken
code lines are split before or after the said character when code blocks
are wrapped. Punctuation characters use active catcodes and are
configurable via further macros ``\sphinxbreaksbeforeactivelist`` and
``\sphinxbreaksafteractivelist``. The defaults in ``sphinx.sty`` can be
modified by imitation in user document preamble.

n.b.: ``\sphinxbreaksatpunct`` has been renamed to ``\sphinxbreaksviaactive``.

sphinx/texinputs/sphinx.sty

@@ -274,41 +274,39 @@
 %        {, <, #, %, $, ' and ": go to next line.
 %        _, }, ^, &, >, - and ~: stay at end of broken line.
 % Use of \textquotesingle for straight quote.
+\newcommand*\sphinxbreaksbeforelist {%
+    \do\PYGZob\{\do\PYGZlt\<\do\PYGZsh\#\do\PYGZpc\%% {, <, #, %,
+    \do\PYGZdl\$\do\PYGZdq\"% $, "
+    \def\PYGZsq
+     {\discretionary{}{\sphinxafterbreak\textquotesingle}{\textquotesingle}}% '
+}
+\newcommand*\sphinxbreaksafterlist {%
+    \do\PYGZus\_\do\PYGZcb\}\do\PYGZca\^\do\PYGZam\&% _, }, ^, &,
+    \do\PYGZgt\>\do\PYGZhy\-\do\PYGZti\~% >, -, ~
+}
 \newcommand*\sphinxbreaksatspecials {%
-    \def\PYGZus{\discretionary{\char`\_}{\sphinxafterbreak}{\char`\_}}%
-    \def\PYGZob{\discretionary{}{\sphinxafterbreak\char`\{}{\char`\{}}%
-    \def\PYGZcb{\discretionary{\char`\}}{\sphinxafterbreak}{\char`\}}}%
-    \def\PYGZca{\discretionary{\char`\^}{\sphinxafterbreak}{\char`\^}}%
-    \def\PYGZam{\discretionary{\char`\&}{\sphinxafterbreak}{\char`\&}}%
-    \def\PYGZlt{\discretionary{}{\sphinxafterbreak\char`\<}{\char`\<}}%
-    \def\PYGZgt{\discretionary{\char`\>}{\sphinxafterbreak}{\char`\>}}%
-    \def\PYGZsh{\discretionary{}{\sphinxafterbreak\char`\#}{\char`\#}}%
-    \def\PYGZpc{\discretionary{}{\sphinxafterbreak\char`\%}{\char`\%}}%
-    \def\PYGZdl{\discretionary{}{\sphinxafterbreak\char`\$}{\char`\$}}%
-    \def\PYGZhy{\discretionary{\char`\-}{\sphinxafterbreak}{\char`\-}}%
-    \def\PYGZsq{\discretionary{}{\sphinxafterbreak\textquotesingle}{\textquotesingle}}%
-    \def\PYGZdq{\discretionary{}{\sphinxafterbreak\char`\"}{\char`\"}}%
-    \def\PYGZti{\discretionary{\char`\~}{\sphinxafterbreak}{\char`\~}}%
+  \def\do##1##2%
+     {\def##1{\discretionary{}{\sphinxafterbreak\char`##2}{\char`##2}}}%
+  \sphinxbreaksbeforelist
+  \def\do##1##2%
+     {\def##1{\discretionary{\char`##2}{\sphinxafterbreak}{\char`##2}}}%
+  \sphinxbreaksafterlist
 }
 
 \def\sphinx@verbatim@nolig@list {\do \`}%
 % Some characters . , ; ? ! / are not pygmentized.
 % This macro makes them "active" and they will insert potential linebreaks
-\newcommand*\sphinxbreaksatpunct {%
-   \lccode`\~`\.\lowercase{\def~}{\discretionary{\char`\.}{\sphinxafterbreak}{\char`\.}}%
-   \lccode`\~`\,\lowercase{\def~}{\discretionary{\char`\,}{\sphinxafterbreak}{\char`\,}}%
-   \lccode`\~`\;\lowercase{\def~}{\discretionary{\char`\;}{\sphinxafterbreak}{\char`\;}}%
-   \lccode`\~`\:\lowercase{\def~}{\discretionary{\char`\:}{\sphinxafterbreak}{\char`\:}}%
-   \lccode`\~`\?\lowercase{\def~}{\discretionary{\char`\?}{\sphinxafterbreak}{\char`\?}}%
-   \lccode`\~`\!\lowercase{\def~}{\discretionary{\char`\!}{\sphinxafterbreak}{\char`\!}}%
-   \lccode`\~`\/\lowercase{\def~}{\discretionary{\char`\/}{\sphinxafterbreak}{\char`\/}}%
-   \catcode`\.\active
-   \catcode`\,\active
-   \catcode`\;\active
-   \catcode`\:\active
-   \catcode`\?\active
-   \catcode`\!\active
-   \catcode`\/\active
+\newcommand*\sphinxbreaksbeforeactivelist {}% none
+\newcommand*\sphinxbreaksafteractivelist  {\do\.\do\,\do\;\do\?\do\!\do\/}
+\newcommand*\sphinxbreaksviaactive {%
+   \def\do##1{\lccode`\~`##1%
+    \lowercase{\def~}{\discretionary{}{\sphinxafterbreak\char`##1}{\char`##1}}%
+    \catcode`##1\active}%
+   \sphinxbreaksbeforeactivelist
+   \def\do##1{\lccode`\~`##1%
+    \lowercase{\def~}{\discretionary{\char`##1}{\sphinxafterbreak}{\char`##1}}%
+    \catcode`##1\active}%
+   \sphinxbreaksafteractivelist
    \lccode`\~`\~
 }
 
@@ -377,7 +375,7 @@
   % Allow breaks at special characters using \PYG... macros.
   \sphinxbreaksatspecials
   % Breaks at punctuation characters . , ; ? ! and / (needs catcode activation)
-  \def\FancyVerbCodes{\sphinxbreaksatpunct}%
+  \def\FancyVerbCodes{\sphinxbreaksviaactive}%
   \fi % end of conditional code for wrapping long code lines
   % go around fancyvrb's check of \@currenvir
   \let\VerbatimEnvironment\sphinxVerbatimEnvironment