Listings - Only highlight between delimiters

Question

I want to implement a function name color highlighting and I use the listings package. My 'regex' for this is def %s( where def (including space) is the first delimiter %s is the function name and ( is the second delimtier. Now my aim is to color only %s in purple. So basically I want to only touch the part between the delimiters and the delimiters should stay untouched.

Here is what I tried so far:

\documentclass{article}
\usepackage{xcolor,listings}
\usepackage[ngerman]{babel}
\usepackage{fontspec}
\setmonofont{Courier New}

\begin{document}

\lstset{language=Python,
    escapebegin=\color{orange},
    keywordstyle=\color{blue}\bfseries,
    commentstyle=\color{orange!80!red},
    stringstyle=\ttfamily\color{gray},
    %moredelim = [is][\color{blue}\bfseries def \mdseries\color{purple}]{def\ }{(},
    moredelim = [s][\color{purple}]{def\ }{(},
    showstringspaces=false}‎
\lstset{literate=%
   *{0}{{{\color{red}0}}}1
    {1}{{{\color{red}1}}}1
    {2}{{{\color{red}2}}}1
    {3}{{{\color{red}3}}}1
    {4}{{{\color{red}4}}}1
    {5}{{{\color{red}5}}}1
    {6}{{{\color{red}6}}}1
    {7}{{{\color{red}7}}}1
    {8}{{{\color{red}8}}}1
    {9}{{{\color{red}9}}}1
}

‎‎\begin{lstlisting}[basicstyle=\ttfamily,mathescape]
def fancy_function_name(page_url = 'tex.stackexchange.com'):
    return page_url.split('.')[0]
\end{lstlisting}

\end{document}

This code will generate:

You can see that it matches the right place but is too greedy and colors the delimiters too. So I thought about the uncommented line: %moredelim = [is][\color{blue}\bfseries def \mdseries\color{purple}]{def\ }{(}, If I use this one and uncomment the line below I get this result:

It's nearly what I wan't but I cannot add the last, now missing ( in black color.

Does anyone has a solution for this without pretouching the code and add all the @@ symbols?

Answer 1

You can define your own command, taking one argument and adding appropriate characters before and after printing this argument:

\documentclass{article}
\usepackage{xcolor,listings}
\usepackage[ngerman]{babel}
%\usepackage{fontspec}
%\setmonofont{Courier New}

\begin{document}

\newcommand{\functionDefHighlight}[1]{\bfseries\textcolor{blue}{def} \textcolor{purple}{\mdseries #1}(}

\lstset{language=Python,
    escapebegin=\color{orange},
    keywordstyle=\color{blue}\bfseries,
    commentstyle=\color{orange!80!red},
    stringstyle=\ttfamily\color{gray},
    %moredelim = [is][\color{blue}\bfseries def \mdseries\color{purple}]{def\ }{(},
    %moredelim = [s][\color{purple}]{def\ }{(},
    moredelim = [is][\functionDefHighlight]{def\ }{(},
    showstringspaces=false}‎
\lstset{literate=%
   *{0}{{{\color{red}0}}}1
    {1}{{{\color{red}1}}}1
    {2}{{{\color{red}2}}}1
    {3}{{{\color{red}3}}}1
    {4}{{{\color{red}4}}}1
    {5}{{{\color{red}5}}}1
    {6}{{{\color{red}6}}}1
    {7}{{{\color{red}7}}}1
    {8}{{{\color{red}8}}}1
    {9}{{{\color{red}9}}}1
}

‎‎\begin{lstlisting}[basicstyle=\ttfamily,mathescape]
def fancy_function_name(page_url = 'tex.stackexchange.com'):
    return page_url.split('.')[0]
\end{lstlisting}

\end{document}