How do I use special characters from the danish alphabet as a part of keywords when using listings?

Question

Im writing a report in overleaf about a programming language im making, I want to be able to use listings to have the syntax of the language highlighted in the report, however since the programming language have keywords in danish, some words are special characters, how do I make the special characters æ, ø and å highlighted, as part of a keyword?

An excerpt of my file is shown below, with an example of text. It should include all from my preamble that are relevant for this question.

\documentclass[12pt,oneside,a4paper,openright]{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[sc]{mathpazo}                       
\usepackage[utf8]{inputenc}
\usepackage[danish, english]{babel}
\usepackage{xcolor}
\usepackage{graphicx}

% Colors for Code
\definecolor{grayC}{RGB}{250,250,250}
\definecolor{Dgray}{RGB}{200,200,200}
\definecolor{bluekeywords}{rgb}{0,0,1}
\definecolor{greencomments}{rgb}{0,0.5,0}
\definecolor{redstrings}{rgb}{0.64,0.08,0.08}
\definecolor{xmlcomments}{rgb}{0.5,0.5,0.5}
\definecolor{types}{rgb}{0.17,0.57,0.68}

\usepackage{listings}

\lstset{
  literate= {Ø}{{\O}}1 {Æ}{{\AE}}1 {Å}{{\AA}}1
}

\lstdefinelanguage{BABs} {
    alsoletter={\O,\AE,\AA},
    morekeywords={
        HVIS,
        GØR,
        FÆRDIG,
        ER,
        IKKE,
        OG,
        ELLER,
        GENTAG,
        OPDATER,
        TABEL,
        RÆKKE,
        VIS,
        INDLÆS,
        SANDHEDSVÆRDI,
        TEKST,
        DECIMALTAL,
        HELTAL,
        SAND,
        FALSK
  },
  sensitive = false, % No case sensitivity of keywords
  morecomment = [s]{\#}{\#},   % Comment with start and end
  morestring = [b]" % Strings are enclosed with "
}

% Some additional settings for BABs
\lstset{language=BABs,
  backgroundcolor=\color{grayC},
  basicstyle=\ttfamily\small,       
  breakatwhitespace=false,          
  breaklines=true,                                  
  commentstyle=\color{greencomments},   
  deletekeywords={...},             
  escapeinside={(*@}{@*)},          
  extendedchars=true,               
  frame=single,                     
  keepspaces=true,                  
  keywordstyle=\color{bluekeywords},   
  numbers=left,                     
  numbersep=5pt,                    
  numberstyle=\tiny\color{black},   
  rulecolor=\color{Dgray},          
  showspaces=false,                 
  showstringspaces=false,           
  showtabs=false,                   
  stepnumber=1,                     
  stringstyle=\color{redstrings},   
  tabsize=2                        
}

\begin{document}

This is a test to show that \lstinline[language=BABs]|GØR{<Stmts>}| and \lstinline[language=BABs]{FÆRDIG} are not properly highlighted, however \lstinline[language=BABs]{HVIS(<BoolExpr>)} is.

\end{document}

Output:

As can be seen FÆRDIG and GØR are not highlighted as keywords, eventhough they are specified using morekeywords and I have added them as letters using alsoletter. The exerpt above, have been made by looking at solutions to similar problems, where the special characters are - or . instead.

Does anyone know how to make it work in my case with the danish keywords containing special characters?

Answer 1

I don't think that it is possible to combine the literate option with the keyword detection - literate doesn't leave the input in a "simple" state. If you really want automatic keyword detection you will imho have to switch to one of the unicode engines (xelatex/lualatex):

\documentclass[12pt,oneside,a4paper,openright]{report}
\usepackage{fontspec}
\setmainfont{TeX Gyre Pagella}
\usepackage[danish, english]{babel}
\usepackage{xcolor}
\usepackage{graphicx}
% Colors for Code
\definecolor{bluekeywords}{rgb}{0,0,1}
\usepackage{listings}

\lstdefinelanguage{BABs} {
    morekeywords={
        HVIS,
        GØR,
        FÆRDIG,
  },
  sensitive = false, % No case sensitivity of keywords
  morecomment = [s]{\#}{\#},   % Comment with start and end
  morestring = [b]" % Strings are enclosed with "
}
% Some additional settings for BABs
\lstset{language=BABs,
  basicstyle=\ttfamily\small,
  keywordstyle=\color{bluekeywords},
}

\begin{document}

This is a test to show that \lstinline|GØR{<Stmts>}| 
and \lstinline[language=BABs]{FÆRDIG} are not properly highlighted,
however \lstinline[language=BABs]{HVIS(<BoolExpr>)} is.

\end{document}