Pattern syntax using luacode

Question

How can I find characters that are not curly braces? If I use this pattern "[^}]" in string.gsub I get an error.

EDIT: This is the part of the code that doesn't work:

\usepackage{luacode}

\begin{luacode}
    function colorize ( s ) 
        s = string.gsub ( s , "K_%w" , "\\textcolor[HTML]{00804d}{%0}" )
        s = string.gsub ( s , "(A)([^}])" , "\\textcolor[HTML]{005ce6}{%1}%2"))         
        return s
    end
\end{luacode}

\newcommand{\colorizeOn}{\directlua{luatexbase.add_to_callback("process_input_buffer", colorize , "colorize" )}}
\newcommand{\colorizeOff}{\directlua{luatexbase.remove_from_callback("process_input_buffer", "colorize" )}}

The first part of the script is ok (it substitutes all "K_" followed by an alphanumeric characters with the same thing but with a color code) while adding the second part (that should replace all "A" that are not followed by a "}" with "A" with its color code) it returns this errors:

Argument of \luacode@grab@lines has an extra }. s = string.gsub ( s , "(A)([^}
Paragraph ended before \luacode@grab@lines was complete. s = string.gsub ( s , "(A)([^}
Extra }, or forgotten \endgroup. s = string.gsub ( s , "(A)([^}
Missing \begin{document}. s = string.gsub ( s , "(A)([^}]
Missing \begin{document}. s = string.gsub ( s , "(A)([^}])" , "\\t

The main problem is the hat character in fact if I use this pattern "[}]" I get similar errors (the compiler expects to find a corresponding "{" before) and in my case I can easily fix that using this pattern instead "[{}]". The problem is that I want the negation of this pattern that should be written as "[^{}]" that doesn't work.

EDIT 2: this is what I expect.

Answer 1

I suggest you use a luacode* environment instead of a luacode environment.

\documentclass{article}
\usepackage{xcolor,luacode}
\begin{luacode*}
function colorize ( s ) 
    s = string.gsub ( s , "K_%w" , "\\textcolor{red}{%0}" )
    s = string.gsub ( s , "(A)([^{}])" , "\\textcolor{blue}{%1}%2")     
    return s
end
\end{luacode*}

\newcommand{\colorizeOn}{\directlua{ luatexbase.add_to_callback( 
   "process_input_buffer", colorize , "colorize" )}}
\newcommand{\colorizeOff}{\directlua{ luatexbase.remove_from_callback( 
   "process_input_buffer", "colorize" )}}

\begin{document}
$K_b$, Au, A{u}

\colorizeOn
$K_b$, Au, A{u}
\end{document}