Arc over multiple columns in table

Question

I want to have a flat arc over some columns in a table (tabu environment, as I am using to define independent colours for each row). Similar to the hhline in which bar are drawn over multiple columns.

More completely, parts of the row can have bar, double bars or arcs over some columns, and row colours should be independently specifiable.

\documentclass[10pt,a4paper]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{tabu}
\usepackage{hhline}
\usepackage[dvips]{color}

\begin{document}
\begin{tabu}{c c c c c}
\hhline{~~~~~}
\rowfont{\color{red}}
x & y & z & q & w\\
\\
\rowfont{\color{blue}}
\hhline{~--~-}
a & b & c & d & e\\
\\
\rowfont{\color{magenta}}
\hhline{~~===}
l & m & n & o & p\\
\end{tabu}
\end{document}

(Arc is the only thing I could not get)

How can I achieve it?

Answer 1

This result is not automated, but it might give you some ideas

\documentclass[10pt,a4paper]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{tabu}
\usepackage{hhline}
\usepackage[dvips]{color}
\usepackage{scalerel}
\usepackage{verbatimbox}

\begin{document}
\begin{tabu}{c c c c c}
\hhline{~~~~~}
\rowfont{\color{red}}
x & y & z & q & w\\
\\
\rowfont{\color{blue}}
\hhline{~--~-}
a & b & c & d & e\\
\\
\rowfont{\color{magenta}}
\hhline{~~===}
l & m & n & o & p\\
\\
&&\multicolumn{3}{l}{\addvbuffer[-1ex]{$\hstretch{4}{\frown}$}}\\
\rowfont{\color{magenta}}
l & m & n & o & p\\
\end{tabu}
\end{document}