Overbrace in lstlisting of Scala code

Question

I want to add an overbrace to some text in a Scala code listing (using lstlisting).

\begin{lstlisting}
object TypeClass extends FooParMain {
  def newApp(args: Array[String]) = new FooParApp {
    def run {
      val x = new Matrix(Seq(Seq(1, 2), Seq(3, 4)))
      val dSeq = Array.fill(worldSize)(x).toDistSeq

      for (res <- dSeq.sumD) {
        pprintln(res, " worldSize = " + worldSize, res == x * worldSize)
      }
    }
  }
}
\end{lstlisting}

Is there any sane way of doing this without breaking the syntax highlighting? (I tried [mathescape], but it doesn't look good)

welcome to tex.sx. where the brace? over the whole thing or over some words in the listing? — David Carlisle, Apr 10 '13 at 11:09
In this case, overbrace on exactly "Array.fill(worldSize)(x)" and another brace over ".toDistSeq". Btw, thank you :) — Felix, Apr 10 '13 at 11:31

score 1 · Answer 1 · answered Apr 10 '13 at 14:12

1

This uses a bit of "by eye" measuring hard to measure it automatically without knowing exactly what listings will do with the text.

enter image description here

(Please for future questions post complete documents showing packages used as below)

\documentclass{article}
\usepackage{listings}

\begin{document}

\small
\begin{lstlisting}[mathescape]
object TypeClass extends FooParMain {
  def newApp(args: Array[String]) = new FooParApp {
    def run {
      val x = new Matrix(Seq(Seq(1, 2), Seq(3, 4)))
      val dSeq = $\rlap{\(\overbrace{\strut\hspace{4.5cm}}\)}$Array.fill(worldSize)(x).toDistSeq

      for (res <- dSeq.sumD) {
        pprintln(res, " worldSize = " + worldSize, res == x * worldSize)
      }
    }
  }
}
\end{lstlisting}

\end{document}

answered Apr 10 '13 at 14:12

David Carlisle

757,742

This solution messes up the layout (background and frame splits up at the line) – Felix Apr 11 '13 at 10:49
you could make it $\smash{\rlap{...}} which would prevent the brace opening up the line height but then you would have to arrange in your general listings settings that the line height is big enough or the brace will over-print the line above. Or you could put the backgrpund ad frame on externally using mdframed which wouldn't care about the internal structure. If a frame is a requirement perhaps you should edit the question example to include one. – David Carlisle Apr 11 '13 at 11:05

score 1 · Answer 2 · edited Apr 13 '17 at 12:35

The following is an adaptation of the approach suggested in Highlight text in code listing while also keeping syntax highlighting. The basic idea is to use listings moredelim option to mark the part to overbrace.

With the moredelim=** syntax you can define delimiters which styles apply on top of all other formattings. In the following I use backticks as delimiters, but you may choose any character:

\lstdefinestyle{...}{
    moredelim=**[is][\btHL]{`}{`},
}

The only issue is the formatting commands to be applied (\btHL) do not get the text to highlight as a macro parameter. Instead, they have to work like the LaTeX font commands (e.g., \bfseries or \color) that take affect until the end of the current group. Hence, we have to catch the content in an lrbox.

Complete MWE (using Java instead of Scala to demonstrate the combination with syntax highlighting):

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{listings,xcolor,beramono,amsmath}


\makeatletter
\newenvironment{btHighlight}[1][]
{\begingroup\def\bt@Highlight@par{#1}\begin{lrbox}{\@tempboxa}}
{\end{lrbox}\bt@HL@box[\bt@Highlight@par]{\@tempboxa}\endgroup}

\newcommand\btHL[1][]{%
\begin{btHighlight}[#1]\bgroup\aftergroup\bt@HL@endenv%
}
\def\bt@HL@endenv{%
\end{btHighlight}%   
\egroup
}
\newcommand{\bt@HL@box}[2][]{%
  $\overset{\text{#1}}{\overbrace{\strut\usebox{#2}}}$%
}
\makeatother

\lstdefinestyle{Java}{
    language={Java},basicstyle=\ttfamily, 
    moredelim=**[is][{\btHL[class name]}]{`}{`},
    moredelim=**[is][{\btHL[important]}]{@}{@},
    escapechar={§},
}

\begin{document}

  A listing with {\btHL[overbrace text] highlighting of all \textbf{important} elements} looks as follows:


\begin{lstlisting}[style=Java]
  public class `HelloWorld` {
    public @static void@ main(String[] args) {
      System.out.println("Hello, World");
    }
  }
\end{lstlisting}
\end{document}

enter image description here

Sorry for adding this so late, but I would like to be able to put text at the overbrace. Is this possible with this approach? — Felix, Apr 10 '13 at 20:22
@Felix: Please see updated code and screen shot. The issue is how to pass the overbrace text. In the updated solution, it can be given as optional parameter to the \btHL[<overbrace text>] command. Basically this means that you have to define an own moredelim for every overbrace text. Does this work for you? — Daniel, Apr 10 '13 at 21:20

Overbrace in lstlisting of Scala code

2 Answers2