[NTG-context] listings.sty

[Aditya Mahajan]

Quoting Mohamed Bana <abbg770 at city.ac.uk>:

> nico <nicolas.marsgui <at> libertysurf.fr> writes:
>
>>
>> I don't see the point. The native ConTeXt verbatim support seems to cover
>> all what listings can do.
>>
>> The wiki page gives some examples:
>> http://wiki.contextgarden.net/Verbatim_text
>>
>> Regards,
>> BG
>>
>
>
> Hi,
>
> take a look at  
> http://vega.soi.city.ac.uk/~abbg770/listing-sample.pdf, note you
> can customize the style of the font numbering, you can place a caption and my
> favourite is the colouring; if you use Eclipse you'll notice that  
> it's the same
> colour the editor uses.

This can be done easily with current ConTeXt, for example:

\setupcolors[state=start]

\starttext
\setuplinenumbering[location=intext]

\setuptyping[option=color]

\startJV
/**
  * The HelloWorldApp class implements an application that
  * simply prints "Hello World!" to standard output.
  */
class HelloWorldApp {
     public static void main(String[] args) {
         System.out.println("Hello World!"); // Display the string.
     }
}
\stopJV


See the wiki page for adding line numbering and frames (or ask here if  
the wiki page is confusing). It is possible to change the color scheme  
and the wiki page gives an example. To make sure that the frames break  
around pages, you will need to use backgroundtext rather than  
framedtext.

The only advantage of listings is that it provides support for a *lot*  
of languages out of the box. Writing a syntax highlighter is not easy.  
I mean, you need to define all kinds of keywords, write regex or  
parser for identifying comments, strings, escape sequences etc. No  
matter what language is used to write a syntax highlighter, writing a  
good syntax highlighter takes time. And hence the advantage of  
listing. In terms of features, I think it is not difficult to add the  
required display features in ConTeXt. Line numbering every n lines[1],  
using proportional fonts, fancy frames, etc are pretty  
straight-forward things.

One option for the long term could be to write a module for mkiv, that  
can parse the syntax highlighting files of some editor and use them  
directly. Since most decent editors have syntax highlighting files for  
lot of languages, we will not have to do the hard work. (well, in case  
you don't like any available syntax highlighting, and want to roll  
your own, then it is a different matter).

There is a module that uses vim to generate syntax highlighting. Mojca  
started the module, and I extended it when I needed syntax  
highlighting for a project. After that, I have not really updated it.  
It works by using vim to generate a tex file which is then read by  
context. The only drawback is the starting and stopping times of vim  
are fairly large (few secs for each file to be transformed).

Aditya

[1] Actually, line numbering every n lines is already supported.