Re: t-vim module: math in "normal" code and background color

[Aditya Mahajan <adityam@umich.edu>]

On Wed, 19 Jul 2017, Gerion Entrup wrote:

> Am Dienstag, 18. Juli 2017, 04:04:51 CEST schrieb Aditya Mahajan:
>> On Mon, 17 Jul 2017, Gerion Entrup wrote:
>>
>>> Hi,
>>>
>>> I have two questions with the vim module.
>>>
>>> 1. I want to use the math mode inside the code. I've seen the escape option,
>>> e.g. here [1], but this seems to work only with comments. Is there a
>>> possibility to use it directly in the code, too?
>>
>> Short answer. No.
>>
>> Long answer. t-vim relies on vim to syntax highlight the code. Since the
>> code is not valid python, the default python syntax highlighting will not
>> work. In principle, it is possible to write a vim syntax highlighting
>> script for a derivative of python where math terms are allowed, but that
>> requires a lot of work for each language. The whole point of t-vim module
>> was that I am lazy and don't want to write the parser for each language
>> :-)
>
> I've invested some time and rewrote parts of the vimscript file of t-vim.
> Now one or more escapechars can be defined, that helps vim to not interpret
> the text:

I'll look at this later....

> Another point I saw is, that highlight together with TeX-code is not really usable:
> ```
> \usemodule[vim]
> \definevimtyping[python][syntax=python, escape=on]
>
> \starttext
> \startpython[highlight=1]
> # Returns \m{\sum_{i=1}^{n}i \in F \int_i f}
> \stoppython
> \stoptext
> ```

By default, the highlighting is done using the bars mechanism. It works 
for simple cases but fails with math mode (the spaces are not covered). 
One option is to highlight using the textbackground mechanism:

\definetextbackground[texthighlight]
     [
       background=color,
       backgroundcolor=gray,
       frame=off,
     ]

\define[1]\texthighlight{\starttexthighlight#1\stoptexthighlight}

\usemodule[vim]
\definevimtyping[python][syntax=python, escape=on, highlightcommand=\texthighlight]

\starttext

\startpython[highlight=3]
for x in 1:n
   print(x)
# Returns \m{\sum_{i=1}^{n}i \in F \int_i f}
for x in 1:n
   print(x)
\stoppython
\stoptext

The spacing in math mode is bad. What is happening is the following. To 
make sure that spaces are obeyed in the code listing, I set (a modified 
version of) \activatespacehandler{on}, so the output that you get is the 
following:

{\obeyspaces
  \def\obeyedspace{\hskip\interwordspace\relax}
\m{\sum_{i=1}^{n}i \in F \int_i f}}

The simplest way to fix this is to define a new command:

\define[1]\MATH{\bgroup\activatespacehandler{off}\m{\rescan{#1}}\egroup}

and use \MATH{....} instead of \m{....}.

I'll test this is a bit, and if the solution is robust, then I will map 
\m{...} to something equivalent to the above in the t-vim environments.


Aditya
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