Re: How to Determine the Current File Name and Line Number in the ConTeXt Source?

[Hans Hagen <pragma@wxs.nl>]

Tad Ashlock wrote:
> Is there a convenient way within a Lua block to determine the current 
> file name and line number of the source file being processed by ConTeXt?
> 
> For example: (test.tex)
> ---------------------------------
> \def\ShowLineNumber{%
>    \ctxlua{print('current line number:', tex.current_line_number())
>               print('current file:', tex.current_file_name())}}
> \starttext
> a line
> \ShowLineNumber
> another line
> 
> \ShowLineNumber
> \stoptext
> ---------------------------------
> 
> With the following displayed:
> ---------------------------------
> current line number: 6
> current file: test.tex
> current line number: 9
> current file: test.tex
> ---------------------------------
> 
> I've considered hooking into the open_read_file callback and tracking 
> the file name and line number (via reader) myself.  But that seems a bit 
> heavy handed if the file name and line number information are available 
> more directly.  And since that information is needed for error 
> reporting, I'm thinking there's a good chance it is accessible.
> 
> (Just in case you're interested, the purpose of this is to be able to 
> assemble code segments during the ConTeXt processing into external files 
> with #line directives ala the C preprocessor.  That way if the 
> subsequent compilation of the external file results in an error, the 
> error message can refer back to the line of code in the ConTeXt source 
> file.  This is part of the literate programming module that Kevin 
> Robbins has been describing in another thread.)

i have no time now to figure out while filenames are not known but 
here's a (wikifyable) hack:

\starttext

% needs to be added to buff-ini.lua
%
% function buffers.raw(name)
%     return data[name] or { }
% end

\startluacode
     local locations = { }

     function document.set_number(name)
         locations[name] = {
             line = status.linenumber,
             file = status.filename
         }
     end

     function document.add_number(name)
         local b, l = buffers.raw(name), locations[name]
         if b and l then
             for i=1,#b do
                 b[i] = string.gsub(b[i],"# line: <number>","# line: " 
.. l.line + 2)
             end
         end
     end
\stopluacode

\ctxlua{document.set_number("oeps")}
\startbuffer[oeps]
# line: <number>

test
test
\stopbuffer
\ctxlua{document.add_number("oeps")}

\typebuffer[oeps]

\stoptext

when i have time (or reason) i'll think about a more integrated approach 
with hooks

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
      tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
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