Hi all,

I've started writing a technical book using Quarto markdown, which uses 
pandoc with Lua filters under the hood to produce a website as well as the 
publisher's pdf format (via LaTeX). 
I quite like to keep the source document as plain as possible, and I'm 
wondering if I could avoid the use of [concept]{.index}, which gets turned 
into \index{concept}, and instead write a Lua filter with my custom list of 
keywords, and have pandoc automatically match them as they appear in the 
text. 
As a proof of principle I wrote the following code (see below), which 
matches specific keywords, and reformats them as small-caps. I quickly 
realised that trailing punctuation, such as "concept, ..." will fail to 
match, so I'm using gsub to strip such punctuation before matching. It 
works, but I'm a bit worried:

- what's the overhead of such a filter, in practice? From what I 
understand, every single string element in the AST will be processed by 
gsub then tested for a match. Are Lua filters walking down the AST fast 
enough that I shouldn't worry about it? (as far as I can tell on small 
examples, it seems fine)

- assuming this idea is reasonable, I might want to do a few similar 
operations, e.g. reformatting program languages (as in this example code), 
wrapping keywords in \index{}, etc., and the exact format will often depend 
on the output target (html vs TeX etc.). Is there a better construct for 
this than successive if/else statements to look for matches? (I don't know 
much Lua)

Best regards,

baptiste

Lua filter:
-----

local text = require 'text'
local pandoc = require 'pandoc'

-- keywords to look for in the document
local langs = {"Matlab", "R", "Julia", "C++"}

function Includes(tab, val)
-- strip trailing punctuation before matching
local bare = string.gsub(val,"[%.|,|;|:]", "")

for index, value in ipairs(tab) do
if value == bare then
return true
end
end

return false
end

function Replace_langname(elem)
if Includes(langs, elem.text) then
return pandoc.SmallCaps(text.lower(elem.text))
else
return elem
end
end

return {{Str = Replace_langname}}










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