Re: Help with Lua filter for markdown to LaTeX with Pandoc

[Bastien DUMONT <bastien.dumont-VwIFZPTo/vqsTnJN9+BGXg@public.gmane.org>]

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I attached two filters. If you run:

pandoc -t latex -L highlight-red.lua -L in-red.lua <<< 'Some *==text in red==*!'

You get:

Some \colorbox{lightred}{{text in red}}!

Le Sunday 26 March 2023 à 02:42:54AM, Pa Sc a écrit :
> Do you mean the two filters that are in the original post? Or what filter do
> you mean?
> 
> Bastien DUMONT schrieb am Sonntag, 26. März 2023 um 00:08:53 UTC+1:
> 
>     Please share the two lua filters you use to parse `==` as a syntax for
>     highlighting and to print in red an emphasized span produced by this
>     filter. We can't figure out what is wrong without them.
> 
>     Le Saturday 25 March 2023 à 03:44:24PM, Pa Sc a écrit :
>     > Yeah, I have a MWE here: [1]https://tex.stackexchange.com/questions/
>     680766/
>     > help-with-lua-filter-for-markdown-to-latex-with-pandoc
>     >
>     > As for the command:
>     > ```
>     > mkdir -p /home/ME/Documents/Obsidian/Output/{{title}}
>     > pandoc -r markdown-auto_identifiers -w latex {{file_path:absolute}} -o /
>     home/ME
>     > /Documents/Obsidian/Output/{{title}}/{{title}}.tex --template="/home/ME/
>     > Documents/LaTeX/My Templates/Proposal/default-proposal.tex" --lua-filter=
>     /home/
>     > ME/Documents/LaTeX/Filters/highlight.lua --lua-filter=/home/ME/Documents/
>     LaTeX/
>     > Filters/highlight-period.lua --lua-filter=/home/ME/Documents/LaTeX/
>     Filters/
>     > Span.lua --lua-filter=/home/ME/Documents/LaTeX/Filters/highlight-red.lua
>     > --lua-filter=/home/ME/Documents/LaTeX/Filters/Span-red.lua
>     > ```
>     >
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>     > [1] mailto:pandoc-discus...-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
>     > [2] [4]https://groups.google.com/d/msgid/pandoc-discuss/
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> References:
> 
> [1] https://tex.stackexchange.com/questions/680766/
> [2] https://groups.google.com/d/msgid/
> [3] http://40googlegroups.com/
> [4] https://groups.google.com/d/msgid/pandoc-discuss/6a7dabf5-1fda-4825-9d21-193b63363937n%40googlegroups.com?utm_medium=email&utm_source=footer
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[-- Attachment #2: highlight-red.lua --]
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--[[
Add support for a custom inline syntax.

This pandoc Lua filter allows to add a custom markup syntax
extension. It is designed to be adjustable; it should not be
necessary to modify the code below the separator line.

The example here allows to add highlighted text by enclosing the
text with `==` on each side. Pandoc supports this for HTML output
out of the box. Other outputs will need additional filters.

Copyright: © 2022 Albert Krewinkel
License: MIT
]]

-- Lua pattern matching the opening markup string.
local opening = [[==]]

-- Lua pattern matching the closing markup string.
local closing = [[==]]

-- Toggle whether the opening markup may be followed by whitespace.
local nospace = true

-- Function converting the enclosed inlines to their internal pandoc
-- representation.
local function markup_inlines (inlines)
  return pandoc.Span(inlines, {class="mark-red"})
end

------------------------------------------------------------------------

local function is_space (inline)
  return inline and
    (inline.t == 'Space' or
     inline.t == 'LineBreak' or
     inline.t == 'SoftBreak')
end

function Inlines (inlines)
  local result = pandoc.Inlines{}
  local markup = nil
  local start = nil
  for i, inline in ipairs(inlines) do
    if inline.tag == 'Str' then
      if not markup then
        local first = inline.text:match('^' .. opening .. '(.*)')
        if first then
          start = inline -- keep element around in case the
                         -- markup is not closed. Check if the
                         -- closing pattern is already in this
                         -- string.
          local selfclosing = first:match('(.*)' .. closing .. '$')
          if selfclosing then
            result:insert(markup_inlines{pandoc.Str(selfclosing)})
          elseif nospace and first == '' and is_space(inlines[i+1]) then
            -- the opening pattern is followed by a space, but the
            -- config disallows this.
            result:insert(inline)
          else
            markup = pandoc.Inlines{pandoc.Str(first)}
          end
        else
          result:insert(inline)
        end
      else
        local last = inline.text:match('(.*)' .. closing .. '$')
        if last then
          markup:insert(pandoc.Str(last))
          result:insert(markup_inlines(markup))
          markup = nil
        else
          markup:insert(inline)
        end
      end
    else
      local acc = markup or result
      acc:insert(inline)
    end
  end

  -- keep unterminated markup
  if markup then
    markup:remove(1) -- the stripped-down first element
    result:insert(start)
    result:extend(markup)
  end
  return result
end

[-- Attachment #3: in-red.lua --]
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function Emph (emph)
  local content = emph.content
  if #content == 1
    and content[1].t == 'Span'
    and content[1].classes:includes 'mark-red' then
    return {
      pandoc.RawInline('latex', '\\colorbox{lightred}{'),
      content[1],
      pandoc.RawInline('latex', '}')
    }
  end
end