_extensions/js/en2em/en2em.lua



--- en2em - replace space-enclosed en-dash with nospace em-dash
---
--- Some typographical styles, including danish,
--- use en-dash with spaces around to indicate a short pause,
--- whereas others, including some british and american styles,
--- use an em-dash without spaces.
---
--- This plugin allows to always use en-dash at the source --
--- which also eases writing with semantic line breaks, like here --
--- and then convert while rendering as needed.
---
--- SPDX-FileCopyrightText: 2025  Jonas Smedegaard <dr@jones.dk>
--- SPDX-License-Identifier: GPL-3.0-or-later

local em_dash = pandoc.Str("\u{2014}")
local nothing = pandoc.Str("")

local TypeIsSpacy = {
  Space = true,
  SoftBreak = true
}

function Para(el)
  for i = 1, #el.content - 1 do
    if el.content[i].t == "Str" and el.content[i].text == "\u{2013}" then
      local el_prev = el.content[i - 1]
      local el_next = el.content[i + 1]
      if el_prev and el_next
        and TypeIsSpacy[el_prev.t] and TypeIsSpacy[el_next.t]
      then
        el.content[i] = em_dash
        el.content[i - 1] = nothing
        el.content[i + 1] = nothing
      end
    end
  end
  return el
end