pandoc confluence markup writer

wiki.lua

-- Invoke with: pandoc -t wiki.lua
--
-- Note:  you need not have lua installed on your system to use this
-- custom writer.  However, if you do have lua installed, you can
-- use it to test changes to the script.  'lua wiki.lua' will
-- produce informative error messages if your code contains
-- syntax errors.

local image_index = 0

-- Character escaping
local function escape(s, in_attribute)
	return s:gsub("[<>&\"']",
		function(x)
			if x == '<' then
				return '&lt;'
			elseif x == '>' then
				return '&gt;'
			elseif x == '&' then
				return '&amp;'
			elseif x == '"' then
				return '&quot;'
			elseif x == "'" then
				return '&#39;'
			else
				return x
			end
		end
	)
end

-- Table to store footnotes, so they can be included at the end.
local notes = {}

-- Blocksep is used to separate block elements.
function Blocksep()
	return "\n"
end

-- This function is called once for the whole document. Parameters:
-- body is a string, metadata is a table, variables is a table.
-- This gives you a fragment.  You could use the metadata table to
-- fill variables in a custom lua template.  Or, pass `--template=...`
-- to pandoc, and pandoc will add do the template processing as
-- usual.
function Doc(body, metadata, variables)
	local buffer = {}
	local function add(s)
		table.insert(buffer, s)
	end
	add(body)
	-- TODO: render notes
	-- if #notes > 0 then
	--    add('<ol class="footnotes">')
	--    for _,note in pairs(notes) do
	--      add(note)
	--    end
	--    add('</ol>')
	-- end
	return table.concat(buffer, "\n") .. "\n"
end

-- The functions that follow render corresponding pandoc elements.
-- s is always a string, attr is always a table of attributes, and
-- items is always an array of strings (the items in a list).
-- Comments indicate the types of other variables.

function Str(s)
	return escape(s)
end

function Space()
	return " "
end

function SoftBreak()
	return " "
end

function LineBreak()
	return "\n"
end

function Para(s)
	return s .. "\n"
end

function Plain(s)
	return s
end

function Emph(s)
	return "_" .. s .. "_"
end

function Strong(s)
	return "*" .. s .. "*"
end

function Subscript(s)
	return "~" .. s .. "~"
end

function Superscript(s)
	return "^" .. s .. "^"
end

function Strikeout(s)
	return '-' .. s .. '-'
end

function Link(s, src, tit)
	if tit:len() > 0 then
		return "[" .. s .. "|" .. escape(src,true) .. " " .. escape(tit,true) .. "]"
	else
		return "[" .. s .. "|" .. escape(src,true) .. "]"
	end
end

function CaptionedImage(src, s, tit)
	image_index = image_index + 1
	return "!" .. escape(src, true) .. "!\n" .. 'FIGURE ' .. image_index .. ". " .. tit .. "\n"
end

function Image(s, src, tit)
	return "!" .. escape(src,true) .. "!"
end

-- lev is an integer, the header level.
function Header(lev, s, attr)
	return "h" .. lev .. ". " .. s .. ""
end

function BlockQuote(s)
	return "{quote}\n" .. s .. "{quote}\n"
end

function HorizontalRule()
	return "----"
end

function Code(s)
	 return '{{' .. s .. '}}'
end

function CodeBlock(s, attr)
	if attr["class"]:len() > 0 then
		return "{code:" .. attr["class"] .. "}\n" .. s .. "\n{code}\n"
	else
		return "{code}\n" .. s .. "\n{code}\n"
	end
end

function Note(s)
	local num = #notes + 1
	return s
	-- TODO: render note back reference
	-- -- insert the back reference right before the final closing tag.
	-- s = string.gsub(s, '(.*)</', '%1 <a href="#fnref' .. num ..  '">&#8617;</a></')
	-- -- add a list item with the note to the note table.
	-- table.insert(notes, '<li id="fn' .. num .. '">' .. s .. '</li>')
	-- -- return the footnote reference, linked to the note.
	-- return '<a id="fnref' .. num .. '" href="#fn' .. num .. '"><sup>' .. num .. '</sup></a>'
end

local function trim(s)
	return s:match("^%s*(.-)%s*$")
end

local function List(items, marker)
	local buffer = {}
	for _, item in pairs(items) do
		table.insert(buffer, marker .. " " .. trim(item:gsub("\n+", "\n")) .. "\n")
	end
	return table.concat(buffer, "")
end

function BulletList(items)
	return List(items, '-')   
end

function OrderedList(items)
	return List(items, '#') 
end

-- Revisit association list STackValue instance.
function DefinitionList(items)
	local buffer = {}
	for _,item in pairs(items) do
		for k, v in pairs(item) do
			table.insert(buffer, Strong(k) .. "\n" .. BulletList(v))
		end
	end
	return table.concat(buffer, "\n")
end

-- Caption is a string, aligns is an array of strings,
-- widths is an array of floats, headers is an array of
-- strings, rows is an array of arrays of strings.
function Table(caption, aligns, widths, headers, rows)
	local buffer = {}
	local function add(s)
		table.insert(buffer, s)
	end
	local header_row = {}
	local empty_header = true
	for i, h in pairs(headers) do
		table.insert(header_row, h)
		empty_header = empty_header and h == ""
	end
	if empty_header then
		head = ""
	else
		add('|| ' .. table.concat(header_row, ' || ') .. ' ||')
	end
	for _, row in pairs(rows) do
		add('| ' .. table.concat(row, ' | ') .. ' |')
	end
	return "\n" .. table.concat(buffer,'\n') .. "\n"
end

-- The following code will produce runtime warnings when you haven't defined
-- all of the functions you need for the custom writer, so it's useful
-- to include when you're working on a writer.
local meta = {}
meta.__index = function(_, key)
	io.stderr:write(string.format("WARNING: Undefined function '%s'\n",key))
	return function() return "" end
end
setmetatable(_G, meta)