Module:unsubst

Documentation for this module may be created at Module:unsubst/doc

local m_template_parser = require("Module:template parser")

local build_template = m_template_parser.buildTemplate
local concat = table.concat
local get_template_invocation_name = m_template_parser.getTemplateInvocationName
local is_valid_title = require("Module:pages").is_valid_title
local new_title = mw.title.new

local is_substing = mw.isSubsting()

local function unsubst_me(frame)
	return frame.args[""]
end

local function get_title(frame)
	local title = new_title(frame:getTitle())
	return is_valid_title(title) and title or
		-- This shouldn't happen.
		error("frame returned an invalid title")
end

local function serialize(title, args)
	return "{{" .. concat(build_template(title, args), "|") .. "}}"
end

local mt = {}

function mt:__index(entry_point)
	-- Cannot unsubst if not currently being substed.
	if not is_substing then
		local frame_title = mw.getCurrentFrame():getTitle()
		if frame_title ~= "Module:unsubst" then
			error(("[[%s]] should not call [[Module:unsubst]] unless mw.isSubsting() returns true"):format(frame_title))
		end
		-- Allow {{#invoke:unsubst|me|=...}}, but otherwise return nothing.
		return entry_point == "me" and unsubst_me or nil
	end
	return function(frame)
		local parent = frame:getParent()
		if parent:getTitle() ~= mw.title.getCurrentTitle().fullText then
			return serialize(get_template_invocation_name(get_title(parent)), parent.args)
		end
		local title = get_title(frame)
		return title.namespace == 828 and
			(serialize(("safesubst:<noinclude/>#invoke:%s|%s"):format(title.text, entry_point), frame.args)) or
			-- This shouldn't happen.
			error(("[[Module:unsubst]] cannot work if the current frame is not in the %s namespace, because the #invoke magic word requires it"):format(mw.site.namespaces[828].canonicalName))
	end
end

return setmetatable({}, mt)