Module:Comma

Module documentation
See Global Lua Modules/Comma
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local p = {}

local i18n = require('Dev:i18n').loadMessages('Comma')
local getArgs = require('Dev:Arguments').getArgs

local trim = mw.text.trim

local function validateTable(items)
	local output = {}
	
	for _,v in ipairs(items) do
		if type(v) == 'string' and trim(v) ~= '' then
			output[#output + 1] = trim(v)
		elseif type(v) == 'number' then
			output[#output + 1] = v
		end
	end
	
	return output
end

function p.main(args, opt)
	opt = opt or {}
	local items = validateTable(args)
	
	local output = ''
	local penultimate = ''
	local tailender = ''
	-- separators
	local comma = opt['sep1'] and opt['sep1'] or i18n:msg('sep1')
	local sep2
	local sep3
	if opt.useAnd then
		sep2 = opt['sep2'] or i18n:msg('sep2and')
		sep3 = opt['sep3'] or i18n:msg('sep3and')
	else
		sep2 = opt['sep2'] or i18n:msg('sep2or')
		sep3 = opt['sep3'] or i18n:msg('sep3or')
	end
	
	for _, v in ipairs(items) do
		if output ~= '' then
			output = output .. comma
		end
		
		output = output .. penultimate
		-- shift
		penultimate = tailender
		tailender = v
	end
	
	-- add penultimate and tailender to the output
	if output ~= '' then
		-- 3 or more items in total
		output = output .. comma .. penultimate .. sep3 .. tailender
	else
		if penultimate ~= '' then
			-- 2 items
			output = penultimate .. sep2 .. tailender
		else
			-- 1 item
			output = tailender
		end
	end
	
	return output
end

function p._main(frame)
	local args = getArgs(frame)
	
	local opt = {
		useAnd = (args['and'] and trim(args['and']) ~= '') and true or false,
		sep1 = (args['sep1'] and trim(args['sep1']) ~= '') and args['sep1'] or nil,
		sep2 = (args['sep2'] and trim(args['sep2']) ~= '') and args['sep2'] or nil,
		sep3 = (args['sep3'] and trim(args['sep3']) ~= '') and args['sep3'] or nil
	}
	
	return p.main(args, opt)
end

return p