Module:Check for unknown parameters

-- This module may be used to compare the arguments passed to the parent
-- with a list of arguments, returning a specified result if an argument is
-- not on the list
local p = {}

local function isnotempty(s)
	return s and s:match( '^%s*(.-)%s*$' ) ~= ''
end

function p.check (frame)
	local args = frame.args
	local pargs = frame:getParent().args
	local ignoreblank = isnotempty(frame.args['ignoreblank'])
	local knownargs = {}
	local unknown = 'Found _VALUE_, '
	
	local res = {}
	
	-- create the list of known args, and the return string
	for k, v in pairs(args) do
		if type(k) == 'number' then
			v = mw.ustring.gsub(v, '^%s*(.-)%s*$', '%1')
			knownargs[v] = 1
		else
			if (k == 'unknown' and type(v) == 'string') then
				unknown = v
			end
		end
	end

	-- loop over the parent args, and make sure they are on the list
	for k,v in pairs(pargs) do
		if (knownargs[k] == nil and type(k) == 'string') then
			if( (not ignoreblank) or (ignoreblank and isnotempty(v)) ) then
				k = mw.ustring.gsub(k, '[^%w\-_ ]', '?')
				local r = mw.ustring.gsub(unknown, '_VALUE_', k)
				table.insert(res, r)
			end
		end
	end

	return table.concat(res)
end

return p