View source for Module:Yesno

--[[
{{Helper module|name=Yesno
|fname1=(arg)
|ftype1=Any value
|fuse1=Reads arg for yes/no and returns the appropriate boolean or nil
|fname2=(arg1,arg2)
|ftype2=Any value, Any value
|fuse2=Reads arg1 for yes/no and returns the appropriate boolean; returns arg2 if arg1 was not an applicable value
}}
--]]
-- <pre>
-- Used to evaluate args to booleans where applicable
--
-- Based on <https://en.wikipedia.org/wiki/Module:Yesno>
-- see page history there for contributors
--

return function( arg, default )
	arg = type( arg ) == 'string' and arg:lower() or arg

	if arg == nil then
		return nil
	end

	if
		arg == true or
		arg == 'yes' or
		arg == 'y' or
		arg == 'true' or
		tonumber( arg ) ==  1
	then
		return true
	end

	if
		arg == false or
		arg == 'no' or
		arg == 'n' or
		arg == 'false' or
		tonumber( arg ) == 0
	then
		return false
	end

	return default
end