function repl(v)
	res, _ = string.gsub(v:gsub('|[()]$', ''), '|[()]', ' \\')
    return res
end

print(repl('abcdef'))
print(repl('abcd|('))
print(repl('abcde|(foo'))
print(repl('abcd|)'))
print(repl('abcde|)foo'))

--if there is no | then do nothing
--if nothing follows of the |( or |) then delete these two characters
--if something follows then replace |( or |) with <space>\