I think what the GP is saying is to do the re-parsing before/after every time you reformat (and then presumably error exit if the ASTs don't match). When/if you

I think what the GP is saying is to do the re-parsing before/after every time you reformat (and then presumably error exit if the ASTs don't match). When/if you no longer have any known bugs like that you might want to remove it, but it does seem like a good idea until you get there.