def filecommands(self, rev, parent=None):
        if not parent:
            parent_dir = []
        else:
            parent_dir = self.dir_by_id[parent['directory']]
        cur_dir = self.dir_by_id[rev['directory']]
        parent_dir = {f['name']: f for f in parent_dir}
        cur_dir = {f['name']: f for f in cur_dir}

        for fname, f in cur_dir.items():
            if ((fname not in parent_dir
                 or f['sha1'] != parent_dir[fname]['sha1']
                 or f['perms'] != parent_dir[fname]['perms'])):
                yield fastimport.commands.FileModifyCommand(
                    path=f['name'],
                    mode=f['perms'],
                    dataref=self.mark(f['sha1']),
                    data=None,
                )

        for fname, f in parent_dir.items():
            if fname not in cur_dir:
                yield fastimport.commands.FileDeleteCommand(
                    path=f['name']
                )