259     struct transform_impl  struct
261         typedef Expr const expr;
262         typedef Expr const &expr_param;
263         typedef State const state;
264         typedef State const &state_param;
265         typedef Data const data;
266         typedef Data const &data_param;
270     struct transform_impl<Expr &, State, Data>  struct
272         typedef Expr expr;
273         typedef Expr &expr_param;
274         typedef State const state;
275         typedef State const &state_param;
276         typedef Data const data;
277         typedef Data const &data_param;
281     struct transform_impl<Expr, State &, Data>  struct
283         typedef Expr const expr;
284         typedef Expr const &expr_param;
285         typedef State state;
286         typedef State &state_param;
287         typedef Data const data;
288         typedef Data const &data_param;
292     struct transform_impl<Expr, State, Data &>  struct
294         typedef Expr const expr;
295         typedef Expr const &expr_param;
296         typedef State const state;
297         typedef State const &state_param;
298         typedef Data data;
299         typedef Data &data_param;
303     struct transform_impl<Expr &, State &, Data>  struct
305         typedef Expr expr;
306         typedef Expr &expr_param;
307         typedef State state;
308         typedef State &state_param;
309         typedef Data const data;
310         typedef Data const &data_param;
314     struct transform_impl<Expr &, State, Data &>  struct
316         typedef Expr expr;
317         typedef Expr &expr_param;
318         typedef State const state;
319         typedef State const &state_param;
320         typedef Data data;
321         typedef Data &data_param;
325     struct transform_impl<Expr, State &, Data &>  struct
327         typedef Expr const expr;
328         typedef Expr const &expr_param;
329         typedef State state;
330         typedef State &state_param;
331         typedef Data data;
332         typedef Data &data_param;
336     struct transform_impl<Expr &, State &, Data &>  struct
338         typedef Expr expr;
339         typedef Expr &expr_param;
340         typedef State state;
341         typedef State &state_param;
342         typedef Data data;
343         typedef Data &data_param;