diff options
| -rw-r--r-- | library/lib.ml | 19 | ||||
| -rw-r--r-- | library/lib.mli | 6 |
2 files changed, 12 insertions, 13 deletions
diff --git a/library/lib.ml b/library/lib.ml index 904824dc1..f6b25e201 100644 --- a/library/lib.ml +++ b/library/lib.ml @@ -659,17 +659,16 @@ let is_label_n n x = | (sp,Leaf o) when object_tag o = "DOT" && n = outLabel o -> true | _ -> false -(* Reset the label registered by [mark_end_of_command()] with number n. *) +(** Reset the label registered by [mark_end_of_command()] with number n, + which should be strictly in the past. *) + let reset_label n = - let current = current_command_label() in - if n < current then - let res = reset_to_gen (is_label_n n) in - set_command_label (n-1); (* forget state numbers after n only if reset succeeded *) - res - else (* optimisation to avoid recaching when not necessary (why is it so long??) *) - match !lib_stk with - | [] -> () - | x :: ls -> (lib_stk := ls;set_command_label (n-1)) + if n >= current_command_label () then + error "Cannot backtrack to the current label or a future one"; + let res = reset_to_gen (is_label_n n) in + (* forget state numbers after n only if reset succeeded *) + set_command_label (n-1); + res let rec back_stk n stk = match stk with diff --git a/library/lib.mli b/library/lib.mli index 8defad867..419f91317 100644 --- a/library/lib.mli +++ b/library/lib.mli @@ -68,9 +68,9 @@ val mark_end_of_command : unit -> unit (** Returns the current label number *) val current_command_label : unit -> int -(** [reset_label n ] resets [lib_stk] to the label n registered by - [mark_end_of_command()]. That is it forgets the label and anything - registered after it. *) +(** [reset_label n] resets [lib_stk] to the label n registered by + [mark_end_of_command()]. It forgets the label and anything + registered after it. The label should be strictly in the past. *) val reset_label : int -> unit (** {6 ... } *) |