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exception IntegerOverflow of unit
(** Signature for a module describing an identifier.
We often need identifiers (for definitions, variables, etc.) and in
order to make sure we don't mix them, we use a generative functor
(see [IdGen]).
*)
module type Id = sig
type id
type 'a vector
val zero : id
val incr : id -> id
val to_string : id -> string
val empty : 'a vector
val id_of_json : Yojson.Basic.t -> (id, string) result
val vector_of_json :
(Yojson.Basic.t -> ('a, string) result) ->
Yojson.Basic.t ->
('a vector, string) result
end
(** Generative functor for identifiers.
See [Id].
*)
module IdGen () : Id = struct
(* TODO: use Int64.t *)
type id = int
type 'a vector = 'a list
let zero = 0
let incr x =
(* Identifiers should never overflow (because max_int is a really big
* value - but we really want to make sure we detect overflows if
* they happen *)
if x == max_int then raise (IntegerOverflow ()) else x + 1
let to_string = string_of_int
let empty = []
let id_of_json js =
match js with
| `Int i -> Ok i
| _ -> Error ("id_of_json: failed on " ^ Yojson.Basic.show js)
let vector_of_json a_of_json js =
OfJsonBasic.combine_error_msgs js "vector_of_json"
(OfJsonBasic.list_of_json a_of_json js)
end
type name = string list [@@deriving yojson]
(** A name such as: `std::collections::vector` (which would be represented as
[["std"; "collections"; "vector"]]) *)
|