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|
module Error = struct
open Concepts.Condition
let unknown_relation name =
condition "unknown-relation" "A plan named a relation that does not exist under this snapshot"
("name" |=| Concepts.Value.String name)
let cancelled () =
condition "evaluation-cancelled" "An evaluation was stopped before it produced its result" empty
end
type plan = Base of string
module Program = Protocols.Program.Make (struct
type t = plan
end)
let execute context = function
| Base name ->
let open Utilities.Result in
match context.Protocols.Context.status () with
| `Cancelled | `Exhausted -> Error (Error.cancelled ())
| `Live ->
let* found = Runtime.Context.resolve context name in
let* handle = Option.to_result ~none:(Error.unknown_relation name) found in
Fun.protect
~finally:(fun () -> Protocols.Handle.release handle)
(fun () ->
let* enumerable = Protocols.Enumerable.require handle in
Protocols.Enumerable.enumerate enumerable context)
class evaluator = object (self)
inherit Kernel.Lifecycle.null
inherit Kernel.Identity.of_id
method invoke ~program context = execute context program
method protocols : Protocols.Handle.protocol list = [Program.make self]
end
let make () = new evaluator |> Protocols.Handle.make
|
