admission protocol for multigroup denial checks

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/protocols/Admission.ml b/lib/protocols/Admission.ml
new file mode 100644
index 0000000..5a20105
--- /dev/null
+++ b/lib/protocols/Admission.ml
@@ -0,0 +1,21 @@
+module Error = struct
+  open Concepts.Condition
+
+  let not_admitting () =
+    condition "not-admitting" "A handle was expected to carry the admission protocol and did not"
+      empty
+end
+
+type violations = (string * Concepts.Tuple.t list) list
+
+class type implementation = object
+  method check : (violations, Concepts.Condition.condition) result
+end
+
+type Handle.protocol += Admission of implementation
+type t = implementation
+
+let make impl = Admission (impl :> implementation)
+let from handle = Handle.into handle (function Admission impl -> Some impl | _ -> None)
+let require handle = from handle |> Option.to_result ~none:(Error.not_admitting ())
+let check i = Handle.invoke i (fun o -> o#check)