Fix observe id invalidation bug

This bug made navigation sometimes fail in manual mode.

language-server/dm/documentManager.ml

@@ -211,17 +211,21 @@ let interpret_in_background st =
   | None -> (st, [])
   | Some {id} -> log ("interpret_to_end id = " ^ Stateid.to_string id); interpret_to ~stateful:true ~background:true st id
 
+let is_above st id1 id2 =
+  let range1 = Document.range_of_id st id1 in
+  let range2 = Document.range_of_id st id2 in
+  Position.compare range1.start range2.start < 0
+
 let validate_document state =
-  let unchanged_id, invalid_ids, document = Document.validate_document state.document in
-  let update_observe_id id =
-    if Stateid.Set.mem id invalid_ids then unchanged_id
-    else Some id
+  let unchanged_id, invalid_roots, document = Document.validate_document state.document in
+  let observe_id = match unchanged_id, state.observe_id with
+    | None, _ | _, None -> None
+    | Some id, Some id' -> if is_above state.document id id' then Some id else Some id'
   in
-  let observe_id = Option.bind state.observe_id update_observe_id in
   let execution_state =
     List.fold_left (fun st id ->
       ExecutionManager.invalidate (Document.schedule state.document) id st
-      ) state.execution_state (Stateid.Set.elements invalid_ids) in
+      ) state.execution_state (Stateid.Set.elements invalid_roots) in
   { state with document; execution_state; observe_id }
 
 let init init_vs ~opts uri ~text =

language-server/tests/dm_tests.ml

@@ -357,3 +357,26 @@ let%test_unit "edit.shift_error_before_sentence" =
   let warning = Stdlib.List.hd @@ DocumentManager.all_diagnostics st in
   [%test_eq: int] 41 (warning.range.start.character);
   [%test_eq: int] 42 (warning.range.end_.character)
+
+let%test_unit "edit.edit_non_root_observe_id_top" =
+  let st, init_events = init_test_doc ~text:"Definition x := 1. Definition y := 2." in
+  let st, (s1, (s2, ())) = dm_parse st (P(P O)) in
+  let st, events = DocumentManager.interpret_to_end st in
+  let todo = Sel.Todo.(add empty init_events) in
+  let todo = Sel.Todo.(add todo events) in
+  let st = handle_events todo st in
+  let st = edit_text st ~start:0 ~stop:18 ~text:"Definition x := 3." in
+  [%test_eq: bool] (ExecutionManager.is_executed (DocumentManager.Internal.execution_state st) s2.id) false;
+  [%test_eq: int option] (Option.map ~f:Stateid.to_int (DocumentManager.Internal.observe_id st)) None
+
+let%test_unit "edit.edit_non_root_observe_id" =
+  let st, init_events = init_test_doc ~text:"Definition x := 1. Definition y := 2. Definition z := 3." in
+  let st, (s1, (s2, (s3, ()))) = dm_parse st (P(P(P O))) in
+  let st, events = DocumentManager.interpret_to_end st in
+  let todo = Sel.Todo.(add empty init_events) in
+  let todo = Sel.Todo.(add todo events) in
+  let st = handle_events todo st in
+  let st = edit_text st ~start:19 ~stop:37 ~text:"Definition y := 4." in
+  [%test_eq: bool] (ExecutionManager.is_executed (DocumentManager.Internal.execution_state st) s3.id) false;
+  [%test_eq: int option] (Option.map ~f:Stateid.to_int (DocumentManager.Internal.observe_id st))
+    (Some (Stateid.to_int s1.id))