text editor issue is a problem with focus resolution

might require Focus.release, but may be incorrect use of Focus.request.

human.ml

@@ -1333,6 +1333,10 @@ module Nottui = struct
   module Ui = struct
     type may_handle = [ `Unhandled | `Handled ]
 
+    let may_handle (type a) (v : a option) (f : a -> may_handle) :
+        may_handle =
+      match v with Some v' -> f v' | None -> `Unhandled
+
     let pp_may_handle ppf = function
       | `Unhandled -> F.pf ppf "`Unhandled"
       | `Handled -> F.pf ppf "`Handled"
@@ -2722,13 +2726,21 @@ module Nottui_widgets = struct
 
   open Lwd.Infix
 
+  let eq_uc_c uc c = Uchar.(equal uc (of_char c))
+
   type line = {
     focus : Focus.handle;
     state : (string * int) Lwd.var;
     ui : Ui.t Lwd.t;
   }
 
-  let eq_uc_c uc c = Uchar.(equal uc (of_char c))
+  let line_make ?(focus = Focus.make ()) str =
+    let state = Lwd.var (str, 0) in
+    { focus; state; ui = edit_field ~focus state }
+
+  let line_append ?(table = Lwd_table.make ()) ?focus str =
+    let row = Lwd_table.append table in
+    Lwd_table.set row (line_make ?focus str)
 
   let copy_line_cursor (x : line) (y : line) =
     let _, xi = Lwd.peek x.state in
@@ -2736,43 +2748,33 @@ module Nottui_widgets = struct
     let yi = Int.max 0 (Int.min xi (String.length ys)) in
     Lwd.set y.state (ys, yi)
 
+  let row_of_cursor cursor f =
+    Ui.may_handle (Lwd.peek cursor) (fun row -> f row)
+
   let line_of_cursor cursor
       (f : line Lwd_table.row -> line -> Ui.may_handle) :
       Ui.may_handle =
-    match Lwd.peek cursor with
+    Ui.may_handle (Lwd.peek cursor) (fun row ->
-    | Some row -> (
+        Ui.may_handle (Lwd_table.get row) (fun line -> f row line))
-        match Lwd_table.get row with
-        | Some line -> f row line
-        | None -> `Unhandled)
-    | None -> `Unhandled
 
   let cursor_move cursor
       (f : line Lwd_table.row -> line Lwd_table.row option) =
     match Lwd.peek cursor with
-    | Some cursor_line -> (
+    | Some cursor_row -> (
-        match f cursor_line with
+        match f cursor_row with
+        | Some new_row ->
+            (match Lwd_table.get new_row with
             | Some new_line ->
-            (match Lwd_table.get new_line with
+                cursor_row |> Lwd_table.get
-            | Some line' ->
+                |> Option.iter (fun cursor_line ->
-                cursor_line |> Lwd_table.get
+                       copy_line_cursor cursor_line new_line);
-                |> Option.iter (fun line ->
+                Focus.request new_line.focus
-                       copy_line_cursor line line');
-                Focus.request line'.focus
             | None -> ());
-            Lwd.set cursor (Some new_line);
+            Lwd.set cursor (Some new_row);
             `Handled
         | None -> `Unhandled)
     | None -> `Unhandled
 
-  let line_make ?(focus = Focus.make ()) str =
-    let state = Lwd.var (str, 0) in
-    { focus; state; ui = edit_field ~focus state }
-
-  let line_append ?(table = Lwd_table.make ())
-      ?(focus = Focus.make ()) str =
-    let row = Lwd_table.append table in
-    Lwd_table.set row (line_make ~focus str)
-
   let line_table_of_string ?(table = Lwd_table.make ())
       ?(focus = Focus.make ()) (s : string) : Ui.t Lwd.t =
     (* Append lines from s to table *)
@@ -2832,12 +2834,12 @@ module Nottui_widgets = struct
                                let str_prev, _ =
                                  Lwd.peek line_prev.state
                                in
+                               Focus.request line_prev.focus;
                                Lwd.set line_prev.state
                                  ( str_prev ^ str,
                                    String.length str_prev );
-                               Focus.request line_prev.focus;
-                               Lwd_table.remove row;
                                Lwd.set cursor (Some row_prev);
+                               Lwd_table.remove row;
                                `Handled
                            | None -> `Unhandled)
                        | _ -> `Unhandled)