From bb48738c4111f5f4e2faa40fe67ae1b8b9d7c2eb Mon Sep 17 00:00:00 2001
From: Sébastien Dailly <sebastien@chimrod.com>
Date: Wed, 29 Nov 2017 15:51:39 +0100
Subject: Rework on the Sheet.ml API : removed low level functions, made the
 sheet mutable

---
 src/actionParser.mly |   4 +-
 src/actions.mli      |   2 +-
 src/main.ml          | 201 +++++++++++++++++++++++++--------------------------
 src/odf/odf.ml       |   2 +-
 src/odf/odfLoader.ml |  10 +--
 src/screen.ml        |  64 +++++++---------
 src/screen.mli       |  11 ++-
 src/selection.ml     |  14 ++++
 src/selection.mli    |   2 +
 src/sheet.ml         | 167 +++++++++++++++++-------------------------
 src/sheet.mli        |  81 +++++----------------
 tests/sheet_test.ml  | 150 ++++++++++++++++++--------------------
 12 files changed, 310 insertions(+), 398 deletions(-)

diff --git a/src/actionParser.mly b/src/actionParser.mly
index 6318ca6..296467a 100755
--- a/src/actionParser.mly
+++ b/src/actionParser.mly
@@ -7,7 +7,6 @@
 %token EOF
 %token LEFT RIGHT UP DOWN
 %token NPAGE PPAGE HOME END
-%token RESIZE
 %token DELETE
 %token SEARCH
 %token E U V Y P
@@ -16,6 +15,7 @@
 %token <int*int>BUTTON1_CLICKED
 %token <int*int>BUTTON1_RELEASED
 %token COMMAND
+%token RESIZE
 
 %start <Actions.actions> normal
 %%
@@ -27,7 +27,6 @@ normal:
   | RIGHT  { Move (Right 1) }
   | UP     { Move (Up 1) }
   | DOWN   { Move (Down 1) }
-  | RESIZE { Resize }
   | DELETE { Delete }
   | E      { Edit }
   | U      { Undo }
@@ -43,3 +42,4 @@ normal:
   | BUTTON1_CLICKED { Button1_clicked $1}
   | BUTTON1_RELEASED{ Button1_released $1}
   | COMMAND { Command }
+  | RESIZE  { Resize }
diff --git a/src/actions.mli b/src/actions.mli
index f955538..9a59aa1 100755
--- a/src/actions.mli
+++ b/src/actions.mli
@@ -13,7 +13,6 @@ type modes =
 
 type actions =
 | Move of direction
-| Resize            (* Resize event *)
 | Escape
 | Delete
 | Yank
@@ -26,3 +25,4 @@ type actions =
 | Button1_clicked of (int * int)
 | Button1_released of (int * int)
 | Command
+| Resize
diff --git a/src/main.ml b/src/main.ml
index 8e557ce..4e49aa3 100755
--- a/src/main.ml
+++ b/src/main.ml
@@ -2,17 +2,15 @@ module E:Sym_expr.SYM_EXPR = Evaluate
 
 let u = UTF8.from_utf8string
 
-let redraw t screen =
-  let screen' =
-     Screen.draw t screen
-  |> Screen.draw_input t in
-  t, screen'
-
-let action f msg (t, screen) = begin
-  let t', count = f t in
-  let t', screen' = redraw t' screen in
-  Screen.status screen' @@ UTF8.from_utf8string (Printf.sprintf msg count);
-  t', screen'
+let redraw t screen selection =
+  Screen.draw t selection screen;
+  Screen.draw_input t selection screen
+
+let action f msg (t, screen, selection) = begin
+  let count = f t in
+  redraw t screen selection;
+  Screen.status screen @@ UTF8.from_utf8string (Printf.sprintf msg count);
+  t, screen, selection
 end
 
 let catalog = Functions.C.compile @@ Functions.built_in Functions.C.empty
@@ -67,187 +65,188 @@ let parser screen = begin
   menhirParser get_value
 end
 
-let rec normal_mode (t, screen) = begin
+let rec normal_mode (t, screen, selection) = begin
   match (parser screen) with
-  | exception x -> normal_mode (t, screen)
+  | exception x -> normal_mode (t, screen, selection)
 
   | Actions.Visual ->
       Screen.status screen @@ u"-- Selection --";
-      selection_mode (t, screen)
+      selection_mode (t, screen, selection)
 
   | Actions.Move direction ->
-      begin match Sheet.move direction t with
-      | Some t' -> normal_mode @@ redraw t' screen
-      | None -> normal_mode (t, screen)
+      begin match Selection.move direction selection with
+      | Some selection ->
+          redraw t screen selection;
+          normal_mode (t, screen, selection)
+      | None -> normal_mode (t, screen, selection)
       end
 
-  | Actions.Resize -> normal_mode (t, Screen.resize t screen)
+  | Actions.Resize -> normal_mode (t, Screen.resize t selection screen, selection)
 
   | Actions.Delete ->
-      let yank_before_delete = fun x -> Sheet.delete (fst (Sheet.yank x)) in
-      normal_mode @@ action yank_before_delete "Deleted %d cells" (t, screen)
+      let yank_before_delete = fun x ->
+        ignore @@ Sheet.yank selection x;
+        Sheet.delete selection x in
+      normal_mode @@ action yank_before_delete "Deleted %d cells" (t, screen, selection)
 
   | Actions.Yank ->
-      normal_mode @@ action Sheet.yank "Yanked %d cells" (t, screen)
+      normal_mode @@ action (Sheet.yank selection) "Yanked %d cells" (t, screen, selection)
 
   | Actions.Paste ->
-      normal_mode @@ action Sheet.paste "Pasted %d cells" (t, screen)
+      let paste = Sheet.paste @@ Selection.extract selection in
+      normal_mode @@ action paste "Pasted %d cells" (t, screen, selection)
 
   | Actions.Undo ->
       begin match Sheet.undo t with
-      | Some t' -> normal_mode @@ redraw t' screen
-      | None -> normal_mode (t, screen)
+      | true ->
+        redraw t screen selection;
+        normal_mode (t, screen, selection)
+      | false -> normal_mode (t, screen, selection)
       end
 
   (* Edit a content *)
   | Actions.Edit ->
-    let position = Selection.extract t.Sheet.selected in
-    let expr = Sheet.Raw.get_expr position t.Sheet.data
-            |> Expression.show in
-    begin match Screen.editor ~position ~prefix:(u"-> ") ~init:expr screen with
+    let position = Selection.extract selection in
+    let expr, _, _ = Sheet.get_cell position t in
+    let expr_repr = Expression.show expr in
+    begin match Screen.editor ~position ~prefix:(u"-> ") ~init:expr_repr screen with
     | None ->
       (* Restore the previous value *)
-      Screen.status screen expr;
-      normal_mode (t, screen)
+      Screen.status screen expr_repr;
+      normal_mode (t, screen, selection)
     | Some content ->
       let expr' = Expression.load content in
-      let _, t' = Sheet.add expr' t in
-      normal_mode @@ redraw t' screen
+      ignore @@ Sheet.add ~history:true expr' position t;
+      redraw t screen selection;
+      normal_mode (t, screen, selection)
     end
 
   (* Insert a new formula, the actual value will be erased *)
   | Actions.InsertFormula ->
-    let position = Selection.extract t.Sheet.selected in
+    let position = Selection.extract selection in
     begin match Screen.editor ~position ~init:(u"=") screen with
     | None ->
       (* Restore the previous value *)
-      let expr = Sheet.Raw.get_expr position t.Sheet.data
-              |> Expression.show in
-      Screen.status screen expr;
-      normal_mode (t, screen)
+      let expr, _, _ = Sheet.get_cell position t in
+      Screen.status screen (Expression.show expr);
+      normal_mode (t, screen, selection)
     | Some content ->
       let expr = Expression.load content in
-      let _, t' = Sheet.add expr t in
-      normal_mode @@ redraw t' screen
+      ignore @@ Sheet.add ~history:true expr position t;
+      redraw t screen selection;
+      normal_mode (t, screen, selection)
     end
 
-(*
-  | Actions.Search ->
-    let expr = Screen.search screen
-    |> Expression.load in
-    (*let pattern = Expression.eval expr (fun _ -> ScTypes.Refs.Single None) in*)
-    let pattern = Expression.eval' expr catalog in
-    begin match Sheet.search (`Pattern (Some pattern)) t with
-    | Some t' -> normal_mode @@ redraw t' screen
-    | None -> normal_mode (t, screen)
-    end
-*)
-
   | Actions.Button1_clicked coord ->
     begin match Screen.get_cell screen coord with
-    | None -> normal_mode (t, screen)
-    | Some (x,y) -> begin match Sheet.move (Actions.Absolute (x,y)) t with
-        | Some t' -> normal_mode @@ redraw t' screen
-        | None -> normal_mode (t, screen)
+    | None -> normal_mode (t, screen, selection)
+    | Some (x,y) -> begin match Selection.move (Actions.Absolute (x,y)) selection with
+        | Some selection' ->
+            redraw t screen selection';
+            normal_mode (t, screen, selection')
+        | None -> normal_mode (t, screen, selection)
       end
     end
 
   | Actions.Button1_released coord ->
     begin match Screen.get_cell screen coord with
-    | Some (x,y) when (x,y) <> (Selection.extract t.Sheet.selected) ->
+    | Some (x,y) when (x,y) <> (Selection.extract selection) ->
       Screen.status screen @@ u"-- Selection -- ";
-      let t' = { t with
-        Sheet.selected = Selection.extends (Actions.Absolute (x,y)) t.Sheet.selected
-      } in
-      let screen' = Screen.draw t' screen in
-      selection_mode (t', screen')
-    | _ -> normal_mode (t, screen)
+      let selection = Selection.extends (Actions.Absolute (x,y)) selection in
+      Screen.draw t selection screen;
+      selection_mode (t, screen, selection)
+    | _ -> normal_mode (t, screen, selection)
     end
 
   | Actions.Command ->
     begin match Screen.editor ~prefix:(u":") screen with
     | None ->
-      normal_mode (t, screen)
+      normal_mode (t, screen, selection)
     | Some content ->
         let args = try
           UTF8.to_utf8string content
           |> Tools.String.split ~by:' '
         with Not_found ->
           (UTF8.to_utf8string content, "") in
-        command (t, screen) args
+        command (t, screen, selection) args
     end
 
-  | _ -> normal_mode (t, screen)
+  | _ -> normal_mode (t, screen, selection)
 
 end
 
-and selection_mode (t, screen) = begin
+and selection_mode (t, screen, selection) = begin
   match (parser screen) with
-  | exception x -> selection_mode (t, screen)
+  | exception x -> selection_mode (t, screen, selection)
 
-  | Actions.Resize -> selection_mode (t, Screen.resize t screen)
+  | Actions.Resize -> selection_mode (t, Screen.resize t selection screen, selection)
 
   | Actions.Delete ->
-     let yank_before_delete = fun x -> Sheet.delete (fst (Sheet.yank x)) in
-     normal_mode @@ action yank_before_delete "Deleted %d cells" (t, screen)
+    let yank_before_delete = fun x ->
+      ignore @@ Sheet.yank selection x;
+      Sheet.delete selection x in
+    normal_mode @@ action yank_before_delete "Deleted %d cells" (t, screen, selection)
 
   | Actions.Yank ->
-     normal_mode @@ action Sheet.yank "Yanked %d cells" (t, screen)
+    normal_mode @@ action (Sheet.yank selection) "Yanked %d cells" (t, screen, selection)
 
   | Actions.Escape ->
-     let t' = { t with Sheet.selected = Selection.create (Selection.extract t.Sheet.selected) } in
-     let screen' = Screen.draw t' screen
-                |> Screen.draw_input t' in
-     Screen.status screen UTF8.empty;
-     normal_mode (t', screen')
+    let selection = Selection.create (Selection.extract selection) in
+    Screen.draw t selection screen;
+    Screen.draw_input t selection screen;
+    Screen.status screen UTF8.empty;
+    normal_mode (t, screen, selection)
 
   | Actions.Move m ->
-     let t' = { t with Sheet.selected = Selection.extends m t.Sheet.selected } in
-     let screen' = Screen.draw t' screen in
-     selection_mode (t', screen')
+    let selection = Selection.extends m selection in
+    Screen.draw t selection screen;
+    selection_mode (t, screen, selection)
 
   | Actions.Button1_clicked coord ->
     begin match Screen.get_cell screen coord with
-    | None -> normal_mode (t, screen)
-    | Some (x,y) -> begin match Sheet.move (Actions.Absolute (x,y)) t with
-      | Some t' ->
+    | None -> normal_mode (t, screen, selection)
+    | Some (x,y) -> begin match Selection.move (Actions.Absolute (x,y)) selection with
+      | Some selection ->
           Screen.status screen UTF8.empty;
-          normal_mode @@ redraw t' screen
-      | None -> normal_mode (t, screen)
+          redraw t screen selection;
+          normal_mode (t, screen, selection)
+      | None -> normal_mode (t, screen, selection)
       end
     end
 
-  | _ -> selection_mode (t, screen)
+  | _ -> selection_mode (t, screen, selection)
 end
 
-and command (t, screen) action = begin
+and command (t, screen, selection) action = begin
   match action with
   | ("w", file) -> (* Save the file *)
-      Odf.save t.Sheet.data file;
-      normal_mode @@ redraw t screen
-(*
-  | ("repr", file) -> (* Save the file *)
-      let out_gv = open_out_bin file in
-      let form = Format.formatter_of_out_channel out_gv in
-      Evaluator.repr form (Evaluator.get_catalog ());
-      close_out out_gv;
-      normal_mode @@ redraw t screen
-*)
+      Odf.save t file;
+      redraw t screen selection;
+      normal_mode (t, screen, selection)
   | ("enew", _) -> (* Start a new spreadsheet *)
-      normal_mode @@ redraw (Sheet.create catalog Sheet.Raw.empty) screen
+      let selection = Selection.create (1, 1)
+      and sheet = Sheet.create catalog in
+      redraw sheet screen selection;
+      normal_mode (sheet, screen, selection)
   | ("q", _) ->  (* Quit *)
       t
-  | _ -> normal_mode @@ redraw t screen
+  | _ ->
+      redraw t screen selection;
+      normal_mode (t, screen, selection)
 end
 
 let () = begin
 
   let sheet =
     if Array.length Sys.argv = 1 then
-      Sheet.Raw.empty
+      Sheet.create catalog
     else
-      Odf.load catalog Sys.argv.(1) in
+      Odf.load catalog Sys.argv.(1)
+
+  and selection = Selection.create (1, 1) in
 
   Screen.run (fun window ->
-      ignore @@ normal_mode @@ redraw (Sheet.create catalog sheet) window)
+    redraw sheet window selection;
+    ignore @@ normal_mode (sheet, window, selection)
+  )
 end
diff --git a/src/odf/odf.ml b/src/odf/odf.ml
index 176e70a..1db9d4b 100755
--- a/src/odf/odf.ml
+++ b/src/odf/odf.ml
@@ -210,7 +210,7 @@ let save sheet file = begin
           Xmlm.output output (`El_start (NS.table_node, []));
 
             Xmlm.output output (`El_start (NS.table_row_node, []));
-            ignore (Sheet.Raw.fold (f output) (1,1) sheet);
+            ignore (Sheet.fold (f output) (1,1) sheet);
             Xmlm.output output `El_end;
 
           Xmlm.output output `El_end;
diff --git a/src/odf/odfLoader.ml b/src/odf/odfLoader.ml
index 93a6c62..280e6bd 100755
--- a/src/odf/odfLoader.ml
+++ b/src/odf/odfLoader.ml
@@ -83,7 +83,7 @@ let build_p (attributes:Xmlm.attribute list) = begin function
 end
 
 
-let build_row (sheet:Sheet.Raw.t ref) (row_num:int ref) catalog (attributes:Xmlm.attribute list) (childs:tree list) = begin
+let build_row (sheet:Sheet.t) (row_num:int ref) (attributes:Xmlm.attribute list) (childs:tree list) = begin
 
   let repetition =
     try int_of_string @@ List.assoc (NS.table, "number-rows-repeated") attributes
@@ -94,7 +94,7 @@ let build_row (sheet:Sheet.Raw.t ref) (row_num:int ref) catalog (attributes:Xmlm
     List.iter (function
     | Cell cell ->
       for i = 1 to cell.repetition do
-        sheet := snd @@ Sheet.Raw.add (!cell_num, !row_num) cell.expression catalog !sheet;
+        ignore @@ Sheet.add ~history:false cell.expression (!cell_num, !row_num) sheet;
         cell_num := !cell_num + cell.cell_width
       done;
     | _ -> ()
@@ -109,13 +109,13 @@ let data str = Data str
 let load catalog source = begin
 
   (* Mutable datas *)
-  let sheet = ref Sheet.Raw.empty in
+  let sheet = Sheet.create catalog in
   let cache = Hashtbl.create 10 in
 
   let table = Base.String_dict.of_alist_exn [
     ((NS.text ^ "p"), build_p);
     ((NS.table ^ "table-cell"), build_cell cache);
-    ((NS.table ^ "table-row"), build_row sheet (ref 1) catalog)
+    ((NS.table ^ "table-row"), build_row sheet (ref 1))
   ] in
 
   let el (((ns, name), attributes):Xmlm.tag) childs = begin
@@ -125,6 +125,6 @@ let load catalog source = begin
   end in
 
   match Xmlm.input_doc_tree ~el ~data source with
-  | _, Unit -> !sheet
+  | _, Unit -> sheet
   | _ -> raise Not_found
 end
diff --git a/src/screen.ml b/src/screen.ml
index c61efea..7888ba5 100755
--- a/src/screen.ml
+++ b/src/screen.ml
@@ -32,16 +32,14 @@ let get_cell screen (x, y) = begin
     Some (x', y')
 end
 
-let center data screen height width = begin
+let center data position screen height width = begin
   let height' = height - 3
   and width'  = (width - screen.left_margin) / cell_size in
   let end_x = (fst screen.start) + width' -1 in
   let end_y = (snd screen.start) + height' -2 in
 
-  let selected = Selection.extract data.Sheet.selected in
-
   let center_axis f replace max_limit shift screen = begin
-    let selected_axis = f selected in
+    let selected_axis = f position in
     match (selected_axis >= f screen.start), (selected_axis > max_limit) with
     | true, false  -> screen
     | _ -> { screen with  start = replace (max 1 (selected_axis - shift)) screen.start }
@@ -65,23 +63,20 @@ let status screen msg = begin
 end
 
 (** Draw the spreadsheet *)
-let draw data screen = begin
-
-  let selected = Selection.extract data.Sheet.selected in
+let draw data selected screen = begin
 
-  let referenced =
-       Sheet.Raw.get_expr selected data.Sheet.data
-    |> Expression.collect_sources
+  let position = Selection.extract selected in
 
-  and sink = Sheet.Raw.get_sink selected data.Sheet.data in
+  let expr, _, sink = Sheet.get_cell position data in
+  let referenced = Expression.collect_sources expr in
 
   let height, width = screen.size in
-  let screen = center data screen height width in
+  let screen = center data position screen height width in
 
   for y = 1 to (height-2) do
     let pos_y = (y + (snd screen.start) - 1) in
     if (Curses.has_colors ()) then begin
-      if Selection.is_selected (Selection.Vertical pos_y) data.Sheet.selected then
+      if Selection.is_selected (Selection.Vertical pos_y) selected then
         Curses.wattrset screen.sheet (Attrs.color_pair 2 )
       else
         Curses.wattrset screen.sheet (Attrs.color_pair 1 )
@@ -95,7 +90,7 @@ let draw data screen = begin
   for x = 0 to ((width - cell_size - screen.left_margin) / cell_size) do
     let pos_x = x + (fst screen.start) in
     if (Curses.has_colors ()) then begin
-      if Selection.is_selected (Selection.Horizontal pos_x) data.Sheet.selected then
+      if Selection.is_selected (Selection.Horizontal pos_x) selected then
         Curses.wattrset screen.sheet (Attrs.color_pair 2 )
       else
         Curses.wattrset screen.sheet (Attrs.color_pair 1 )
@@ -112,7 +107,7 @@ let draw data screen = begin
       let pos_y = y + (snd screen.start) - 1 in
 
       if (Curses.has_colors ()) then begin
-        if Selection.is_selected (Selection.Cell (pos_x, pos_y)) data.Sheet.selected then
+        if Selection.is_selected (Selection.Cell (pos_x, pos_y)) selected then
           Curses.wattrset screen.sheet (Attrs.color_pair 3 )
         else if Cell.Set.mem (pos_x, pos_y) referenced then
           Curses.wattrset screen.sheet (Attrs.color_pair 4 )
@@ -124,8 +119,9 @@ let draw data screen = begin
 
 
       (* Get the content from the cell *)
-      let content = Sheet.Raw.get_value (pos_x, pos_y) data.Sheet.data
-        |> Option.map (fun x -> UTF8.split ~sep:(u"\n") (ScTypes.Result.show x))
+
+      let _, value, _ = Sheet.get_cell (pos_x, pos_y) data in
+      let content = Option.map (fun x -> UTF8.split ~sep:(u"\n") (ScTypes.Result.show x)) value
         |> Option.default UTF8.empty in
 
       (* If the content is defined, try to encode it and print it*)
@@ -143,8 +139,7 @@ let draw data screen = begin
       )
     done
   done;
-  ignore @@ Curses.wrefresh screen.sheet;
-  screen
+  ignore @@ Curses.wrefresh screen.sheet
 
 end
 
@@ -190,15 +185,13 @@ let close {window} = begin
   Curses.endwin()
 end
 
-let draw_input t screen = begin
+let draw_input t selected screen = begin
 
   let height, width = screen.size in
 
-  let expr = Sheet.Raw.get_expr (Selection.extract t.Sheet.selected) t.Sheet.data
-          |> Expression.show in
+  let expr, value, _ = Sheet.get_cell (Selection.extract selected) t in
 
-  let result = Sheet.Raw.get_value (Selection.extract t.Sheet.selected) t.Sheet.data
-            |> Option.map ScTypes.Result.show
+  let result = Option.map ScTypes.Result.show value
             |> Option.default UTF8.empty in
 
   UTF8.encode result |> Option.iter (fun encoded_result ->
@@ -214,11 +207,14 @@ let draw_input t screen = begin
 
     && Curses.wrefresh screen.input)
   );
-  status screen expr;
-  screen
+  status screen (Expression.show expr);
+  ()
 end
 
-(** Wait for an event and return the key pressed
+(** Wait for an event and return the key pressed.
+
+    Non blocking for other running Lwt thread.
+
     If the key code contains more than one char, they are both returned
  *)
 let read_key {window} = begin
@@ -238,7 +234,7 @@ let read_key {window} = begin
   Buffer.contents buff
 end
 
-let resize data t = begin
+let resize data selection t = begin
   let size = Curses.getmaxyx t.window in
   if (size <> t.size) then (
     let height, width = size in
@@ -253,7 +249,8 @@ let resize data t = begin
     && Curses.mvwin t.status (height - 1) 0);
     Curses.wclear t.status;
     ignore @@ Curses.wrefresh t.status;
-    draw data t
+    draw data selection t;
+    t
   ) else t
 end
 
@@ -441,15 +438,6 @@ let editor ?position ?(prefix=UTF8.empty) ?(init=UTF8.empty) t = begin
       try _edit (UTF8.rev_explode init) [] @@ read_key t
       with _ -> None)
     (fun () -> ignore @@ Curses.curs_set 0)
-
-end
-
-let search screen = begin
-  let result = editor ~prefix:(u"/") screen in
-  begin match result with
-  | Some content -> content
-  | None -> UTF8.empty
-  end
 end
 
 let run f =
diff --git a/src/screen.mli b/src/screen.mli
index b5f74b2..0d9dc69 100755
--- a/src/screen.mli
+++ b/src/screen.mli
@@ -7,11 +7,11 @@ val run: (t -> 'a) -> 'a
 
 (** {2 Screen updates} *)
 
-val draw: Sheet.t -> t -> t
+val draw: Sheet.t -> Selection.t -> t -> unit
 
-val draw_input: Sheet.t -> t -> t
+val draw_input: Sheet.t -> Selection.t -> t -> unit
 
-val resize: Sheet.t -> t -> t 
+val resize: Sheet.t -> Selection.t -> t -> t 
 
 (** Display a message in the status bar. *)
 val status: t -> UTF8.t -> unit
@@ -22,8 +22,7 @@ val status: t -> UTF8.t -> unit
 val read_key : t -> string
 (** The keycode is always NULL terminated *)
 
-val search: t -> UTF8.t
-
-val get_cell: t -> int * int -> (int * int) option
+(** Get the cell matching the terminal coordinates *)
+val get_cell: t -> int * int -> Sheet.cell option
 
 val editor: ?position: int * int -> ?prefix:UTF8.t -> ?init:UTF8.t -> t -> UTF8.t option
diff --git a/src/selection.ml b/src/selection.ml
index 2bf41ce..28e11fa 100755
--- a/src/selection.ml
+++ b/src/selection.ml
@@ -71,3 +71,17 @@ end
 let shift = function
   | Single (start_x, start_y) -> fun (x, y) -> (x - start_x, y - start_y)
   | Multiple ((start_x, start_y), _) -> fun (x, y) -> (x - start_x, y - start_y)
+
+let move direction t =
+  let position = extract t in
+  let position' = begin match direction with
+  | Actions.Left quant ->  Tools.Tuple2.replace1 (max 1 ((fst position) - quant)) position
+  | Actions.Right quant -> Tools.Tuple2.replace1 ((fst position) + quant) position
+  | Actions.Up quant ->    Tools.Tuple2.replace2 (max 1 ((snd position) - quant)) position
+  | Actions.Down quant ->  Tools.Tuple2.replace2 ((snd position) + quant) position
+  | Actions.Absolute (x, y)-> (x, y)
+  end in
+  if position = position' then
+    None
+  else
+    Some (create position')
diff --git a/src/selection.mli b/src/selection.mli
index fb207e4..aa14e38 100755
--- a/src/selection.mli
+++ b/src/selection.mli
@@ -18,3 +18,5 @@ val shift: t -> (int * int) -> (int * int)
 val fold: ('a -> int * int -> 'a) -> 'a -> t -> 'a
 
 val extends:  Actions.direction -> t -> t
+
+val move: Actions.direction -> t -> t option
diff --git a/src/sheet.ml b/src/sheet.ml
index 6d3c34a..881bf58 100755
--- a/src/sheet.ml
+++ b/src/sheet.ml
@@ -1,11 +1,5 @@
 type cell = int * int
 
-type search = [
-  | `Pattern of ScTypes.Result.t option
-  | `Next
-  | `Previous
-]
-
 module Raw = struct
 
   type content = {
@@ -25,14 +19,10 @@ module Raw = struct
   of 8×8 cells, and each array is stored in a tree. *)
   module Map = PageMap.SplayMap(struct type t = content let default = empty_cell end)
 
-  type t = Map.t
-
   (** The sheet is a map which always contains evaluated values. When a cell is
       updated, all the cell which references this value are also updated.
     *)
-  let empty = Map.empty
-
-  let get_value id t = (Map.find id t).value
+  type t = Map.t
 
   let get_expr id t = (Map.find id t).expr
 
@@ -41,7 +31,7 @@ module Raw = struct
       @return Some map if the map has been updated
    *)
   let update catalog cell content t = begin
-    let new_val = Expression.eval content.expr catalog (fun id -> get_value id t) in
+    let new_val = Expression.eval content.expr catalog (fun id -> (Map.find id t).value) in
     match content.value with
     | None ->
       (* If the previous value wasn't defined, update the map *)
@@ -188,7 +178,7 @@ module Raw = struct
       let f cell t = begin
         { cell with
           expr = expression ;
-          value = Some (Expression.eval expression catalog (fun id -> get_value id t)) }
+          value = Some (Expression.eval expression catalog (fun id -> (Map.find id t).value)) }
       end in
       add_element catalog id f t
   end
@@ -198,147 +188,120 @@ module Raw = struct
     let f cell t =
       { cell with
         expr = expr ;
-        value = Some (Expression.eval expr catalog (fun id -> get_value id t))
+        value = Some (Expression.eval expr catalog (fun id -> (Map.find id t).value))
       } in
     add_element catalog id f t
   end
 
-  let search pattern t = begin
-    let exception Found of (int * int) in
-
-    let _search key content () =
-      if content.value = pattern then raise (Found key) in
-
-    try
-      (* Iteration*)
-      Map.fold _search t ();
-      None
-    with Found key -> Some key
-  end
-
   let get_sink id t =
     try (Map.find id t).sink
     with Not_found -> Cell.Set.empty
 
-  (** Fold over each defined value *)
-  let fold f a t = begin
-    Map.fold (fun key content a ->
-      match content.value with
-      | None -> a
-      | Some x ->
-        f a key (content.expr, x)
-    ) t a
-  end
-
 end
 
-type yank = cell * Raw.content
-type history = ((cell * Expression.t) list) list
-
-type t = {
-  selected: Selection.t;    (* The selected cell *)
+type sheet = {
   data: Raw.t;
-  history: history;    (* Unlimited history *)
-  yank: yank list;
+  history: ((cell * Expression.t) list) list;    (* Unlimited history *)
+  yank: (cell * Raw.content) list;
   catalog: Functions.C.t;
 }
 
+type t = sheet ref
+
 let undo t = begin
-  match t.history with
-  | [] -> None
+  let catalog = (!t).catalog in
+  match (!t).history with
+  | [] -> false
   | hd::tl ->
     let data = List.fold_left (
     fun data (id, expression) ->
       if Expression.is_defined expression then
-        snd @@ Raw.add id expression t.catalog data
+        snd @@ Raw.add id expression catalog data
       else
-        snd @@ Raw.remove id t.catalog data
-    ) t.data hd in
-    Some { t with data = data; history = tl}
+        snd @@ Raw.remove id catalog data
+    ) (!t).data hd in
+    t:= { (!t) with data = data; history = tl};
+    true
 end
 
-let move direction t =
-  let position = Selection.extract t.selected in
-  let position' = begin match direction with
-  | Actions.Left quant ->  Tools.Tuple2.replace1 (max 1 ((fst position) - quant)) position
-  | Actions.Right quant -> Tools.Tuple2.replace1 ((fst position) + quant) position
-  | Actions.Up quant ->    Tools.Tuple2.replace2 (max 1 ((snd position) - quant)) position
-  | Actions.Down quant ->  Tools.Tuple2.replace2 ((snd position) + quant) position
-  | Actions.Absolute (x, y) -> (x, y)
-  end in
-  if position = position' then
-    None
-  else
-    Some {t with selected = Selection.create position'}
-
-let delete t = begin
-  let catalog = t.catalog in
-  let history = Selection.fold (fun acc id -> (id, Raw.get_expr id t.data)::acc) [] t.selected in
-  let count, data' = Selection.fold (fun (count, c) t ->
-    (count + 1, snd @@ Raw.remove t catalog c)) (0, t.data) t.selected in
-  let t' = { t with
+let delete selected t = begin
+  let catalog = (!t).catalog in
+  let history = Selection.fold (fun acc id -> (id, Raw.get_expr id (!t).data)::acc) [] selected in
+  let count, data' = Selection.fold (fun (count, data) c ->
+    (count + 1, snd @@ Raw.remove c catalog (!t).data)) (0, (!t).data) selected in
+  t := { !t with
     data = data';
-    history = history::t.history
-  } in
-  t', count
+    history = history::(!t).history
+  };
+  count
 end
 
-let yank t = begin
+let yank selected t = begin
 
-  let shift = Selection.shift t.selected in
+  let shift = Selection.shift selected in
   let origin = shift (0, 0) in
   let _yank (count, extracted) cell = begin
     let content =
-    try let content = (Raw.Map.find cell t.data) in
+    try let content = (Raw.Map.find cell (!t).data) in
     { content with Raw.expr = Expression.shift origin content.Raw.expr }
     with Not_found ->  Raw.empty_cell in
 
     count + 1, (shift cell,content)::extracted
   end in
 
-  let count, yanked = Selection.fold _yank (0, []) t.selected in
-  let t' = { t with yank = List.rev yanked; } in
-  t', count
+  let count, yanked = Selection.fold _yank (0, []) selected in
+  t := { !t with yank = List.rev yanked; };
+  count
 end
 
-let paste t = begin
-  let catalog = t.catalog in
+let paste shift t = begin
+  let catalog = (!t).catalog in
   (* Origin of first cell *)
-  let (shift_x, shift_y) as shift = Selection.extract t.selected in
+  let (shift_x, shift_y) as shift = shift in
 
   let history' = List.map (fun ((x, y), content) ->
     let id = shift_x + x, shift_y + y in
-    id, Raw.get_expr id t.data) t.yank in
+    id, Raw.get_expr id (!t).data) (!t).yank in
 
   let _paste (count, t) ((x, y), content) = begin
     count + 1, snd @@ Raw.paste catalog (shift_x + x, shift_y + y) shift content t
   end in
 
-  let count, data' = List.fold_left _paste (0, t.data) t.yank in
-  let t' = { t with data = data'; history = history'::t.history } in
-  t', count
+  let count, data' = List.fold_left _paste (0, (!t).data) (!t).yank in
+  t := { !t with data = data'; history = history'::(!t).history };
+  count
 end
 
-let add expression t = begin
-  let id = Selection.extract t.selected in
-  let prev_expression = Raw.get_expr id t.data in
-  let cells, data' = Raw.add id expression t.catalog t.data in
-  cells, { t with data = data'; history = [id, prev_expression]::t.history }
-end
+let add ~history expression id t = begin
+  let prev_expression = Raw.get_expr id (!t).data in
+  let cells, data' = Raw.add id expression (!t).catalog (!t).data in
 
-let search action t = begin match action with
-  | `Pattern pattern ->
-    begin match Raw.search pattern t.data with
-    | None -> None
-    | Some x -> Some {t with selected = Selection.create x}
-    end
-  | _ -> None
+  let () = if history then
+    t:= { !t with data = data'; history = [id, prev_expression]::(!t).history }
+  else
+    t:= { !t with data = data' } in
+
+  cells
 end
 
-let create catalog data = {
-  data = data;
-  selected = Selection.create (1, 1);
+let create catalog = ref {
+  data = Raw.Map.empty;
   history = [];
   yank = [];
   catalog = catalog
 }
+
+(** Fold over each defined value *)
+let fold f a t = begin
+  Raw.Map.fold (fun key content a ->
+    match content.Raw.value with
+    | None -> a
+    | Some x ->
+      f a key (content.Raw.expr, x)
+  ) (!t).data a
+end
+
+let get_cell id t = begin
+  let cell = Raw.Map.find id (!t).data in
+  cell.expr, cell.value, cell.sink
+end
diff --git a/src/sheet.mli b/src/sheet.mli
index 14856d4..169932e 100755
--- a/src/sheet.mli
+++ b/src/sheet.mli
@@ -1,80 +1,37 @@
 (** This module represent a sheet *)
 
 type cell = int * int
-  
-module Raw: sig
 
-  type t
-  
-  (** An empty sheet *)
-  val empty: t
-  
-  (** Add a new value in the sheet. The previous value is replaced 
-    @return All the successors to update and the new sheet.
-  *)
-  val add: cell -> Expression.t -> Functions.C.t -> t -> Cell.Set.t * t
-  
-  val remove: cell -> Functions.C.t -> t -> Cell.Set.t * t
+type t
 
-  (** Get the value content. 
-      @return None if the cell is not defined
-   *)
-  val get_value: cell -> t -> ScTypes.Result.t option
-  
-  val get_expr: cell -> t -> Expression.t
+(** Crate an empty sheet. *)
+val create: Functions.C.t -> t
 
-  val get_sink: cell -> t -> Cell.Set.t
-  
-  (** Fold over all the defined values *)
-  val fold: ('a -> cell -> (Expression.t * ScTypes.Result.t ) -> 'a) -> 'a -> t -> 'a
-
-end
-
-type yank
-type history
-
-type t = {
-  selected: Selection.t;    (* The selected cell *)
-  data: Raw.t;
-  history: history;    (* Unlimited history *)
-  yank: yank list;           (* All the selected cells *)
-  catalog: Functions.C.t
-}
-
-type search = [
-  | `Pattern of ScTypes.Result.t option
-  | `Next
-  | `Previous
-]
-
-(** Undo the last action and return the previous state, if any *)
-val undo: t -> t option
+(** Add or update the sheet.
+    The expression is added at given position.
+    @return A set containing all updated cells. *)
+val add: history:bool -> Expression.t -> cell -> t -> Cell.Set.t
 
-(** Move the cursor in one direction, return the state updated if the move is
-    allowed *) 
-val move: Actions.direction -> t -> t option
+(** Undo the last action and return true if something has been undone *)
+val undo: t -> bool
 
 (** Delete the content of selected cells.
     @return The sheet and the number of cells deleted
 *)
-val delete: t -> t * int
+val delete: Selection.t -> t -> int
 
 (** Copy the selected cells 
     @return The sheet and the number of cells deleted
 *)
-val yank: t -> t * int
-
-(** Search for a pattern on the sheet 
-    @return The state updated if the pattern has been found. *)
-val search: search -> t -> t option
+val yank: Selection.t -> t -> int
 
-val paste: t -> t * int
+(** Paste all the selection at the given position. *)
+val paste: cell -> t -> int
 
-(** Add or update the sheet.
-    The expression is added at current selection.
-    @return A set containing all updated cells, and the tree updated. *)
-val add: Expression.t -> t -> Cell.Set.t * t
-
-(** Create an empty sheet *)
-val create: Functions.C.t -> Raw.t -> t
+(** Fold over all the defined values *)
+val fold: ('a -> cell -> (Expression.t * ScTypes.Result.t) -> 'a) -> 'a -> t -> 'a
 
+(** Get the content from a cell.
+    Also return all the other cell pointing to it.
+*)
+val get_cell: cell -> t -> Expression.t *  ScTypes.Result.t option * Cell.Set.t
diff --git a/tests/sheet_test.ml b/tests/sheet_test.ml
index dfa8da4..197cf88 100755
--- a/tests/sheet_test.ml
+++ b/tests/sheet_test.ml
@@ -23,11 +23,11 @@ let build_num value = ScTypes.Type.number @@ DataType.Num.of_int value
 (** Test a simple references between two cells *)
 let test_create_ref_1 ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (3,3) (Expression.load @@ u"=-1") catalog
-       |> snd |> Sheet.Raw.add (0,0) (Expression.load @@ u"=C3") catalog
-       |> snd in
-  let result = (Sheet.Raw.get_value (0, 0) s) in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=-1") (3,3) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=C3") (0,0) s;
+
+  let _, result, _ = Sheet.get_cell (0, 0) s in
   let expected = Some (ScTypes.Result.Ok (build_num (-1))) in
 
   assert_equal
@@ -38,14 +38,12 @@ end
 
 let test_create_ref_2 ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (2,2) (Expression.load @@ u"=C3") catalog
-       |> snd |> Sheet.Raw.add (3,3) (Expression.load @@ u"=A1") catalog
-       |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"123") catalog
-       |> snd in
-
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=C3") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (3,3) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"123") (1,1) s;
 
-  let result = (Sheet.Raw.get_value (2, 2) s) in
+  let _, result, _ = Sheet.get_cell (2, 2) s in
   let expected = Some (ScTypes.Result.Ok (build_num 123)) in
 
   assert_equal
@@ -56,10 +54,10 @@ end
 
 let test_create_direct_cycle ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (2,2) (Expression.load @@ u"=B2 + 1") catalog
-       |> snd in
-  let result = (Sheet.Raw.get_value (2, 2) s) in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=B2 + 1") (2,2) s;
+
+  let _, result, _ = Sheet.get_cell (2, 2) s in
   let expected = Some (ScTypes.Result.Error Errors.TypeError) in
 
   assert_equal
@@ -71,11 +69,11 @@ end
 (** Overide the value after a cycle. *)
 let test_recover_from_cycle ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (2,2) (Expression.load @@ u"=B2 + 1") catalog
-       |> snd |> Sheet.Raw.add (2,2) (Expression.load @@ u"=6") catalog
-       |> snd in
-  let result = (Sheet.Raw.get_value (2, 2) s) in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=B2 + 1") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=6") (2,2) s;
+
+  let _, result, _ = Sheet.get_cell (2, 2) s in
   let expected = Some (ScTypes.Result.Ok (build_num (6))) in
 
   assert_equal
@@ -86,13 +84,13 @@ end
 
 let test_create_indirect_cycle ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (2,2) (Expression.load @@ u"=A1") catalog
-       |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"=2") catalog
-       |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"=B2+1") catalog
-       |> snd |> Sheet.Raw.add (0,0) (Expression.load @@ u"=A1") catalog
-       |> snd in
-  let result = (Sheet.Raw.get_value (0, 0) s) in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=2") (1,1) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=B2+1") (1,1) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (0,0) s;
+
+  let _, result, _ = Sheet.get_cell (0, 0) s in
   let expected = Some (ScTypes.Result.Error Errors.Cycle) in
 
   assert_equal
@@ -103,18 +101,18 @@ end
 
 let test_check_cycle3 ctx = begin
 
-  let s = Sheet.Raw.empty
-      (* First set A1 to 3 *)
-      |> Sheet.Raw.add (1,1) (Expression.load @@ u"=3") catalog
-      |> snd |> Sheet.Raw.add (1,2) (Expression.load @@ u"=A1") catalog
-      |> snd |> Sheet.Raw.add (2,2) (Expression.load @@ u"=A1") catalog
-      |> snd |> Sheet.Raw.add (5,5) (Expression.load @@ u"=B2") catalog
-      (* A3 = A1 + A1 = 6 *)
-      |> snd |> Sheet.Raw.add (1,3) (Expression.load @@ u"=A2 + E5") catalog
-      (* Then set A1 to 2 *)
-      |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"=2") catalog
-      |> snd in
-  let result = (Sheet.Raw.get_value (1, 3) s) in
+  let s = Sheet.create catalog in
+  (* First set A1 to 3 *)
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=3") (1,1) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (1,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=B2") (5,5) s;
+  (* A3 = A1 + A1 = 6 *)
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A2 + E5") (1,3) s;
+  (* Then set A1 to 2 *)
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=2") (1,1) s;
+
+  let _, result, _ = Sheet.get_cell (1, 3) s in
   (* A3 = A1 + A1 = 4 *)
   let expected = Some (ScTypes.Result.Ok (build_num 4)) in
 
@@ -126,13 +124,12 @@ end
 
 let test_delete ctx = begin
 
-  let s = Sheet.Raw.empty
-       |> Sheet.Raw.add (2,2) (Expression.load @@ u"=C3") catalog
-       |> snd |> Sheet.Raw.add (3,3) (Expression.load @@ u"=A1") catalog
-       |> snd |> Sheet.Raw.remove (2,2) catalog
-       |> snd |> Sheet.Raw.remove (3,3) catalog
-       |> snd in
-  let result = (Sheet.Raw.get_value (3, 3) s) in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=C3") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1") (3,3) s;
+  ignore @@ Sheet.delete (Selection.create (2,2)) s;
+  ignore @@ Sheet.delete (Selection.create (3,3)) s;
+  let _, result, _ = Sheet.get_cell (3, 3) s in
   let expected = None in
 
   assert_equal
@@ -143,12 +140,12 @@ end
 
 let test_update_succs1 ctx = begin
 
-  let result = Sheet.Raw.empty
-       |> Sheet.Raw.add (1,1) (Expression.load @@ u" =1") catalog
-       |> snd |> Sheet.Raw.add (2,2) (Expression.load @@ u"=A2") catalog
-       |> snd |> Sheet.Raw.add (1,2) (Expression.load @@ u"=A1/1") catalog
-       |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"=2") catalog
-       |> fst in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u" =1") (1,1) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A2") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1/1") (1,2) s;
+
+  let result = Sheet.add ~history:false (Expression.load @@ u"=2") (1,1) s in
 
   (* All the cells are updated by the change *)
   let expected = Cell.Set.of_list [(1,1); (1, 2); (2,2)] in
@@ -164,12 +161,13 @@ end
 
 let test_update_succs2 ctx = begin
 
-  let result = Sheet.Raw.empty
-       |> Sheet.Raw.add (1,1) (Expression.load @@ u"=1") catalog
-       |> snd |> Sheet.Raw.add (2,2) (Expression.load @@ u"=A2") catalog
-       |> snd |> Sheet.Raw.add (1,2) (Expression.load @@ u"=A1/0") catalog
-       |> snd |> Sheet.Raw.add (1,1) (Expression.load @@ u"=2") catalog
-       |> fst in
+  let s = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=1") (1,1) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A2") (2,2) s;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=A1/0") (1,2) s;
+
+  let result = Sheet.add ~history:false (Expression.load @@ u"=2") (1,1) s in
+
   (* Only (1, 1) is updated ; (2, 2) does not change, neither (2, 2) *)
   let expected = Cell.Set.of_list [(1,1)] in
 
@@ -180,19 +178,14 @@ end
 
 let test_paste_undo ctx = begin
 
-  let empty = Sheet.create catalog Sheet.Raw.empty in
-
   (* The expected result for the whole test *)
   let expected = Some (ScTypes.Result.Ok (ScTypes.Type.number (DataType.Num.of_int 6))) in
 
-  let sheet = empty
-      |> Tools.Option.test @@ Sheet.move (Actions.Absolute (2, 1))
-      |> Sheet.add (Expression.load @@ u"=6")
-      |> snd
-      |> Tools.Option.test @@ Sheet.move (Actions.Absolute (1, 1))
-      |> Sheet.add (Expression.load @@ u"=B1")
-      |> snd in
-  let result = Sheet.Raw.get_value (1, 1) sheet.Sheet.data in
+  let sheet = Sheet.create catalog in
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=6") (2, 1) sheet;
+  ignore @@ Sheet.add ~history:false (Expression.load @@ u"=B1") (1, 1) sheet;
+
+  let _, result, _ = Sheet.get_cell (1, 1) sheet in
 
   (* Ensure the value is correctly evaluated *)
   assert_equal
@@ -200,17 +193,14 @@ let test_paste_undo ctx = begin
     expected
     result;
 
-  let sheet2 =
-    (* Copy the cell *)
-       fst @@ Sheet.yank sheet
-    |> Tools.Option.test @@ Sheet.move (Actions.Absolute (2, 1))
-    (* Paste it on another value *)
-    |> Sheet.paste
-    |> fst
-    (* Undo the paste *)
-    |> Tools.Option.test @@ Sheet.undo in
-
-  let result = Sheet.Raw.get_value (1, 1) sheet2.Sheet.data in
+  (* Copy the cell *)
+  ignore @@ Sheet.yank (Selection.create (1, 1)) sheet;
+  (* Paste it on another value *)
+  ignore @@ Sheet.paste (2, 1) sheet;
+  (* Undo the paste *)
+  assert_equal true (Sheet.undo sheet);
+
+  let _, result, _ = Sheet.get_cell (1, 1) sheet in
 
   (* The value should be the same as the first evaluation *)
   assert_equal
-- 
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