Add initial support for horizontal filling

lib/line.ml

@@ -8,8 +8,10 @@ type chunk = {
 let fmt_chunk { styles; string } = ANSITerminal.sprintf styles "%s" string
 
 let padding_chunk width =
-  let padding = String.make width ' ' in
-  { styles = []; string = padding }
+  if width <= 0 then { styles = []; string = "" }
+  else
+    let padding = String.make width ' ' in
+    { styles = []; string = padding }
 
 type t = {
   chunks : chunk list;

lib/list_extra.ml

@@ -15,3 +15,5 @@ let rec take n = function
   | _ when n <= 0 -> []
   | [] -> []
   | x :: xs -> x :: take (n - 1) xs
+
+let max_on f list = List.fold_left (fun acc x -> max acc (f x)) 0 list

lib/pretty.ml

@@ -32,25 +32,76 @@ let zip_lines (l : Line.t list) (r : Line.t list) =
         else
           let padding_chunk = Line.padding_chunk (max_len_l - left_len) in
           let new_line =
-            Line.append hd_l (Line.append (Line.of_chunks [ padding_chunk ]) hd_r)
+            Line.append hd_l
+              (Line.append (Line.of_chunks [ padding_chunk ]) hd_r)
           in
           new_line :: zip tl_l tl_r
   in
 
   zip l r
 
+type prerender_pass_info = {
+  has_fill : bool;
+  size_taken : int;
+}
+
+type prerender =
+  | Rendered of Line.t list
+  | Fill
+
 let rec render_to_lines ~width = function
   | Str (styles, string) -> [ Line.of_chunks [ { styles; string } ] ]
   | Horizontal_fill -> [ Line.of_chunks [ Line.padding_chunk width ] ]
   | Vertical rows -> List.concat_map (render_to_lines ~width) rows
-  | Horizontal cols -> (
-      match cols with
-      | [] -> []
-      (* TODO: This is potentially really slow; optimise *)
-      | hd :: tl ->
-          List.fold_left
-            (fun acc col -> zip_lines acc (render_to_lines ~width col))
-            (render_to_lines ~width hd) tl)
+  | Horizontal cols -> horizontal_to_lines ~width cols
+
+and horizontal_to_lines ~width cols =
+  (* Step [prerender]. Check if there's Horizontal_fill, render everything else
+     and calculate rendered size. *)
+  let pass_info, prerendered =
+    List.fold_left
+      (fun (pass_info, prerendered) col ->
+        let new_pass_info, new_prerendered =
+          match col with
+          | Horizontal_fill ->
+              ({ has_fill = true; size_taken = pass_info.size_taken }, Fill)
+          | other ->
+              (* WARNING: This will pass the total width to the left-most Horizontal_fill *)
+              let rendered = render_to_lines ~width other in
+              let max_line_width = List_extra.max_on Line.length rendered in
+              ( {
+                  has_fill = pass_info.has_fill;
+                  size_taken = pass_info.size_taken + max_line_width;
+                },
+                Rendered rendered )
+        in
+        (* TODO: This is suboptimal *)
+        (new_pass_info, prerendered @ [ new_prerendered ]))
+      ({ has_fill = false; size_taken = 0 }, [])
+      cols
+  in
+
+  (* Step [fill_size]. Calculate the size of remaining fill *)
+  let fill_width = width - pass_info.size_taken in
+
+  (* Step [fill]. Fill the first Horizontal_fill *)
+  let _, rendered =
+    List.fold_left
+      (fun (remaining_width, rendered) prerendered ->
+        match prerendered with
+        | Rendered lines -> (remaining_width, rendered @ [ lines ])
+        | Fill ->
+            ( 0,
+              rendered
+              @ [ [ Line.(of_chunks [ padding_chunk remaining_width ]) ] ] ))
+      (fill_width, []) prerendered
+  in
+
+  (* Step [combine]. Combine the final columns of lines. *)
+  match rendered with
+  | [] -> []
+  (* TODO: This is potentially really slow; optimise *)
+  | hd :: tl -> List.fold_left zip_lines hd tl
 
 let render ~width doc =
   doc |> render_to_lines ~width |> List.map Line.fmt |> String_extra.unlines

lib/tui/app.ml

@@ -8,9 +8,7 @@ let init ~repo ~root_dir_path : Model.initial_data =
     | Fs.Dir (_, files) -> files
   in
   let height = Option.value (Terminal_size.get_rows ()) ~default:120 in
-  let width =
-    Option.value (Terminal_size.get_columns ()) ~default:140
-  in
+  let width = Option.value (Terminal_size.get_columns ()) ~default:140 in
   { repo; root_dir_path; files; width; height }
 
 let app = Minttea.app ~init:Init.init ~update:Update.update ~view:View.view ()

lib/tui/view.ml

@@ -3,9 +3,7 @@ let style_selected = ANSITerminal.[ Bold; green ]
 let style_directory = ANSITerminal.[ Bold; magenta ]
 
 let debug_section (model : Model.t) =
-  let debug_info =
-    Printf.sprintf "%dw x %dh" model.width model.height
-  in
+  let debug_info = Printf.sprintf "%dw x %dh" model.width model.height in
   Pretty.str debug_info
 
 let tabs_section cur_tab =
@@ -28,9 +26,12 @@ let code_section (code_tab : Model.code_tab) =
   Pretty.vertical [ current_path_doc; fs_doc ]
 
 let tab_content_section (model : Model.t) =
-  match model.current_tab with
-  | Code -> code_section model.code_tab
-  | Issues | PullRequests -> Pretty.str ""
+  let tab_doc =
+    match model.current_tab with
+    | Code -> code_section model.code_tab
+    | Issues | PullRequests -> Pretty.str ""
+  in
+  Pretty.(horizontal [ tab_doc; horizontal_fill; str "This is test" ])
 
 let to_doc (model : Model.t) =
   let open Pretty in