refactor: generalize center/align with a single construct

src/PrintBox.ml

@@ -39,8 +39,11 @@ type view =
     }
   | Frame of t
   | Pad of position * t (* vertical and horizontal padding *)
-  | Align_right of t (* dynamic left-padding *)
-  | Center of t (* center vertically and horizontally *)
+  | Align of {
+      h: [`Left | `Center | `Right];
+      v: [`Top | `Center | `Bottom];
+      inner: t;
+    }
   | Grid of [`Bars | `None] * t array array
   | Tree of int * t * t array
 
@@ -95,8 +98,13 @@ let pad b = pad' ~col:1 ~lines:1 b
 let hpad col b = pad' ~col ~lines:0 b
 let vpad lines b = pad' ~col:0 ~lines b
 
-let align_right b = Align_right b
-let center b = Center b
+let align ~h ~v b : t = Align {h; v; inner=b}
+let align_bottom b = align ~h:`Left ~v:`Bottom b
+let align_right b = align ~h:`Right ~v:`Top b
+let align_bottom_right b = align ~h:`Right ~v:`Bottom b
+let center_h b = align ~h:`Center ~v:`Top b
+let center_v b = align ~h:`Left ~v:`Center b
+let center_hv b = align ~h:`Center ~v:`Center b
 
 let map_matrix f m =
   Array.map (Array.map f) m
@@ -173,8 +181,6 @@ module Simple = struct
   type t =
     [ `Empty
     | `Pad of t
-    | `Align_right of t
-    | `Center of t
     | `Text of string
     | `Vlist of t list
     | `Hlist of t list
@@ -185,8 +191,6 @@ module Simple = struct
   let rec to_box = function
     | `Empty -> empty
     | `Pad b -> pad (to_box b)
-    | `Align_right b -> align_right (to_box b)
-    | `Center b -> center (to_box b)
     | `Text t -> text t
     | `Vlist l -> vlist (List.map to_box l)
     | `Hlist l -> hlist (List.map to_box l)

src/PrintBox.mli

@@ -105,8 +105,7 @@ type t
 (** The type [view] can be used to observe the inside of the box,
     now that [t] is opaque.
 
-    @since NEXT_RELEASE added [Align_right]
-    @since NEXT_RELEASE added [Center]
+    @since NEXT_RELEASE added [Align]
 *)
 type view = private
   | Empty
@@ -116,8 +115,11 @@ type view = private
     }
   | Frame of t
   | Pad of position * t (* vertical and horizontal padding *)
-  | Align_right of t (* dynamic left-padding *)
-  | Center of t (* center vertically and horizontally *)
+  | Align of {
+      h: [`Left | `Center | `Right];
+      v: [`Top | `Center | `Bottom];
+      inner: t;
+    } (** Alignment within the surrounding box *)
   | Grid of [`Bars | `None] * t array array
   | Tree of int * t * t array (* int: indent *)
 
@@ -179,12 +181,34 @@ val vpad : int -> t -> t
 val hpad : int -> t -> t
 (** Pad horizontally by [n] spaces *)
 
+val align : h:[`Left | `Right | `Center] -> v:[`Top | `Bottom | `Center] -> t -> t
+(** Control alignment of the given box wrt its surrounding box, if any.
+    @param h horizontal alignment
+    @param v vertical alignment
+    @since NEXT_RELEASE *)
+
 val align_right : t -> t
-(** Left-pad to the size of the surrounding box
+(** Left-pad to the size of the surrounding box, as in [align ~h:`Right ~v:`Top]
+    @since NEXT_RELEASE *)
+
+val align_bottom : t -> t
+(** Align to the bottom, as in [align ~h:`Left ~v:`Bottom]
+    @since NEXT_RELEASE *)
+
+val align_bottom_right : t -> t
+(** Align to the right and to the bottom, as in [align ~h:`Right ~v:`Bottom]
+    @since NEXT_RELEASE *)
+
+val center_h : t -> t
+(** Horizontal center, as in .
+    @since NEXT_RELEASE *)
+
+val center_v : t -> t
+(** Vertical center.
     @since NEXT_RELEASE *)
 
-val center : t -> t
-(** Try to center within the surrounding box
+val center_hv : t -> t
+(** Try to center within the surrounding box, as in [align ~h:`Center ~v:`Center]
     @since NEXT_RELEASE *)
 
 val grid :
@@ -290,8 +314,6 @@ module Simple : sig
   type t =
     [ `Empty
     | `Pad of t
-    | `Align_right of t
-    | `Center of t
     | `Text of string
     | `Vlist of t list
     | `Hlist of t list

src/PrintBox_text.ml

@@ -239,8 +239,11 @@ end = struct
       }
     | Frame of 'a
     | Pad of position * 'a (* vertical and horizontal padding *)
-    | Align_right of 'a (* dynamic left-padding *)
-    | Center of 'a
+    | Align of {
+        h: [`Left | `Center | `Right];
+        v: [`Top | `Center | `Bottom];
+        inner: 'a (* dynamic centering/alignment *)
+      }
     | Grid of [`Bars | `None] * 'a array array
     | Tree of int * 'a * 'a array
 
@@ -321,8 +324,7 @@ end = struct
     | Frame t -> Pos.move (size t) 2 2
     | Pad (dim, b') ->
       Pos.(size b' + (2 * dim))
-    | Align_right b' -> size b'
-    | Center b' -> size b'
+    | Align {inner=b';_} -> size b'
     | Grid (style,m) ->
       let bars = match style with
         | `Bars -> true
@@ -368,8 +370,7 @@ end = struct
         Text {l=List.rev !acc; style}
       | B.Frame t -> Frame (of_box t)
       | B.Pad (dim, t) -> Pad (dim, of_box t)
-      | B.Align_right t -> Align_right (of_box t)
-      | B.Center t -> Center (of_box t)
+      | B.Align {h;v;inner} -> Align {h;v;inner=of_box inner}
       | B.Grid (bars, m) -> Grid (bars, B.map_matrix of_box m)
       | B.Tree (i, b, l) -> Tree (i, of_box b, Array.map of_box l)
     in
@@ -428,23 +429,19 @@ end = struct
         | Some p -> Some Pos.(p - (2*dim))
       in
       render_rec ~offset:Pos.(offset+dim) ~ansi ?expected_size ~out b' Pos.(pos + dim)
-    | Align_right b' ->
+    | Align {h;v;inner=b'} ->
       begin match expected_size with
         | Some expected_size ->
           (* add padding on the left *)
-          let left_pad = max 0 (expected_size.x - (size b').x) in
-          let pos' = Pos.move pos left_pad 0 in
-          (* just render [b'] with new offset *)
-          render_rec ~offset ~ansi ~out b' pos';
-        | None ->
-          render_rec ~ansi ~offset ~out b' pos
-      end
-    | Center b' ->
-      begin match expected_size with
-        | Some expected_size ->
-          (* add padding on every size *)
-          let hpad = max 0 ((expected_size.x - (size b').x) / 2) in
-          let vpad = max 0 ((expected_size.y - (size b').y) / 2) in
+          let hpad = match h with
+            | `Left -> 0
+            | `Center -> max 0 ((expected_size.x - (size b').x) / 2)
+            | `Right -> max 0 (expected_size.x - (size b').x)
+          and vpad = match v with
+            | `Top -> 0
+            | `Center -> max 0 ((expected_size.y - (size b').y) / 2)
+            | `Bottom -> max 0 (expected_size.y - (size b').y)
+          in
           let pos' = Pos.move pos hpad vpad in
           (* just render [b'] with new offset *)
           render_rec ~offset ~ansi ~out b' pos';

src/html/PrintBox_html.ml

@@ -58,10 +58,11 @@ let rec to_html_rec (b: B.t) : [< Html_types.flow5 > `Div `Ul `Table `P] html =
     H.p ~a l
   | B.Pad (_, b)
   | B.Frame b -> to_html_rec b
-  | B.Align_right b ->
+  | B.Align {h=`Right;inner=b;v=_} ->
     H.div ~a:[H.a_class ["align-right"]] [ to_html_rec b ]
-  | B.Center b ->
+  | B.Align {h=`Center;inner=b;v=_} ->
     H.div ~a:[H.a_class ["center"]] [ to_html_rec b ]
+  | B.Align {inner=b;_} -> to_html_rec b
   | B.Grid (bars, a) ->
     let class_ = match bars with
       | `Bars -> "framed"

test/test1.ml

@@ -28,7 +28,7 @@ let () =
 let grid =
   B.frame @@ B.grid_l
     [ [B.text "the center of the triangle is"; B.empty];
-      [B.center @@ B.text "lil' ol' me";
+      [B.center_hv @@ B.text "lil' ol' me";
        B.pad' ~col:0 ~lines:6 @@ B.text "t\na\nl\nl"];
       [B.align_right (B.text "i'm aligned right"); B.empty];
        [ B.text "loooooooooooooooooooooooooooooooooong"; B.empty; ];
@@ -60,9 +60,9 @@ module Box_in = struct
     let open B in
     frame @@ grid_l [
       [ text "a"; text "looooooooooooooooooooooooo\noonng"];
-      [ text "bx"; center @@ frame @@ record ["x", int 1; "y", int 2]];
+      [ text "bx"; center_hv @@ frame @@ record ["x", int 1; "y", int 2]];
       [ pad' ~col:2 ~lines:2 @@ text "?";
-        center @@ record ["x", int 10; "y", int 20]];
+        center_hv @@ record ["x", int 10; "y", int 20]];
     ]
 
   let () = print_endline @@ PrintBox_text.to_string b
@@ -75,7 +75,7 @@ module Unicode = struct
     B.(frame @@ vlist [text "nice unicode! 💪"; frame @@
     hlist [
       vlist[text "oï ωεird nums:\nπ/2\nτ/4";
-        center @@ tree (text "0")[text "1"; tree (text "ω") [text "ω²"]]];
+        center_hv @@ tree (text "0")[text "1"; tree (text "ω") [text "ω²"]]];
       frame @@ frame @@ frame
       @@ vlist [text "sum=Σ_i a·xᵢ²\n—————\n1+1"; align_right @@ text "Ōₒ\nÀ"]]]);;