parser-shims: Vendor Format_doc.pp_two_columns

vendor/parser-shims/ocamlformat_parser_shims.ml

@@ -220,3 +220,32 @@ module Builtin_attributes = struct
 
   let mark_payload_attrs_used _ = ()
 end
+
+module Format_doc = struct
+  open Format
+
+  type 'a t = formatter -> 'a -> unit
+
+  let compat t ppf x = t ppf x
+
+  let pp_two_columns ?(sep = "|") ?max_lines ppf (lines: (string * string) list) =
+    let left_column_size =
+      List.fold_left (fun acc (s, _) -> Int.max acc (String.length s)) 0 lines in
+    let lines_nb = List.length lines in
+    let ellipsed_first, ellipsed_last =
+      match max_lines with
+      | Some max_lines when lines_nb > max_lines ->
+          let printed_lines = max_lines - 1 in (* the ellipsis uses one line *)
+          let lines_before = printed_lines / 2 + printed_lines mod 2 in
+          let lines_after = printed_lines / 2 in
+          (lines_before, lines_nb - lines_after - 1)
+      | _ -> (-1, -1)
+    in
+    fprintf ppf "@[<v>";
+    List.iteri (fun k (line_l, line_r) ->
+        if k = ellipsed_first then fprintf ppf "...@,";
+        if ellipsed_first <= k && k <= ellipsed_last then ()
+        else fprintf ppf "%*s %s %s@," left_column_size line_l sep line_r
+      ) lines;
+    fprintf ppf "@]"
+end

vendor/parser-shims/ocamlformat_parser_shims.mli

@@ -90,3 +90,9 @@ module Builtin_attributes : sig
 
   val mark_payload_attrs_used : 'a -> unit
 end
+
+module Format_doc : sig
+  type 'a t
+  val compat : 'a t -> Format.formatter -> 'a -> unit
+  val pp_two_columns : ?sep : string -> ?max_lines:int -> (string * string) list t
+end