review: use Astring

Author: Octachron

src/latex/raw.ml

@@ -209,20 +209,13 @@ let ocamltag tag pp ppf x = create2 "ocamltag" Fmt.string pp ppf tag x
 
 let math ppf x = Fmt.pf ppf {|$%s$|} x
 
-let remove_empty_last_line x =
-  let rec find_last_line pos x =
-    if pos < 0 then x
-    else
-      match x.[pos] with
-      | ' ' | '\012' | '\n' | '\r' | '\t' -> find_last_line (pos - 1) x
-      | _ -> if pos = String.length x - 1 then x else String.sub x 0 (pos + 1)
-  in
-  find_last_line (String.length x - 1) x
-
 let equation ppf x =
   let name = "equation*" in
   mbegin ppf name;
   Fmt.cut ppf ();
-  Fmt.string ppf (remove_empty_last_line x);
+  (* A blank line before \end{equation*} is a latex error,
+     we trim on the right the user input to avoid any surprise *)
+  let x = Astring.String.drop ~rev:true ~sat:Astring.Char.Ascii.is_white x in
+  Fmt.string ppf x;
   Fmt.cut ppf ();
   mend ppf name