From 5a7ca4ca2ed845ac83e67f60d09b7cd73a594aed Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Tue, 1 Nov 2022 22:20:56 -0400
Subject: [PATCH] feat(util): improve debug printer wrt newlines

---
 src/util/Log.ml   |  5 ++++-
 src/util/Util.ml  | 12 ++++++++++++
 src/util/Util.mli |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/util/Log.ml b/src/util/Log.ml
index 0a116641..95c9df4a 100644
--- a/src/util/Log.ml
+++ b/src/util/Log.ml
@@ -15,13 +15,16 @@ let start_ = Unix.gettimeofday ()
 let[@inline never] debug_real_ l k =
   k (fun fmt ->
       let now = Unix.gettimeofday () -. start_ in
+      (* print into buf_ in one go, so that outputs of nested debug calls
+         do not interleave on stdout *)
       Buffer.clear buf_;
       let once_done _fmt =
         Format.fprintf _fmt "@]@?";
         let msg = Buffer.contents buf_ in
         (* forward to profiling *)
         if Profile.enabled () then Profile.instant msg;
-        Format.fprintf !debug_fmt_ "@[<2>@{<Blue>[%d|%.3f]@}@ %s@]@." l now msg
+        Format.fprintf !debug_fmt_ "@[<2>@{<Blue>[%d|%.3f]@}@ %a@]@." l now
+          Util.pp_string_with_lines msg
       in
 
       Format.fprintf buf_fmt_ "@[<2>";
diff --git a/src/util/Util.ml b/src/util/Util.ml
index 8513f088..8d200ed2 100644
--- a/src/util/Util.ml
+++ b/src/util/Util.ml
@@ -10,6 +10,18 @@ let pp_sep sep out () = Format.fprintf out "%s@," sep
 let pp_list ?(sep = " ") pp out l = Fmt.list ~sep:(pp_sep sep) pp out l
 let pp_iter ?(sep = " ") pp out l = Fmt.iter ~sep:(pp_sep sep) pp out l
 
+let pp_string_with_lines out (s : string) : unit =
+  Fmt.fprintf out "@[<v>";
+  let i = ref 0 in
+  let n = String.length s in
+  while !i < n do
+    let j = try String.index_from s !i '\n' with Not_found -> n in
+    if !i > 0 then Fmt.fprintf out "@,";
+    Fmt.substring out (s, !i, j - !i);
+    i := j + 1
+  done;
+  Fmt.fprintf out "@]"
+
 let pp_pair ?(sep = " ") pp1 pp2 out t =
   Fmt.pair ~sep:(pp_sep sep) pp1 pp2 out t
 
diff --git a/src/util/Util.mli b/src/util/Util.mli
index 2353ed04..514c2572 100644
--- a/src/util/Util.mli
+++ b/src/util/Util.mli
@@ -8,6 +8,7 @@ val pp_list : ?sep:string -> 'a printer -> 'a list printer
 val pp_iter : ?sep:string -> 'a printer -> 'a Iter.t printer
 val pp_array : ?sep:string -> 'a printer -> 'a array printer
 val pp_pair : ?sep:string -> 'a printer -> 'b printer -> ('a * 'b) printer
+val pp_string_with_lines : string printer
 val flat_map_l_arr : ('a -> 'b array) -> 'a list -> 'b list
 
 val array_of_list_map : ('a -> 'b) -> 'a list -> 'b array