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diff --git a/lib/ppstyle.ml b/lib/ppstyle.ml
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+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2015     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+open Util
+
+type t = string
+(** We use the concatenated string, with dots separating each string. We
+    forbid the use of dots in the strings. *)
+
+let tags : Terminal.style option String.Map.t ref = ref String.Map.empty
+
+let make ?style tag =
+  let check s = if String.contains s '.' then invalid_arg "Ppstyle.make" in
+  let () = List.iter check tag in
+  let name = String.concat "." tag in
+  let () = assert (not (String.Map.mem name !tags)) in
+  let () = tags := String.Map.add name style !tags in
+  name
+
+let repr t = String.split '.' t
+
+let get_style tag =
+  try String.Map.find tag !tags with Not_found -> assert false
+
+let set_style tag st =
+  try tags := String.Map.update tag st !tags with Not_found -> assert false
+
+let clear_styles () =
+  tags := String.Map.map (fun _ -> None) !tags
+
+let dump () = String.Map.bindings !tags
+
+let parse_config s =
+  let styles = Terminal.parse s in
+  let set accu (name, st) =
+    try String.Map.update name (Some st) accu with Not_found -> accu
+  in
+  tags := List.fold_left set !tags styles
+
+let tag = Pp.Tag.create "ppstyle"
+
+(** Default tag is to reset everything *)
+let default = Terminal.({
+  fg_color = Some `DEFAULT;
+  bg_color = Some `DEFAULT;
+  bold = Some false;
+  italic = Some false;
+  underline = Some false;
+  negative = Some false;
+})
+
+let empty = Terminal.make ()
+
+let make_style_stack style_tags =
+  (** Not thread-safe. We should put a lock somewhere if we print from
+      different threads. Do we? *)
+  let style_stack = ref [] in
+  let peek () = match !style_stack with
+  | [] -> default (** Anomalous case, but for robustness *)
+  | st :: _ -> st
+  in
+  let push tag =
+    let style =
+      try
+        begin match String.Map.find tag style_tags with
+        | None -> empty
+        | Some st -> st
+        end
+      with Not_found -> empty
+    in
+    (** Use the merging of the latest tag and the one being currently pushed.
+    This may be useful if for instance the latest tag changes the background and
+    the current one the foreground, so that the two effects are additioned. *)
+    let style = Terminal.merge (peek ()) style in
+    let () = style_stack := style :: !style_stack in
+    Terminal.eval style
+  in
+  let pop _ = match !style_stack with
+  | [] ->
+    (** Something went wrong, we fallback *)
+    Terminal.eval default
+  | _ :: rem ->
+    let () = style_stack := rem in
+    Terminal.eval (peek ())
+  in
+  let clear () = style_stack := [] in
+  push, pop, clear
+
+let error_tag =
+  let style = Terminal.make ~bold:true ~fg_color:`WHITE ~bg_color:`RED () in
+  make ~style ["message"; "error"]
+
+let warning_tag =
+  let style = Terminal.make ~bold:true ~fg_color:`WHITE ~bg_color:`YELLOW () in
+  make ~style ["message"; "warning"]
+
+let debug_tag =
+  let style = Terminal.make ~bold:true ~fg_color:`WHITE ~bg_color:`MAGENTA () in
+  make ~style ["message"; "debug"]
+
+let pp_tag t = match Pp.Tag.prj t tag with
+| None -> ""
+| Some key -> key
+
+let init_color_output () =
+  let push_tag, pop_tag, clear_tag = make_style_stack !tags in
+  let tag_handler = {
+    Format.mark_open_tag = push_tag;
+    Format.mark_close_tag = pop_tag;
+    Format.print_open_tag = ignore;
+    Format.print_close_tag = ignore;
+  } in
+  let open Pp_control in
+  let () = Format.pp_set_mark_tags !std_ft true in
+  let () = Format.pp_set_mark_tags !err_ft true in
+  let () = Format.pp_set_formatter_tag_functions !std_ft tag_handler in
+  let () = Format.pp_set_formatter_tag_functions !err_ft tag_handler in
+  let pptag = tag in
+  let open Pp in
+  let msg ?header ft strm =
+    let strm = match header with
+    | None -> hov 0 strm
+    | Some (h, t) ->
+      let tag = Pp.Tag.inj t pptag in
+      let h = Pp.tag tag (str h ++ str ":") in
+      hov 0 (h ++ spc () ++ strm)
+    in
+    pp_with ~pp_tag ft strm;
+    Format.pp_print_newline ft ();
+    Format.pp_print_flush ft ();
+    (** In case something went wrong, we reset the stack *)
+    clear_tag ();
+  in
+  let logger level strm = match level with
+  | Debug _ -> msg ~header:("Debug", debug_tag) !std_ft strm
+  | Info -> msg !std_ft strm
+  | Notice -> msg !std_ft strm
+  | Warning ->
+    let header = ("Warning", warning_tag) in
+    Flags.if_warn (fun () -> msg ~header !err_ft strm) ()
+  | Error -> msg ~header:("Error", error_tag) !err_ft strm
+  in
+  let () = set_logger logger in
+  ()