Make api-diff output colored

NathanReb · NathanReb · commit a3abba666103 · 2024-08-28T14:19:58.000+02:00
Signed-off-by: Nathan Rebours &lt;nathan.p.rebours@gmail.com&gt;
diff --git a/api-watch.opam b/api-watch.opam
@@ -13,6 +13,7 @@ depends: [
   "ppx_deriving"
   "logs"
   "containers"
+  "fmt"
   "cmdliner" {>= "1.1.0"}
   "diffutils"
   "odoc" {with-doc}
diff --git a/bin/api_diff.ml b/bin/api_diff.ml
@@ -37,7 +37,7 @@ let run (`Main_module main_module) (`Ref_cmi reference) (`Current_cmi current) =
   | None -> Ok 0
   | Some diff ->
       let text_diff = Api_watch.Text_diff.from_diff diff in
-      Api_watch.Text_diff.pp Format.std_formatter text_diff;
+      Api_watch.Text_diff.With_colors.pp Format.std_formatter text_diff;
       Ok 1
 
 let named f = Cmdliner.Term.(app (const f))
@@ -81,5 +81,6 @@ let info =
 let term = Cmdliner.Term.(const run $ main_module $ ref_cmi $ current_cmi)
 
 let () =
+  Fmt_tty.setup_std_outputs ();
   let exit_code = Cmdliner.Cmd.eval_result' (Cmdliner.Cmd.v info term) in
   exit exit_code
diff --git a/bin/dune b/bin/dune
@@ -1,4 +1,4 @@
 (executable
  (name api_diff)
  (public_name api-diff)
- (libraries api-watch cmdliner compiler-libs.common))
+ (libraries api-watch cmdliner compiler-libs.common fmt.tty))
diff --git a/dune-project b/dune-project
@@ -20,5 +20,6 @@
   ppx_deriving
   logs
   containers
+  fmt
   (cmdliner (>= 1.1.0))
   diffutils))
diff --git a/lib/dune b/lib/dune
@@ -3,4 +3,4 @@
  (public_name api-watch)
  (preprocess
   (pps ppx_deriving.std))
- (libraries compiler-libs.common diffutils unix containers))
+ (libraries compiler-libs.common diffutils unix containers fmt))
diff --git a/lib/text_diff.ml b/lib/text_diff.ml
@@ -88,10 +88,35 @@ let from_diff (diff : Diff.module_) : Diffutils.Diff.t String_map.t =
   in
   process_module_diff diff.mname diff String_map.empty
 
-let pp fmt t =
+let pp_diff fmt diff = Diffutils.Diff.pp Diffutils.Diff.git_printer fmt diff
+
+let gen_pp pp_diff fmt t =
   let print_module_diff module_path diff =
     Format.fprintf fmt "diff module %s:\n" module_path;
-    Diffutils.Diff.pp Diffutils.Diff.git_printer Format.std_formatter diff;
+    pp_diff fmt diff;
     Format.fprintf fmt "\n"
   in
   String_map.iter print_module_diff t
+
+let pp fmt t = gen_pp pp_diff fmt t
+
+module With_colors = struct
+  let pp_l fmt ~color ~prefix ~line =
+    Format.fprintf fmt "%a%a\n"
+      Fmt.(styled color string)
+      prefix
+      Fmt.(styled color string)
+      line
+
+  let pp_add fmt line = pp_l fmt ~color:`Green ~prefix:"+" ~line
+  let pp_remove fmt line = pp_l fmt ~color:`Red ~prefix:"-" ~line
+  let pp_keep fmt line = Format.fprintf fmt " %s\n" line
+
+  let printer =
+    Diffutils.Diff.printer ~same:pp_keep ~diff:(fun fmt { orig; new_ } ->
+        List.iter (pp_remove fmt) orig;
+        List.iter (pp_add fmt) new_)
+
+  let pp_diff fmt diff = Diffutils.Diff.pp printer fmt diff
+  let pp fmt t = gen_pp pp_diff fmt t
+end
diff --git a/lib/text_diff.mli b/lib/text_diff.mli
@@ -24,3 +24,9 @@ val from_diff : Diff.module_ -> Diffutils.Diff.t String_map.t
 
 val pp : Format.formatter -> t -> unit
 (** Pretty-print the text diff in a human readable, git diff like format. *)
+
+module With_colors : sig
+  val pp : Format.formatter -> t -> unit
+  (** Same as regular [pp] but prints added lines in green and removed lines
+    in red. *)
+end
