Add -json-only-diff

lib/replacement/replacement.ml

@@ -21,7 +21,7 @@ let empty_result =
   }
 [@@deriving yojson]
 
-let to_json replacements path diff result =
+let to_json diff_only replacements path diff result =
   let value = `List (List.map ~f:to_yojson replacements) in
   let uri =
     match path with
@@ -33,20 +33,29 @@ let to_json replacements path diff result =
     | Some diff -> `String diff
     | None -> `Null
   in
-  `Assoc
-    [ ("uri", uri)
-    ; ("rewritten_source", `String result)
-    ; ("in_place_substitutions", value)
-    ; ("diff", diff)
-    ]
+  if diff_only then
+    `Assoc
+      [ ("uri", uri)
+      ; ("diff", diff)
+      ]
+  else
+    `Assoc
+      [ ("uri", uri)
+      ; ("rewritten_source", `String result)
+      ; ("in_place_substitutions", value)
+      ; ("diff", diff)
+      ]
 
 let yojson_to_string kind json =
   match kind with
   | `Pretty -> Yojson.Safe.pretty_to_string json
   | `Lines -> Yojson.Safe.to_string json
 
-let pp_json_pretty ppf (source_path, replacements, replacement_content, diff) =
-  Format.fprintf ppf "%s" @@ yojson_to_string `Pretty @@ to_json replacements source_path diff replacement_content
+let pp_json_pretty ppf (source_path, replacements, replacement_content, diff, diff_only) =
+  Format.fprintf ppf "%s" @@ yojson_to_string `Pretty @@ to_json diff_only replacements source_path diff replacement_content
 
-let pp_json_line ppf (source_path, replacements, replacement_content, diff) =
-  Format.fprintf ppf "%s" @@ Yojson.Safe.to_string @@ to_json replacements source_path diff replacement_content
+let pp_json_pretty_diff_only ppf (source_path, replacements, replacement_content, diff, diff_only) =
+  Format.fprintf ppf "%s" @@ yojson_to_string `Pretty @@ to_json diff_only replacements source_path diff replacement_content
+
+let pp_json_line ppf (source_path, replacements, replacement_content, diff, diff_only) =
+  Format.fprintf ppf "%s" @@ Yojson.Safe.to_string @@ to_json diff_only replacements source_path diff replacement_content

lib/replacement/replacement.mli

@@ -15,6 +15,6 @@ type result =
 
 val empty_result : result
 
-val pp_json_pretty : Format.formatter -> string option * t list * string * string option -> unit
+val pp_json_pretty : Format.formatter -> string option * t list * string * string option * bool -> unit
 
-val pp_json_line : Format.formatter -> string option * t list * string * string option -> unit
+val pp_json_line : Format.formatter -> string option * t list * string * string option * bool -> unit

src/command_configuration.ml

@@ -102,6 +102,7 @@ type output_options =
   { color : bool
   ; json_pretty : bool
   ; json_lines : bool
+  ; json_only_diff : bool
   ; in_place : bool
   ; diff : bool
   ; stdout : bool
@@ -211,11 +212,15 @@ module Printer = struct
       | Plain
       | Colored
 
+    type json_kind =
+      | Everything
+      | Diff
+
     type replacement_output =
       | In_place
       | Stdout
-      | Json_lines
-      | Json_pretty
+      | Json_lines of json_kind
+      | Json_pretty of json_kind
       | Diff of diff_kind
       | Match_only
 
@@ -229,19 +234,31 @@ module Printer = struct
       | Plain
       | Colored
 
+    type json_kind =
+      | Everything
+      | Diff
+
     type replacement_output =
       | In_place
       | Stdout
-      | Json_lines
-      | Json_pretty
+      | Json_lines of json_kind
+      | Json_pretty of json_kind
       | Diff of diff_kind
       | Match_only
 
     let convert output_options : replacement_output =
       match output_options with
       | { in_place = true; _ } -> In_place
-      | { json_pretty = true; in_place = false; _ } -> Json_pretty
-      | { json_lines = true; in_place = false; _ } -> Json_lines
+      | { json_pretty = true; in_place = false; _ } ->
+        if output_options.json_only_diff then
+          Json_pretty Diff
+        else
+          Json_pretty Everything
+      | { json_lines = true; in_place = false; _ } ->
+        if output_options.json_only_diff then
+          Json_lines Diff
+        else
+          Json_lines Everything
       | { stdout = true; _ } -> Stdout
       | { diff = true; color = false; _ } -> Diff Plain
       | { color = true; _ }
@@ -252,13 +269,21 @@ module Printer = struct
       match replacement_output with
       | Stdout ->
         Format.fprintf ppf "%s" replacement_content
-      | Json_pretty ->
+      | Json_pretty Everything ->
         let diff = Diff_configuration.get_diff Plain path source_content replacement_content in
-        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_pretty (path, replacements, replacement_content, diff) in
+        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_pretty (path, replacements, replacement_content, diff, false) in
         Option.value_map diff ~default:() ~f:(fun diff -> print (Some diff))
-      | Json_lines ->
+      | Json_pretty Diff ->
         let diff = Diff_configuration.get_diff Plain path source_content replacement_content in
-        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_line (path, replacements, replacement_content, diff) in
+        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_pretty (path, replacements, replacement_content, diff, true) in
+        Option.value_map diff ~default:() ~f:(fun diff -> print (Some diff))
+      | Json_lines Everything ->
+        let diff = Diff_configuration.get_diff Plain path source_content replacement_content in
+        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_line (path, replacements, replacement_content, diff, false) in
+        Option.value_map diff ~default:() ~f:(fun diff -> print (Some diff))
+      | Json_lines Diff ->
+        let diff = Diff_configuration.get_diff Plain path source_content replacement_content in
+        let print diff = Format.fprintf ppf "%a@." Replacement.pp_json_line (path, replacements, replacement_content, diff, true) in
         Option.value_map diff ~default:() ~f:(fun diff -> print (Some diff))
       | Diff Plain ->
         let diff = Diff_configuration.get_diff Plain path source_content replacement_content in
@@ -316,6 +341,8 @@ let validate_errors { input_options; run_options = _; output_options } =
             (*Format.printf "checking %s %b@." dir (Sys.is_directory dir = `No);*)
             not (Sys.is_directory dir = `Yes))
     , "One or more directories specified with -templates is not a directory"
+    ; output_options.json_only_diff && (not output_options.json_lines && not output_options.json_pretty)
+    , "-json-only-diff can only be supplied with -json-lines or -json-pretty."
     ; let result = Rule.create input_options.rule in
       Or_error.is_error result
     , if Or_error.is_error result then

src/command_configuration.mli

@@ -21,6 +21,7 @@ type output_options =
   { color : bool
   ; json_pretty : bool
   ; json_lines : bool
+  ; json_only_diff : bool
   ; in_place : bool
   ; diff : bool
   ; stdout : bool

src/main.ml

@@ -305,6 +305,7 @@ let base_command_parameters : (unit -> 'result) Command.Param.t =
     and zip_file = flag "zip" ~aliases:["z"] (optional string) ~doc:"zipfile A zip file containing files to rewrite"
     and json_pretty = flag "json-pretty" no_arg ~doc:"Output pretty JSON format"
     and json_lines = flag "json-lines" no_arg ~doc:"Output JSON line format"
+    and json_only_diff = flag "json-only-diff" no_arg ~doc:"Output only the URI and diff in JSON line format"
     and in_place = flag "in-place" no_arg ~doc:"Rewrite files on disk, in place"
     and number_of_workers = flag "jobs" (optional_with_default 4 int) ~doc:"n Number of worker processes. Default: 4"
     and dump_statistics = flag "statistics" ~aliases:["stats"] no_arg ~doc:"Dump statistics to stderr"
@@ -354,6 +355,7 @@ let base_command_parameters : (unit -> 'result) Command.Param.t =
             ; count
             ; json_pretty
             ; json_lines
+            ; json_only_diff
             ; in_place
             ; diff
             ; stdout

test/test_cli.ml

@@ -730,3 +730,20 @@ let%expect_test "infer_and_honor_extensions" =
     -// foo()
     +// bar()
      } |}]
+
+let%expect_test "diff_only" =
+  let source = "hello world" in
+  let command_args = Format.sprintf "'hello' 'world' -stdin -sequential -json-lines -json-only-diff" in
+  let command = Format.sprintf "%s %s" binary_path command_args in
+  let result = read_source_from_stdin command source in
+  print_string result;
+  [%expect{|
+    {"uri":null,"diff":"--- /dev/null\n+++ /dev/null\n@@ -1,1 +1,1 @@\n-hello world\n+world world"} |}];
+
+  let source = "hello world" in
+  let command_args = Format.sprintf "'hello' 'world' -stdin -sequential -json-only-diff" in
+  let command = Format.sprintf "%s %s" binary_path command_args in
+  let result = read_source_from_stdin command source in
+  print_string result;
+  [%expect{|
+    -json-only-diff can only be supplied with -json-lines or -json-pretty. |}];