refactor, add bytes

ppx/ppx_unicode.ml

@@ -1,61 +1,67 @@
 open Ppxlib
 
-let has_attr name attrs =
-  List.find_opt (fun attr -> attr.attr_name.txt = name) attrs
-  |> Option.is_some
+let attr_filter attr =
+  let n = attr.attr_name.txt in
+  n = "uchar" || n = "unicode.uchar" || n = "bytes" || n = "unicode.bytes"
+    || n = "utf8" || n = "unicode.utf8"
+
+let attr_uchar_filter attr =
+  let n = attr.attr_name.txt in
+  n = "uchar" || n = "unicode.uchar"
+
+let attr_bytes_filter attr =
+  let n = attr.attr_name.txt in
+  n = "bytes" || n = "unicode.bytes"
 
 let decode_single_uchar_opt str =
   if String.is_valid_utf_8 str then
     let res = String.get_utf_8_uchar str 0 in
     if (Uchar.utf_decode_is_valid res) && (Uchar.utf_decode_length res == String.length str) then
-      Some (Uchar.utf_decode_uchar res |> Uchar.to_int)
+      Some (Uchar.utf_decode_uchar res |> Uchar.to_int |> Int.to_string)
     else
       None
   else
     None
 
-let nfc_mapper = object
+let utf8_attr_mapper = object
   inherit Ast_traverse.map as super
 
   method! expression =
     fun { pexp_desc; pexp_loc; pexp_loc_stack; pexp_attributes } ->
-      if has_attr "uchar" pexp_attributes then
-        let pexp_attributes =
-          List.filter (fun attr -> attr.attr_name.txt <> "uchar") pexp_attributes in
       match pexp_desc with
-        | Pexp_constant (Pconst_string (value, loc, _)) ->
-          begin match decode_single_uchar_opt value with
-          | Some cp ->
-            let cp = Pconst_integer (Int.to_string cp, None) in
-            let cp = {
-              pexp_desc = Pexp_constant cp;
-              pexp_loc; pexp_loc_stack; pexp_attributes
-            } in
-            [%expr Uchar.of_int [%e cp]]
+      | Pexp_constant (Pconst_string (value, str_loc, delim)) ->
+        begin
+        let loc = pexp_loc in
+        let attrs = pexp_attributes in
+        let pexp_attributes = List.filter (fun attr -> not @@ attr_filter attr) attrs in
+        let make_expr pexp_desc =
+          { pexp_desc; pexp_loc; pexp_loc_stack; pexp_attributes } in
+        let make_err msg =
+          make_expr @@ Pexp_extension (Location.error_extensionf ~loc msg) in
+        if List.find_opt attr_uchar_filter attrs |> Option.is_some then
+          match decode_single_uchar_opt value with
+          | Some value ->
+            let value = Pexp_constant (Pconst_integer (value, None)) in
+            let value = { pexp_desc = value; pexp_loc; pexp_loc_stack; pexp_attributes = [] } in
+            { [%expr Uchar.of_int [%e value]] with pexp_attributes }
           | None ->
-            let err_ext =
-              Pexp_extension begin Location.error_extensionf ~loc:loc
-                "[@uchar] string must consist of a single valid utf-8 codepoint" end
-            in { pexp_desc = err_ext; pexp_loc; pexp_loc_stack; pexp_attributes }
-          end
-        | _ ->
-          let err_ext =
-            Pexp_extension begin Location.error_extensionf ~loc:pexp_loc
-              "[@uchar] attribute must be on a string constant" end
-          in { pexp_desc = err_ext; pexp_loc; pexp_loc_stack; pexp_attributes }
+            make_err "[@uchar] must be a single utf-8 codepoint literal"
+        else if List.find_opt attr_bytes_filter attrs |> Option.is_some then
+          let value_expr = Pexp_constant (Pconst_string (value, str_loc, delim)) in
+          let value_expr =
+            { pexp_desc = value_expr; pexp_loc; pexp_loc_stack; pexp_attributes = [] } in
+          { [%expr Bytes.of_string [%e value_expr]] with pexp_attributes }
+        else if String.is_valid_utf_8 value then
+          let value = Uunf_string.normalize_utf_8 `NFC value in
+          make_expr @@ Pexp_constant (Pconst_string (value, str_loc, delim))
         else
-        super#expression { pexp_desc; pexp_loc; pexp_loc_stack; pexp_attributes }
+          make_err "string literal is not valid utf-8"
+        end
+      | _ -> super#expression { pexp_desc; pexp_loc; pexp_loc_stack; pexp_attributes }
+end
 
-  method! constant = function
-    | Pconst_string (value, loc, delim) ->
-      if String.is_valid_utf_8 value then
-        Pconst_string ((Uunf_string.normalize_utf_8 `NFC value), loc, delim)
-      else
-        Location.raise_errorf ~loc "invalid utf-8 in string literal"
-    | const -> super#constant const
-end
 
 let () =
   Driver.register_transformation
-    ~impl:nfc_mapper#structure
-    "ppx_unicode"
+    ~impl:utf8_attr_mapper#structure
+    "unicode"

test/test_ppx_unicode.ml

@@ -1,3 +1,7 @@
 let () =
   let a = "å"[@uchar] in
-  ignore a
+  let b = Buffer.create 16 in
+  Buffer.add_utf_8_uchar b a;
+  Buffer.add_utf_8_uchar b a;
+  let str = Buffer.to_bytes b |> String.of_bytes in
+  Printf.printf "meow meow: %s\n%!" str