Improve output of Dict.has to use inlined JS' in operator (#7342)

Author: DZakh

CHANGELOG.md

@@ -24,6 +24,7 @@
 
 - Remove `Stdlib_Char` module for now. https://github.com/rescript-lang/rescript/pull/7367
 - Convert internal JavaScript codebase into ESM, ReScript package itself is now ESM (`"type": "module"`). https://github.com/rescript-lang/rescript/pull/6899
+- Add built-in support for the JavaScript `in` operator. https://github.com/rescript-lang/rescript/pull/7342
 
 #### :nail_care: Polish
 

compiler/core/j.ml

@@ -86,6 +86,7 @@ and expression_desc =
      [typeof] is an operator
   *)
   | Typeof of expression
+  | In of expression * expression (* prop in obj *)
   | Js_not of expression (* !v *)
   (* TODO: Add some primitives so that [js inliner] can do a better job *)
   | Seq of expression * expression

compiler/core/js_analyzer.ml

@@ -111,6 +111,7 @@ let rec no_side_effect_expression_desc (x : J.expression_desc) =
     && Ext_list.for_all strings no_side_effect
     && Ext_list.for_all values no_side_effect
   | Js_not e -> no_side_effect e
+  | In (prop, obj) -> no_side_effect prop && no_side_effect obj
   | Cond (a, b, c) -> no_side_effect a && no_side_effect b && no_side_effect c
   | Call ({expression_desc = Str {txt = "Array.isArray"}}, [e], _) ->
     no_side_effect e
@@ -227,7 +228,7 @@ let rec eq_expression ({expression_desc = x0} : J.expression)
       eq_expression_list ls0 ls1 && flag0 = flag1 && eq_expression tag0 tag1
     | _ -> false)
   | Length _ | Is_null_or_undefined _ | String_append _ | Typeof _ | Js_not _
-  | Cond _ | FlatCall _ | New _ | Fun _ | Raw_js_code _ | Array _
+  | In _ | Cond _ | FlatCall _ | New _ | Fun _ | Raw_js_code _ | Array _
   | Caml_block_tag _ | Object _ | Tagged_template _ | Await _ ->
     false
   | Spread _ -> false

compiler/core/js_dump.ml

@@ -166,8 +166,8 @@ let rec exp_need_paren ?(arrow = false) (e : J.expression) =
   | Length _ | Call _ | Caml_block_tag _ | Seq _ | Static_index _ | Cond _
   | Bin _ | Is_null_or_undefined _ | String_index _ | Array_index _
   | String_append _ | Var _ | Undefined _ | Null | Str _ | Array _
-  | Caml_block _ | FlatCall _ | Typeof _ | Number _ | Js_not _ | Bool _ | New _
-    ->
+  | Caml_block _ | FlatCall _ | Typeof _ | Number _ | Js_not _ | In _ | Bool _
+  | New _ ->
     false
   | Await _ -> false
   | Spread _ -> false
@@ -677,6 +677,11 @@ and expression_desc cxt ~(level : int) f x : cxt =
     P.cond_paren_group f (level > 13) (fun _ ->
         P.string f "!";
         expression ~level:13 cxt f e)
+  | In (prop, obj) ->
+    P.cond_paren_group f (level > 12) (fun _ ->
+        let cxt = expression ~level:0 cxt f prop in
+        P.string f " in ";
+        expression ~level:0 cxt f obj)
   | Typeof e ->
     P.string f "typeof";
     P.space f;

compiler/core/js_exp_make.ml

@@ -1128,6 +1128,9 @@ let or_ ?comment (e1 : t) (e2 : t) =
     | Some e -> e
     | None -> {expression_desc = Bin (Or, e1, e2); comment})
 
+let in_ (prop : t) (obj : t) : t =
+  {expression_desc = In (prop, obj); comment = None}
+
 let not (e : t) : t =
   match e.expression_desc with
   | Number (Int {i; _}) -> bool (i = 0l)

compiler/core/js_exp_make.mli

@@ -356,6 +356,8 @@ val and_ : ?comment:string -> t -> t -> t
 
 val or_ : ?comment:string -> t -> t -> t
 
+val in_ : t -> t -> t
+
 (** we don't expose a general interface, since a general interface is generally not safe *)
 
 val dummy_obj : ?comment:string -> Lam_tag_info.t -> t

compiler/core/js_fold.ml

@@ -103,6 +103,10 @@ class fold =
       | Js_not _x0 ->
         let _self = _self#expression _x0 in
         _self
+      | In (_x0, _x1) ->
+        let _self = _self#expression _x0 in
+        let _self = _self#expression _x1 in
+        _self
       | Seq (_x0, _x1) ->
         let _self = _self#expression _x0 in
         let _self = _self#expression _x1 in

compiler/core/js_record_fold.ml

@@ -109,6 +109,10 @@ let expression_desc : 'a. ('a, expression_desc) fn =
   | Js_not _x0 ->
     let st = _self.expression _self st _x0 in
     st
+  | In (_x0, _x1) ->
+    let st = _self.expression _self st _x0 in
+    let st = _self.expression _self st _x1 in
+    st
   | Seq (_x0, _x1) ->
     let st = _self.expression _self st _x0 in
     let st = _self.expression _self st _x1 in

compiler/core/js_record_iter.ml

@@ -91,6 +91,9 @@ let expression_desc : expression_desc fn =
   | Bool _ -> ()
   | Typeof _x0 -> _self.expression _self _x0
   | Js_not _x0 -> _self.expression _self _x0
+  | In (_x0, _x1) ->
+    _self.expression _self _x0;
+    _self.expression _self _x1
   | Seq (_x0, _x1) ->
     _self.expression _self _x0;
     _self.expression _self _x1

compiler/core/js_record_map.ml

@@ -109,6 +109,10 @@ let expression_desc : expression_desc fn =
   | Js_not _x0 ->
     let _x0 = _self.expression _self _x0 in
     Js_not _x0
+  | In (_x0, _x1) ->
+    let _x0 = _self.expression _self _x0 in
+    let _x1 = _self.expression _self _x1 in
+    In (_x0, _x1)
   | Seq (_x0, _x1) ->
     let _x0 = _self.expression _self _x0 in
     let _x1 = _self.expression _self _x1 in