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

compiler/core/lam_analysis.ml

@@ -78,7 +78,7 @@ let rec no_side_effects (lam : Lam.t) : bool =
     (* list primitives *)
     | Pmakelist
     (* dict primitives *)
-    | Pmakedict
+    | Pmakedict | Pdict_has
     (* Test if the argument is a block or an immediate integer *)
     | Pisint | Pis_poly_var_block
     (* Test if the (integer) argument is outside an interval *)

compiler/core/lam_compile_primitive.ml

@@ -574,6 +574,13 @@ let translate output_prefix loc (cxt : Lam_compile_context.t)
                  Some (Js_op.Lit txt, expr)
                | _ -> None))
     | _ -> assert false)
+  | Pdict_has -> (
+    match args with
+    | [obj; prop] -> E.in_ prop obj
+    | _ ->
+      Location.raise_errorf ~loc
+        "Invalid external \"%%dict_has\" type signature. Expected to have two \
+         arguments.")
   | Parraysetu -> (
     match args with
     (* wrong*)

compiler/core/lam_convert.ml

@@ -314,6 +314,7 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
   | Parraysets -> prim ~primitive:Parraysets ~args loc
   | Pmakelist _mutable_flag (*FIXME*) -> prim ~primitive:Pmakelist ~args loc
   | Pmakedict -> prim ~primitive:Pmakedict ~args loc
+  | Pdict_has -> prim ~primitive:Pdict_has ~args loc
   | Pawait -> prim ~primitive:Pawait ~args loc
   | Pimport -> prim ~primitive:Pimport ~args loc
   | Pinit_mod -> (

compiler/core/lam_primitive.ml

@@ -137,6 +137,7 @@ type t =
   | Pmakelist
   (* dict primitives *)
   | Pmakedict
+  | Pdict_has
   (* promise *)
   | Pawait
   (* etc or deprecated *)
@@ -215,7 +216,7 @@ let eq_primitive_approx (lhs : t) (rhs : t) =
   (* List primitives *)
   | Pmakelist
   (* dict primitives *)
-  | Pmakedict
+  | Pmakedict | Pdict_has
   (* promise *)
   | Pawait
   (* etc *)

compiler/core/lam_primitive.mli

@@ -132,6 +132,7 @@ type t =
   | Pmakelist
   (* dict primitives *)
   | Pmakedict
+  | Pdict_has
   (* promise *)
   | Pawait
   (* etc or deprecated *)

compiler/core/lam_print.ml

@@ -194,6 +194,7 @@ let primitive ppf (prim : Lam_primitive.t) =
   | Pmakearray -> fprintf ppf "makearray"
   | Pmakelist -> fprintf ppf "makelist"
   | Pmakedict -> fprintf ppf "makedict"
+  | Pdict_has -> fprintf ppf "dict.has"
   | Parrayrefu -> fprintf ppf "array.unsafe_get"
   | Parraysetu -> fprintf ppf "array.unsafe_set"
   | Parrayrefs -> fprintf ppf "array.get"

compiler/ml/lambda.ml

@@ -271,6 +271,7 @@ type primitive =
   | Pmakelist of Asttypes.mutable_flag
   (* dict primitives *)
   | Pmakedict
+  | Pdict_has
   (* promise *)
   | Pawait
   (* module *)

compiler/ml/lambda.mli

@@ -238,6 +238,7 @@ type primitive =
   | Pmakelist of Asttypes.mutable_flag
   (* dict primitives *)
   | Pmakedict
+  | Pdict_has
   (* promise *)
   | Pawait
   (* modules *)

compiler/ml/printlambda.ml

@@ -229,6 +229,7 @@ let primitive ppf = function
   | Pmakelist Mutable -> fprintf ppf "makelist"
   | Pmakelist Immutable -> fprintf ppf "makelist_imm"
   | Pmakedict -> fprintf ppf "makedict"
+  | Pdict_has -> fprintf ppf "dict.has"
   | Pisint -> fprintf ppf "isint"
   | Pisout -> fprintf ppf "isout"
   | Pisnullable -> fprintf ppf "isnullable"

compiler/ml/translcore.ml

@@ -346,6 +346,7 @@ let primitives_table =
       ("%array_unsafe_set", Parraysetu);
       (* dict primitives *)
       ("%makedict", Pmakedict);
+      ("%dict_has", Pdict_has);
       (* promise *)
       ("%await", Pawait);
       (* module *)

lib/es6/Stdlib_Dict.js

@@ -22,13 +22,10 @@ function mapValues(dict, f) {
   return target;
 }
 
-let has = ((dict, key) => key in dict);
-
 export {
   $$delete$1 as $$delete,
   forEach,
   forEachWithKey,
   mapValues,
-  has,
 }
 /* No side effect */

lib/js/Stdlib_Dict.js

@@ -22,11 +22,8 @@ function mapValues(dict, f) {
   return target;
 }
 
-let has = ((dict, key) => key in dict);
-
 exports.$$delete = $$delete$1;
 exports.forEach = forEach;
 exports.forEachWithKey = forEachWithKey;
 exports.mapValues = mapValues;
-exports.has = has;
 /* No side effect */

runtime/Stdlib_Dict.res

@@ -41,6 +41,6 @@ let mapValues = (dict, f) => {
   target
 }
 
-let has: (dict<'a>, string) => bool = %raw(`(dict, key) => key in dict`)
+external has: (dict<'a>, string) => bool = "%dict_has"
 
 external ignore: dict<'a> => unit = "%ignore"

runtime/Stdlib_Dict.resi

@@ -246,17 +246,20 @@ let mapValues: (dict<'a>, 'a => 'b) => dict<'b>
 /**
 `has(dictionary, "key")` returns true if the "key" is present in the dictionary.
 
+Be aware that it uses the JavaScript `in` operator under the hood.
+
 ## Examples
 
 ```rescript
 let dict = dict{"key1": Some(1), "key2": None}
 
-dict->Dict.has("key1") // true
-dict->Dict.has("key2") // true
-dict->Dict.has("key3") // false
+dict->Dict.has("key1")->assertEqual(true)
+dict->Dict.has("key2")->assertEqual(true)
+dict->Dict.has("key3")->assertEqual(false)
+dict->Dict.has("toString")->assertEqual(true)
 ```
 */
-let has: (dict<'a>, string) => bool
+external has: (dict<'a>, string) => bool = "%dict_has"
 
 /**
   `ignore(dict)` ignores the provided dict and returns unit.