Complete implementation of shift operators

I looked back at the last session with Gwansik and realized that,
I had misguided him by simply misunderstanding a particular syntx error.

Gwansik's initial approach was quite close.

Co-authored-by: gwansikk <gwansik.kim@gwansik.dev>

Author: cometkim

compiler/syntax/src/res_core.ml

@@ -2138,27 +2138,6 @@ and parse_operand_expr ~context p =
     (* pexp_loc = mkLoc startPos endPos *)
   }
 
-and parse_shift_operator (p : Parser.t) =
-  let start_pos = p.start_pos in
-  let end_pos = p.end_pos in
-  if p.token = LessThan && Scanner.is_left_shift p.scanner start_pos.pos_cnum
-  then (
-    Parser.next p;
-    {p with token = LeftShift; start_pos; prev_end_pos = end_pos})
-  else if
-    p.token = GreaterThan
-    && Scanner.is_right_shift_unsigned p.scanner start_pos.pos_cnum
-  then (
-    Parser.next p;
-    Parser.next p;
-    {p with token = RightShiftUnsigned; start_pos; prev_end_pos = end_pos})
-  else if
-    p.token = GreaterThan && Scanner.is_right_shift p.scanner start_pos.pos_cnum
-  then (
-    Parser.next p;
-    {p with token = RightShift; start_pos; prev_end_pos = end_pos})
-  else p
-
 (* a binary expression is an expression that combines two expressions with an
  * operator. Examples:
  *    a + b
@@ -2171,11 +2150,6 @@ and parse_binary_expr ?(context = OrdinaryExpr) ?a p prec =
     | None -> parse_operand_expr ~context p
   in
   let rec loop a =
-    let p =
-      match p.token with
-      | LessThan | GreaterThan -> parse_shift_operator p
-      | _ -> p
-    in
     let token = p.Parser.token in
     let token_prec =
       match token with
@@ -2205,11 +2179,6 @@ and parse_binary_expr ?(context = OrdinaryExpr) ?a p prec =
       Parser.leave_breadcrumb p (Grammar.ExprBinaryAfterOp token);
       let start_pos = p.start_pos in
       Parser.next p;
-      (* let p =
-        match p.token with
-        | LessThan | GreaterThan -> parse_shift_operator p
-        | _ -> p
-      in *)
       let end_pos = p.prev_end_pos in
       let token_prec =
         (* exponentiation operator is right-associative *)

compiler/syntax/src/res_scanner.ml

@@ -886,24 +886,30 @@ let rec scan scanner =
       | _ ->
         next scanner;
         Token.Plus)
-    | '>' -> (
+    | '>' when not (in_diamond_mode scanner) -> (
       match peek scanner with
-      | '=' when not (in_diamond_mode scanner) ->
+      | '=' ->
         next2 scanner;
         Token.GreaterEqual
+      | '>' -> (
+        match peek2 scanner with
+        | '>' ->
+          next3 scanner;
+          Token.RightShiftUnsigned
+        | _ ->
+          next2 scanner;
+          Token.RightShift)
       | _ ->
         next scanner;
         Token.GreaterThan)
-    | '<' when not (in_diamond_mode scanner) -> (
-      match peek scanner with
-      | '=' ->
-        next2 scanner;
-        Token.LessEqual
-      | _ ->
-        next scanner;
-        Token.LessThan)
+    | '>' ->
+      next scanner;
+      Token.GreaterThan
     | '<' when not (in_jsx_mode scanner) -> (
       match peek scanner with
+      | '<' when not (in_diamond_mode scanner) ->
+        next2 scanner;
+        Token.LeftShift
       | '=' ->
         next2 scanner;
         Token.LessEqual
@@ -1054,26 +1060,3 @@ let is_binary_op src start_cnum end_cnum =
       || is_whitespace (String.unsafe_get src end_cnum)
     in
     left_ok && right_ok)
-
-let is_left_shift scanner _start_cnum =
-  (* print_endline ("@@@@@ is_left_shift ch: " ^ (Char.escaped scanner.ch)); *)
-  (* print_endline ("@@@@@ is_left_shift cnum: " ^ (string_of_int _start_cnum)); *)
-  (* print_endline ("@@@@@ is_left_shift peek: " ^ (Char.escaped (peek scanner))); *)
-  match scanner.ch with
-  | '<' -> true
-  | _ -> false
-
-let is_right_shift scanner _start_cnum =
-  (* print_endline ("@@@@@ is_right_shift ch: " ^ (Char.escaped scanner.ch)); *)
-  (* print_endline ("@@@@@ is_right_shift cnum: " ^ (string_of_int _start_cnum)); *)
-  (* print_endline ("@@@@@ is_right_shift peek: " ^ (Char.escaped (peek scanner))); *)
-  match scanner.ch with
-  | '>' -> true
-  | _ -> false
-
-let is_right_shift_unsigned scanner _start_cnum =
-  (* print_endline ("@@@@@ is_right_shift_unsigned ch: " ^ (Char.escaped scanner.ch)); *)
-  (* print_endline ("@@@@@ is_right_shift_unsigned peek: " ^ (Char.escaped (peek scanner))); *)
-  match (scanner.ch, peek scanner) with
-  | '>', '>' -> true
-  | _ -> false

compiler/syntax/src/res_scanner.mli

@@ -26,10 +26,6 @@ val scan : t -> Lexing.position * Lexing.position * Res_token.t
 
 val is_binary_op : string -> int -> int -> bool
 
-val is_left_shift : t -> int -> bool
-val is_right_shift : t -> int -> bool
-val is_right_shift_unsigned : t -> int -> bool
-
 val set_jsx_mode : t -> unit
 val set_diamond_mode : t -> unit
 val pop_mode : t -> mode -> unit

tests/syntax_tests/data/parsing/errors/typexpr/expected/typeConstructorArgs.res.txt

@@ -38,18 +38,20 @@
 
 
   Syntax error!
-  syntax_tests/data/parsing/errors/typexpr/typeConstructorArgs.res:9:28
+  syntax_tests/data/parsing/errors/typexpr/typeConstructorArgs.res:8:16-17
 
+   6 │ type t<'a> = private Belt.Map.t('a)
    7 │ 
    8 │ type t = option<<node<int>>
    9 │ type t = option(<node<int>>)
   10 │ 
 
-  I'm not sure what to parse here when looking at ")".
+  I'm not sure what to parse here when looking at "<<".
 
 type nonrec 'a node = {
   _value: 'a Js.Nullable.value }
 type nonrec 'a t = 'a Belt.Map.t
 type nonrec 'a t = private 'a Belt.Map.t
-type nonrec t = int node option
+type nonrec t = option
+;;node < (int >> ([%rescript.exprhole ]))
 type nonrec t = int node option

tests/syntax_tests/data/parsing/grammar/expressions/expected/binary.res.txt

@@ -15,6 +15,9 @@ let x = (a + (-1)) + (-2)
 let x = (a + (((-1))[@attr ])) + (((-2))[@attr ])
 let x = (a % a) == 0
 let x = a ^ (a == 0)
+let x = (a << a) == 0
+let x = (a >> a) == 0
+let x = (a >>> a) == 0
 let x = a - b
 let x = a -. b
 ;;Constructor (a, b)

tests/syntax_tests/data/printer/expr/expected/binary.res.txt

@@ -86,6 +86,9 @@ x + y / z
 x / y + z
 x % y * z
 x ^ y + z
+x << y + z
+x >> y + z
+x >>> y + z
 100 * x / total
 2 / 3 * 10 / 2 + 2
 let rotateX = (range / rect.height * refY - range / 2) * getXMultiplication(rect.width)

tests/tests/src/belt_int_test.mjs

@@ -37,6 +37,9 @@ Mocha.describe("Belt_int_test", () => {
     Test_utils.eq("File \"belt_int_test.res\", line 42, characters 7-14", 0, 0);
     Test_utils.eq("File \"belt_int_test.res\", line 43, characters 7-14", 0, 0);
     Test_utils.eq("File \"belt_int_test.res\", line 44, characters 7-14", 1, 1);
+    Test_utils.eq("File \"belt_int_test.res\", line 45, characters 7-14", 16, 16);
+    Test_utils.eq("File \"belt_int_test.res\", line 46, characters 7-14", 2, 2);
+    Test_utils.eq("File \"belt_int_test.res\", line 47, characters 7-14", 2, 2);
   });
 });
 

tests/tests/src/unified_ops_test.mjs

@@ -75,8 +75,18 @@ function bxor_bigint(a, b) {
   return a ^ b;
 }
 
+let shl_bigint = (1n << 2n);
+
+let shr_bigint = (8n >> 2n);
+
 let int = 3;
 
+let shl_int = 4;
+
+let shr_int = 2;
+
+let lsr_int = 2147483647;
+
 export {
   int,
   float,
@@ -101,5 +111,10 @@ export {
   pow_overflow,
   bxor_int,
   bxor_bigint,
+  shl_int,
+  shr_int,
+  lsr_int,
+  shl_bigint,
+  shr_bigint,
 }
 /* No side effect */