Fix mul/div precedence to parse left to right (#126)

Multiply and divide should apply left to right when not parenthesized

Author: gregorybchris

scrapscript.py

@@ -303,8 +303,8 @@ def xp(n: float) -> Prec:
     ">>": lp(14),
     "<<": lp(14),
     "^": rp(13),
-    "*": lp(12),
-    "/": lp(12),
+    "*": rp(12),
+    "/": rp(12),
     "//": lp(12),
     "%": lp(12),
     "+": lp(11),
@@ -1926,6 +1926,12 @@ def test_mul_binds_tighter_than_add_left(self) -> None:
             Binop(BinopKind.ADD, Binop(BinopKind.MUL, Int(1), Int(2)), Int(3)),
         )
 
+    def test_mul_and_div_bind_left_to_right(self) -> None:
+        self.assertEqual(
+            parse([IntLit(1), Operator("/"), IntLit(3), Operator("*"), IntLit(3)]),
+            Binop(BinopKind.MUL, Binop(BinopKind.DIV, Int(1), Int(3)), Int(3)),
+        )
+
     def test_exp_binds_tighter_than_mul_right(self) -> None:
         self.assertEqual(
             parse([IntLit(5), Operator("*"), IntLit(2), Operator("^"), IntLit(3)]),
@@ -3930,6 +3936,16 @@ def test_any_short_circuits(self) -> None:
             Variant("true", Hole()),
         )
 
+    def test_mul_and_div_have_left_to_right_precedence(self) -> None:
+        self.assertEqual(
+            self._run(
+                """
+        1 / 3 * 3
+        """
+            ),
+            Float(1.0),
+        )
+
 
 class BencodeTests(unittest.TestCase):
     def test_bencode_int(self) -> None: