Support optional fields in record patterns

Author: Emilios1995

grammar.js

@@ -886,6 +886,7 @@ module.exports = grammar({
     record_pattern: $ => seq(
       '{',
       commaSep1t(seq(
+        optional("?"),
         choice(
           $.value_identifier,
           $.value_identifier_path,

test/corpus/expressions.txt

@@ -762,6 +762,7 @@ switch person {
   }) => 20
 | Student({status: Sick}) => 30
 | Student({name}) => 40
+| Student({?age}) => 50
 }
 
 --------------------------------------------------------------------------------
@@ -825,7 +826,16 @@ switch person {
               (value_identifier))))
         (sequence_expression
           (expression_statement
-            (number)))))))
+            (number))))
+        (switch_match
+          (variant_pattern
+          (variant_identifier)
+          (formal_parameters
+            (record_pattern
+              (value_identifier))))
+           (sequence_expression
+             (expression_statement
+               (number)))))))
 
 ================================================================================
 Switch of lists

test/corpus/let_bindings.txt

@@ -101,6 +101,8 @@ Record destructuring
 let {bar, baz} = foo
 let {bar, baz: qux} = foo
 let {Bar.Bar.bar: bar} = foo
+let {?Bar.bar} = foo
+let {?bar} = foo
 
 --------------------------------------------------------------------------------
 
@@ -127,6 +129,18 @@ let {Bar.Bar.bar: bar} = foo
             (module_identifier))
           (value_identifier))
         (value_identifier))
+      (value_identifier)))
+  (let_declaration
+    (let_binding
+      (record_pattern
+        (value_identifier_path
+          (module_identifier)
+          (value_identifier)))
+      (value_identifier)))
+  (let_declaration
+    (let_binding
+      (record_pattern
+        (value_identifier))
       (value_identifier))))
 
 ================================================================================