module attribute is optional

corpus/declarations.txt

@@ -18,17 +18,87 @@ module with attributes
 ======================
 
 defmodule Name do
-  @moduledoc "an apple a day, keeps the moduledoc away"
+  @after_compile
+  @before_compile
   @behaviour Good.Module
   @custom_attr [:hello, "world"]
   # TODO @custom_attr [hello: "world"]
+  # TODO @dialyzer {:nowarn_function, my_fun: 1}
+  @file "hello.ex"
+  @external_resource
+  @moduledoc "an apple a day, keeps the moduledoc away"
+  @on_load
+  @vsn "1.0"
 end
 
 ---
 
 (program
   (module (alias)
-    (module_attribute (string))
+    (module_attribute)
+    (module_attribute)
     (module_attribute (alias))
     (module_attribute (list (atom) (string)))
+    (comment)
+    (comment)
+    (module_attribute (string))
+    (module_attribute)
+    (module_attribute (string))
+    (module_attribute)
+    (module_attribute (string))))
+
+===============================
+module with function attributes
+===============================
+
+defmodule Name do
+  @deprecated "Use Module.bar/0 instead"
+  @doc "Hello world"
+  # TODO 
+  # @doc """
+  # Doesn't do much.
+  # """
+  # TODO @doc deprecated: "Use Module.bar/0 instead"
+  # TODO @doc since: "1.1.0"
+  @impl true
+  @impl Module
+  @on_definition
+  # def foo() do
+  # end
+end
+
+---
+
+(program
+  (module (alias)
+    (module_attribute (string))
+    (module_attribute (string))
+    (comment)
+    (comment)
+    (comment)
+    (comment)
+    (comment)
+    (comment)
+    (module_attribute (true))
+    (module_attribute (alias))
+    (module_attribute)
+    (comment)
+    (comment)))
+
+===========================
+module with type attributes
+===========================
+
+defmodule Name do
+  @typedoc "This type"
+  # TODO @typedoc since: "1.1.0"
+  # TODO @type t :: term
+end
+
+---
+
+(program
+  (module (alias)
+    (module_attribute (string))
+    (comment)
     (comment)))

grammar.js

@@ -173,7 +173,7 @@ module.exports = grammar({
 
     module_attribute: $ => seq(
       /@\w+/,
-      $._value,
+      optional($._value),
     ),
 
     comment: $ => token(seq('#', /.*/)),

src/grammar.json

@@ -649,8 +649,16 @@
           "value": "@\\w+"
         },
         {
-          "type": "SYMBOL",
-          "name": "_value"
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "_value"
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
         }
       ]
     },