Name variable node for expansions

corpus/label.txt

@@ -60,7 +60,8 @@ LABEL key="value${FOO}"
 		(label_pair
 			key: (unquoted_string)
 			value: (double_quoted_string
-				(expansion)))))
+				(expansion
+					(variable))))))
 
 ==================
 Stopsignal
@@ -72,7 +73,8 @@ STOPSIGNAL $FOO
 
 (source_file
 	(stopsignal_instruction
-		(expansion)))
+		(expansion
+			(variable))))
 
 ==================
 User
@@ -85,8 +87,10 @@ USER foo$FOO:bar$BAR
 (source_file
 	(user_instruction
 		user: (unquoted_string
-			(expansion))
+			(expansion
+				(variable)))
 		group: (unquoted_string
-			(expansion))))
+			(expansion
+				(variable)))))
 		
 

corpus/vars.txt

@@ -9,9 +9,11 @@ ADD /$FOO ./${bar}
 (source_file
 	(add_instruction
 		(path
-			(expansion))
+			(expansion
+				(variable)))
 		(path
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Copy
@@ -24,9 +26,11 @@ COPY $FOO ./${bar}
 (source_file
 	(copy_instruction
 		(path
-			(expansion))
+			(expansion
+				(variable)))
 		(path
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Special chars
@@ -39,9 +43,11 @@ COPY $FOO ./${bar:-abc}
 (source_file
 	(copy_instruction
 		(path
-			(expansion))
+			(expansion
+				(variable)))
 		(path
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Env
@@ -60,19 +66,23 @@ ENV TEST="foo$BAR" \
 		(env_pair
 			name: (unquoted_string)
 			value: (double_quoted_string
-				(expansion)))
+				(expansion
+					(variable))))
 		(env_pair
 			name: (unquoted_string)
 			value: (unquoted_string
-				(expansion)))
+				(expansion
+					(variable))))
 		(env_pair
 			name: (unquoted_string)
 			value: (double_quoted_string
-				(expansion)))
+				(expansion
+					(variable))))
 		(env_pair
 			name: (unquoted_string)
 			value: (unquoted_string
-				(expansion)))))
+				(expansion
+					(variable))))))
 
 ==================
 Expose
@@ -86,7 +96,8 @@ EXPOSE $FOO
 (source_file
 	(expose_instruction
 		(expose_port
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 From
@@ -100,13 +111,17 @@ FROM foo/$FOO:$BAR@sha256:$BAZ AS baz$QUX
 	(from_instruction
 		(image_spec
 		    name: (image_name
-				(expansion))
+				(expansion
+					(variable)))
 		    tag: (image_tag
-				(expansion))
+				(expansion
+					(variable)))
 		    digest: (image_digest
-				(expansion)))
+				(expansion
+					(variable))))
 		as: (image_alias
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Label
@@ -121,7 +136,8 @@ LABEL key="value$FOO"
 		(label_pair
 			key: (unquoted_string)
 			value: (double_quoted_string
-				(expansion)))))
+				(expansion
+					(variable))))))
 
 ==================
 Stopsignal
@@ -133,7 +149,8 @@ STOPSIGNAL $FOO
 
 (source_file
 	(stopsignal_instruction
-		(expansion)))
+		(expansion
+			(variable))))
 
 ==================
 User
@@ -146,9 +163,11 @@ USER foo$FOO:bar${bar}
 (source_file
 	(user_instruction
 		user: (unquoted_string
-			(expansion))
+			(expansion
+				(variable)))
 		group: (unquoted_string
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Volume
@@ -162,9 +181,11 @@ volume /my$FOO /my${bar}
 (source_file
 	(volume_instruction
 		(path
-			(expansion))
+			(expansion
+				(variable)))
 		(path
-			(expansion))))
+			(expansion
+				(variable)))))
 
 ==================
 Workdir
@@ -177,7 +198,8 @@ WORKDIR /tmp/$FOO
 (source_file
 	(workdir_instruction
 		(path
-			(expansion))))
+			(expansion
+				(variable)))))
 
 		
 ==================
@@ -192,6 +214,8 @@ ONBUILD ADD /$FOO ./${bar}
 	(onbuild_instruction
 		(add_instruction
 			(path
-				(expansion))
+				(expansion
+					(variable)))
 			(path
-				(expansion)))))
+				(expansion
+					(variable))))))

grammar.js

@@ -194,12 +194,14 @@ module.exports = grammar({
 
 				expansion: $ => seq(
 					'$',
-					repeat1(choice(
+					choice(
-						token.immediate(/[a-zA-Z][a-zA-Z0-9_]*/),
+						$.variable,
-						seq('{', /[^\}]+/, '}'),
+						seq('{', alias(/[^\}]+/, $.variable), '}'),
-					))
+					)
 				),
 
+				variable: $ => token.immediate(/[a-zA-Z][a-zA-Z0-9_]*/),
+
 
 				env_pair: $ => seq(
 					field("name", alias(/[a-zA-Z][a-zA-Z0-9_]+[a-zA-Z0-9]/, $.unquoted_string)),

src/grammar.json

@@ -801,39 +801,45 @@
           "value": "$"
         },
         {
-          "type": "REPEAT1",
+          "type": "CHOICE",
-          "content": {
+          "members": [
-            "type": "CHOICE",
+            {
-            "members": [
+              "type": "SYMBOL",
-              {
+              "name": "variable"
-                "type": "IMMEDIATE_TOKEN",
+            },
-                "content": {
+            {
-                  "type": "PATTERN",
+              "type": "SEQ",
-                  "value": "[a-zA-Z][a-zA-Z0-9_]*"
+              "members": [
-                }
+                {
-              },
+                  "type": "STRING",
-              {
+                  "value": "{"
-                "type": "SEQ",
+                },
-                "members": [
+                {
-                  {
+                  "type": "ALIAS",
-                    "type": "STRING",
+                  "content": {
-                    "value": "{"
-                  },
-                  {
                     "type": "PATTERN",
                     "value": "[^\\}]+"
                   },
-                  {
+                  "named": true,
-                    "type": "STRING",
+                  "value": "variable"
-                    "value": "}"
+                },
-                  }
+                {
-                ]
+                  "type": "STRING",
-              }
+                  "value": "}"
-            ]
+                }
-          }
+              ]
+            }
+          ]
         }
       ]
     },
+    "variable": {
+      "type": "IMMEDIATE_TOKEN",
+      "content": {
+        "type": "PATTERN",
+        "value": "[a-zA-Z][a-zA-Z0-9_]*"
+      }
+    },
     "env_pair": {
       "type": "SEQ",
       "members": [

src/node-types.json

@@ -177,7 +177,17 @@
   {
     "type": "expansion",
     "named": true,
-    "fields": {}
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "variable",
+          "named": true
+        }
+      ]
+    }
   },
   {
     "type": "expose_instruction",
@@ -861,6 +871,10 @@
     "type": "escape_sequence",
     "named": true
   },
+  {
+    "type": "variable",
+    "named": true
+  },
   {
     "type": "{",
     "named": false