Allow ENV values to have spaces and be multiline

corpus/env.txt

@@ -122,3 +122,39 @@ ENV TZ America/Toronto
 		(env_pair
 			name: (unquoted_string)
 			value: (unquoted_string))))
+
+================================================================================
+Space syntax where value has spaces
+================================================================================
+
+ENV BUILD_PACKAGES bash curl
+
+--------------------------------------------------------------------------------
+
+(source_file
+	(env_instruction
+		(env_pair
+			name: (unquoted_string)
+      value: (unquoted_string
+        (shell_fragment)))))
+
+================================================================================
+Space syntax where value has spaces and multiple lines
+================================================================================
+
+ENV BUILD_PACKAGES bash curl \
+  openssl \
+  tar xz gcc python
+
+--------------------------------------------------------------------------------
+
+(source_file
+	(env_instruction
+		(env_pair
+			name: (unquoted_string)
+      value: (unquoted_string
+        (shell_fragment)
+        (line_continuation)
+        (shell_fragment)
+        (line_continuation)
+        (shell_fragment)))))

grammar.js

@@ -224,7 +224,12 @@ module.exports = grammar({
       seq(
         field("name", $._env_key),
         token.immediate(/\s+/),
-        field("value", choice($.double_quoted_string, $.unquoted_string))
+        field("value", 
+          choice(
+            $.double_quoted_string, 
+            $.unquoted_string, 
+            alias($.shell_command, $.unquoted_string)
+          ))
       ),
 
     _env_key: ($) =>

src/grammar.json

@@ -1028,6 +1028,15 @@
               {
                 "type": "SYMBOL",
                 "name": "unquoted_string"
+              },
+              {
+                "type": "ALIAS",
+                "content": {
+                  "type": "SYMBOL",
+                  "name": "shell_command"
+                },
+                "named": true,
+                "value": "unquoted_string"
               }
             ]
           }

src/node-types.json

@@ -716,9 +716,21 @@
       "multiple": true,
       "required": false,
       "types": [
+        {
+          "type": "comment",
+          "named": true
+        },
         {
           "type": "expansion",
           "named": true
+        },
+        {
+          "type": "line_continuation",
+          "named": true
+        },
+        {
+          "type": "shell_fragment",
+          "named": true
         }
       ]
     }