add connection attributes

grammar.js

@@ -13,7 +13,9 @@ module.exports = grammar({
       seq(
         $.identifier,
         repeat1(seq($.arrow, $.identifier)),
-        optional(seq($._colon, $.label)),
+        optional(
+          choice(seq($.dot, $._connection_attribute), seq($._colon, $.label))
+        ),
         $._end
       ),
 
@@ -21,9 +23,8 @@ module.exports = grammar({
       seq(
         $.identifier,
         repeat(seq($.dot, $.identifier)),
-        choice(
-          optional(seq($.dot, $._shape_attribute)),
-          optional(seq($._colon, $.label))
+        optional(
+          choice(seq($.dot, $._shape_attribute), seq($._colon, $.label))
         ),
         $._end
       ),
@@ -54,6 +55,9 @@ module.exports = grammar({
         $._style_attribute
       ),
 
+    _connection_attribute: ($) =>
+      seq(alias($._connection_attr_key, $.attr_key), $._colon, $.attr_value),
+
     _shape_attr_key: ($) =>
       choice(
         "shape",

src/grammar.json

@@ -53,15 +53,33 @@
           "type": "CHOICE",
           "members": [
             {
-              "type": "SEQ",
+              "type": "CHOICE",
               "members": [
                 {
-                  "type": "SYMBOL",
-                  "name": "_colon"
+                  "type": "SEQ",
+                  "members": [
+                    {
+                      "type": "SYMBOL",
+                      "name": "dot"
+                    },
+                    {
+                      "type": "SYMBOL",
+                      "name": "_connection_attribute"
+                    }
+                  ]
                 },
                 {
-                  "type": "SYMBOL",
-                  "name": "label"
+                  "type": "SEQ",
+                  "members": [
+                    {
+                      "type": "SYMBOL",
+                      "name": "_colon"
+                    },
+                    {
+                      "type": "SYMBOL",
+                      "name": "label"
+                    }
+                  ]
                 }
               ]
             },
@@ -118,14 +136,6 @@
                     }
                   ]
                 },
-                {
-                  "type": "BLANK"
-                }
-              ]
-            },
-            {
-              "type": "CHOICE",
-              "members": [
                 {
                   "type": "SEQ",
                   "members": [
@@ -138,11 +148,11 @@
                       "name": "label"
                     }
                   ]
-                },
-                {
-                  "type": "BLANK"
                 }
               ]
+            },
+            {
+              "type": "BLANK"
             }
           ]
         },
@@ -278,6 +288,28 @@
         }
       ]
     },
+    "_connection_attribute": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "ALIAS",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_connection_attr_key"
+          },
+          "named": true,
+          "value": "attr_key"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "_colon"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "attr_value"
+        }
+      ]
+    },
     "_shape_attr_key": {
       "type": "CHOICE",
       "members": [

src/node-types.json

@@ -36,6 +36,18 @@
           "type": "arrow",
           "named": true
         },
+        {
+          "type": "attr_key",
+          "named": true
+        },
+        {
+          "type": "attr_value",
+          "named": true
+        },
+        {
+          "type": "dot",
+          "named": true
+        },
         {
           "type": "identifier",
           "named": true