feat: interpolated attributes without names

Fixes #28.

README.md

@@ -44,9 +44,10 @@ These are used as tags that aren't actually present in the final HTML.
 These are implemented by special-casing unnamed elements in the external lexer.
 
 #### Attribute interpolations
-These are special attributes that evaluate to the result of a TypeScript expression. Astro's docs call these "expressions".
+These are special attributes that evaluate to the result of a TypeScript expression. Astro's docs call these "expressions". They come in two forms:
 ```astro
 <div style={styleMap}></div>
+<div {...attrMap}></div>
 ```
 These are just handled as injected TypeScript.
 

corpus/interpolated-attribute-map.txt

@@ -0,0 +1,26 @@
+===
+Interpolated attribute map (without equal sign or name)
+===
+
+<div regattr="hi" {...specialinterp} reginterp={interp}>
+</div>
+
+-------
+
+(document
+  (element
+    (start_tag
+      (tag_name)
+      (attribute
+        (attribute_name)
+        (quoted_attribute_value
+          (attribute_value)))
+      (attribute
+        (attribute_interpolation
+          (attribute_js_expr)))
+      (attribute
+        (attribute_name)
+        (attribute_interpolation
+          (attribute_js_expr))))
+    (end_tag
+      (tag_name))))

grammar.js

@@ -94,6 +94,9 @@ module.exports = grammar(HTML, {
                     $.attribute_backtick_string,
                 ),
             ),
+            // Astro directly allows attributes without equal signs,
+            // e.g. <div {...attrs} />
+            $.attribute_interpolation,
         ),
 
         attribute_interpolation: $ => seq(

src/grammar.json

@@ -474,6 +474,10 @@
               ]
             }
           ]
+        },
+        {
+          "type": "SYMBOL",
+          "name": "attribute_interpolation"
         }
       ]
     },