parse comments

compiler/parse/state/tag.js

@@ -22,6 +22,20 @@ const specials = {
 export default function tag ( parser ) {
 	const start = parser.index++;
 
+	if ( parser.eat( '!--' ) ) {
+		const data = parser.readUntil( /-->/ );
+		parser.eat( '-->' );
+
+		parser.current().children.push({
+			start,
+			end: parser.index,
+			type: 'Comment',
+			data
+		});
+
+		return null;
+	}
+
 	const isClosingTag = parser.eat( '/' );
 
 	// TODO handle cases like <li>one<li>two

test/parser/comment/input.svelte

@@ -0,0 +1 @@
+<!-- a comment -->

test/parser/comment/output.json

@@ -0,0 +1,17 @@
+{
+	"html": {
+		"start": 0,
+		"end": 18,
+		"type": "Fragment",
+		"children": [
+			{
+				"start": 0,
+				"end": 18,
+				"type": "Comment",
+				"data": " a comment "
+			}
+		]
+	},
+	"css": null,
+	"js": null
+}