format comments (markdoc#216)

src/formatter.test.ts

@@ -77,9 +77,11 @@ break
 Markdoc uses…
 `;
 
+const tokenizer = new Markdoc.Tokenizer({ allowComments: true });
+
 function check(source, expected, options = {}) {
   const a = expected?.trimStart();
-  const b = format(Markdoc.parse(source), options);
+  const b = format(Markdoc.parse(tokenizer.tokenize(source)), options);
   // console.log(a, b);
   const d = diff(a, b);
   if (d && d.includes('Compared values have no visual difference.')) return;
@@ -103,6 +105,25 @@ describe('Formatter', () => {
     stable(expected);
   });
 
+  it('comments', () => {
+    const source = `<!--
+    comment -->
+
+<!-- comment
+   with more
+  than one
+line  -->
+`;
+    const expected = `<!-- comment -->
+<!-- comment
+   with more
+  than one
+line -->
+`;
+
+    check(source, expected);
+  });
+
   it('frontmatter', () => {
     const source = `---
 title: Title

src/formatter.ts

@@ -353,6 +353,10 @@ function* formatNode(n: Node, o: Options = {}) {
       yield* formatChildren(n, no);
       break;
     }
+    case 'comment': {
+      yield '<!-- ' + n.attributes.content + ' -->\n';
+      break;
+    }
     case 'error':
     case 'node':
       break;

src/types.ts

@@ -64,6 +64,7 @@ export type LocationEdge = {
 export type NodeType =
   | 'blockquote'
   | 'code'
+  | 'comment'
   | 'document'
   | 'em'
   | 'error'