add brackets property of url node

docs/syntax.md

@@ -475,6 +475,7 @@ http://hoge.jp/abc
 ```
 
 ## ノード
+構文1:
 ```js
 {
   type: 'url',
@@ -484,6 +485,29 @@ http://hoge.jp/abc
 }
 ```
 
+または
+
+```js
+{
+  type: 'url',
+  props: {
+    url: 'https://misskey.io/@ai',
+    brackets: false
+  }
+}
+```
+
+構文2:
+```js
+{
+  type: 'url',
+  props: {
+    url: 'https://misskey.io/@ai',
+    brackets: true
+  }
+}
+```
+
 ## 詳細
 - インライン構文。
 

src/internal/parser.pegjs

@@ -362,7 +362,7 @@ hashtagChar
 url
 	= "<" url:altUrlFormat ">"
 {
-	return N_URL(url);
+	return N_URL(url, true);
 }
 	/ url:urlFormat
 {

src/internal/util.ts

@@ -79,7 +79,12 @@ export function stringifyNode(node: MfmNode): string {
 			return `#${ node.props.hashtag }`;
 		}
 		case 'url': {
-			return node.props.url;
+			if (node.props.brackets) {
+				return `<${ node.props.url }>`;
+			}
+			else {
+				return node.props.url;
+			}
 		}
 		case 'link': {
 			const prefix = node.props.silent ? '?' : '';

src/node.ts

@@ -143,10 +143,11 @@ export type MfmUrl = {
 	type: 'url';
 	props: {
 		url: string;
+		brackets?: boolean;
 	};
 	children?: [];
 };
-export const N_URL = (value: string): NodeType<'url'> => { return { type:'url', props: { url: value } }; };
+export const N_URL = (value: string, brackets?: boolean): NodeType<'url'> => { return { type:'url', props: { url: value, brackets } }; };
 
 export type MfmLink = {
 	type: 'link';

test/parser.ts

@@ -878,7 +878,7 @@ hoge`;
 		it('match non-ascii characters contained url with angle brackets', () => {
 			const input = '<https://大石泉すき.example.com>';
 			const output = [
-				N_URL('https://大石泉すき.example.com'),
+				N_URL('https://大石泉すき.example.com', true),
 			];
 			assert.deepStrictEqual(mfm.parse(input), output);
 		});