[MFM] Better hashtag detection

src/mfm/parser.ts

@@ -162,7 +162,7 @@ const mfm = P.createLanguage({
 			let hashtag = match[1];
 			hashtag = hashtag.substr(0, getTrailingPosition(hashtag));
 			if (hashtag.match(/^[0-9]+$/)) return P.makeFailure(i, 'not a hashtag');
-			if (!['\n', ' ', '　', '(', '「', null, undefined].includes(input[i - 1])) return P.makeFailure(i, 'require space before "#"');
+			if (input[i - 1] != null && input[i - 1].match(/[a-z0-9]/i)) return P.makeFailure(i, 'not a hashtag');
 			return P.makeSuccess(i + ('#' + hashtag).length, makeNode('hashtag', { hashtag: hashtag }));
 		}),
 	//#endregion

test/mfm.ts

@@ -187,9 +187,9 @@ describe('Text', () => {
 			});
 
 			it('with text (zenkaku)', () => {
-				const tokens = analyze('こんにちは　#世界');
+				const tokens = analyze('こんにちは#世界');
 				assert.deepEqual([
-					text('こんにちは　'),
+					text('こんにちは'),
 					node('hashtag', { hashtag: '世界' })
 				], tokens);
 			});