add parsing for hashtags

__tests__/extensions.ts

@@ -12,6 +12,9 @@ const specParser = new SpecParser(parser, {
   t: "TaskMarker",
   EM: "Embed",
   eM: "EmbedMark",
+  H: "Hashtag",
+  hm: "HashtagMark",
+  hl: "HashtagLabel",
   IL: "InternalLink",
   iM: "InternalMark",
   iP: "InternalPath",
@@ -244,4 +247,14 @@ Line 5}
 {HR:---}
   `
   );
+
+  test(
+    "Hashtag",
+    `
+{P:Some text. {H:{hm:#}{hl:tag}} {H:{hm:#}{hl:other-tag9}}^not part
+{H:{hm:#}{hl:ñáø√}}}
+
+{P:Test number #1234}
+  `
+  );
 });

src/extensions.ts

@@ -1,4 +1,4 @@
-import { Input, PartialParse, Tree } from "@lezer/common";
+import { Input } from "@lezer/common";
 import {
   BlockContext,
   Element,
@@ -61,6 +61,36 @@ export const TaskList: MarkdownConfig = {
 };
 /* End Copyright */
 
+const hashtagRE =
+  /^[^\u2000-\u206F\u2E00-\u2E7F'!"#$%&()*+,.:;<=>?@^`{|}~\[\]\\\s]+/;
+
+export const Hashtag: MarkdownConfig = {
+  defineNodes: ["Hashtag", "HashtagMark", "HashtagLabel"],
+  parseInline: [
+    {
+      name: "Hashtag",
+      parse(cx, next, pos) {
+        if (next != 35 /* # */) {
+          return -1;
+        }
+        const start = pos;
+        pos += 1;
+        const match = hashtagRE.exec(cx.text.slice(pos - cx.offset));
+        if (match && /\D/.test(match[0])) {
+          pos += match[0].length;
+          return cx.addElement(
+            cx.elt("Hashtag", start, pos, [
+              cx.elt("HashtagMark", start, start + 1),
+              cx.elt("HashtagLabel", start + 1, pos),
+            ])
+          );
+        }
+        return -1;
+      },
+    },
+  ],
+};
+
 function parseInternalLink(cx: InlineContext, pos: number): Element | null {
   if (
     cx.char(pos) != 91 /* [ */ ||
@@ -322,11 +352,12 @@ export const YAMLFrontMatter: MarkdownConfig = {
 
 export const ObsidianMDExtensions = [
   Footnote,
-  YAMLFrontMatter,
+  Hashtag,
   InternalLink,
   Strikethrough,
   Table,
   TaskList,
+  YAMLFrontMatter,
 ];
 
 export const parser = defParser.configure(ObsidianMDExtensions);