Reimplement MD024/no-duplicate-heading using micromark tokens.

lib/md024.js

@@ -2,7 +2,8 @@
 
 "use strict";
 
-const { addErrorContext, forEachHeading } = require("../helpers");
+const { addErrorContext } = require("../helpers");
+const { filterByTypes, getHeadingLevel, getHeadingText } = require("../helpers/micromark.cjs");
 
 // eslint-disable-next-line jsdoc/valid-types
 /** @type import("./markdownlint").Rule */
@@ -10,15 +11,20 @@ module.exports = {
   "names": [ "MD024", "no-duplicate-heading" ],
   "description": "Multiple headings with the same content",
   "tags": [ "headings" ],
-  "parser": "markdownit",
+  "parser": "micromark",
   "function": function MD024(params, onError) {
     const siblingsOnly = !!params.config.siblings_only || false;
     const knownContents = [ null, [] ];
     let lastLevel = 1;
     let knownContent = knownContents[lastLevel];
-    forEachHeading(params, (heading, content) => {
+    const headings = filterByTypes(
+      params.parsers.micromark.tokens,
+      [ "atxHeading", "setextHeading" ]
+    );
+    for (const heading of headings) {
+      const headingText = getHeadingText(heading);
       if (siblingsOnly) {
-        const newLevel = heading.tag.slice(1);
+        const newLevel = getHeadingLevel(heading);
         while (lastLevel < newLevel) {
           lastLevel++;
           knownContents[lastLevel] = [];
@@ -30,16 +36,16 @@ module.exports = {
         knownContent = knownContents[newLevel];
       }
       // @ts-ignore
-      if (knownContent.includes(content)) {
+      if (knownContent.includes(headingText)) {
         addErrorContext(
           onError,
-          heading.lineNumber,
-          heading.line.trim()
+          heading.startLine,
+          headingText.trim()
         );
       } else {
         // @ts-ignore
-        knownContent.push(content);
+        knownContent.push(headingText);
       }
-    });
+    }
   }
 };