feat: Initial clean release of CHM

packages/editor/ProseMirror/utils/forEachHeading.ts

@@ -0,0 +1,27 @@
+import uslug from '@joplin/fork-uslug/lib/uslug';
+import { Node } from 'prosemirror-model';
+
+type OnHeading = (node: Node, hash: string, pos: number)=> boolean|void;
+
+const forEachHeading = (doc: Node, callback: OnHeading) => {
+	let done = false;
+	const seenHashes = new Set<string>();
+	doc.descendants((node, pos) => {
+		if (node.type.name === 'heading') {
+			const originalHash = uslug(node.textContent);
+
+			let hash = originalHash;
+			let counter = 1;
+			while (seenHashes.has(hash)) {
+				counter++;
+				hash = `${originalHash}-${counter}`;
+			}
+			seenHashes.add(hash);
+
+			done = !!callback(node, hash, pos);
+		}
+		return !done;
+	});
+};
+
+export default forEachHeading;