CodeMirror Document incremental parser statefield

main.ts

import { Plugin } from 'obsidian';
import { treeParser } from './tree-parser';
import { OTHER_EXTENSION } from './other-extension';

// Obsidian plugin file
export default class YOURPLUGIN extends Plugin {
	async onload() {
		// ...
		this.registerEditorExtension([treeParser, OTHER_EXTENSION]);
	}
}

other-extension.ts

import { treeParser } from './tree-parser';

import { EditorState } from '@codemirror/state';

export const OTHER_EXTENSION = EditorState.transactionFilter.of(tr => {
	const tree = tr.startState.field(treeParser).tree
	// Do whatever you want with the tree

	return tr;
});

tree-parser.ts

import { StateField } from '@codemirror/state';
import type { ChangedRange } from '@lezer/common';
import { TreeFragment } from '@lezer/common';

import { YOURPARSER } from './parser';

// Removed // @ts-ignore comments for brevity, but there are a couple places where you might have to add them in again

export const treeParser = StateField.define({
	create(state) {
		const tree = YOURPARSER.parser.parse(state.doc.toString());
		const fragments = TreeFragment.addTree(tree);
		return {
			tree: tree,
			fragments: fragments,
		}
	},

	update(value, tr) {
		if (!tr.docChanged) return value;

		const changed_ranges: ChangedRange[] = [];
		tr.changes.iterChangedRanges((from, to, fromB, toB) =>
			changed_ranges.push({fromA: from, toA: to, fromB: fromB, toB: toB})
		);

		let fragments = TreeFragment.applyChanges(value.fragments, changed_ranges);
		const tree = criticmarkupLanguage.parser.parse(tr.state.doc.toString(), fragments);
		fragments = TreeFragment.addTree(tree, fragments);

		return {
			tree: tree,
			fragments: fragments,
		}
	},
});