Get all headings for table of contents

Hello,

is it possible to get all headings from a string in an extension? I need this for autogenerating a table of contents.

Thank you in advance

The issue names no files, tests, or entry points. Start by locating the extension API that parses a string and inspect how headings are represented or exposed; done means an extension can retrieve every heading for table-of-contents generation, with coverage for that behavior.

Written by the indexing model from the issue text.