I think Microsoft did that in their Roslyn dot.net compiler. There is a server that is fed source code changes and it updates the AST internally incrementally.

I think Microsoft did that in their Roslyn dot.net compiler. There is a server that is fed source code changes and it updates the AST internally incrementally. The text editor can then make queries against that AST. I believe Microsoft also took a portion of this as added it to Visual Studio Code.