llvm-clang: incremental or online parser?

Is there anyway to use the llvm-clang parser in an incremental/online manner?

Say I'm writing an editor and I want to be able to parse the C++ code I have in front of me.

I don't want to write my own hacked up parser.

I'd like to use something full featured, like llvm-clang.

Is there an easy way to hijack the llvm-clang parser? (And is it fast enough to run it continuously in the background)?

Thanks!