This looks like one of the perfect application of wasm. You could do ruleset -> C -> wasm and run the wasm in process with wasmer/wasmtime. From my understand

This looks like one of the perfect application of wasm. You could do ruleset -> C -> wasm and run the wasm in process with wasmer/wasmtime. From my understanding wasmer might be easier to use. It sounds like this should solve the immediate problem, the main downside I can see is that it might be a new significant dependency whose cost can be hard to judge.