Initial (non-functional) code.

- Kill Externalities Error type requirement.

substrate/executor/src/native_executor.rs

@@ -0,0 +1,34 @@
+use primitives::contract::CallData;
+use state_machine::{Externalities, CodeExecutor};
+use error::{Error, ErrorKind, Result};
+use native_runtime as runtime;
+use runtime_support;
+
+struct NativeExecutor;
+
+impl CodeExecutor for NativeExecutor {
+	type Error = Error;
+
+	fn call<E: Externalities>(
+		&self,
+		ext: &mut E,
+		code: &[u8],
+		method: &str,
+		data: &CallData,
+	) -> Result<Vec<u8>> {
+		// WARNING!!! This assumes that the runtime was built *before* the main project. Until we
+		// get a proper build script, this must be strictly adhered to or things will go wrong.
+		let native_equivalent = include_bytes!("../../wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm");
+		if code == &native_equivalent[..] {
+			runtime_support::with_externalities(ext, || match method {
+				// TODO: Panic handler that comes back with error.
+				"execute_block" => Ok(runtime::execute_block(data.0)),
+				"execute_transaction" => Ok(runtime::execute_transaction(data.0)),
+				_ => Err(ErrorKind::MethodNotFound(method.to_owned()).into()),
+			})
+		} else {
+			// call into wasm.
+			unimplemented!()
+		}
+	}
+}