Allow single opcode stepping for EVM

ethcore/evm/Cargo.toml

@@ -5,6 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 
 [dependencies]
 bit-set = "0.4"
+parity-bytes = { git = "https://github.com/paritytech/parity-common" }
 ethereum-types = "0.3"
 heapsize = "0.4"
 lazy_static = "1.0"

ethcore/evm/src/evm.rs

@@ -55,6 +55,12 @@ impl Finalize for Result<GasLeft> {
 	}
 }
 
+impl Finalize for Error {
+	fn finalize<E: Ext>(self, _ext: E) -> Result<FinalizationResult> {
+		Err(self)
+	}
+}
+
 /// Cost calculation type. For low-gas usage we calculate costs using usize instead of U256
 pub trait CostType: Sized + From<usize> + Copy
 	+ ops::Mul<Output=Self> + ops::Div<Output=Self> + ops::Add<Output=Self> +ops::Sub<Output=Self>

ethcore/evm/src/factory.rs

@@ -17,8 +17,9 @@
 //! Evm factory.
 //!
 use std::sync::Arc;
-use vm::Vm;
+use vm::{Vm, Schedule};
 use ethereum_types::U256;
+use super::vm::ActionParams;
 use super::interpreter::SharedCache;
 use super::vmtype::VMType;
 
@@ -32,12 +33,12 @@ pub struct Factory {
 impl Factory {
 	/// Create fresh instance of VM
 	/// Might choose implementation depending on supplied gas.
-	pub fn create(&self, gas: &U256) -> Box<Vm> {
+	pub fn create(&self, params: ActionParams, schedule: &Schedule, depth: usize) -> Box<Vm> {
 		match self.evm {
-			VMType::Interpreter => if Self::can_fit_in_usize(gas) {
-				Box::new(super::interpreter::Interpreter::<usize>::new(self.evm_cache.clone()))
+			VMType::Interpreter => if Self::can_fit_in_usize(&params.gas) {
+				Box::new(super::interpreter::Interpreter::<usize>::new(params, self.evm_cache.clone(), schedule, depth))
 			} else {
-				Box::new(super::interpreter::Interpreter::<U256>::new(self.evm_cache.clone()))
+				Box::new(super::interpreter::Interpreter::<U256>::new(params, self.evm_cache.clone(), schedule, depth))
 			}
 		}
 	}
@@ -68,7 +69,14 @@ impl Default for Factory {
 
 #[test]
 fn test_create_vm() {
-	let _vm = Factory::default().create(&U256::zero());
+	use vm::Ext;
+	use vm::tests::FakeExt;
+	use bytes::Bytes;
+
+	let mut params = ActionParams::default();
+	params.code = Some(Arc::new(Bytes::default()));
+	let ext = FakeExt::new();
+	let _vm = Factory::default().create(params, ext.schedule(), ext.depth());
 }
 
 /// Create tests by injecting different VM factories