Extract SimpleAddressDeterminator (#716)

substrate/demo/runtime/src/lib.rs

@@ -204,28 +204,9 @@ impl treasury::Trait for Runtime {
 /// Treasury module for this concrete runtime.
 pub type Treasury = treasury::Module<Runtime>;
 
-/// Address calculated from the code (of the constructor), input data to the constructor
-/// and account id which requested the account creation.
-///
-/// Formula: `blake2_256(blake2_256(code) + blake2_256(data) + origin)`
-pub struct DetermineContractAddress;
-impl contract::ContractAddressFor<AccountId> for DetermineContractAddress {
-	fn contract_address_for(code: &[u8], data: &[u8], origin: &AccountId) -> AccountId {
-		use runtime_primitives::traits::Hash;
-
-		let code_hash = BlakeTwo256::hash(code);
-		let data_hash = BlakeTwo256::hash(data);
-		let mut buf = [0u8, 32 + 32 + 32];
-		&mut buf[0..32].copy_from_slice(&code_hash);
-		&mut buf[32..64].copy_from_slice(&data_hash);
-		&mut buf[64..96].copy_from_slice(origin);
-		AccountId::from(BlakeTwo256::hash(&buf[..]))
-	}
-}
-
 impl contract::Trait for Runtime {
 	type Gas = u64;
-	type DetermineContractAddress = DetermineContractAddress;
+	type DetermineContractAddress = contract::SimpleAddressDeterminator<Runtime>;
 }
 
 /// Contract module for this concrete runtime.

substrate/substrate/runtime/contract/src/lib.rs

@@ -103,8 +103,9 @@ use account_db::{AccountDb, OverlayAccountDb};
 use double_map::StorageDoubleMap;
 
 use rstd::prelude::*;
+use rstd::marker::PhantomData;
 use codec::Codec;
-use runtime_primitives::traits::{As, SimpleArithmetic, OnFinalise};
+use runtime_primitives::traits::{Hash, As, SimpleArithmetic, OnFinalise};
 use runtime_support::dispatch::Result;
 use runtime_support::{Parameter, StorageMap, StorageValue};
 use system::ensure_signed;
@@ -121,6 +122,31 @@ pub trait ContractAddressFor<AccountId: Sized> {
 	fn contract_address_for(code: &[u8], data: &[u8], origin: &AccountId) -> AccountId;
 }
 
+/// Simple contract address determintator.
+///
+/// Address calculated from the code (of the constructor), input data to the constructor
+/// and account id which requested the account creation.
+///
+/// Formula: `blake2_256(blake2_256(code) + blake2_256(data) + origin)`
+pub struct SimpleAddressDeterminator<T: Trait>(PhantomData<T>);
+
+impl<T: Trait> ContractAddressFor<T::AccountId> for SimpleAddressDeterminator<T>
+where
+	T::AccountId: From<T::Hash> + AsRef<[u8]>
+{
+	fn contract_address_for(code: &[u8], data: &[u8], origin: &T::AccountId) -> T::AccountId {
+		let code_hash = T::Hashing::hash(code);
+		let data_hash = T::Hashing::hash(data);
+
+		let mut buf = Vec::new();
+		buf.extend_from_slice(code_hash.as_ref());
+		buf.extend_from_slice(data_hash.as_ref());
+		buf.extend_from_slice(origin.as_ref());
+
+		T::Hashing::hash(&buf[..]).into()
+	}
+}
+
 decl_module! {
 	/// Contracts module.
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {