Rename Palette to FRAME (#4182)

* palette -> frame

* PALETTE, Palette -> FRAME

* Move folder pallete -> frame

* Update docs/Structure.adoc

Co-Authored-By: Benjamin Kampmann <ben.kampmann@googlemail.com>

* Update docs/README.adoc

Co-Authored-By: Benjamin Kampmann <ben.kampmann@googlemail.com>

* Update README.adoc

substrate/frame/evm/src/backend.rs

@@ -0,0 +1,187 @@
+use rstd::marker::PhantomData;
+use rstd::vec::Vec;
+#[cfg(feature = "std")]
+use serde::{Serialize, Deserialize};
+use codec::{Encode, Decode};
+use primitives::{U256, H256, H160};
+use sr_primitives::traits::UniqueSaturatedInto;
+use support::storage::{StorageMap, StorageDoubleMap};
+use sha3::{Keccak256, Digest};
+use evm::Config;
+use evm::backend::{Backend as BackendT, ApplyBackend, Apply};
+use crate::{Trait, Accounts, AccountStorages, AccountCodes, Module, Event};
+
+#[derive(Clone, Eq, PartialEq, Encode, Decode, Default)]
+#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
+/// Ethereum account nonce, balance and code. Used by storage.
+pub struct Account {
+	/// Account nonce.
+	pub nonce: U256,
+	/// Account balance.
+	pub balance: U256,
+}
+
+#[derive(Clone, Eq, PartialEq, Encode, Decode)]
+#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
+/// Ethereum log. Used for `deposit_event`.
+pub struct Log {
+	/// Source address of the log.
+	pub address: H160,
+	/// Topics of the log.
+	pub topics: Vec<H256>,
+	/// Bytearray data of the log.
+	pub data: Vec<u8>,
+}
+
+#[derive(Clone, Eq, PartialEq, Encode, Decode, Default)]
+#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
+/// External input from the transaction.
+pub struct Vicinity {
+	/// Current transaction gas price.
+	pub gas_price: U256,
+	/// Origin of the transaction.
+	pub origin: H160,
+}
+
+/// Gasometer config used for executor. Currently this is hard-coded to
+/// Istanbul hard fork.
+pub static GASOMETER_CONFIG: Config = Config::istanbul();
+
+/// Substrate backend for EVM.
+pub struct Backend<'vicinity, T> {
+	vicinity: &'vicinity Vicinity,
+	_marker: PhantomData<T>,
+}
+
+impl<'vicinity, T> Backend<'vicinity, T> {
+	/// Create a new backend with given vicinity.
+	pub fn new(vicinity: &'vicinity Vicinity) -> Self {
+		Self { vicinity, _marker: PhantomData }
+	}
+}
+
+impl<'vicinity, T: Trait> BackendT for Backend<'vicinity, T> {
+	fn gas_price(&self) -> U256 { self.vicinity.gas_price }
+	fn origin(&self) -> H160 { self.vicinity.origin }
+
+	fn block_hash(&self, number: U256) -> H256 {
+		if number > U256::from(u32::max_value()) {
+			H256::default()
+		} else {
+			let number = T::BlockNumber::from(number.as_u32());
+			H256::from_slice(system::Module::<T>::block_hash(number).as_ref())
+		}
+	}
+
+	fn block_number(&self) -> U256 {
+		let number: u128 = system::Module::<T>::block_number().unique_saturated_into();
+		U256::from(number)
+	}
+
+	fn block_coinbase(&self) -> H160 {
+		H160::default()
+	}
+
+	fn block_timestamp(&self) -> U256 {
+		let now: u128 = timestamp::Module::<T>::get().unique_saturated_into();
+		U256::from(now)
+	}
+
+	fn block_difficulty(&self) -> U256 {
+		U256::zero()
+	}
+
+	fn block_gas_limit(&self) -> U256 {
+		U256::zero()
+	}
+
+	fn chain_id(&self) -> U256 {
+		U256::from(runtime_io::misc::chain_id())
+	}
+
+	fn exists(&self, _address: H160) -> bool {
+		true
+	}
+
+	fn basic(&self, address: H160) -> evm::backend::Basic {
+		let account = Accounts::get(&address);
+
+		evm::backend::Basic {
+			balance: account.balance,
+			nonce: account.nonce,
+		}
+	}
+
+	fn code_size(&self, address: H160) -> usize {
+		AccountCodes::decode_len(&address).unwrap_or(0)
+	}
+
+	fn code_hash(&self, address: H160) -> H256 {
+		H256::from_slice(Keccak256::digest(&AccountCodes::get(&address)).as_slice())
+	}
+
+	fn code(&self, address: H160) -> Vec<u8> {
+		AccountCodes::get(&address)
+	}
+
+	fn storage(&self, address: H160, index: H256) -> H256 {
+		AccountStorages::get(address, index)
+	}
+}
+
+impl<'vicinity, T: Trait> ApplyBackend for Backend<'vicinity, T> {
+	fn apply<A, I, L>(
+		&mut self,
+		values: A,
+		logs: L,
+		delete_empty: bool,
+	) where
+		A: IntoIterator<Item=Apply<I>>,
+		I: IntoIterator<Item=(H256, H256)>,
+		L: IntoIterator<Item=evm::backend::Log>,
+	{
+		for apply in values {
+			match apply {
+				Apply::Modify {
+					address, basic, code, storage, reset_storage,
+				} => {
+					Accounts::mutate(&address, |account| {
+						account.balance = basic.balance;
+						account.nonce = basic.nonce;
+					});
+
+					if let Some(code) = code {
+						AccountCodes::insert(address, code);
+					}
+
+					if reset_storage {
+						AccountStorages::remove_prefix(address);
+					}
+
+					for (index, value) in storage {
+						if value == H256::default() {
+							AccountStorages::remove(address, index);
+						} else {
+							AccountStorages::insert(address, index, value);
+						}
+					}
+
+					if delete_empty {
+						Module::<T>::remove_account_if_empty(&address);
+					}
+				},
+				Apply::Delete { address } => {
+					Module::<T>::remove_account(&address)
+				},
+			}
+		}
+
+		for log in logs {
+			Module::<T>::deposit_event(Event::Log(Log {
+				address: log.address,
+				topics: log.topics,
+				data: log.data,
+			}));
+		}
+	}
+}