From 53f4b226b94844c4f8517c6d63f4b17a9ddd3512 Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Sun, 13 Dec 2015 21:36:17 +0100
Subject: [PATCH] Add Account and State classes.

---
 src/account.rs | 77 ++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs     |  1 +
 src/state.rs   | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+)
 create mode 100644 src/account.rs
 create mode 100644 src/state.rs

diff --git a/src/account.rs b/src/account.rs
new file mode 100644
index 000000000..995f1c71e
--- /dev/null
+++ b/src/account.rs
@@ -0,0 +1,77 @@
+use std::collections::HashMap;
+use util::hash::*;
+use util::hashdb::*;
+use util::bytes::*;
+use util::trie::*;
+use util::rlp::*;
+use util::uint::*;
+
+enum HashOrData {
+	Hash(H256),
+	Data(Bytes),
+	Both(H256, Bytes),
+}
+
+pub struct Account {
+	balance: U256,
+	nonce: U256,
+	// Trie-backed storage.
+	storage_root: H256,
+	// Overlay on trie-backed storage.
+	storage_overlay: HashMap<H256, H256>,
+	code: HashOrData,
+}
+
+impl Account {
+	pub fn new_with_balance(balance: U256) -> Account {
+		Account {
+			balance: balance,
+			nonce: U256::from(0u8),
+			code: HashOrData::Data(vec![]),
+			storage_root: SHA3_NULL_RLP,
+			storage_overlay: HashMap::new(),
+		}
+	}
+
+	pub fn from_rlp(_rlp: &[u8]) -> Account {
+		//TODO
+		Account {
+			balance: U256::from(0u8),
+			nonce: U256::from(0u8),
+			code: HashOrData::Hash(SHA3_NULL_RLP),
+			storage_root: SHA3_NULL_RLP,
+			storage_overlay: HashMap::new(),
+		}
+	}
+
+	pub fn balance(&self) -> &U256 { &self.balance }
+	pub fn nonce(&self) -> &U256 { &self.nonce }
+	pub fn code_hash(&self) -> Option<&H256> {
+		match self.code {
+			HashOrData::Hash(ref h) | HashOrData::Both(ref h, _) => Some(h),
+			_ => None,
+		}
+	}
+	pub fn storage_root(&self) -> Option<&H256> { if self.storage_overlay.is_empty() {Some(&self.storage_root)} else {None} }
+
+	/// Commit the `storage_overlay` to the backing DB and update `storage_root`.
+	pub fn commit_storage(&mut self, db: &mut HashDB) {
+		let mut t = TrieDB::new(db, &mut self.storage_root);
+		for (k, v) in self.storage_overlay.iter() {
+			// cast key and value to trait type,
+			// so we can call overloaded `to_bytes` method
+			t.insert(k, v);
+		}
+		self.storage_overlay.clear();
+	}
+
+	/// Commit any unsaved code and ensure code is not `HashOrData::Data`.
+	pub fn commit_code(&mut self, db: &mut HashDB) {
+		if let Some(new_code) = match self.code {
+			HashOrData::Data(ref d) => { Some(HashOrData::Both(db.insert(d), d.clone())) },
+			_ => None,
+		}{
+			self.code = new_code;
+		}
+	}
+}
diff --git a/src/lib.rs b/src/lib.rs
index 07fea5389..8a562cec2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -82,6 +82,7 @@ pub use util::uint::*;
 pub use util::bytes::*;
 
 pub mod state;
+pub mod account;
 pub mod blockheader;
 pub mod transaction;
 pub mod networkparams;
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 000000000..86331a5af
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,92 @@
+use std::collections::HashMap;
+use util::hash::*;
+use util::hashdb::*;
+use util::overlaydb::*;
+use util::trie::*;
+use util::rlp::*;
+use util::uint::*;
+use account::Account;
+
+pub struct State {
+	db: OverlayDB,
+	root: H256,
+	_cache: HashMap<Address, Option<Account>>,
+
+	_account_start_nonce: U256,
+}
+
+impl State {
+	/// Creates new state with empty state root
+	pub fn new(mut db: OverlayDB, account_start_nonce: U256) -> State {
+		let mut root = H256::new();
+		{
+			// init trie and reset root too null
+			let _ = TrieDB::new(&mut db, &mut root);
+		}
+
+		State {
+			db: db,
+			root: root,
+			_cache: HashMap::new(),
+			_account_start_nonce: account_start_nonce,
+		}
+	}
+
+	/// Creates new state with existing state root
+	pub fn new_existing(mut db: OverlayDB, mut root: H256, account_start_nonce: U256) -> State {
+		{
+			// trie should panic! if root does not exist
+			let _ = TrieDB::new_existing(&mut db, &mut root);
+		}
+
+		State {
+			db: db,
+			root: root,
+			_cache: HashMap::new(),
+			_account_start_nonce: account_start_nonce,
+		}
+	}
+
+	/// Create temporary state object
+	pub fn new_temp() -> State {
+		Self::new(OverlayDB::new_temp(), U256::from(0u8))
+	}
+
+	/// Return reference to root
+	pub fn root(&self) -> &H256 {
+		&self.root
+	}
+
+	/// Commit everything to the disk
+	pub fn commit_db(&mut self) {
+		self.db.commit().expect("Number of kills exceeded number of inserts!");
+	}
+
+	/// Commit accounts to TrieDB. This is simplified version of
+	/// cpp-ethereum's dev::eth::commit.
+	pub fn commit(db: &mut HashDB, mut root: H256, accounts: &mut HashMap<Address, Account>) -> H256 {
+		// first, commit the sub trees.
+		for (_, ref mut account) in accounts.iter_mut() {
+			account.commit_storage(db);
+			account.commit_code(db);
+		}
+
+		{
+			let mut trie = TrieDB::new_existing(db, &mut root);
+			for (address, account) in accounts.iter() {
+				let mut stream = RlpStream::new_list(4);
+				stream.append(account.nonce());
+				stream.append(account.balance());
+				stream.append(account.storage_root().unwrap());
+				stream.append(account.code_hash().unwrap());
+				trie.insert(address, &stream.out());
+			}
+		}
+		root
+	}
+
+	pub fn insert_accounts(&mut self, accounts: &mut HashMap<Address, Account>) {
+		let r = self.root.clone();
+		self.root = Self::commit(&mut self.db, r, accounts);
+	}
+}