package ethchain import ( "github.com/ethereum/eth-go/ethutil" "math/big" ) // States within the ethereum protocol are used to store anything // within the merkle trie. States take care of caching and storing // nested states. It's the general query interface to retrieve: // * Contracts // * Accounts type State struct { // The trie for this structure trie *ethutil.Trie // Nested states states map[string]*State } // Create a new state from a given trie func NewState(trie *ethutil.Trie) *State { return &State{trie: trie, states: make(map[string]*State)} } // Resets the trie and all siblings func (s *State) Reset() { s.trie.Undo() // Reset all nested states for _, state := range s.states { state.Reset() } } // Syncs the trie and all siblings func (s *State) Sync() { s.trie.Sync() // Sync all nested states for _, state := range s.states { state.Sync() } } // Purges the current trie. func (s *State) Purge() int { return s.trie.NewIterator().Purge() } func (s *State) GetContract(addr []byte) *Contract { data := s.trie.Get(string(addr)) if data == "" { return nil } // Whet get contract is called the retrieved value might // be an account. The StateManager uses this to check // to see if the address a tx was sent to is a contract // or an account value := ethutil.NewValueFromBytes([]byte(data)) if value.Len() == 2 { return nil } // build contract contract := &Contract{} contract.RlpDecode([]byte(data)) // Check if there's a cached state for this contract cachedState := s.states[string(addr)] if cachedState != nil { contract.state = cachedState } else { // If it isn't cached, cache the state s.states[string(addr)] = contract.state } return contract } func (s *State) UpdateContract(addr []byte, contract *Contract) { s.trie.Update(string(addr), string(contract.RlpEncode())) } func Compile(code []string) (script []string) { script = make([]string, len(code)) for i, val := range code { instr, _ := ethutil.CompileInstr(val) script[i] = string(instr) } return } func (s *State) GetAccount(addr []byte) (account *Account) { data := s.trie.Get(string(addr)) if data == "" { account = NewAccount(big.NewInt(0)) } else { account = NewAccountFromData([]byte(data)) } return } func (s *State) UpdateAccount(addr []byte, account *Account) { s.trie.Update(string(addr), string(account.RlpEncode())) } func (s *State) Cmp(other *State) bool { return s.trie.Cmp(other.trie) } type ObjType byte const ( NilTy ObjType = iota AccountTy ContractTy UnknownTy ) // Returns the object stored at key and the type stored at key // Returns nil if nothing is stored func (s *State) Get(key []byte) (*ethutil.Value, ObjType) { // Fetch data from the trie data := s.trie.Get(string(key)) // Returns the nil type, indicating nothing could be retrieved. // Anything using this function should check for this ret val if data == "" { return nil, NilTy } var typ ObjType val := ethutil.NewValueFromBytes([]byte(data)) // Check the length of the retrieved value. // Len 2 = Account // Len 3 = Contract // Other = invalid for now. If other types emerge, add them here if val.Len() == 2 { typ = AccountTy } else if val.Len() == 3 { typ = ContractTy } else { typ = UnknownTy } return val, typ }