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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) *StateObject {
data := s.trie.Get(string(addr))
if data == "" {
return nil
}
// build contract
contract := NewStateObjectFromBytes(addr, []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) GetAccount(addr []byte) (account *StateObject) {
data := s.trie.Get(string(addr))
if data == "" {
account = NewAccount(addr, big.NewInt(0))
} else {
account = NewStateObjectFromBytes(addr, []byte(data))
}
return
}
func (s *State) Cmp(other *State) bool {
return s.trie.Cmp(other.trie)
}
func (s *State) Copy() *State {
return NewState(s.trie.Copy())
}
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) GetStateObject(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
}
// Updates any given state object
func (s *State) UpdateStateObject(object *StateObject) {
addr := object.Address()
if object.state != nil {
s.states[string(addr)] = object.state
}
s.trie.Update(string(addr), string(object.RlpEncode()))
}
func (s *State) Put(key, object []byte) {
s.trie.Update(string(key), string(object))
}
func (s *State) Root() interface{} {
return s.trie.Root
}
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