state_transition.go

package ethchain

import (
	"fmt"
	"math/big"
)

/*
 * The State transitioning model
 *
 * A state transition is a change made when a transaction is applied to the current world state
 * The state transitioning model does all all the necessary work to work out a valid new state root.
 * 1) Nonce handling
 * 2) Pre pay / buy gas of the coinbase (miner)
 * 3) Create a new state object if the recipient is \0*32
 * 4) Value transfer
 * == If contract creation ==
 * 4a) Attempt to run transaction data
 * 4b) If valid, use result as code for the new state object
 * == end ==
 * 5) Run Script section
 * 6) Derive new state root
 */
type StateTransition struct {
	coinbase, receiver []byte
	tx                 *Transaction
	gas, gasPrice      *big.Int
	value              *big.Int
	data               []byte
	state              *State
	block              *Block

	cb, rec, sen *StateObject
}

func NewStateTransition(coinbase *StateObject, tx *Transaction, state *State, block *Block) *StateTransition {
	return &StateTransition{coinbase.Address(), tx.Recipient, tx, new(big.Int), new(big.Int).Set(tx.GasPrice), tx.Value, tx.Data, state, block, coinbase, nil, nil}
}

func (self *StateTransition) Coinbase() *StateObject {
	if self.cb != nil {
		return self.cb
	}

	self.cb = self.state.GetAccount(self.coinbase)
	return self.cb
}
func (self *StateTransition) Sender() *StateObject {
	if self.sen != nil {
		return self.sen
	}

	self.sen = self.state.GetAccount(self.tx.Sender())

	return self.sen
}
func (self *StateTransition) Receiver() *StateObject {
	if self.tx != nil && self.tx.CreatesContract() {
		return nil
	}

	if self.rec != nil {
		return self.rec
	}

	self.rec = self.state.GetAccount(self.tx.Recipient)
	return self.rec
}

func (self *StateTransition) MakeStateObject(state *State, tx *Transaction) *StateObject {