1 files changed, 275 insertions, 0 deletions
diff --git a/light/state.go b/light/state.go
new file mode 100644
index 000000000..e18f9cdc5
--- /dev/null
+++ b/light/state.go
@@ -0,0 +1,275 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package light
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"golang.org/x/net/context"
+)
+
+// StartingNonce determines the default nonce when new accounts are being created.
+var StartingNonce uint64
+
+// LightState is a memory representation of a state.
+// This version is ODR capable, caching only the already accessed part of the
+// state, retrieving unknown parts on-demand from the ODR backend. Changes are
+// never stored in the local database, only in the memory objects.
+type LightState struct {
+	odr  OdrBackend
+	trie *LightTrie
+
+	stateObjects map[string]*StateObject
+}
+
+// NewLightState creates a new LightState with the specified root.
+// Note that the creation of a light state is always successful, even if the
+// root is non-existent. In that case, ODR retrieval will always be unsuccessful
+// and every operation will return with an error or wait for the context to be
+// cancelled.
+func NewLightState(root common.Hash, odr OdrBackend) *LightState {
+	tr := NewLightTrie(root, odr, true)
+	return &LightState{
+		odr:          odr,
+		trie:         tr,
+		stateObjects: make(map[string]*StateObject),
+	}
+}
+
+// HasAccount returns true if an account exists at the given address
+func (self *LightState) HasAccount(ctx context.Context, addr common.Address) (bool, error) {
+	so, err := self.GetStateObject(ctx, addr)
+	return so != nil, err
+}
+
+// GetBalance retrieves the balance from the given address or 0 if the account does
+// not exist
+func (self *LightState) GetBalance(ctx context.Context, addr common.Address) (*big.Int, error) {
+	stateObject, err := self.GetStateObject(ctx, addr)
+	if err != nil {
+		return common.Big0, err
+	}
+	if stateObject != nil {
+		return stateObject.balance, nil
+	}
+
+	return common.Big0, nil
+}
+
+// GetNonce returns the nonce at the given address or 0 if the account does
+// not exist
+func (self *LightState) GetNonce(ctx context.Context, addr common.Address) (uint64, error) {
+	stateObject, err := self.GetStateObject(ctx, addr)
+	if err != nil {
+		return 0, err
+	}
+	if stateObject != nil {
+		return stateObject.nonce, nil
+	}
+	return 0, nil
+}
+
+// GetCode returns the contract code at the given address or nil if the account
+// does not exist
+func (self *LightState) GetCode(ctx context.Context, addr common.Address) ([]byte, error) {
+	stateObject, err := self.GetStateObject(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+	if stateObject != nil {
+		return stateObject.code, nil
+	}
+	return nil, nil
+}
+
+// GetState returns the contract storage value at storage address b from the
+// contract address a or common.Hash{} if the account does not exist
+func (self *LightState) GetState(ctx context.Context, a common.Address, b common.Hash) (common.Hash, error) {
+	stateObject, err := self.GetStateObject(ctx, a)
+	if err == nil && stateObject != nil {
+		return stateObject.GetState(ctx, b)
+	}
+	return common.Hash{}, err
+}
+
+// IsDeleted returns true if the given account has been marked for deletion
+// or false if the account does not exist
+func (self *LightState) IsDeleted(ctx context.Context, addr common.Address) (bool, error) {
+	stateObject, err := self.GetStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		return stateObject.remove, nil
+	}
+	return false, err
+}
+
+/*
+ * SETTERS
+ */
+
+// AddBalance adds the given amount to the balance of the specified account
+func (self *LightState) AddBalance(ctx context.Context, addr common.Address, amount *big.Int) error {
+	stateObject, err := self.GetOrNewStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		stateObject.AddBalance(amount)
+	}
+	return err
+}
+
+// SetNonce sets the nonce of the specified account
+func (self *LightState) SetNonce(ctx context.Context, addr common.Address, nonce uint64) error {
+	stateObject, err := self.GetOrNewStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		stateObject.SetNonce(nonce)
+	}
+	return err
+}
+
+// SetCode sets the contract code at the specified account
+func (self *LightState) SetCode(ctx context.Context, addr common.Address, code []byte) error {
+	stateObject, err := self.GetOrNewStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		stateObject.SetCode(code)
+	}
+	return err
+}
+
+// SetState sets the storage value at storage address key of the account addr
+func (self *LightState) SetState(ctx context.Context, addr common.Address, key common.Hash, value common.Hash) error {
+	stateObject, err := self.GetOrNewStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		stateObject.SetState(key, value)
+	}
+	return err
+}
+
+// Delete marks an account to be removed and clears its balance
+func (self *LightState) Delete(ctx context.Context, addr common.Address) (bool, error) {
+	stateObject, err := self.GetOrNewStateObject(ctx, addr)
+	if err == nil && stateObject != nil {
+		stateObject.MarkForDeletion()
+		stateObject.balance = new(big.Int)
+
+		return true, nil
+	}
+
+	return false, err
+}
+
+//
+// Get, set, new state object methods
+//
+
+// GetStateObject returns the state object of the given account or nil if the
+// account does not exist
+func (self *LightState) GetStateObject(ctx context.Context, addr common.Address) (stateObject *StateObject, err error) {
+	stateObject = self.stateObjects[addr.Str()]
+	if stateObject != nil {
+		if stateObject.deleted {
+			stateObject = nil
+		}
+		return stateObject, nil
+	}
+	data, err := self.trie.Get(ctx, addr[:])
+	if err != nil {
+		return nil, err
+	}
+	if len(data) == 0 {
+		return nil, nil
+	}
+
+	stateObject, err = DecodeObject(ctx, addr, self.odr, []byte(data))
+	if err != nil {
+		return nil, err
+	}
+
+	self.SetStateObject(stateObject)
+
+	return stateObject, nil
+}
+
+// SetStateObject sets the state object of the given account
+func (self *LightState) SetStateObject(object *StateObject) {
+	self.stateObjects[object.Address().Str()] = object
+}
+
+// GetOrNewStateObject returns the state object of the given account or creates a
+// new one if the account does not exist
+func (self *LightState) GetOrNewStateObject(ctx context.Context, addr common.Address) (*StateObject, error) {
+	stateObject, err := self.GetStateObject(ctx, addr)
+	if err == nil && (stateObject == nil || stateObject.deleted) {
+		stateObject, err = self.CreateStateObject(ctx, addr)
+	}
+	return stateObject, err
+}
+
+// newStateObject creates a state object whether it exists in the state or not
+func (self *LightState) newStateObject(addr common.Address) *StateObject {
+	if glog.V(logger.Core) {
+		glog.Infof("(+) %x\n", addr)
+	}
+
+	stateObject := NewStateObject(addr, self.odr)
+	stateObject.SetNonce(StartingNonce)
+	self.stateObjects[addr.Str()] = stateObject
+
+	return stateObject
+}
+
+// CreateStateObject creates creates a new state object and takes ownership.
+// This is different from "NewStateObject"
+func (self *LightState) CreateStateObject(ctx context.Context, addr common.Address) (*StateObject, error) {
+	// Get previous (if any)
+	so, err := self.GetStateObject(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+	// Create a new one
+	newSo := self.newStateObject(addr)
+
+	// If it existed set the balance to the new account
+	if so != nil {
+		newSo.balance = so.balance
+	}
+
+	return newSo, nil
+}
+
+//
+// Setting, copying of the state methods
+//
+
+// Copy creates a copy of the state
+func (self *LightState) Copy() *LightState {
+	// ignore error - we assume state-to-be-copied always exists
+	state := NewLightState(common.Hash{}, self.odr)
+	state.trie = self.trie
+	for k, stateObject := range self.stateObjects {
+		state.stateObjects[k] = stateObject.Copy()
+	}
+
+	return state
+}
+
+// Set copies the contents of the given state onto this state, overwriting
+// its contents
+func (self *LightState) Set(state *LightState) {
+	self.trie = state.trie
+	self.stateObjects = state.stateObjects
+}