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// 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 state
import (
"bytes"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/trie"
)
// NodeIterator is an iterator to traverse the entire state trie post-order,
// including all of the contract code and contract state tries.
type NodeIterator struct {
state *StateDB // State being iterated
stateIt *trie.NodeIterator // Primary iterator for the global state trie
dataIt *trie.NodeIterator // Secondary iterator for the data trie of a contract
accountHash common.Hash // Hash of the node containing the account
codeHash common.Hash // Hash of the contract source code
code []byte // Source code associated with a contract
Hash common.Hash // Hash of the current entry being iterated (nil if not standalone)
Entry interface{} // Current state entry being iterated (internal representation)
Parent common.Hash // Hash of the first full ancestor node (nil if current is the root)
Error error // Failure set in case of an internal error in the iterator
}
// NewNodeIterator creates an post-order state node iterator.
func NewNodeIterator(state *StateDB) *NodeIterator {
return &NodeIterator{
state: state,
}
}
// Next moves the iterator to the next node, returning whether there are any
// further nodes. In case of an internal error this method returns false and
// sets the Error field to the encountered failure.
func (it *NodeIterator) Next() bool {
// If the iterator failed previously, don't do anything
if it.Error != nil {
return false
}
// Otherwise step forward with the iterator and report any errors
if err := it.step(); err != nil {
it.Error = err
return false
}
return it.retrieve()
}
// step moves the iterator to the next entry of the state trie.
func (it *NodeIterator) step() error {
// Abort if we reached the end of the iteration
if it.state == nil {
return nil
}
// Initialize the iterator if we've just started
if it.stateIt == nil {
it.stateIt = trie.NewNodeIterator(it.state.trie.Trie)
}
// If we had data nodes previously, we surely have at least state nodes
if it.dataIt != nil {
if cont := it.dataIt.Next(); !cont {
if it.dataIt.Error != nil {
return it.dataIt.Error
}
it.dataIt = nil
}
return nil
}
// If we had source code previously, discard that
if it.code != nil {
it.code = nil
return nil
}
// Step to the next state trie node, terminating if we're out of nodes
if cont := it.stateIt.Next(); !cont {
if it.stateIt.Error != nil {
return it.stateIt.Error
}
it.state, it.stateIt = nil, nil
return nil
}
// If the state trie node is an internal entry, leave as is
if !it.stateIt.Leaf {
return nil
}
// Otherwise we've reached an account node, initiate data iteration
var account struct {
Nonce uint64
Balance *big.Int
Root common.Hash
CodeHash []byte
}
if err := rlp.Decode(bytes.NewReader(it.stateIt.LeafBlob), &account); err != nil {
return err
}
dataTrie, err := trie.New(account.Root, it.state.db)
if err != nil {
return err
}
it.dataIt = trie.NewNodeIterator(dataTrie)
if !it.dataIt.Next() {
it.dataIt = nil
}
if bytes.Compare(account.CodeHash, emptyCodeHash) != 0 {
it.codeHash = common.BytesToHash(account.CodeHash)
it.code, err = it.state.db.Get(account.CodeHash)
if err != nil {
return fmt.Errorf("code %x: %v", account.CodeHash, err)
}
}
it.accountHash = it.stateIt.Parent
return nil
}
// retrieve pulls and caches the current state entry the iterator is traversing.
// The method returns whether there are any more data left for inspection.
func (it *NodeIterator) retrieve() bool {
// Clear out any previously set values
it.Hash, it.Entry = common.Hash{}, nil
// If the iteration's done, return no available data
if it.state == nil {
return false
}
// Otherwise retrieve the current entry
switch {
case it.dataIt != nil:
it.Hash, it.Entry, it.Parent = it.dataIt.Hash, it.dataIt.Node, it.dataIt.Parent
if it.Parent == (common.Hash{}) {
it.Parent = it.accountHash
}
case it.code != nil:
it.Hash, it.Entry, it.Parent = it.codeHash, it.code, it.accountHash
case it.stateIt != nil:
it.Hash, it.Entry, it.Parent = it.stateIt.Hash, it.stateIt.Node, it.stateIt.Parent
}
return true
}
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