github.com/alexanderbez/go-ethereum@v1.8.17-0.20181024144731-0a57b29f0c8e/core/state/iterator.go

// 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 (
	"github.com/ethereum/go-ethereum/common"
	"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)
	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 = it.state.trie.NodeIterator(nil)
// 	}
// 	// If we had data nodes previously, we surely have at least state nodes
// 	if it.dataIt != nil {
// 		if cont := it.dataIt.Next(true); !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(true); !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 Account
// 	if err := rlp.Decode(bytes.NewReader(it.stateIt.LeafBlob()), &account); err != nil {
// 		return err
// 	}
// 	dataTrie, err := it.state.db.OpenStorageTrie(common.BytesToHash(it.stateIt.LeafKey()), account.Root)
// 	if err != nil {
// 		return err
// 	}
// 	it.dataIt = dataTrie.NodeIterator(nil)
// 	if !it.dataIt.Next(true) {
// 		it.dataIt = nil
// 	}
// 	if !bytes.Equal(account.CodeHash, emptyCodeHash) {
// 		it.codeHash = common.BytesToHash(account.CodeHash)
// 		addrHash := common.BytesToHash(it.stateIt.LeafKey())
// 		it.code, err = it.state.db.ContractCode(addrHash, common.BytesToHash(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 = common.Hash{}

// 	// 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.Parent = it.dataIt.Hash(), it.dataIt.Parent()
// 		if it.Parent == (common.Hash{}) {
// 			it.Parent = it.accountHash
// 		}
// 	case it.code != nil:
// 		it.Hash, it.Parent = it.codeHash, it.accountHash
// 	case it.stateIt != nil:
// 		it.Hash, it.Parent = it.stateIt.Hash(), it.stateIt.Parent()
// 	}
// 	return true
// }