github.com/neatlab/neatio@v1.7.3-0.20220425043230-d903e92fcc75/chain/trie/iterator.go

package trie

import (
	"bytes"
	"container/heap"
	"errors"

	"github.com/neatlab/neatio/utilities/common"
	"github.com/neatlab/neatio/utilities/rlp"
)

type Iterator struct {
	nodeIt NodeIterator

	Key   []byte
	Value []byte
	Err   error
}

func NewIterator(it NodeIterator) *Iterator {
	return &Iterator{
		nodeIt: it,
	}
}

func (it *Iterator) Next() bool {
	for it.nodeIt.Next(true) {
		if it.nodeIt.Leaf() {
			it.Key = it.nodeIt.LeafKey()
			it.Value = it.nodeIt.LeafBlob()
			return true
		}
	}
	it.Key = nil
	it.Value = nil
	it.Err = it.nodeIt.Error()
	return false
}

func (it *Iterator) Prove() [][]byte {
	return it.nodeIt.LeafProof()
}

type NodeIterator interface {
	Next(bool) bool

	Error() error

	Hash() common.Hash

	Parent() common.Hash

	Path() []byte

	Leaf() bool

	LeafKey() []byte

	LeafBlob() []byte

	LeafProof() [][]byte
}

type nodeIteratorState struct {
	hash    common.Hash
	node    node
	parent  common.Hash
	index   int
	pathlen int
}

type nodeIterator struct {
	trie  *Trie
	stack []*nodeIteratorState
	path  []byte
	err   error
}

var errIteratorEnd = errors.New("end of iteration")

type seekError struct {
	key []byte
	err error
}

func (e seekError) Error() string {
	return "seek error: " + e.err.Error()
}

func newNodeIterator(trie *Trie, start []byte) NodeIterator {
	if trie.Hash() == emptyState {
		return new(nodeIterator)
	}
	it := &nodeIterator{trie: trie}
	it.err = it.seek(start)
	return it
}

func (it *nodeIterator) Hash() common.Hash {
	if len(it.stack) == 0 {
		return common.Hash{}
	}
	return it.stack[len(it.stack)-1].hash
}

func (it *nodeIterator) Parent() common.Hash {
	if len(it.stack) == 0 {
		return common.Hash{}
	}
	return it.stack[len(it.stack)-1].parent
}

func (it *nodeIterator) Leaf() bool {
	return hasTerm(it.path)
}

func (it *nodeIterator) LeafKey() []byte {
	if len(it.stack) > 0 {
		if _, ok := it.stack[len(it.stack)-1].node.(valueNode); ok {
			return hexToKeybytes(it.path)
		}
	}
	panic("not at leaf")
}

func (it *nodeIterator) LeafBlob() []byte {
	if len(it.stack) > 0 {
		if node, ok := it.stack[len(it.stack)-1].node.(valueNode); ok {
			return []byte(node)
		}
	}
	panic("not at leaf")
}

func (it *nodeIterator) LeafProof() [][]byte {
	if len(it.stack) > 0 {
		if _, ok := it.stack[len(it.stack)-1].node.(valueNode); ok {
			hasher := newHasher(nil)
			defer returnHasherToPool(hasher)

			proofs := make([][]byte, 0, len(it.stack))

			for i, item := range it.stack[:len(it.stack)-1] {

				node, _, _ := hasher.hashChildren(item.node, nil)
				hashed, _ := hasher.store(node, nil, false)
				if _, ok := hashed.(hashNode); ok || i == 0 {
					enc, _ := rlp.EncodeToBytes(node)
					proofs = append(proofs, enc)
				}
			}
			return proofs
		}
	}
	panic("not at leaf")
}

func (it *nodeIterator) Path() []byte {
	return it.path
}

func (it *nodeIterator) Error() error {
	if it.err == errIteratorEnd {
		return nil
	}
	if seek, ok := it.err.(seekError); ok {
		return seek.err
	}
	return it.err
}

func (it *nodeIterator) Next(descend bool) bool {
	if it.err == errIteratorEnd {
		return false
	}
	if seek, ok := it.err.(seekError); ok {
		if it.err = it.seek(seek.key); it.err != nil {
			return false
		}
	}

	state, parentIndex, path, err := it.peek(descend)
	it.err = err
	if it.err != nil {
		return false
	}
	it.push(state, parentIndex, path)
	return true
}

func (it *nodeIterator) seek(prefix []byte) error {

	key := keybytesToHex(prefix)
	key = key[:len(key)-1]

	for {
		state, parentIndex, path, err := it.peek(bytes.HasPrefix(key, it.path))
		if err == errIteratorEnd {
			return errIteratorEnd
		} else if err != nil {
			return seekError{prefix, err}
		} else if bytes.Compare(path, key) >= 0 {
			return nil
		}
		it.push(state, parentIndex, path)
	}
}

func (it *nodeIterator) peek(descend bool) (*nodeIteratorState, *int, []byte, error) {
	if len(it.stack) == 0 {

		root := it.trie.Hash()
		state := &nodeIteratorState{node: it.trie.root, index: -1}
		if root != emptyRoot {
			state.hash = root
		}
		err := state.resolve(it.trie, nil)
		return state, nil, nil, err
	}
	if !descend {

		it.pop()
	}

	for len(it.stack) > 0 {
		parent := it.stack[len(it.stack)-1]
		ancestor := parent.hash
		if (ancestor == common.Hash{}) {
			ancestor = parent.parent
		}
		state, path, ok := it.nextChild(parent, ancestor)
		if ok {
			if err := state.resolve(it.trie, path); err != nil {
				return parent, &parent.index, path, err
			}
			return state, &parent.index, path, nil
		}

		it.pop()
	}
	return nil, nil, nil, errIteratorEnd
}

func (st *nodeIteratorState) resolve(tr *Trie, path []byte) error {
	if hash, ok := st.node.(hashNode); ok {
		resolved, err := tr.resolveHash(hash, path)
		if err != nil {
			return err
		}
		st.node = resolved
		st.hash = common.BytesToHash(hash)
	}
	return nil
}

func (it *nodeIterator) nextChild(parent *nodeIteratorState, ancestor common.Hash) (*nodeIteratorState, []byte, bool) {
	switch node := parent.node.(type) {
	case *fullNode:

		for i := parent.index + 1; i < len(node.Children); i++ {
			side := node.Children[i]
			if side != nil {
				hash, _ := side.cache()
				state := &nodeIteratorState{
					hash:    common.BytesToHash(hash),
					node:    side,
					parent:  ancestor,
					index:   -1,
					pathlen: len(it.path),
				}
				path := append(it.path, byte(i))
				parent.index = i - 1
				return state, path, true
			}
		}
	case *shortNode:

		if parent.index < 0 {
			hash, _ := node.Val.cache()
			state := &nodeIteratorState{
				hash:    common.BytesToHash(hash),
				node:    node.Val,
				parent:  ancestor,
				index:   -1,
				pathlen: len(it.path),
			}
			path := append(it.path, node.Key...)
			return state, path, true
		}
	}
	return parent, it.path, false
}

func (it *nodeIterator) push(state *nodeIteratorState, parentIndex *int, path []byte) {
	it.path = path
	it.stack = append(it.stack, state)
	if parentIndex != nil {
		*parentIndex++
	}
}

func (it *nodeIterator) pop() {
	parent := it.stack[len(it.stack)-1]
	it.path = it.path[:parent.pathlen]
	it.stack = it.stack[:len(it.stack)-1]
}

func compareNodes(a, b NodeIterator) int {
	if cmp := bytes.Compare(a.Path(), b.Path()); cmp != 0 {
		return cmp
	}
	if a.Leaf() && !b.Leaf() {
		return -1
	} else if b.Leaf() && !a.Leaf() {
		return 1
	}
	if cmp := bytes.Compare(a.Hash().Bytes(), b.Hash().Bytes()); cmp != 0 {
		return cmp
	}
	if a.Leaf() && b.Leaf() {
		return bytes.Compare(a.LeafBlob(), b.LeafBlob())
	}
	return 0
}

type differenceIterator struct {
	a, b  NodeIterator
	eof   bool
	count int
}

func NewDifferenceIterator(a, b NodeIterator) (NodeIterator, *int) {
	a.Next(true)
	it := &differenceIterator{
		a: a,
		b: b,
	}
	return it, &it.count
}

func (it *differenceIterator) Hash() common.Hash {
	return it.b.Hash()
}

func (it *differenceIterator) Parent() common.Hash {
	return it.b.Parent()
}

func (it *differenceIterator) Leaf() bool {
	return it.b.Leaf()
}

func (it *differenceIterator) LeafKey() []byte {
	return it.b.LeafKey()
}

func (it *differenceIterator) LeafBlob() []byte {
	return it.b.LeafBlob()
}

func (it *differenceIterator) LeafProof() [][]byte {
	return it.b.LeafProof()
}

func (it *differenceIterator) Path() []byte {
	return it.b.Path()
}

func (it *differenceIterator) Next(bool) bool {

	if !it.b.Next(true) {
		return false
	}
	it.count++

	if it.eof {

		return true
	}

	for {
		switch compareNodes(it.a, it.b) {
		case -1:

			if !it.a.Next(true) {
				it.eof = true
				return true
			}
			it.count++
		case 1:

			return true
		case 0:

			hasHash := it.a.Hash() == common.Hash{}
			if !it.b.Next(hasHash) {
				return false
			}
			it.count++
			if !it.a.Next(hasHash) {
				it.eof = true
				return true
			}
			it.count++
		}
	}
}

func (it *differenceIterator) Error() error {
	if err := it.a.Error(); err != nil {
		return err
	}
	return it.b.Error()
}

type nodeIteratorHeap []NodeIterator

func (h nodeIteratorHeap) Len() int            { return len(h) }
func (h nodeIteratorHeap) Less(i, j int) bool  { return compareNodes(h[i], h[j]) < 0 }
func (h nodeIteratorHeap) Swap(i, j int)       { h[i], h[j] = h[j], h[i] }
func (h *nodeIteratorHeap) Push(x interface{}) { *h = append(*h, x.(NodeIterator)) }
func (h *nodeIteratorHeap) Pop() interface{} {
	n := len(*h)
	x := (*h)[n-1]
	*h = (*h)[0 : n-1]
	return x
}

type unionIterator struct {
	items *nodeIteratorHeap
	count int
}

func NewUnionIterator(iters []NodeIterator) (NodeIterator, *int) {
	h := make(nodeIteratorHeap, len(iters))
	copy(h, iters)
	heap.Init(&h)

	ui := &unionIterator{items: &h}
	return ui, &ui.count
}

func (it *unionIterator) Hash() common.Hash {
	return (*it.items)[0].Hash()
}

func (it *unionIterator) Parent() common.Hash {
	return (*it.items)[0].Parent()
}

func (it *unionIterator) Leaf() bool {
	return (*it.items)[0].Leaf()
}

func (it *unionIterator) LeafKey() []byte {
	return (*it.items)[0].LeafKey()
}

func (it *unionIterator) LeafBlob() []byte {
	return (*it.items)[0].LeafBlob()
}

func (it *unionIterator) LeafProof() [][]byte {
	return (*it.items)[0].LeafProof()
}

func (it *unionIterator) Path() []byte {
	return (*it.items)[0].Path()
}

func (it *unionIterator) Next(descend bool) bool {
	if len(*it.items) == 0 {
		return false
	}

	least := heap.Pop(it.items).(NodeIterator)

	for len(*it.items) > 0 && ((!descend && bytes.HasPrefix((*it.items)[0].Path(), least.Path())) || compareNodes(least, (*it.items)[0]) == 0) {
		skipped := heap.Pop(it.items).(NodeIterator)

		if skipped.Next(skipped.Hash() == common.Hash{}) {
			it.count++

			heap.Push(it.items, skipped)
		}
	}
	if least.Next(descend) {
		it.count++
		heap.Push(it.items, least)
	}
	return len(*it.items) > 0
}

func (it *unionIterator) Error() error {
	for i := 0; i < len(*it.items); i++ {
		if err := (*it.items)[i].Error(); err != nil {
			return err
		}
	}
	return nil
}