plugeth-utils/restricted/trie/iterator.go

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2023-06-02 14:19:23 +00:00
package trie
import (
"bytes"
"github.com/openrelayxyz/plugeth-utils/core"
)
type NodeIterator = core.NodeIterator
// Iterator is a key-value trie iterator that traverses a Trie.
type Iterator struct {
nodeIt core.NodeIterator
Key []byte // Current data key on which the iterator is positioned on
Value []byte // Current data value on which the iterator is positioned on
Err error
}
// NewIterator creates a new key-value iterator from a node iterator.
// Note that the value returned by the iterator is raw. If the content is encoded
// (e.g. storage value is RLP-encoded), it's caller's duty to decode it.
func NewIterator(it core.NodeIterator) *Iterator {
return &Iterator{
nodeIt: it,
}
}
// Next moves the iterator forward one key-value entry.
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
}
// Prove generates the Merkle proof for the leaf node the iterator is currently
// positioned on.
func (it *Iterator) Prove() [][]byte {
return it.nodeIt.LeafProof()
}
type differenceIterator struct {
a, b core.NodeIterator // Nodes returned are those in b - a.
eof bool // Indicates a has run out of elements
count int // Number of nodes scanned on either trie
}
// NewDifferenceIterator constructs a NodeIterator that iterates over elements in b that
// are not in a. Returns the iterator, and a pointer to an integer recording the number
// of nodes seen.
func NewDifferenceIterator(a, b core.NodeIterator) (core.NodeIterator, *int) {
a.Next(true)
it := &differenceIterator{
a: a,
b: b,
}
return it, &it.count
}
func (it *differenceIterator) Hash() core.Hash {
return it.b.Hash()
}
func (it *differenceIterator) Parent() core.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) NodeBlob() []byte {
return it.b.NodeBlob()
}
func (it *differenceIterator) AddResolver(resolver core.NodeResolver) {
panic("not implemented")
}
func (it *differenceIterator) Next(bool) bool {
// Invariants:
// - We always advance at least one element in b.
// - At the start of this function, a's path is lexically greater than b's.
if !it.b.Next(true) {
return false
}
it.count++
if it.eof {
// a has reached eof, so we just return all elements from b
return true
}
for {
switch compareNodes(it.a, it.b) {
case -1:
// b jumped past a; advance a
if !it.a.Next(true) {
it.eof = true
return true
}
it.count++
case 1:
// b is before a
return true
case 0:
// a and b are identical; skip this whole subtree if the nodes have hashes
hasHash := it.a.Hash() == core.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()
}
func compareNodes(a, b core.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
}