Add tracker package, update and simplify #1

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roysc merged 5 commits from dev into main 2023-09-19 16:58:25 +00:00
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@ -129,10 +129,9 @@ func (tr *Tracker) Restore(makeIterator iter.IteratorConstructor) ([]trie.NodeIt
}
// force the lower bound path to an even length (required by geth API/HexToKeyBytes)
if len(recoveredPath)&0b1 == 1 {
// decrement first to avoid skipped nodes
decrementPath(recoveredPath)
recoveredPath = append(recoveredPath, 0)
if len(recoveredPath)&1 == 1 {
// to avoid skipped nodes, we must rewind by one index
recoveredPath = rewindPath(recoveredPath)
}
it := makeIterator(iter.HexToKeyBytes(recoveredPath))
boundIt := iter.NewPrefixBoundIterator(it, endPath)
@ -185,25 +184,22 @@ func (it *Iterator) Next(descend bool) bool {
return ret
}
// Subtracts 1 from the last byte in a path slice, carrying if needed.
// Does nothing, returning false, for all-zero inputs (underflow).
func decrementPath(path []byte) bool {
// check for all zeros
allzero := true
for i := 0; i < len(path); i++ {
allzero = allzero && path[i] == 0
// Rewinds to the path of the previous (pre-order) node:
// If the last byte of the path is zero, pops it. Otherwise, decrements it
// and pads with 0xF to 64 bytes (e.g. [1] => [0 f f f ...]).
// Returns the passed path (which is also modified in place)
func rewindPath(path []byte) []byte {
if len(path) == 0 {
return path
}
if allzero {
return false
if path[len(path)-1] == 0 {
return path[:len(path)-1]
}
for i := len(path) - 1; i >= 0; i-- {
val := path[i]
path[i]--
if val == 0 {
path[i] = 0xf
} else {
return true
}
path[len(path)-1]--
padded := make([]byte, 64)
i := copy(padded, path)
for ; i < len(padded); i++ {
padded[i] = 0xf
}
return true
return padded
}