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