f4a5c5ee8d
When nil is returned by Hash(), the merkle generation will treat it as a nil node, and ignore the hash along the way.
98 lines
1.8 KiB
Go
98 lines
1.8 KiB
Go
package trie
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import (
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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)
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type node struct {
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hash *chainhash.Hash
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links [256]*node
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value Value
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}
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func newNode(val Value) *node {
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return &node{links: [256]*node{}, value: val}
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}
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// We clear the Merkle Hash for every node along the path, including the root.
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// Calculation of the hash happens much less frequently then updating to the MerkleTrie.
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func update(n *node, key Key, val Value) {
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n.hash = nil
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// Follow the path to reach the node.
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for _, k := range key {
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if n.links[k] == nil {
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// The path didn't exist yet. Build it.
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n.links[k] = newNode(nil)
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}
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n.hash = nil
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n = n.links[k]
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}
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n.value = val
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n.hash = nil
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}
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func prune(n *node) *node {
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if n == nil {
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return nil
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}
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var ret *node
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for i, v := range n.links {
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if n.links[i] = prune(v); n.links[i] != nil {
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ret = n
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}
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}
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if n.value != nil {
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ret = n
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}
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return ret
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}
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func traverse(n *node, prefix Key, visit Visit) error {
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if n == nil {
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return nil
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}
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for i, v := range n.links {
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if v == nil {
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continue
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}
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p := append(prefix, byte(i))
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if err := visit(p, v.value); err != nil {
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return err
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}
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if err := traverse(v, p, visit); err != nil {
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return err
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}
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}
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return nil
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}
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// merkle recursively caculates the Merkle Hash of a given node
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// It works with both pruned or unpruned nodes.
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func merkle(n *node) *chainhash.Hash {
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if n.hash != nil {
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return n.hash
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}
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buf := Key{}
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for i, v := range n.links {
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if v == nil {
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continue
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}
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if h := merkle(v); h != nil {
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buf = append(buf, byte(i))
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buf = append(buf, h[:]...)
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}
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}
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if n.value != nil {
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if h := n.value.Hash(); h != nil {
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buf = append(buf, h[:]...)
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}
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}
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if len(buf) != 0 {
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// At least one of the sub nodes has contributed a value hash.
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h := chainhash.DoubleHashH(buf)
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n.hash = &h
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}
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return n.hash
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}
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