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package trie
import "bytes"
type Iterator struct {
trie *Trie
Key []byte
Value []byte
}
func NewIterator(trie *Trie) *Iterator {
return &Iterator{trie: trie, Key: make([]byte, 32)}
}
func (self *Iterator) Next() bool {
self.trie.mu.Lock()
defer self.trie.mu.Unlock()
key := RemTerm(CompactHexDecode(string(self.Key)))
k := self.next(self.trie.root, key)
self.Key = []byte(DecodeCompact(k))
return len(k) > 0
}
func (self *Iterator) next(node Node, key []byte) []byte {
if node == nil {
return nil
}
switch node := node.(type) {
case *FullNode:
if len(key) > 0 {
k := self.next(node.branch(key[0]), key[1:])
if k != nil {
return append([]byte{key[0]}, k...)
}
}
var r byte
if len(key) > 0 {
r = key[0] + 1
}
for i := r; i < 16; i++ {
k := self.key(node.branch(byte(i)))
if k != nil {
return append([]byte{i}, k...)
}
}
case *ShortNode:
k := RemTerm(node.Key())
if vnode, ok := node.Value().(*ValueNode); ok {
if bytes.Compare([]byte(k), key) > 0 {
self.Value = vnode.Val()
return k
}
} else {
cnode := node.Value()
var ret []byte
skey := key[len(k):]
if BeginsWith(key, k) {
ret = self.next(cnode, skey)
} else if bytes.Compare(k, key[:len(k)]) > 0 {
ret = self.key(node)
}
if ret != nil {
return append(k, ret...)
}
}
}
return nil
}
func (self *Iterator) key(node Node) []byte {
switch node := node.(type) {
case *ShortNode:
// Leaf node
if vnode, ok := node.Value().(*ValueNode); ok {
k := RemTerm(node.Key())
self.Value = vnode.Val()
return k
} else {
k := RemTerm(node.Key())
return append(k, self.key(node.Value())...)
}
case *FullNode:
if node.Value() != nil {
self.Value = node.Value().(*ValueNode).Val()
return []byte{16}
}
for i := 0; i < 16; i++ {
k := self.key(node.branch(byte(i)))
if k != nil {
return append([]byte{byte(i)}, k...)
}
}
}
return nil
}
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