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511 lines
12 KiB
511 lines
12 KiB
/*
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This tree is not concurrency safe.
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If you want to use it from multiple goroutines, you need to wrap all calls to *IAVLTree
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with a mutex.
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*/
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package merkle
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import (
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. "github.com/tendermint/tendermint/binary"
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"bytes"
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"io"
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"crypto/sha256"
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)
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const HASH_BYTE_SIZE int = 4+32
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// Immutable AVL Tree (wraps the Node root)
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type IAVLTree struct {
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db Db
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root *IAVLNode
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}
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func NewIAVLTree(db Db) *IAVLTree {
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return &IAVLTree{db:db, root:nil}
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}
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func NewIAVLTreeFromHash(db Db, hash ByteSlice) *IAVLTree {
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root := &IAVLNode{
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hash: hash,
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flags: IAVLNODE_FLAG_PERSISTED | IAVLNODE_FLAG_PLACEHOLDER,
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}
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root.fill(db)
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return &IAVLTree{db:db, root:root}
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}
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func (t *IAVLTree) Root() Node {
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return t.root
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}
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func (t *IAVLTree) Size() uint64 {
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if t.root == nil { return 0 }
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return t.root.Size()
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}
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func (t *IAVLTree) Height() uint8 {
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if t.root == nil { return 0 }
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return t.root.Height()
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}
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func (t *IAVLTree) Has(key Key) bool {
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if t.root == nil { return false }
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return t.root.has(t.db, key)
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}
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func (t *IAVLTree) Put(key Key, value Value) (updated bool) {
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if t.root == nil {
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t.root = NewIAVLNode(key, value)
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return false
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}
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t.root, updated = t.root.put(t.db, key, value)
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return updated
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}
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func (t *IAVLTree) Hash() (ByteSlice, uint64) {
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if t.root == nil { return nil, 0 }
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return t.root.Hash()
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}
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func (t *IAVLTree) Save() {
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if t.root == nil { return }
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if t.root.hash == nil {
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t.root.Hash()
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}
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t.root.Save(t.db)
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}
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func (t *IAVLTree) Get(key Key) (value Value) {
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if t.root == nil { return nil }
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return t.root.get(t.db, key)
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}
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func (t *IAVLTree) Remove(key Key) (value Value, err error) {
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if t.root == nil { return nil, NotFound(key) }
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newRoot, _, value, err := t.root.remove(t.db, key)
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if err != nil {
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return nil, err
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}
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t.root = newRoot
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return value, nil
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}
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func (t *IAVLTree) Copy() Tree {
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return &IAVLTree{db:t.db, root:t.root}
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}
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func (t *IAVLTree) Traverse(cb func(Node) bool) {
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if t.root == nil { return }
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t.root.traverse(t.db, cb)
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}
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func (t *IAVLTree) Values() <-chan Value {
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root := t.root
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ch := make(chan Value)
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go func() {
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root.traverse(func(n Node) {
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if n.Height() == 0 { ch <- n.Value() }
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})
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close(ch)
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}
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return ch
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}
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// Node
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type IAVLNode struct {
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key Key
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value Value
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size uint64
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height uint8
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hash ByteSlice
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left *IAVLNode
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right *IAVLNode
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// volatile
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flags byte
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}
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const (
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IAVLNODE_FLAG_PERSISTED = byte(0x01)
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IAVLNODE_FLAG_PLACEHOLDER = byte(0x02)
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)
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func NewIAVLNode(key Key, value Value) *IAVLNode {
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return &IAVLNode{
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key: key,
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value: value,
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size: 1,
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}
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}
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func (self *IAVLNode) Copy() *IAVLNode {
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if self.height == 0 {
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panic("Why are you copying a value node?")
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}
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return &IAVLNode{
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key: self.key,
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size: self.size,
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height: self.height,
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left: self.left,
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right: self.right,
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hash: nil,
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flags: byte(0),
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}
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}
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func (self *IAVLNode) Key() Key {
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return self.key
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}
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func (self *IAVLNode) Value() Value {
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return self.value
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}
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func (self *IAVLNode) Size() uint64 {
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return self.size
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}
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func (self *IAVLNode) Height() uint8 {
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return self.height
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}
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func (self *IAVLNode) has(db Db, key Key) (has bool) {
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if self.key.Equals(key) {
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return true
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}
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if self.height == 0 {
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return false
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} else {
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if key.Less(self.key) {
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return self.leftFilled(db).has(db, key)
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} else {
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return self.rightFilled(db).has(db, key)
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}
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}
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}
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func (self *IAVLNode) get(db Db, key Key) (value Value) {
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if self.height == 0 {
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if self.key.Equals(key) {
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return self.value
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} else {
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return nil
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}
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} else {
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if key.Less(self.key) {
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return self.leftFilled(db).get(db, key)
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} else {
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return self.rightFilled(db).get(db, key)
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}
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}
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}
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func (self *IAVLNode) Hash() (ByteSlice, uint64) {
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if self.hash != nil {
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return self.hash, 0
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}
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hasher := sha256.New()
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_, hashCount, err := self.saveToCountHashes(hasher, false)
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if err != nil { panic(err) }
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self.hash = hasher.Sum(nil)
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return self.hash, hashCount+1
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}
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func (self *IAVLNode) Save(db Db) {
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if self.hash == nil {
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panic("savee.hash can't be nil")
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}
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if self.flags & IAVLNODE_FLAG_PERSISTED > 0 ||
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self.flags & IAVLNODE_FLAG_PLACEHOLDER > 0 {
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return
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}
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// children
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if self.height > 0 {
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self.left.Save(db)
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self.right.Save(db)
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}
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// save self
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buf := bytes.NewBuffer(nil)
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_, err := self.WriteTo(buf)
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if err != nil { panic(err) }
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db.Put([]byte(self.hash), buf.Bytes())
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self.flags |= IAVLNODE_FLAG_PERSISTED
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}
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func (self *IAVLNode) put(db Db, key Key, value Value) (_ *IAVLNode, updated bool) {
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if self.height == 0 {
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if key.Less(self.key) {
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return &IAVLNode{
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key: self.key,
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height: 1,
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size: 2,
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left: NewIAVLNode(key, value),
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right: self,
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}, false
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} else if self.key.Equals(key) {
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return NewIAVLNode(key, value), true
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} else {
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return &IAVLNode{
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key: key,
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height: 1,
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size: 2,
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left: self,
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right: NewIAVLNode(key, value),
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}, false
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}
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} else {
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self = self.Copy()
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if key.Less(self.key) {
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self.left, updated = self.leftFilled(db).put(db, key, value)
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} else {
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self.right, updated = self.rightFilled(db).put(db, key, value)
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}
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if updated {
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return self, updated
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} else {
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self.calcHeightAndSize(db)
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return self.balance(db), updated
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}
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}
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}
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// newKey: new leftmost leaf key for tree after successfully removing 'key' if changed.
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func (self *IAVLNode) remove(db Db, key Key) (newSelf *IAVLNode, newKey Key, value Value, err error) {
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if self.height == 0 {
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if self.key.Equals(key) {
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return nil, nil, self.value, nil
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} else {
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return self, nil, nil, NotFound(key)
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}
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} else {
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if key.Less(self.key) {
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var newLeft *IAVLNode
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newLeft, newKey, value, err = self.leftFilled(db).remove(db, key)
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if err != nil {
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return self, nil, value, err
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} else if newLeft == nil { // left node held value, was removed
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return self.right, self.key, value, nil
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}
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self = self.Copy()
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self.left = newLeft
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} else {
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var newRight *IAVLNode
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newRight, newKey, value, err = self.rightFilled(db).remove(db, key)
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if err != nil {
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return self, nil, value, err
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} else if newRight == nil { // right node held value, was removed
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return self.left, nil, value, nil
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}
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self = self.Copy()
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self.right = newRight
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if newKey != nil {
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self.key = newKey
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newKey = nil
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}
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}
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self.calcHeightAndSize(db)
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return self.balance(db), newKey, value, err
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}
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}
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func (self *IAVLNode) WriteTo(w io.Writer) (n int64, err error) {
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n, _, err = self.saveToCountHashes(w, true)
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return
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}
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func (self *IAVLNode) saveToCountHashes(w io.Writer, meta bool) (n int64, hashCount uint64, err error) {
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var _n int64
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if meta {
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// height & size
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_n, err = UInt8(self.height).WriteTo(w)
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if err != nil { return } else { n += _n }
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_n, err = UInt64(self.size).WriteTo(w)
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if err != nil { return } else { n += _n }
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// key
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_n, err = Byte(GetBinaryType(self.key)).WriteTo(w)
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if err != nil { return } else { n += _n }
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_n, err = self.key.WriteTo(w)
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if err != nil { return } else { n += _n }
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}
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if self.height == 0 {
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// value
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_n, err = Byte(GetBinaryType(self.value)).WriteTo(w)
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if err != nil { return } else { n += _n }
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if self.value != nil {
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_n, err = self.value.WriteTo(w)
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if err != nil { return } else { n += _n }
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}
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} else {
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// left
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leftHash, leftCount := self.left.Hash()
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hashCount += leftCount
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_n, err = leftHash.WriteTo(w)
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if err != nil { return } else { n += _n }
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// right
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rightHash, rightCount := self.right.Hash()
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hashCount += rightCount
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_n, err = rightHash.WriteTo(w)
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if err != nil { return } else { n += _n }
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}
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return
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}
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// Given a placeholder node which has only the hash set,
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// load the rest of the data from db.
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// Not threadsafe.
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func (self *IAVLNode) fill(db Db) {
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if self.hash == nil {
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panic("placeholder.hash can't be nil")
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}
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buf := db.Get(self.hash)
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r := bytes.NewReader(buf)
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// node header
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self.height = uint8(ReadUInt8(r))
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self.size = uint64(ReadUInt64(r))
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// key
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key := ReadBinary(r)
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self.key = key.(Key)
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if self.height == 0 {
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// value
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self.value = ReadBinary(r)
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} else {
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// left
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var leftHash ByteSlice
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leftHash = ReadByteSlice(r)
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self.left = &IAVLNode{
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hash: leftHash,
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flags: IAVLNODE_FLAG_PERSISTED | IAVLNODE_FLAG_PLACEHOLDER,
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}
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// right
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var rightHash ByteSlice
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rightHash = ReadByteSlice(r)
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self.right = &IAVLNode{
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hash: rightHash,
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flags: IAVLNODE_FLAG_PERSISTED | IAVLNODE_FLAG_PLACEHOLDER,
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}
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if r.Len() != 0 {
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panic("buf not all consumed")
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}
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}
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self.flags &= ^IAVLNODE_FLAG_PLACEHOLDER
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}
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func (self *IAVLNode) leftFilled(db Db) *IAVLNode {
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if self.left.flags & IAVLNODE_FLAG_PLACEHOLDER > 0 {
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self.left.fill(db)
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}
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return self.left
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}
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func (self *IAVLNode) rightFilled(db Db) *IAVLNode {
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if self.right.flags & IAVLNODE_FLAG_PLACEHOLDER > 0 {
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self.right.fill(db)
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}
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return self.right
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}
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func (self *IAVLNode) rotateRight(db Db) *IAVLNode {
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self = self.Copy()
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sl := self.leftFilled(db).Copy()
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slr := sl.right
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sl.right = self
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self.left = slr
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self.calcHeightAndSize(db)
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sl.calcHeightAndSize(db)
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return sl
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}
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func (self *IAVLNode) rotateLeft(db Db) *IAVLNode {
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self = self.Copy()
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sr := self.rightFilled(db).Copy()
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srl := sr.left
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sr.left = self
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self.right = srl
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self.calcHeightAndSize(db)
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sr.calcHeightAndSize(db)
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return sr
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}
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func (self *IAVLNode) calcHeightAndSize(db Db) {
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self.height = maxUint8(self.leftFilled(db).Height(), self.rightFilled(db).Height()) + 1
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self.size = self.leftFilled(db).Size() + self.rightFilled(db).Size()
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}
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func (self *IAVLNode) calcBalance(db Db) int {
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return int(self.leftFilled(db).Height()) - int(self.rightFilled(db).Height())
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}
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func (self *IAVLNode) balance(db Db) (newSelf *IAVLNode) {
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balance := self.calcBalance(db)
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if (balance > 1) {
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if (self.leftFilled(db).calcBalance(db) >= 0) {
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// Left Left Case
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return self.rotateRight(db)
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} else {
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// Left Right Case
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self = self.Copy()
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self.left = self.leftFilled(db).rotateLeft(db)
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//self.calcHeightAndSize()
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return self.rotateRight(db)
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}
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}
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if (balance < -1) {
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if (self.rightFilled(db).calcBalance(db) <= 0) {
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// Right Right Case
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return self.rotateLeft(db)
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} else {
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// Right Left Case
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self = self.Copy()
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self.right = self.rightFilled(db).rotateRight(db)
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//self.calcHeightAndSize()
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return self.rotateLeft(db)
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}
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}
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// Nothing changed
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return self
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}
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func (self *IAVLNode) lmd(db Db) (*IAVLNode) {
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if self.height == 0 {
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return self
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}
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return self.leftFilled(db).lmd(db)
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}
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func (self *IAVLNode) rmd(db Db) (*IAVLNode) {
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if self.height == 0 {
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return self
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}
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return self.rightFilled(db).rmd(db)
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}
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func (self *IAVLNode) traverse(db Db, cb func(Node)bool) bool {
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stop := cb(self)
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if stop { return stop }
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if self.height > 0 {
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stop = self.leftFilled(db).traverse(db, cb)
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if stop { return stop }
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stop = self.rightFilled(db).traverse(db, cb)
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if stop { return stop }
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}
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return false
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}
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