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list.go
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list.go
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package quicklist
import (
"encoding/binary"
"errors"
"math"
)
// +------------------------------ QuickList -----------------------------+
// | +-----------+ +-----------+ +-----------+ |
// head --- | listpack0 | <-> | listpack1 | <-> ... <-> | listpackN | --- tail
// +-----------+ +-----------+ +-----------+
//
// QuickList is double linked listpack.
type QuickList struct {
head, tail *Node
}
type Node struct {
*ListPack
prev, next *Node
}
func SetMaxListPackSize(s int) {
maxListPackSize = s
}
// New create a quicklist instance.
func New() *QuickList {
n := newNode()
return &QuickList{head: n, tail: n}
}
func newNode() *Node {
return &Node{ListPack: NewListPack()}
}
func (ls *QuickList) lpush(key string) {
if len(ls.head.data)+len(key) >= maxListPackSize {
n := newNode()
n.next = ls.head
ls.head.prev = n
ls.head = n
}
ls.head.Insert(0, key)
}
// LPush
func (ls *QuickList) LPush(keys ...string) {
for _, k := range keys {
ls.lpush(k)
}
}
func (ls *QuickList) rpush(key string) {
if len(ls.tail.data)+len(key) >= maxListPackSize {
n := newNode()
ls.tail.next = n
n.prev = ls.tail
ls.tail = n
}
ls.tail.Insert(-1, key)
}
// RPush
func (ls *QuickList) RPush(keys ...string) {
for _, k := range keys {
ls.rpush(k)
}
}
// Index
func (ls *QuickList) Index(i int) (val string, ok bool) {
ls.Range(i, i+1, func(key []byte) bool {
val, ok = string(key), true
return true
})
return
}
// LPop
func (ls *QuickList) LPop() (string, bool) {
return ls.Remove(0)
}
// RPop
func (ls *QuickList) RPop() (key string, ok bool) {
for lp := ls.tail; lp != nil; lp = lp.prev {
if lp.size > 0 {
return lp.Remove(-1)
}
ls.free(lp)
}
return
}
// free release empty list node.
func (ls *QuickList) free(n *Node) {
if n.size == 0 && n.prev != nil && n.next != nil {
n.prev.next = n.next
n.next.prev = n.prev
bpool.Put(n.data)
n = nil
}
}
// find quickly locates `listpack` and it `indexInternal` based on index.
func (ls *QuickList) find(index int) (*Node, int) {
var n *Node
for n = ls.head; n != nil && index >= n.Size(); n = n.next {
index -= n.Size()
}
return n, index
}
// Set
func (ls *QuickList) Set(index int, key string) bool {
lp, indexInternal := ls.find(index)
if lp != nil {
return lp.Set(indexInternal, key)
}
return false
}
// Remove
func (ls *QuickList) Remove(index int) (val string, ok bool) {
lp, indexInternal := ls.find(index)
if lp != nil {
val, ok = lp.Remove(indexInternal)
ls.free(lp)
}
return
}
// RemoveFirst
func (ls *QuickList) RemoveFirst(key string) (res int, ok bool) {
for lp := ls.head; lp != nil; lp = lp.next {
if lp.size == 0 {
ls.free(lp)
} else {
n, ok := lp.RemoveFirst(key)
if ok {
return res + n, true
} else {
res += lp.Size()
}
}
}
return 0, false
}
// Size
func (ls *QuickList) Size() (n int) {
for lp := ls.head; lp != nil; lp = lp.next {
n += lp.Size()
}
return
}
type lsIterator func(data []byte) (stop bool)
func (ls *QuickList) iterFront(start, end int, f lsIterator) {
count := end - start
if end == -1 {
count = math.MaxInt
}
if start < 0 || count < 0 {
return
}
lp, indexInternal := ls.find(start)
var stop bool
for !stop && count > 0 && lp != nil {
lp.Range(indexInternal, -1, func(data []byte, _ int) bool {
stop = f(data)
count--
return stop || count == 0
})
lp = lp.next
indexInternal = 0
}
}
func (ls *QuickList) iterBack(start, end int, f lsIterator) {
count := end - start
if end == -1 {
count = math.MaxInt
}
if start < 0 || count < 0 {
return
}
lp := ls.tail
for start > lp.Size() {
start -= lp.Size()
lp = lp.prev
if lp == nil {
return
}
}
var stop bool
for !stop && count > 0 && lp != nil {
lp.RevRange(start, -1, func(data []byte, _ int) bool {
stop = f(data)
count--
return stop || count == 0
})
lp = lp.prev
start = 0
}
}
// Range
func (ls *QuickList) Range(start, end int, f lsIterator) {
ls.iterFront(start, end, f)
}
// RevRange
func (ls *QuickList) RevRange(start, end int, f lsIterator) {
ls.iterBack(start, end, f)
}
var order = binary.LittleEndian
// MarshalBinary
func (ls *QuickList) MarshalBinary() ([]byte, error) {
data := bpool.Get(1024)[:0]
for lp := ls.head; lp != nil && lp.size > 0; lp = lp.next {
data = append(data, lp.ToBytes()...)
}
return data, nil
}
var ErrUnmarshal = errors.New("unmarshal error: invalid data")
// UnmarshalBinary
func (ls *QuickList) UnmarshalBinary(src []byte) error {
if len(src) < 8 {
return ErrUnmarshal
}
ls.head = nil
var last *Node
for index := 0; len(src)-index >= 8; {
// dataLen
dataLen := order.Uint32(src[index+4:])
// bound check
if index+8+int(dataLen) > len(src) {
return ErrUnmarshal
}
lp, err := NewFromBytes(src[index:])
if err != nil {
return err
}
node := &Node{ListPack: lp}
node.prev = last
index = index + 8 + int(dataLen)
if ls.head == nil {
ls.head = node
}
if last != nil {
last.next = node
}
ls.tail = node
last = node
}
return nil
}