forked from eosspark/geos
/
deque.go
111 lines (88 loc) · 1.7 KB
/
deque.go
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package database
import (
"container/list"
"sync"
)
/* FIXME Re-implement, remove reflection */
type deque struct {
sync.RWMutex
container *list.List
capacity int
}
func newDeque() *deque {
return newCappedDeque(-1)
}
func newCappedDeque(capacity int) *deque {
return &deque{
container: list.New(),
capacity: capacity,
}
}
func (s *deque) Append(item interface{}) bool {
s.Lock()
defer s.Unlock()
if s.capacity < 0 || s.container.Len() < s.capacity {
s.container.PushBack(item)
return true
}
return false
}
func (s *deque) PopFront() interface{} {
s.Lock()
defer s.Unlock()
var item interface{} = nil
var firstContainerItem *list.Element = nil
firstContainerItem = s.container.Front()
if firstContainerItem != nil {
item = s.container.Remove(firstContainerItem)
}
return item
}
func (s *deque) LastSecond() interface{} {
last := s.Pop()
second := s.Pop()
s.Append(second)
s.Append(last)
return second
}
func (s *deque) Pop() interface{} {
s.Lock()
defer s.Unlock()
var item interface{} = nil
var lastContainerItem *list.Element = nil
lastContainerItem = s.container.Back()
if lastContainerItem != nil {
item = s.container.Remove(lastContainerItem)
}
return item
}
func (s *deque) Size() int {
s.RLock()
defer s.RUnlock()
return s.container.Len()
}
func (s *deque) First() interface{} {
s.RLock()
defer s.RUnlock()
item := s.container.Front()
if item != nil {
return item.Value
} else {
return nil
}
}
func (s *deque) Last() interface{} {
s.RLock()
defer s.RUnlock()
item := s.container.Back()
if item != nil {
return item.Value
} else {
return nil
}
}
func (s *deque) Empty() bool {
s.RLock()
defer s.RUnlock()
return s.container.Len() == 0
}