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moby--moby/pkg/collections/orderedintset.go

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package collections
import (
"sync"
)
// OrderedIntSet is a thread-safe sorted set and a stack.
type OrderedIntSet struct {
sync.RWMutex
set []int
}
// NewOrderedSet returns an initialized OrderedSet
func NewOrderedIntSet() *OrderedIntSet {
return &OrderedIntSet{}
}
// Push takes a string and adds it to the set. If the elem aready exists, it has no effect.
func (s *OrderedIntSet) Push(elem int) {
s.RLock()
for _, e := range s.set {
if e == elem {
s.RUnlock()
return
}
}
s.RUnlock()
s.Lock()
// Make sure the list is always sorted
for i, e := range s.set {
if elem < e {
s.set = append(s.set[:i], append([]int{elem}, s.set[i:]...)...)
s.Unlock()
return
}
}
// If we reach here, then elem is the biggest elem of the list.
s.set = append(s.set, elem)
s.Unlock()
}
// Pop is an alias to PopFront()
func (s *OrderedIntSet) Pop() int {
return s.PopFront()
}
// Pop returns the first elemen from the list and removes it.
// If the list is empty, it returns 0
func (s *OrderedIntSet) PopFront() int {
s.RLock()
for i, e := range s.set {
ret := e
s.RUnlock()
s.Lock()
s.set = append(s.set[:i], s.set[i+1:]...)
s.Unlock()
return ret
}
s.RUnlock()
return 0
}
// PullBack retrieve the last element of the list.
// The element is not removed.
// If the list is empty, an empty element is returned.
func (s *OrderedIntSet) PullBack() int {
if len(s.set) == 0 {
return 0
}
return s.set[len(s.set)-1]
}
// Exists checks if the given element present in the list.
func (s *OrderedIntSet) Exists(elem int) bool {
for _, e := range s.set {
if e == elem {
return true
}
}
return false
}
// Remove removes an element from the list.
// If the element is not found, it has no effect.
func (s *OrderedIntSet) Remove(elem int) {
for i, e := range s.set {
if e == elem {
s.set = append(s.set[:i], s.set[i+1:]...)
return
}
}
}