lnd.xprv/queue/priority_queue.go

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package queue
import (
"container/heap"
)
// PriorityQueueItem is an interface that represents items in a PriorityQueue.
// Users of PriorityQueue will need to define a Less function such that
// PriorityQueue will be able to use that to build and restore an underlying
// heap.
type PriorityQueueItem interface {
Less(other PriorityQueueItem) bool
}
type priorityQueue []PriorityQueueItem
// Len returns the length of the priorityQueue.
func (pq priorityQueue) Len() int { return len(pq) }
// Less is used to order PriorityQueueItem items in the queue.
func (pq priorityQueue) Less(i, j int) bool {
return pq[i].Less(pq[j])
}
// Swap swaps two items in the priorityQueue. Swap is used by heap.Interface.
func (pq priorityQueue) Swap(i, j int) {
pq[i], pq[j] = pq[j], pq[i]
}
// Push adds a new item the the priorityQueue.
func (pq *priorityQueue) Push(x interface{}) {
item := x.(PriorityQueueItem)
*pq = append(*pq, item)
}
// Pop removes the top item from the priorityQueue.
func (pq *priorityQueue) Pop() interface{} {
old := *pq
n := len(old)
item := old[n-1]
old[n-1] = nil
*pq = old[0 : n-1]
return item
}
// Priority wrap a standard heap in a more object-oriented structure.
type PriorityQueue struct {
queue priorityQueue
}
// Len returns the length of the queue.
func (pq *PriorityQueue) Len() int {
return len(pq.queue)
}
// Empty returns true if the queue is empty.
func (pq *PriorityQueue) Empty() bool {
return len(pq.queue) == 0
}
// Push adds an item to the priority queue.
func (pq *PriorityQueue) Push(item PriorityQueueItem) {
heap.Push(&pq.queue, item)
}
// Pop removes the top most item from the queue.
func (pq *PriorityQueue) Pop() PriorityQueueItem {
return heap.Pop(&pq.queue).(PriorityQueueItem)
}
// Top returns the top most item from the queue without removing it.
func (pq *PriorityQueue) Top() PriorityQueueItem {
return pq.queue[0]
}