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package common
import (
"container/heap"
)
type Heap struct {
pq priorityQueue
}
func NewHeap() *Heap {
return &Heap{pq:make([]*pqItem, 0)}
}
func (h *Heap) Len() int {
return len(h.pq)
}
func (h *Heap) Push(value interface{}, priority int) {
heap.Push(&h.pq, &pqItem{value:value, priority:priority})
}
func (h *Heap) Pop() interface{} {
item := heap.Pop(&h.pq).(*pqItem)
return item.value
}
/*
func main() {
h := NewHeap()
h.Push(String("msg1"), 1)
h.Push(String("msg3"), 3)
h.Push(String("msg2"), 2)
fmt.Println(h.Pop())
fmt.Println(h.Pop())
fmt.Println(h.Pop())
}
*/
///////////////////////
// From: http://golang.org/pkg/container/heap/#example__priorityQueue
type pqItem struct {
value interface{}
priority int
index int
}
type priorityQueue []*pqItem
func (pq priorityQueue) Len() int { return len(pq) }
func (pq priorityQueue) Less(i, j int) bool {
return pq[i].priority < pq[j].priority
}
func (pq priorityQueue) Swap(i, j int) {
pq[i], pq[j] = pq[j], pq[i]
pq[i].index = i
pq[j].index = j
}
func (pq *priorityQueue) Push(x interface{}) {
n := len(*pq)
item := x.(*pqItem)
item.index = n
*pq = append(*pq, item)
}
func (pq *priorityQueue) Pop() interface{} {
old := *pq
n := len(old)
item := old[n-1]
item.index = -1 // for safety
*pq = old[0 : n-1]
return item
}
func (pq *priorityQueue) Update(item *pqItem, value interface{}, priority int) {
heap.Remove(pq, item.index)
item.value = value
item.priority = priority
heap.Push(pq, item)
}