package common import ( "container/heap" ) type Comparable interface { Less(o interface{}) bool } //----------------------------------------------------------------------------- /* Example usage: 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()) */ type Heap struct { pq priorityQueue } func NewHeap() *Heap { return &Heap{pq: make([]*pqItem, 0)} } func (h *Heap) Len() int64 { return int64(len(h.pq)) } func (h *Heap) Push(value interface{}, priority Comparable) { heap.Push(&h.pq, &pqItem{value: value, priority: priority}) } func (h *Heap) Peek() interface{} { if len(h.pq) == 0 { return nil } return h.pq[0].value } func (h *Heap) Update(value interface{}, priority Comparable) { h.pq.Update(h.pq[0], value, priority) } func (h *Heap) Pop() interface{} { item := heap.Pop(&h.pq).(*pqItem) return item.value } //----------------------------------------------------------------------------- /////////////////////// // From: http://golang.org/pkg/container/heap/#example__priorityQueue type pqItem struct { value interface{} priority Comparable 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.Less(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 Comparable) { item.value = value item.priority = priority heap.Fix(pq, item.index) }