structure_old/priority_queue/priority_queue.go

package plist

import (
	"github.com/emirpasic/gods/utils"
)

// PriorityQueue 优先队列 适合数据量不大, 加索引
type PriorityQueue struct {
	data *Tree

	Head       *AvlNode
	Tail       *AvlNode
	comparator utils.Comparator
}

// NewWithInt compare use int
func NewWithInt() *PriorityQueue {
	p := new(PriorityQueue)

	p.comparator = func(a, b interface{}) int {
		if a.(int) > b.(int) {
			return 1
		}
		return -1
	}

	p.data = NewWith(p.comparator)

	return p
}

func (pq *PriorityQueue) String() string {
	return pq.data.String()
}

func (pq *PriorityQueue) Top() (interface{}, bool) {
	return pq.Head, pq.Head != nil
}

func (pq *PriorityQueue) Bottom() (interface{}, bool) {
	return pq.Tail, pq.Tail != nil
}

func (pq *PriorityQueue) Get(index int) (interface{}, bool) {
	var cur *AvlNode
	if index >= 0 {
		cur := pq.Head
		for index > 0 && cur != nil {
			index--
			cur = cur.Prev()
		}
	} else {
		cur := pq.Tail
		for index < -1 && cur != nil {
			index++
			cur = cur.Next()
		}
	}

	return cur, cur != nil
}

func (pq *PriorityQueue) Push(v interface{}) {

	pnode := pq.data.Put(v)
	if pq.Head == nil {
		pq.Head = pnode
		pq.Tail = pnode
		return
	}

	if pq.comparator(v, pq.Head.Value) > 0 {
		pq.Head = pnode
		return
	}

	if pq.comparator(v, pq.Tail.Value) < 0 {
		pq.Tail = pnode
		return
	}
}

func (pq *PriorityQueue) Remove(index int) interface{} {
	return nil
}

func (pq *PriorityQueue) Values(index int) []interface{} {
	return pq.data.Values()
}