1 |
3a515b92
|
cagy
|
function Queue () {
|
2 |
|
|
this.head = new Item('head', null)
|
3 |
|
|
}
|
4 |
|
|
module.exports = Queue
|
5 |
|
|
|
6 |
|
|
Queue.prototype.append = function append (kind, value) {
|
7 |
|
|
var item = new Item(kind, value)
|
8 |
|
|
this.head.prepend(item)
|
9 |
|
|
return item
|
10 |
|
|
}
|
11 |
|
|
|
12 |
|
|
Queue.prototype.isEmpty = function isEmpty () {
|
13 |
|
|
return this.head.prev === this.head
|
14 |
|
|
}
|
15 |
|
|
|
16 |
|
|
Queue.prototype.first = function first () {
|
17 |
|
|
return this.head.next
|
18 |
|
|
}
|
19 |
|
|
|
20 |
|
|
function Item (kind, value) {
|
21 |
|
|
this.prev = this
|
22 |
|
|
this.next = this
|
23 |
|
|
this.kind = kind
|
24 |
|
|
this.value = value
|
25 |
|
|
}
|
26 |
|
|
|
27 |
|
|
Item.prototype.prepend = function prepend (other) {
|
28 |
|
|
other.prev = this.prev
|
29 |
|
|
other.next = this
|
30 |
|
|
other.prev.next = other
|
31 |
|
|
other.next.prev = other
|
32 |
|
|
}
|
33 |
|
|
|
34 |
|
|
Item.prototype.dequeue = function dequeue () {
|
35 |
|
|
var prev = this.prev
|
36 |
|
|
var next = this.next
|
37 |
|
|
|
38 |
|
|
prev.next = next
|
39 |
|
|
next.prev = prev
|
40 |
|
|
this.prev = this
|
41 |
|
|
this.next = this
|
42 |
|
|
|
43 |
|
|
return this.value
|
44 |
|
|
}
|
45 |
|
|
|
46 |
|
|
Item.prototype.isEmpty = function isEmpty () {
|
47 |
|
|
return this.prev === this
|
48 |
|
|
}
|