60 lines
884 B
Go
60 lines
884 B
Go
|
package queue
|
||
|
|
|
||
|
|
// "Generic" item.
|
||
|
|
// When type parameters will land this type became
|
||
|
|
// type Item[T any] T
|
||
|
|
type Item interface{}
|
||
|
|
|
||
|
|
type Queue interface {
|
||
|
|
Enqueue(Item)
|
||
|
|
Dequeue() Item
|
||
|
|
Size() int
|
||
|
|
IsEmpty() bool
|
||
|
|
}
|
||
|
|
|
||
|
|
// We use linked list as internal data structure
|
||
|
|
// to get O(1) speed for push and pop opeartions
|
||
|
|
type node struct {
|
||
|
|
item Item
|
||
|
|
next *node
|
||
|
|
}
|
||
|
|
|
||
|
|
type queue struct {
|
||
|
|
size int
|
||
|
|
head *node
|
||
|
|
tail *node
|
||
|
|
}
|
||
|
|
|
||
|
|
func NewQueue() Queue {
|
||
|
|
return &queue{}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (q *queue) Enqueue(item Item) {
|
||
|
|
oldTail := q.tail
|
||
|
|
q.tail = &node{item: item, next: nil}
|
||
|
|
if q.IsEmpty() {
|
||
|
|
q.head = q.tail
|
||
|
|
} else {
|
||
|
|
oldTail.next = q.tail
|
||
|
|
}
|
||
|
|
q.size++
|
||
|
|
}
|
||
|
|
|
||
|
|
func (q *queue) Dequeue() Item {
|
||
|
|
first := q.head
|
||
|
|
q.head = q.head.next
|
||
|
|
if q.IsEmpty() {
|
||
|
|
q.tail = nil
|
||
|
|
}
|
||
|
|
q.size--
|
||
|
|
return first.item
|
||
|
|
}
|
||
|
|
|
||
|
|
func (q *queue) Size() int {
|
||
|
|
return q.size
|
||
|
|
}
|
||
|
|
|
||
|
|
func (q *queue) IsEmpty() bool {
|
||
|
|
return q.head == nil
|
||
|
|
}
|