Introduction

A simple queue can be implemented in GO using

1. container/list package
2. slice

A queue will have below operations:

1. Enqueue
2. Dequeue
3. Front
4. Size
5. Empty

List Implementation

package main
import (
"container/list"
"fmt"
)
type customQueue struct {
queue *list.List
}
func (c *customQueue) Enqueue(value string) {
c.queue.PushBack(value)
}
func (c *customQueue) Dequeue() error {
if c.queue.Len() > 0 {
ele := c.queue.Front()
c.queue.Remove(ele)
}
return fmt.Errorf("Pop Error: Queue is empty")
}
func (c *customQueue) Front() (string, error) {
if c.queue.Len() > 0 {
if val, ok := c.queue.Front().Value.(string); ok {
return val, nil
}
return "", fmt.Errorf("Peep Error: Queue Datatype is incorrect")
}
return "", fmt.Errorf("Peep Error: Queue is empty")
}
func (c *customQueue) Size() int {
return c.queue.Len()
}
func (c *customQueue) Empty() bool {
return c.queue.Len() == 0
}
func main() {
customQueue := &customQueue{
queue: list.New(),
}
fmt.Printf("Enqueue: A\n")
customQueue.Enqueue("A")
fmt.Printf("Enqueue: B\n")
customQueue.Enqueue("B")
fmt.Printf("Size: %d\n", customQueue.Size())
for customQueue.Size() > 0 {
frontVal, _ := customQueue.Front()
fmt.Printf("Front: %s\n", frontVal)
fmt.Printf("Dequeue: %s\n", frontVal)
customQueue.Dequeue()
}
fmt.Printf("Size: %d\n", customQueue.Size())
}

Output:

Enqueue: A
Enqueue: B
Size: 2
Front: A
Dequeue: A
Front: B
Dequeue: B
Size: 0

Slice Implementation

package main
import (
"fmt"
"sync"
)
type customQueue struct {
queue []string
lock sync.RWMutex
}
func (c *customQueue) Enqueue(name string) {
c.lock.Lock()
defer c.lock.Unlock()
c.queue = append(c.queue, name)
}
func (c *customQueue) Dequeue() error {
if len(c.queue) > 0 {
c.lock.Lock()
defer c.lock.Unlock()
c.queue = c.queue[1:]
return nil
}
return fmt.Errorf("Pop Error: Queue is empty")
}
func (c *customQueue) Front() (string, error) {
if len(c.queue) > 0 {
c.lock.Lock()
defer c.lock.Unlock()
return c.queue[0], nil
}
return "", fmt.Errorf("Peep Error: Queue is empty")
}
func (c *customQueue) Size() int {
return len(c.queue)
}
func (c *customQueue) Empty() bool {
return len(c.queue) == 0
}
func main() {
customQueue := &customQueue{
queue: make([]string, 0),
}
fmt.Printf("Enqueue: A\n")
customQueue.Enqueue("A")
fmt.Printf("Enqueue: B\n")
customQueue.Enqueue("B")
fmt.Printf("Len: %d\n", customQueue.Size())
for customQueue.Size() > 0 {
frontVal, _ := customQueue.Front()
fmt.Printf("Front: %s\n", frontVal)
fmt.Printf("Dequeue: %s\n", frontVal)
customQueue.Dequeue()
}
fmt.Printf("Len: %d\n", customQueue.Size())
}

Output:

Enqueue: A
Enqueue: B
Size: 2
Front: A
Dequeue: A
Front: B
Dequeue: B
Size: 0