Golang FIFO Queue Example

FIFOQueue.go

package main

import (
	"fmt"
)

var queue_front int64 = 0
var queue_rear int64 = 0
var queue_init bool = false
var queue_size int64 = 0

const max_queue_size int64 = 5

var queue [max_queue_size]string

func main() {
	queue_test()
}

type QueueTestObject struct {
	Type  string
	Value string
}

func queue_test() {
	var testing []QueueTestObject
	testing = append(testing, QueueTestObject{"push", "Test"})
	testing = append(testing, QueueTestObject{"push", "Test1"})
	testing = append(testing, QueueTestObject{"push", "Test2"})
	testing = append(testing, QueueTestObject{"push", "Test3"})
	testing = append(testing, QueueTestObject{"push", "Test4"})
	testing = append(testing, QueueTestObject{"push", "Test5"})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"push", "Test6"})
	testing = append(testing, QueueTestObject{"push", "Test7"})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"push", "Test8"})
	testing = append(testing, QueueTestObject{"push", "Test9"})
	testing = append(testing, QueueTestObject{"push", "Test10"})
	testing = append(testing, QueueTestObject{"push", "Test11"})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	testing = append(testing, QueueTestObject{"pop", ""})
	for _, v := range testing {
		switch v.Type {
		case "push":
			err := push(v.Value)
			if err != nil {
				fmt.Printf("push data error:%v data:%v\n", err, v.Value)
			}

		case "pop":
			data, err := pop()
			if err != nil {
				fmt.Printf("pop data error:%v\n", err)
			} else {
				fmt.Printf("pop data:%v\n", data)
			}
		}

		dump()
	}
	dump()
}

func dump() {
	fmt.Printf("[Queue][%v][%v] size:%d\n", queue_front, queue_rear, queue_size)
	for k, v := range queue {
		fmt.Printf("[%v]:%v ", k, v)
	}
	fmt.Println("")
}
func push(data string) error {
	if full() {
		return fmt.Errorf("Queue has full.")
	}
	queue_rear++
	if queue_rear >= max_queue_size {
		queue_rear = 0
	}
	queue[queue_rear] = data
	queue_size++
	if !queue_init {
		queue_init = true
	}

	return nil
}

func pop() (string, error) {
	queue_size--
	if queue_size < 0 {
		queue_size = 0
		return "", fmt.Errorf("empty")
	}
	queue_front++
	if queue_front >= max_queue_size {
		queue_front = 0
	}
	data := queue[queue_front]
	queue[queue_front] = ""

	return data, nil
}

func full() bool {
	if queue_size >= max_queue_size && queue_init {
		return true
	}
	return false
}




/*
====================================================
Queue Result
====================================================
[Queue][0][1] size:1
[0]: [1]:Test [2]: [3]: [4]: 
[Queue][0][2] size:2
[0]: [1]:Test [2]:Test1 [3]: [4]: 
[Queue][0][3] size:3
[0]: [1]:Test [2]:Test1 [3]:Test2 [4]: 
[Queue][0][4] size:4
[0]: [1]:Test [2]:Test1 [3]:Test2 [4]:Test3 
[Queue][0][0] size:5
[0]:Test4 [1]:Test [2]:Test1 [3]:Test2 [4]:Test3 
push data error:Queue has full. data:Test5
[Queue][0][0] size:5
[0]:Test4 [1]:Test [2]:Test1 [3]:Test2 [4]:Test3 
pop data:Test
[Queue][1][0] size:4
[0]:Test4 [1]: [2]:Test1 [3]:Test2 [4]:Test3 
pop data:Test1
[Queue][2][0] size:3
[0]:Test4 [1]: [2]: [3]:Test2 [4]:Test3 
pop data:Test2
[Queue][3][0] size:2
[0]:Test4 [1]: [2]: [3]: [4]:Test3 
[Queue][3][1] size:3
[0]:Test4 [1]:Test6 [2]: [3]: [4]:Test3 
[Queue][3][2] size:4
[0]:Test4 [1]:Test6 [2]:Test7 [3]: [4]:Test3 
pop data:Test3
[Queue][4][2] size:3
[0]:Test4 [1]:Test6 [2]:Test7 [3]: [4]: 
pop data:Test4
[Queue][0][2] size:2
[0]: [1]:Test6 [2]:Test7 [3]: [4]: 
pop data:Test6
[Queue][1][2] size:1
[0]: [1]: [2]:Test7 [3]: [4]: 
pop data:Test7
[Queue][2][2] size:0
[0]: [1]: [2]: [3]: [4]: 
pop data error:empty
[Queue][2][2] size:0
[0]: [1]: [2]: [3]: [4]: 
pop data error:empty
[Queue][2][2] size:0
[0]: [1]: [2]: [3]: [4]: 
[Queue][2][3] size:1
[0]: [1]: [2]: [3]:Test8 [4]: 
[Queue][2][4] size:2
[0]: [1]: [2]: [3]:Test8 [4]:Test9 
[Queue][2][0] size:3
[0]:Test10 [1]: [2]: [3]:Test8 [4]:Test9 
[Queue][2][1] size:4
[0]:Test10 [1]:Test11 [2]: [3]:Test8 [4]:Test9 
pop data:Test8
[Queue][3][1] size:3
[0]:Test10 [1]:Test11 [2]: [3]: [4]:Test9 
pop data:Test9
[Queue][4][1] size:2
[0]:Test10 [1]:Test11 [2]: [3]: [4]: 
pop data:Test10
[Queue][0][1] size:1
[0]: [1]:Test11 [2]: [3]: [4]: 
[Queue][0][1] size:1
[0]: [1]:Test11 [2]: [3]: [4]: 
*/