Queue data structure Golang

main.go

package main

import (
	"fmt"
)

type Queue[T any] struct {
	elements []T
	size     uint
	rear     uint
}

func NewQueue[T any](size uint) *Queue[T] {
	elements := make([]T, size)

	return &Queue[T]{
		elements: elements,
		size:     size,
		rear:     0,
	}
}

func (q *Queue[T]) Elements() []T {
	return q.elements
}

func (q *Queue[T]) Enq(t T) {
	if q.rear == q.size {
		newSize := q.size << 1
		q.size = newSize
		newElements := make([]T, newSize)
		copy(newElements, q.elements)

		q.elements = newElements
	}

	q.elements[q.rear] = t
	q.rear = q.rear + 1
}

func (q *Queue[T]) Deq() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[0]

	q.elements = q.elements[1:q.rear]

	q.rear = q.rear - 1

	if q.rear <= (q.size >> 2) {
		newSize := q.size >> 2
		q.size = newSize
		newElements := make([]T, newSize)
		copy(newElements, q.elements)

		q.elements = newElements
	}

	return &t
}

func (q *Queue[T]) Peek() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[0]

	return &t
}

func (q *Queue[T]) Last() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[q.rear-1]

	return &t
}

func (q *Queue[T]) Size() uint {
	return q.size
}

func main() {
	q := NewQueue[string](5)

	q.Enq("alex")
	q.Enq("bony")
	q.Enq("andy")

	fmt.Println("-------------------")
	fmt.Println("size: ", q.Size())

	fmt.Println(q.Elements())

	fmt.Println("-------------------")
	q.Enq("cece")
	q.Enq("coci")
	q.Enq("dody")

	fmt.Println("-------------------")
	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

	t := q.Peek()
	if t != nil {
		fmt.Println(*t)
	}

	l := q.Last()
	if l != nil {
		fmt.Println(*l)
	}

	fmt.Println("-------------------")
	q.Deq()
	q.Deq()
	q.Deq()
	q.Deq()
	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

	fmt.Println("-------------------")
	q.Enq("alex")
	q.Enq("bony")
	q.Enq("andy")

	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

}

v2.go

package main

import (
	"fmt"
)

type Queue[T any] struct {
	elements []T
	size     uint
	head     uint
	rear     uint
}

func NewQueue[T any](size uint) *Queue[T] {
	elements := make([]T, size)

	return &Queue[T]{
		elements: elements,
		size:     size,
		head:     0,
		rear:     0,
	}
}

func (q *Queue[T]) Elements() []T {
	return q.elements[q.head:q.rear]
}

func (q *Queue[T]) Enq(t T) {
	if q.rear == q.size {
		newSize := q.size << 1
		q.size = newSize
		newElements := make([]T, newSize)
		copy(newElements, q.elements)

		q.elements = newElements
	}

	q.elements[q.rear] = t
	q.rear = q.rear + 1
}

func (q *Queue[T]) Deq() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[q.head]

	q.head = (q.head + 1) % q.size

	if q.rear <= (q.size >> 2) {
		newSize := q.size >> 2
		q.size = newSize
		newElements := make([]T, newSize)
		copy(newElements, q.elements)

		q.elements = newElements
	}

	return &t
}

func (q *Queue[T]) Peek() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[0]

	return &t
}

func (q *Queue[T]) Last() *T {
	if q.rear <= 0 {
		return nil
	}

	t := q.elements[q.rear-1]

	return &t
}

func (q *Queue[T]) Size() uint {
	return q.size
}

func main() {
	q := NewQueue[string](5)

	q.Enq("alex")
	q.Enq("bony")
	q.Enq("andy")

	fmt.Println("-------------------")
	fmt.Println("size: ", q.Size())

	fmt.Println(q.Elements())

	fmt.Println("-------------------")
	q.Enq("cece")
	q.Enq("coci")
	q.Enq("dody")

	fmt.Println("-------------------")
	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

	t := q.Peek()
	if t != nil {
		fmt.Println(*t)
	}

	l := q.Last()
	if l != nil {
		fmt.Println(*l)
	}

	fmt.Println("--------- deque ----------")
	fmt.Println(*q.Deq())
	fmt.Println(*q.Deq())
	fmt.Println(*q.Deq())
	fmt.Println(*q.Deq())
	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

	fmt.Println("-------------------")
	q.Enq("alex")
	q.Enq("bony")
	q.Enq("andy")

	fmt.Println(*q.Deq())

	q.Enq("wury")

	fmt.Println("size: ", q.Size())
	fmt.Println(q.Elements())

}