feat: add LinkedQueue

datastructure/node.go

@@ -26,7 +26,7 @@ func NewStackNode[T any](value T) *StackNode[T] {
 // QueueNode is a node in a queue, which have a Value and Next pointer points to next node in the queue.
 type QueueNode[T any] struct {
 	Value T
-	Next  *StackNode[T]
+	Next  *QueueNode[T]
 }
 
 // NewQueueNode return a QueueNode pointer

datastructure/queue/linkedqueue.go

@@ -0,0 +1,104 @@
+package datastructure
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/duke-git/lancet/datastructure"
+)
+
+// LinkedQueue implements queue with link list
+type LinkedQueue[T any] struct {
+	head   *datastructure.QueueNode[T]
+	tail   *datastructure.QueueNode[T]
+	length int
+}
+
+// NewLinkedQueue return a empty LinkedQueue pointer
+func NewLinkedQueue[T any]() *LinkedQueue[T] {
+	return &LinkedQueue[T]{head: nil, tail: nil, length: 0}
+}
+
+// Data return queue data
+func (q *LinkedQueue[T]) Data() []T {
+	res := []T{}
+	current := q.head
+
+	for current != nil {
+		res = append(res, current.Value)
+		current = current.Next
+	}
+	return res
+}
+
+// Size return length of queue data
+func (q *LinkedQueue[T]) Size() int {
+	return q.length
+}
+
+// IsEmpty checks if queue is empty or not
+func (q *LinkedQueue[T]) IsEmpty() bool {
+	return q.length == 0
+}
+
+// EnQueue add element into queue
+func (q *LinkedQueue[T]) EnQueue(value T) {
+	newNode := datastructure.NewQueueNode(value)
+
+	if q.IsEmpty() {
+		q.head = newNode
+		q.tail = newNode
+	} else {
+		q.tail.Next = newNode
+		q.tail = newNode
+	}
+	q.length++
+}
+
+// DeQueue delete head element of queue then return it, if queue is empty, return nil and error
+func (q *LinkedQueue[T]) DeQueue() (*T, error) {
+	if q.IsEmpty() {
+		return nil, errors.New("queue is empty")
+	}
+
+	head := q.head
+	q.head = q.head.Next
+	q.length--
+
+	return &head.Value, nil
+}
+
+// Front return front value of queue
+func (q *LinkedQueue[T]) Front() (*T, error) {
+	if q.IsEmpty() {
+		return nil, errors.New("queue is empty")
+	}
+	return &q.head.Value, nil
+}
+
+// Back return back value of queue
+func (q *LinkedQueue[T]) Back() (*T, error) {
+	if q.IsEmpty() {
+		return nil, errors.New("queue is empty")
+	}
+	return &q.tail.Value, nil
+}
+
+// Clear clear the queue data
+func (q *LinkedQueue[T]) Clear() {
+	q.head = nil
+	q.tail = nil
+	q.length = 0
+}
+
+// Print all nodes info of queue link
+func (s *LinkedQueue[T]) Print() {
+	current := s.head
+	info := "[ "
+	for current != nil {
+		info += fmt.Sprintf("%+v, ", current)
+		current = current.Next
+	}
+	info += " ]"
+	fmt.Println(info)
+}

datastructure/queue/linkedqueue_test.go

@@ -0,0 +1,84 @@
+package datastructure
+
+import (
+	"testing"
+
+	"github.com/duke-git/lancet/internal"
+)
+
+func TestLinkedQueue_EnQueue(t *testing.T) {
+	assert := internal.NewAssert(t, "TestLinkedQueue_EnQueue")
+
+	queue := NewLinkedQueue[int]()
+	queue.EnQueue(1)
+	queue.EnQueue(2)
+	queue.EnQueue(3)
+
+	queue.Print()
+
+	assert.Equal([]int{1, 2, 3}, queue.Data())
+	assert.Equal(3, queue.Size())
+}
+
+func TestLinkedQueue_DeQueue(t *testing.T) {
+	assert := internal.NewAssert(t, "TestLinkedQueue_DeQueue")
+
+	queue := NewLinkedQueue[int]()
+	queue.EnQueue(1)
+	queue.EnQueue(2)
+	queue.EnQueue(3)
+
+	val, _ := queue.DeQueue()
+
+	queue.Print()
+
+	assert.Equal([]int{2, 3}, queue.Data())
+	assert.Equal(1, *val)
+}
+
+func TestLinkedQueue_Front(t *testing.T) {
+	assert := internal.NewAssert(t, "TestLinkedQueue_Front")
+
+	queue := NewLinkedQueue[int]()
+	val, err := queue.Front()
+	assert.IsNotNil(err)
+
+	queue.EnQueue(1)
+	queue.EnQueue(2)
+	queue.EnQueue(3)
+
+	val, err = queue.Front()
+	assert.Equal(1, *val)
+	assert.IsNil(err)
+}
+
+func TestLinkedQueue_Back(t *testing.T) {
+	assert := internal.NewAssert(t, "TestLinkedQueue_Back")
+
+	queue := NewLinkedQueue[int]()
+	val, err := queue.Back()
+	assert.IsNotNil(err)
+
+	queue.EnQueue(1)
+	queue.EnQueue(2)
+	queue.EnQueue(3)
+
+	val, err = queue.Back()
+	assert.Equal(3, *val)
+	assert.IsNil(err)
+}
+
+func TestLinkedQueue_Clear(t *testing.T) {
+	assert := internal.NewAssert(t, "TestLinkedQueue_Back")
+
+	queue := NewLinkedQueue[int]()
+	assert.Equal(true, queue.IsEmpty())
+
+	queue.EnQueue(1)
+	queue.EnQueue(2)
+	queue.EnQueue(3)
+	assert.Equal(false, queue.IsEmpty())
+
+	queue.Clear()
+	assert.Equal(true, queue.IsEmpty())
+}