From cd3878d6986efcad47a0323c2a79778c133e5056 Mon Sep 17 00:00:00 2001
From: Gregory <neogen570@gmail.com>
Date: Wed, 15 Dec 2021 23:35:58 +0200
Subject: [PATCH] generic queue

---
 fundamentals/queue/queue.go      | 35 ++++++++++++++------------------
 fundamentals/queue/queue_test.go |  6 +++---
 go.mod                           |  2 +-
 3 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/fundamentals/queue/queue.go b/fundamentals/queue/queue.go
index 519e482..d485d89 100644
--- a/fundamentals/queue/queue.go
+++ b/fundamentals/queue/queue.go
@@ -1,37 +1,32 @@
 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
+type Queue[T any] interface {
+	Enqueue(T)
+	Dequeue() T
 	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 {
+type node[Item any] struct {
 	item Item
-	next *node
+	next *node[Item]
 }
 
-type queue struct {
+type queue[OfType any] struct {
 	size int
-	head *node
-	tail *node
+	head *node[OfType]
+	tail *node[OfType]
 }
 
-func NewQueue() Queue {
-	return &queue{}
+func NewQueue[OfType any]() Queue[OfType] {
+	return &queue[OfType]{}
 }
 
-func (q *queue) Enqueue(item Item) {
+func (q *queue[T]) Enqueue(item T) {
 	oldTail := q.tail
-	q.tail = &node{item: item, next: nil}
+	q.tail = &node[T]{item: item, next: nil}
 	if q.IsEmpty() {
 		q.head = q.tail
 	} else {
@@ -40,7 +35,7 @@ func (q *queue) Enqueue(item Item) {
 	q.size++
 }
 
-func (q *queue) Dequeue() Item {
+func (q *queue[T]) Dequeue() T {
 	first := q.head
 	q.head = q.head.next
 	if q.IsEmpty() {
@@ -50,10 +45,10 @@ func (q *queue) Dequeue() Item {
 	return first.item
 }
 
-func (q *queue) Size() int {
+func (q *queue[T]) Size() int {
 	return q.size
 }
 
-func (q *queue) IsEmpty() bool {
+func (q *queue[T]) IsEmpty() bool {
 	return q.head == nil
 }
diff --git a/fundamentals/queue/queue_test.go b/fundamentals/queue/queue_test.go
index 32e0c20..848bd66 100644
--- a/fundamentals/queue/queue_test.go
+++ b/fundamentals/queue/queue_test.go
@@ -6,13 +6,13 @@ import (
 )
 
 func TestSimple(t *testing.T) {
-	queue := NewQueue()
+	queue := NewQueue[int]()
 
 	queue.Enqueue(10)
 	queue.Enqueue(20)
 	queue.Enqueue(30)
 
-	first, second := queue.Dequeue().(int), queue.Dequeue().(int)
+	first, second := queue.Dequeue(), queue.Dequeue()
 
 	if first != 10 && second != 20 {
 		log.Fatal("wrong order")
@@ -20,7 +20,7 @@ func TestSimple(t *testing.T) {
 }
 
 func TestSize(t *testing.T) {
-	queue := NewQueue()
+	queue := NewQueue[int]()
 
 	if queue.Size() != 0 {
 		log.Fatal("empty queue should have size 0")
diff --git a/go.mod b/go.mod
index 44584f2..db7c2c3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module github.com/fotonmoton/algorithms
 
-go 1.16
+go 1.18