fix: align slice/set equality and harden queue API

queue.go

@@ -6,6 +6,7 @@ import (
 )
 
 var QueueFullErr = errors.New("queue full")
+var QueueEmptyErr = errors.New("queue empty")
 
 type Queue[T any] struct {
 	size  uint64
@@ -27,37 +28,48 @@ func (q *Queue[T]) IsFull() bool  { return q.Len() == q.size }
 func (q *Queue[T]) Size() uint64  { return q.size }
 
 func (q *Queue[T]) Enqueue(el T) error {
-	if q.IsFull() {
+	q.mu.Lock()
+	defer q.mu.Unlock()
+
+	if uint64(len(q.queue)) == q.size {
 		return QueueFullErr
 	}
 	q.queue = q.queue.Push(el)
 	return nil
 }
 
-func (q *Queue[T]) Dequeue() T {
-	q.mu.RLock()
-	el := q.queue.Get(0)
-	q.mu.RUnlock()
+func (q *Queue[T]) Dequeue() (T, error) {
+	q.mu.Lock()
+	defer q.mu.Unlock()
 
-	if q.Len() == 1 {
-		q.mu.Lock()
-		q.queue = make(Slice[T], 0)
-		q.mu.Unlock()
-		return el
+	var zero T
+	if len(q.queue) == 0 {
+		return zero, QueueEmptyErr
 	}
 
-	q.mu.Lock()
-	q.queue = q.queue.Pop(0)
-	q.mu.Unlock()
-	return el
+	el := q.queue[0]
+	copy(q.queue, q.queue[1:])
+	q.queue[len(q.queue)-1] = zero
+	q.queue = q.queue[:len(q.queue)-1]
+
+	return el, nil
 }
 
-func (q *Queue[T]) Peak() T {
+func (q *Queue[T]) Peak() (T, error) {
 	q.mu.RLock()
 	defer q.mu.RUnlock()
-	return q.queue.Get(0)
+
+	var zero T
+	if len(q.queue) == 0 {
+		return zero, QueueEmptyErr
+	}
+
+	return q.queue[0], nil
 }
 
 func (q *Queue[T]) Raw() Slice[T] {
-	return q.queue
+	q.mu.RLock()
+	defer q.mu.RUnlock()
+
+	return NewSliceFrom(q.queue)
 }