added dequeue and peek, easy

include/queue.h

@@ -34,7 +34,7 @@ public:
 
     std::expected<T, QueueErr> peek();
 
-    std::expected<T, QueueErr> unqueue();
+    std::expected<T, QueueErr> dequeue();
 
     void display();
 };
@@ -89,5 +89,62 @@ QueueErr Queue<T>::enqueue(T value) {
     this->data[this->head] = value;
     this->len++;
     this->head = (this->head + 1) % this->cap;
+    return QueueErr::ok;
+}
+
+template <typename T>
+requires std::formattable<T, char>
+std::expected<T, QueueErr> Queue<T>::dequeue() {
+    if (this->len == 0) {
+        return std::unexpected(QueueErr::empty);
+    }
+
+    if (this->cap > DEFAULT_QUEUE_SIZE && this->cap / 4 > this->len) {
+        uint64_t new_cap = this->cap / 2;
+        if (new_cap < DEFAULT_QUEUE_SIZE) {
+            new_cap = DEFAULT_QUEUE_SIZE;
+        }
+
+        T *tmp;
+        try {
+            tmp = new T[new_cap];
+        } catch(const std::bad_alloc& e) {
+            return std::unexpected(QueueErr::bad_alloc);
+        }
+
+        for (uint64_t i = 0; i < this->len; i++) {
+            uint64_t index = (this->tail) % this->cap;
+            tmp[i] = this->data[index];
+        }
+
+        delete[] this->data;
+        this->data = tmp;
+        this->cap = new_cap;
+        this->tail = 0;
+        this->head = this->len;
+
+    }
+
+    T out;
+    out = this->data[this->tail];
+    this->len--;
+    this->tail = (this->tail + 1) % this->cap;
+
+    return out;
+}
+
+template <typename T>
+requires std::formattable<T, char>
+std::expected<T, QueueErr> Queue<T>::peek() {
+    if (this->len == 0) {
+        return std::unexpected(QueueErr::empty);
+    }
+
+    T out;
+    out = this->data[this->tail];
+    this->len--;
+    this->tail = (this->tail + 1) % this->cap;
+
+    return out;
 }
 #endif // !QUEUE_H