Add a CircularQueue template class to AK.

AK/CircularQueue.h

@@ -0,0 +1,56 @@
+#pragma once
+
+#include "Types.h"
+#include "kstdio.h"
+
+namespace AK {
+
+template<typename T, size_t capacity>
+class CircularQueue {
+public:
+    CircularQueue()
+    {
+        for (size_t i = 0; i < capacity; ++i)
+            m_elements[i] = T();
+    }
+
+    bool isEmpty() const { return !m_size; }
+    size_t size() const { return m_size; }
+
+    void dump() const
+    {
+        kprintf("CircularQueue<%zu>:\n", capacity);
+        kprintf(" size: %zu\n", m_size);
+        for (size_t i = 0; i < capacity; ++i) {
+            kprintf(" [%zu] %d %c\n", i, m_elements[i], i == m_head ? '*' : ' ');
+        }
+    }
+
+    void enqueue(const T& t)
+    {
+        m_elements[(m_head + m_size) % capacity] = t;
+        if (m_size == capacity)
+            m_head = (m_head + 1) % capacity;
+        else
+            ++m_size;
+    }
+
+    T dequeue()
+    {
+        ASSERT(!isEmpty());
+        T value = m_elements[m_head];
+        m_head = (m_head + 1) % capacity;
+        --m_size;
+        return value;
+    }
+
+private:
+    T m_elements[capacity];
+    size_t m_size { 0 };
+    size_t m_head { 0 };
+};
+
+}
+
+using AK::CircularQueue;
+