Add RingBuffer template

Source/Engine/Core/Collections/RingBuffer.h

@@ -0,0 +1,95 @@
+// Copyright (c) 2012-2021 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Platform/Platform.h"
+#include "Engine/Core/Memory/Memory.h"
+#include "Engine/Core/Memory/Allocation.h"
+
+/// <summary>
+/// Template for ring buffer with variable capacity.
+/// </summary>
+template<typename T, typename AllocationType = HeapAllocation>
+class RingBuffer
+{
+public:
+
+	typedef T ItemType;
+	typedef typename AllocationType::template Data<T> AllocationData;
+
+private:
+
+	int32 _front = 0, _back = 0, _count = 0, _capacity = 0;
+	AllocationData _allocation;
+
+public:
+
+	~RingBuffer()
+	{
+		Memory::DestructItems(Get() + Math::Min(_front, _back), _count);
+	}
+
+	FORCE_INLINE T* Get()
+	{
+		return _allocation.Get();
+	}
+
+	FORCE_INLINE int32 Count() const
+	{
+		return _count;
+	}
+
+	FORCE_INLINE int32 Capacity() const
+	{
+		return _capacity;
+	}
+
+	void PushBack(const T& data)
+	{
+		if (_capacity == 0 || _capacity == _count)
+		{
+			const int32 capacity = _allocation.CalculateCapacityGrow(_capacity, 0);
+			AllocationData alloc;
+			alloc.Allocate(capacity);
+			const int32 frontCount = Math::Min(_capacity - _front, _count);
+			Memory::MoveItems(alloc.Get(), _allocation.Get() + _front, frontCount);
+			Memory::DestructItems(_allocation.Get() + _front, frontCount);
+			const int32 backCount = _count - frontCount;
+			Memory::MoveItems(alloc.Get() + frontCount, _allocation.Get(), backCount);
+			Memory::DestructItems(_allocation.Get(), backCount);
+			_allocation.Swap(alloc);
+			_front = 0;
+			_back = _count;
+			_capacity = capacity;
+		}
+		Memory::ConstructItems(_allocation.Get() + _back, &data, 1);
+		_back = (_back + 1) % _capacity;
+		_count++;
+	}
+
+	FORCE_INLINE T& PeekFront()
+	{
+		ASSERT(_front != _back);
+		return _allocation.Get()[_front];
+	}
+
+	FORCE_INLINE const T& PeekFront() const
+	{
+		ASSERT(_front != _back);
+		return _allocation.Get()[_front];
+	}
+
+	void PopFront()
+	{
+		ASSERT(_front != _back);
+		Memory::DestructItems(_allocation.Get() + _front, 1);
+		_front = (_front + 1) % _capacity;
+		_count--;
+	}
+
+	void Clear()
+	{
+		Memory::DestructItems(Get() + Math::Min(_front, _back), _count);
+		_front = _back = _count = 0;
+	}
+};