1 files changed, 174 insertions, 0 deletions
diff --git a/source/10-common/RingBuffer.hpp b/source/10-common/RingBuffer.hpp
new file mode 100644
index 0000000..c4ff851
--- /dev/null
+++ b/source/10-common/RingBuffer.hpp
@@ -0,0 +1,174 @@
+#pragma once
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <iterator>
+
+template <typename T>
+class RingBuffer {
+public:
+	class Sentinel {};
+	class Iterator {
+	public:
+		friend class RingBuffer;
+		using difference_type = ptrdiff_t;
+		using value_type = T;
+		using pointer = T*;
+		using reference = T&;
+		using iterator_category = std::random_access_iterator_tag;
+
+	private:
+		RingBuffer* mContainer;
+		size_t mCurr;
+		bool mNeedsWrapAround;
+		bool mHasWrapped = false;
+
+	public:
+		// NOTE: default constructed Iterator is in an undefined state
+
+		T& operator*() const {
+			return mContainer->mRing[mCurr];
+		}
+
+		Iterator& operator++() {
+			assert(*this != Sentinel{});
+			++mCurr;
+			if (mNeedsWrapAround && mCurr == mContainer->mCapacity) {
+				mHasWrapped = true;
+				mCurr = 0;
+			}
+			return *this;
+		}
+
+		bool operator==(const Iterator& that) const {
+			assert(this->mContainer == that.mContainer);
+			return this->mCurr == that.mCurr;
+		}
+
+		bool operator==(const Sentinel&) const {
+			return mCurr == mContainer->mTailIdx && (!mNeedsWrapAround || mHasWrapped);
+		}
+	};
+
+	using value_type = T;
+	using reference = T&;
+	using const_reference = const T&;
+	using iterator = Iterator;
+	// using const_iterator = void; // TODO
+	using difference_type = ptrdiff_t;
+	using size_type = size_t;
+
+private:
+	T* mRing = nullptr;
+	size_t mHeadIdx = 0;
+	size_t mTailIdx = 0;
+	size_t mCapacity = 0;
+	size_t mSize = 0;
+
+public:
+	RingBuffer() noexcept = default;
+
+	~RingBuffer() noexcept {
+		delete mRing;
+	}
+
+	RingBuffer(const RingBuffer&) noexcept = delete;
+	RingBuffer& operator=(const RingBuffer&) noexcept = delete;
+
+	RingBuffer(RingBuffer&& that) noexcept
+		: mRing{ that.mRing }
+		, mHeadIdx{ that.mHeadIdx }
+		, mTailIdx{ that.mTailIdx }
+		, mCapacity{ that.mCapacity }
+		, mSize{ that.mSize } {
+		that.mRing = nullptr;
+	}
+
+	RingBuffer& operator=(RingBuffer&& that) noexcept {
+		if (this != &that) {
+			auto oldThisRing = this->mRing;
+			this->mRing = that.mRing;
+			that.mRing = nullptr;
+			delete oldThisRing;
+
+			this->mHeadIdx = that.mHeadIdx;
+			this->mTailIdx = that.mTailIdx;
+			this->mCapacity = that.mCapacity;
+			this->mSize = that.mSize;
+		}
+
+		return *this;
+	}
+
+	Iterator begin() {
+		Iterator it;
+		it.mContainer = this;
+		it.mCurr = mHeadIdx;
+		it.mNeedsWrapAround = mHeadIdx >= mTailIdx;
+		return it;
+	}
+
+	Sentinel end() {
+		return Sentinel{};
+	}
+
+	const T& operator[](size_t i) const {
+		size_t idx = mHeadIdx + i;
+		if (idx >= mCapacity) {
+			idx -= mCapacity;
+		}
+		return mRing[idx];
+	}
+	T& operator[](size_t i) { return const_cast<T&>(const_cast<const RingBuffer&>(*this)[i]); }
+
+	void push_back(T t) {
+		if (mTailIdx == mCapacity) {
+			// Ring buffer is filled to the right, warp around to the beginning
+			// mHeadIdx > 0 must be true, since we checked that as condition (1) above
+			mRing[0] = std::move(t);
+			mTailIdx = 1;
+		} else {
+			mRing[mTailIdx] = std::move(t);
+			mTailIdx += 1;
+		}
+
+		// Push mHeadIdx backwards if overwrote element in a filled buffer
+		bool bufferFilled = mSize == mCapacity;
+		if (bufferFilled && mTailIdx > mHeadIdx) {
+			mHeadIdx += 1;
+			if (mHeadIdx == mCapacity) {
+				mHeadIdx = 0;
+			}
+		}
+
+		if (!bufferFilled) {
+			++mSize;
+		}
+	}
+
+	[[nodiscard]] size_t capacity() const {
+		return mCapacity;
+	}
+
+	[[nodiscard]] size_t size() const {
+		return mSize;
+	}
+
+	[[nodiscard]] T* GetBuffer() const { return mRing; }
+	[[nodiscard]] size_t GetHeadIdx() const { return mHeadIdx; }
+	[[nodiscard]] size_t GetTailIdx() const { return mTailIdx; }
+
+	void resize(size_t newCapacity) {
+		auto size = this->size();
+
+		auto oldRing = mRing;
+		auto newRing = mRing = new T[newCapacity];
+		std::rotate_copy(oldRing, oldRing + mHeadIdx, oldRing + mCapacity, newRing);
+		delete oldRing;
+
+		mCapacity = newCapacity;
+		mHeadIdx = 0;
+		mTailIdx = size;
+	}
+};