Simple RingBuffer

ringbuffer.hpp

#pragma once
#include <vector>

namespace types {

template <typename T>
class RingBuffer
{
	T empty_item;
	std::vector<T> data;
	int head = 0; // read
	int tail = 0; // write
public:
	RingBuffer<T>(int size, T empty_item):
		empty_item(empty_item),
		data(size + 1, empty_item)
	{}

	bool resize(int n)
	{
		if (n <= size())
			return false;

		// TODO: reduce copying here.

		std::vector<T> data2(n + 1, empty_item);
		T next = pop();
		int i = 0;
		while (next != empty_item) {
			data2[i] = next;
			i++;

			next = pop();
		}

		data = data2;
		head = 0;
		tail = i;
		return true;
	}

	void clear()
	{
		head = 0;
		tail = 0;
	}

	bool empty() const
	{
		return tail == head;
	}

	int size() const
	{
		if (tail >= head)
			return tail - head;
		else
			return data.size() - head + tail;
	}

	int max_size() const
	{
		return data.max_size() - 1;
	}

	int capacity() const
	{
		return data.size() - 1;
	}

	bool push(T item)
	{
		int next_tail = (tail + 1) % data.size();
		if (next_tail == head)
			return false;

		data[tail] = item;
		tail = next_tail;
		return true;
	}

	T pop()
	{
		if (head == tail)
			return empty_item;

		T retval = data[head];
		head = (head + 1) % data.size();

		return retval;
	}

	T pop_front()
	{
		if (head == tail)
			return empty_item;

		tail--;
		if (tail < 0)
			tail = data.size() - 1;
		T retval = data[tail];

		return retval;
	}
};

};

ringbuffer_tests.hpp

#pragma once
#include <sstream>
#include "../types/ring_buffer.hpp"
#include "../types.hpp"
#include "../vectors.hpp"

class RingBufferSizeTest : public AutoTest
{
public:
	virtual bool setup()
	{
		return true;
	}

	virtual bool run()
	{
		// Basic pop/push
		RingBuffer<int> buff(10, 0);
		TEST(buff.size() == 0);
		TEST(buff.capacity() == 10);
		for (int i = 1; i < 50; i++) {
			TEST(buff.push(i));
			TEST(buff.size() == 1);
			TEST(!buff.empty());
			TEST(buff.pop() != 0);
			TEST(buff.empty());
			TEST(buff.size() == 0);
		}

		// Add ten items
		for (int i = 0; i < 10; i++) {
			TEST(buff.push(i + 1));
			TEST(buff.size() == i + 1);
			TEST(!buff.empty());
		}
		TEST(!buff.push(11));
		TEST(buff.size() == 10);
		TEST(!buff.resize(10));
		TEST(!buff.resize(5));
		TEST(buff.size() == 10);

		// Resize to fit 20
		TEST(buff.resize(20));
		TEST(buff.size() == 10);
		TEST(buff.capacity() == 20);

		// Add ten more
		for (int i = 10; i < 20; i++) {
			TEST(buff.push(i + 1));
			TEST(buff.size() == i + 1);
			TEST(!buff.empty());
		}
		TEST(!buff.push(21));
		TEST(buff.size() == 20);

		// Check pop
		for (int i = 0; i < 20; i++) {
			TEST(buff.size() == 20 - i);
			TEST(buff.pop() != 0);
			TEST(buff.size() == 20 - i - 1);
		}
		TEST(buff.size() == 0);
		TEST(buff.empty());
		TEST(buff.capacity() == 20);

		// Clear
		buff.clear();
		TEST(buff.size() == 0);
		TEST(buff.empty());
		TEST(buff.capacity() == 20);
		for (int i = 1; i < 50; i++) {
			TEST(buff.push(i));
			TEST(buff.size() == 1);
			TEST(buff.pop() != 0);
			TEST(buff.size() == 0);
		}

		TEST(buff.empty());
		TEST(buff.capacity() == 20);
		for (int i = 0; i < 20; i++) {
			TEST(buff.push(i + 1));
			TEST(buff.size() == i + 1);
		}
		for (int i = 0; i < 20; i++) {
			TEST(buff.size() == 20 - i);
			TEST(buff.pop_front() == 20 - i);
			TEST(buff.size() == 20 - i - 1);
		}
		TEST(buff.size() == 0);

		return true;
	}

	virtual void teardown()
	{}
};

bool do_ringbuffer_tests()
{
	bool passed = true;

	passed = do_test("RingBufferSizeTest", new RingBufferSizeTest()) && passed;

	return passed;
}