TL/include/tl/memory_buffer.h

#pragma once

#include "tl/detail/prologue.h"
#include <cstdint>
#include <algorithm>
#include "tl/api.h"
#include "tl/hash_map.h"
#include "tl/plain_assert.h"
#include "tl/murmur_hash.h"
#include <unordered_map>

namespace tl
{

class TL_API memory_buffer
{
public:
	using iterator = uint8_t *;
	using const_iterator = const uint8_t *;
	using value_type = uint8_t;

	memory_buffer();
	~memory_buffer();

	explicit memory_buffer(size_t size, uint8_t value = 0);
	memory_buffer(const uint8_t* start, const uint8_t* end);
	memory_buffer(const uint8_t* start, size_t size);

	memory_buffer(const memory_buffer& other);
	memory_buffer& operator=(const memory_buffer& other);

	memory_buffer(memory_buffer&& other) noexcept;
	memory_buffer& operator=(memory_buffer&& other) noexcept;

	bool operator==(const memory_buffer& other) const;
	bool operator!=(const memory_buffer& other) const;

	inline void push_back(uint8_t c);
	void append(const memory_buffer& other);
	void append(const uint8_t* start, const uint8_t* end);
	void append(const uint8_t* start, size_t size);
	void assign(const uint8_t* start, const uint8_t* end);
	void erase(iterator begin, iterator end);

	void resize(size_t size, uint8_t value = 0);
	void resize_uninitialized(size_t size);
	void reserve(size_t capacity);
	void shrink_to_fit();

	inline void swap(memory_buffer& other) noexcept;

	void clear();

	inline const uint8_t* data() const;
	inline uint8_t* data();

	inline const uint8_t& operator[](size_t i) const;
	inline uint8_t& operator[](size_t i);

	inline uint8_t front() const;
	inline uint8_t back() const;
	inline uint8_t& front();
	inline uint8_t& back();

	inline bool empty() const;
	inline size_t size() const;
	inline size_t capacity() const;

	inline iterator begin();
	inline iterator end();

	inline const_iterator begin() const;
	inline const_iterator end() const;

private:
	//inline uint32_t& _capacity_unsafe();
	//inline const uint32_t& _capacity_unsafe() const;
	static size_t get_grow_capacity(size_t needed, size_t capacity);

	//We're storing the sizes in uint32_t and in the allocated buffer itself to save some memory. 
	//This means the memory_buffer is limited to 4GB!
	//Trying to go over 4GB will result in a crash
	struct Header// this is only for sizeof purposes
	{
		uint32_t m_capacity;
		uint32_t m_size;
	};

	uint8_t* m_buf;
};

}

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

#define _size() (*reinterpret_cast<uint32_t*>(m_buf))
#define _capacity() (*reinterpret_cast<uint32_t*>(m_buf + sizeof(uint32_t)))
#define _data() (m_buf + sizeof(Header))

namespace tl
{

inline void memory_buffer::swap(memory_buffer& other) noexcept
{
	std::swap(m_buf, other.m_buf);
}

inline void memory_buffer::push_back(uint8_t c)
{
	const size_t size = _size();
	const size_t capacity = _capacity();
	if (size >= capacity)
		reserve(get_grow_capacity(size + 1u, capacity));

	m_buf[sizeof(Header) + size] = c;
	_size() = uint32_t(size + 1);
}
inline const uint8_t* memory_buffer::data() const
{
	return size() > 0 ? _data() : nullptr;
}
inline uint8_t* memory_buffer::data()
{
	return size() > 0 ? _data() : nullptr;
}
inline size_t memory_buffer::size() const
{
	return _size();
}
inline size_t memory_buffer::capacity() const
{
	return _capacity();
}
inline const uint8_t& memory_buffer::operator[](size_t i) const
{
	TL_PLAIN_ASSERT(i < size());
	return _data()[i];
}
inline uint8_t& memory_buffer::operator[](size_t i)
{
	TL_PLAIN_ASSERT(i < size());
	return _data()[i];
}
inline uint8_t memory_buffer::front() const
{
	TL_PLAIN_ASSERT(size() > 0);
	return *_data();
}
inline uint8_t memory_buffer::back() const
{
	TL_PLAIN_ASSERT(size() > 0);
	return _data()[_size() - 1];
}
inline uint8_t& memory_buffer::front()
{
	TL_PLAIN_ASSERT(size() > 0);
	return *_data();
}
inline uint8_t& memory_buffer::back()
{
	TL_PLAIN_ASSERT(size() > 0);
	return _data()[_size() - 1];
}

inline bool memory_buffer::empty() const
{
	return size() == 0;
}

inline memory_buffer::iterator memory_buffer::begin()
{
	return _data();
}
inline memory_buffer::iterator memory_buffer::end()
{
	return _data() + _size();
}

inline memory_buffer::const_iterator memory_buffer::begin() const
{
	return _data();
}
inline memory_buffer::const_iterator memory_buffer::end() const
{
	return _data() + _size();
}

}

inline void swap(tl::memory_buffer& a, tl::memory_buffer& b) noexcept
{
	a.swap(b);
}

template <> struct std::hash<tl::memory_buffer>
{
	size_t operator()(tl::memory_buffer const& s) const noexcept
	{
		if (s.empty())
			return 0;
		return tl::murmur32(s.data(), s.size(), 0u);
	}
};

template <> struct eastl::hash<tl::memory_buffer>
{
	size_t operator()(tl::memory_buffer const& s) const
	{
		if (s.empty())
			return 0;
		return tl::murmur32(s.data(), s.size(), 0u);
	}
};



#undef _size
#undef _capacity
#undef _data