TTripleBuffer/Project1/msg_vector.h

#pragma once
#include <vector>
class MessageVector {
public:
	struct header_t {
		size_t len_{};
	};

	size_t get_buff_size() const
	{
		return buffer_.size();
	}
	size_t get_buff_capacity() const
	{
		return buffer_.capacity();
	}

	void clear() {
		buffer_.clear();
	}

	void shrink(size_t size) {
		buffer_.reserve(size);
	}

	template<typename T, typename... Types>
	static size_t get_len(T value, Types... args)
	{
		if constexpr (std::is_convertible_v<T, std::size_t>) {
			return  value ;
		}
		return 0;
	}		
		
	template<typename... Types>
	bool put(Types&&... args){
		size_t total_len = (... + get_len(std::forward<Types>(args))) ;

		size_t buff_used = buffer_.size();
		buffer_.resize(buff_used + total_len + sizeof(header_t));

		header_t* p = (header_t*)(buffer_.data() + buff_used);
		p->len_ = total_len;
		char* pbuff = (char*)p + sizeof(header_t);

		auto func = [&pbuff](auto func, void* pdata, size_t len, auto&&... args) {
			memcpy(pbuff, pdata, len);
			pbuff += len;
			if constexpr (sizeof ... (args) > 0) {
				func(func, args...);
			}			
		};

		func(func, std::forward<Types>(args)...);
	
		return true;
	}

	bool peek(size_t& it, const void*& pdata, size_t& len) const
	{
		size_t pos = it + sizeof(header_t);
		if(pos > buffer_.size()) {
			return false;
		}

		header_t* p = (header_t*)(buffer_.data() + it);
		if(pos + p->len_ > buffer_.size())
		{
			return false;
		}

		it = pos + p->len_;
		pdata = buffer_.data() + pos;
		len = p->len_;
		return true;
	}
private:
	std::vector<char> buffer_;
};