mutable_buffer_sequence_of_strings.cpp

#include <boost/asio/buffer.hpp>
#include <boost/container/deque.hpp>
#include <boost/iterator/iterator_adaptor.hpp>
#include <string>

struct strings_deque_buffer_reference
{
    std::string& str;
    operator boost::asio::mutable_buffer() const noexcept { return boost::asio::buffer(str); }
    operator boost::asio::const_buffer() const noexcept { return boost::asio::buffer(str); }
};

template <typename BaseIterator, typename Buffer>
struct strings_buffer_sequence_iterator final:
    boost::iterator_adaptor <strings_buffer_sequence_iterator<BaseIterator, Buffer>, 
                             BaseIterator,
                             Buffer,
                             boost::use_default,
                             strings_deque_buffer_reference>
{
    strings_buffer_sequence_iterator (BaseIterator base) noexcept:
        strings_buffer_sequence_iterator::iterator_adaptor_(std::move(base)) {}
    strings_deque_buffer_reference dereference() const noexcept { return {*this->base_reference()}; }
};

template <typename C>
struct mutable_buffer_sequence_of_strings
{
    using value_type = boost::asio::mutable_buffer;
    using const_iterator = strings_buffer_sequence_iterator<typename C::iterator,
                                                            value_type>;

    mutable_buffer_sequence_of_strings(C& c): c_(c) {}

    auto begin() const noexcept { return const_iterator(c_.begin()); }
    auto end() const noexcept { return const_iterator(c_.end()); }

    C& c_;
};

static_assert(boost::asio::is_mutable_buffer_sequence<mutable_buffer_sequence_of_strings
                                        <boost::container::deque<std::string>>>::value);

#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/read.hpp>
#include <iostream>

int
main()
{
    boost::container::deque<std::string> deque;
    mutable_buffer_sequence_of_strings deque_buf_seq{deque};

    auto it = boost::asio::buffer_sequence_begin (deque_buf_seq);
    auto end = boost::asio::buffer_sequence_end (deque_buf_seq);
    while (it != end)
    {
        ++it;
        --it;
        ++it;
        boost::asio::mutable_buffer buf = *it;
    }

    boost::asio::io_context io_context;
    boost::asio::ip::tcp::socket socket {io_context};
    boost::system::error_code ec;

    deque.emplace_back().resize(100);
    std::cout << boost::asio::read (socket, deque_buf_seq, ec) << "\n";
    std::cout << ec.message() << "\n";
}