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//
// connect_pair.cpp
// ~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include <array>
#include <iostream>
#include <string>
#include <cctype>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
using boost::asio::local::stream_protocol;
class uppercase_filter
{
public:
uppercase_filter(stream_protocol::socket sock)
: socket_(std::move(sock))
{
read();
}
private:
void read()
{
socket_.async_read_some(boost::asio::buffer(data_),
[this](boost::system::error_code ec, std::size_t size)
{
if (!ec)
{
// Compute result.
for (std::size_t i = 0; i < size; ++i)
data_[i] = std::toupper(data_[i]);
// Send result.
write(size);
}
else
{
throw boost::system::system_error(ec);
}
});
}
void write(std::size_t size)
{
boost::asio::async_write(socket_, boost::asio::buffer(data_, size),
[this](boost::system::error_code ec, std::size_t /*size*/)
{
if (!ec)
{
// Wait for request.
read();
}
else
{
throw boost::system::system_error(ec);
}
});
}
stream_protocol::socket socket_;
std::array<char, 512> data_;
};
int main()
{
try
{
boost::asio::io_context io_context;
// Create a connected pair and pass one end to a filter.
stream_protocol::socket socket(io_context);
stream_protocol::socket filter_socket(io_context);
boost::asio::local::connect_pair(socket, filter_socket);
uppercase_filter filter(std::move(filter_socket));
// The io_context runs in a background thread to perform filtering.
boost::thread thread(
[&io_context]()
{
try
{
io_context.run();
}
catch (std::exception& e)
{
std::cerr << "Exception in thread: " << e.what() << "\n";
std::exit(1);
}
});
for (;;)
{
// Collect request from user.
std::cout << "Enter a string: ";
std::string request;
std::getline(std::cin, request);
// Send request to filter.
boost::asio::write(socket, boost::asio::buffer(request));
// Wait for reply from filter.
std::vector<char> reply(request.size());
boost::asio::read(socket, boost::asio::buffer(reply));
// Show reply to user.
std::cout << "Result: ";
std::cout.write(&reply[0], request.size());
std::cout << std::endl;
}
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
std::exit(1);
}
}
#else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
# error Local sockets not available on this platform.
#endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
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