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-rw-r--r--3rdparty/asio/src/examples/cpp11/operations/composed_5.cpp64
1 files changed, 55 insertions, 9 deletions
diff --git a/3rdparty/asio/src/examples/cpp11/operations/composed_5.cpp b/3rdparty/asio/src/examples/cpp11/operations/composed_5.cpp
index 9f7901da512..06a7af40f41 100644
--- a/3rdparty/asio/src/examples/cpp11/operations/composed_5.cpp
+++ b/3rdparty/asio/src/examples/cpp11/operations/composed_5.cpp
@@ -2,12 +2,13 @@
// composed_5.cpp
// ~~~~~~~~~~~~~~
//
-// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2003-2024 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 <asio/deferred.hpp>
#include <asio/io_context.hpp>
#include <asio/ip/tcp.hpp>
#include <asio/use_future.hpp>
@@ -142,15 +143,26 @@ template <typename T, typename CompletionToken>
auto async_write_message(tcp::socket& socket,
const T& message, CompletionToken&& token)
// The return type of the initiating function is deduced from the combination
- // of CompletionToken type and the completion handler's signature. When the
- // completion token is a simple callback, the return type is always void.
- // In this example, when the completion token is asio::yield_context
- // (used for stackful coroutines) the return type would be also be void, as
+ // of:
+ //
+ // - the CompletionToken type,
+ // - the completion handler signature, and
+ // - the asynchronous operation's initiation function object.
+ //
+ // When the completion token is a simple callback, the return type is always
+ // void. In this example, when the completion token is asio::yield_context
+ // (used for stackful coroutines) the return type would also be void, as
// there is no non-error argument to the completion handler. When the
- // completion token is asio::use_future it would be std::future<void>.
- -> typename asio::async_result<
- typename std::decay<CompletionToken>::type,
- void(std::error_code)>::return_type
+ // completion token is asio::use_future it would be std::future<void>. When
+ // the completion token is asio::deferred, the return type differs for each
+ // asynchronous operation.
+ //
+ // In C++11 we deduce the type from the call to asio::async_initiate.
+ -> decltype(
+ asio::async_initiate<
+ CompletionToken, void(std::error_code)>(
+ async_write_message_initiation(), token,
+ std::ref(socket), std::declval<std::unique_ptr<std::string>>()))
{
// Encode the message and copy it into an allocated buffer. The buffer will
// be maintained for the lifetime of the asynchronous operation.
@@ -207,6 +219,39 @@ void test_callback()
//------------------------------------------------------------------------------
+void test_deferred()
+{
+ asio::io_context io_context;
+
+ tcp::acceptor acceptor(io_context, {tcp::v4(), 55555});
+ tcp::socket socket = acceptor.accept();
+
+ // Test our asynchronous operation using the deferred completion token. This
+ // token causes the operation's initiating function to package up the
+ // operation and its arguments to return a function object, which may then be
+ // used to launch the asynchronous operation.
+ auto op = async_write_message(socket,
+ std::string("abcdef"), asio::deferred);
+
+ // Launch the operation using a lambda as a callback.
+ std::move(op)(
+ [](const std::error_code& error)
+ {
+ if (!error)
+ {
+ std::cout << "Message sent\n";
+ }
+ else
+ {
+ std::cout << "Error: " << error.message() << "\n";
+ }
+ });
+
+ io_context.run();
+}
+
+//------------------------------------------------------------------------------
+
void test_future()
{
asio::io_context io_context;
@@ -239,5 +284,6 @@ void test_future()
int main()
{
test_callback();
+ test_deferred();
test_future();
}