Initial Commit

include/asio/immediate.hpp

@@ -0,0 +1,142 @@
+//
+// immediate.hpp
+// ~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 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)
+//
+
+#ifndef ASIO_IMMEDIATE_HPP
+#define ASIO_IMMEDIATE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include "asio/associated_immediate_executor.hpp"
+#include "asio/async_result.hpp"
+#include "asio/dispatch.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+template <typename Executor>
+class initiate_immediate
+{
+public:
+  typedef Executor executor_type;
+
+  explicit initiate_immediate(const Executor& ex)
+    : ex_(ex)
+  {
+  }
+
+  executor_type get_executor() const noexcept
+  {
+    return ex_;
+  }
+
+  template <typename CompletionHandler>
+  void operator()(CompletionHandler&& handler) const
+  {
+    typename associated_immediate_executor<
+      CompletionHandler, executor_type>::type ex =
+        (get_associated_immediate_executor)(handler, ex_);
+    (dispatch)(ex, static_cast<CompletionHandler&&>(handler));
+  }
+
+private:
+  Executor ex_;
+};
+
+} // namespace detail
+
+/// Launch a trivial asynchronous operation that completes immediately.
+/**
+ * The async_immediate function is intended for use by composed operations,
+ * which can delegate to this operation in order to implement the correct
+ * semantics for immediate completion.
+ *
+ * @param ex The asynchronous operation's I/O executor.
+ *
+ * @param token The completion token.
+ *
+ * The completion handler is immediately submitted for execution by calling
+ * asio::dispatch() on the handler's associated immediate executor.
+ *
+ * If the completion handler does not have a customised associated immediate
+ * executor, then the handler is submitted as if by calling asio::post()
+ * on the supplied I/O executor.
+ *
+ * @par Completion Signature
+ * @code void() @endcode
+ */
+template <typename Executor,
+    ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
+      = default_completion_token_t<Executor>>
+inline auto async_immediate(const Executor& ex,
+    NullaryToken&& token = default_completion_token_t<Executor>(),
+    constraint_t<
+      (execution::is_executor<Executor>::value
+          && can_require<Executor, execution::blocking_t::never_t>::value)
+        || is_executor<Executor>::value
+    > = 0)
+  -> decltype(
+    async_initiate<NullaryToken, void()>(
+      declval<detail::initiate_immediate<Executor>>(), token))
+{
+  return async_initiate<NullaryToken, void()>(
+      detail::initiate_immediate<Executor>(ex), token);
+}
+
+/// Launch a trivial asynchronous operation that completes immediately.
+/**
+ * The async_immediate function is intended for use by composed operations,
+ * which can delegate to this operation in order to implement the correct
+ * semantics for immediate completion.
+ *
+ * @param ex The execution context used to obtain the asynchronous operation's
+ * I/O executor.
+ *
+ * @param token The completion token.
+ *
+ * The completion handler is immediately submitted for execution by calling
+ * asio::dispatch() on the handler's associated immediate executor.
+ *
+ * If the completion handler does not have a customised associated immediate
+ * executor, then the handler is submitted as if by calling asio::post()
+ * on the I/O executor obtained from the supplied execution context.
+ *
+ * @par Completion Signature
+ * @code void() @endcode
+ */
+template <typename ExecutionContext,
+    ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
+      = default_completion_token_t<typename ExecutionContext::executor_type>>
+inline auto async_immediate(ExecutionContext& ctx,
+    NullaryToken&& token = default_completion_token_t<
+      typename ExecutionContext::executor_type>(),
+    constraint_t<
+      is_convertible<ExecutionContext&, execution_context&>::value
+    > = 0)
+  -> decltype(
+    async_initiate<NullaryToken, void()>(
+      declval<detail::initiate_immediate<
+        typename ExecutionContext::executor_type>>(), token))
+{
+  return async_initiate<NullaryToken, void()>(
+      detail::initiate_immediate<
+        typename ExecutionContext::executor_type>(
+          ctx.get_executor()), token);
+}
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_IMMEDIATE_HPP