Initial Commit

include/asio/default_completion_token.hpp

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+//
+// default_completion_token.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_DEFAULT_COMPLETION_TOKEN_HPP
+#define ASIO_DEFAULT_COMPLETION_TOKEN_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include "asio/detail/type_traits.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+class deferred_t;
+
+namespace detail {
+
+template <typename T, typename = void>
+struct default_completion_token_impl
+{
+  typedef deferred_t type;
+};
+
+template <typename T>
+struct default_completion_token_impl<T,
+    void_t<typename T::default_completion_token_type>
+  >
+{
+  typedef typename T::default_completion_token_type type;
+};
+
+} // namespace detail
+
+#if defined(GENERATING_DOCUMENTATION)
+
+/// Traits type used to determine the default completion token type associated
+/// with a type (such as an executor).
+/**
+ * A program may specialise this traits type if the @c T template parameter in
+ * the specialisation is a user-defined type.
+ *
+ * Specialisations of this trait may provide a nested typedef @c type, which is
+ * a default-constructible completion token type.
+ *
+ * If not otherwise specialised, the default completion token type is
+ * asio::deferred_t.
+ */
+template <typename T>
+struct default_completion_token
+{
+  /// If @c T has a nested type @c default_completion_token_type,
+  /// <tt>T::default_completion_token_type</tt>. Otherwise the typedef @c type
+  /// is asio::deferred_t.
+  typedef see_below type;
+};
+#else
+template <typename T>
+struct default_completion_token
+  : detail::default_completion_token_impl<T>
+{
+};
+#endif
+
+template <typename T>
+using default_completion_token_t = typename default_completion_token<T>::type;
+
+#define ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(e) \
+  = typename ::asio::default_completion_token<e>::type
+#define ASIO_DEFAULT_COMPLETION_TOKEN(e) \
+  = typename ::asio::default_completion_token<e>::type()
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#include "asio/deferred.hpp"
+
+#endif // ASIO_DEFAULT_COMPLETION_TOKEN_HPP