added asio

include/asio/redirect_disposition.hpp

@@ -0,0 +1,115 @@
+//
+// redirect_disposition.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_REDIRECT_DISPOSITION_HPP
+#define ASIO_REDIRECT_DISPOSITION_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/disposition.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+/// A @ref completion_token adapter used to specify that the disposition
+/// produced by an asynchronous operation is captured to a variable.
+/**
+ * The redirect_disposition_t class is used to indicate that any disposition
+ * produced by an asynchronous operation is captured to a specified variable.
+ */
+template <typename CompletionToken, ASIO_DISPOSITION Disposition>
+class redirect_disposition_t
+{
+public:
+  /// Constructor.
+  template <typename T>
+  redirect_disposition_t(T&& completion_token, Disposition& d)
+    : token_(static_cast<T&&>(completion_token)),
+      d_(d)
+  {
+  }
+
+//private:
+  CompletionToken token_;
+  Disposition& d_;
+};
+
+/// A function object type that adapts a @ref completion_token to capture
+/// any disposition produced by an asynchronous operation to a variable.
+/**
+ * May also be used directly as a completion token, in which case it adapts the
+ * asynchronous operation's default completion token (or asio::deferred
+ * if no default is available).
+ */
+template <ASIO_DISPOSITION Disposition>
+class partial_redirect_disposition
+{
+public:
+  /// Constructor that specifies the variable used to capture disposition
+  /// values.
+  explicit partial_redirect_disposition(Disposition& d)
+    : d_(d)
+  {
+  }
+
+  /// Adapt a @ref completion_token to specify that the completion handler
+  /// should capture disposition values to a variable.
+  template <typename CompletionToken>
+  ASIO_NODISCARD inline
+  constexpr redirect_disposition_t<decay_t<CompletionToken>, Disposition>
+  operator()(CompletionToken&& completion_token) const
+  {
+    return redirect_disposition_t<decay_t<CompletionToken>, Disposition>(
+        static_cast<CompletionToken&&>(completion_token), d_);
+  }
+
+//private:
+  Disposition& d_;
+};
+
+/// Create a partial completion token adapter that captures disposition values
+/// to a variable.
+/**
+ * @note When redirecting to a variable of type @c std::exception_ptr, other
+ * disposition types will be automatically converted to @c std::exception_ptr.
+ */
+template <ASIO_DISPOSITION Disposition>
+ASIO_NODISCARD inline partial_redirect_disposition<Disposition>
+redirect_disposition(Disposition& d)
+{
+  return partial_redirect_disposition<Disposition>(d);
+}
+
+/// Adapt a @ref completion_token to capture disposition values to a variable.
+/**
+ * @note When redirecting to a variable of type @c std::exception_ptr, other
+ * disposition types will be automatically converted to @c std::exception_ptr.
+ */
+template <typename CompletionToken, ASIO_DISPOSITION Disposition>
+ASIO_NODISCARD inline
+redirect_disposition_t<decay_t<CompletionToken>, Disposition>
+redirect_disposition(CompletionToken&& completion_token, Disposition& d)
+{
+  return redirect_disposition_t<decay_t<CompletionToken>, Disposition>(
+      static_cast<CompletionToken&&>(completion_token), d);
+}
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#include "asio/impl/redirect_disposition.hpp"
+
+#endif // ASIO_REDIRECT_DISPOSITION_HPP