Squashed 'OpenVPN Adapter/Vendors/asio/' content from commit 524288c

git-subtree-dir: OpenVPN Adapter/Vendors/asio
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asio/src/doc/requirements/ShutdownHandler.qbk

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+[/
+ / Copyright (c) 2003-2016 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)
+ /]
+
+[section:ShutdownHandler SSL shutdown handler requirements]
+
+A shutdown handler must meet the requirements for a [link
+asio.reference.Handler handler]. A value `h` of a shutdown handler
+class should work correctly in the expression `h(ec)`, where `ec` is an lvalue
+of type `const error_code`.
+
+[heading Examples]
+
+A free function as a shutdown handler:
+
+  void shutdown_handler(
+      const asio::error_code& ec)
+  {
+    ...
+  }
+
+A shutdown handler function object:
+
+  struct shutdown_handler
+  {
+    ...
+    void operator()(
+        const asio::error_code& ec)
+    {
+      ...
+    }
+    ...
+  };
+
+A lambda as a shutdown handler:
+
+  ssl_stream.async_shutdown(...,
+      [](const asio::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a shutdown handler using
+`std::bind()`:
+
+  void my_class::shutdown_handler(
+      const asio::error_code& ec)
+  {
+    ...
+  }
+  ...
+  ssl_stream.async_shutdown(
+      std::bind(&my_class::shutdown_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to a shutdown handler using
+`boost::bind()`:
+
+  void my_class::shutdown_handler(
+      const asio::error_code& ec)
+  {
+    ...
+  }
+  ...
+  ssl_stream.async_shutdown(
+      boost::bind(&my_class::shutdown_handler,
+        this, asio::placeholders::error));
+
+[endsect]