/*
  Copyright(c) 2015 - 2018 Denis Blank <denis.blank at outlook dot com>

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files(the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions :

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/

namespace cti {
/** \page tutorial-chaining-continuables Chaining continuables
\brief Explains how to chain multiple \ref continuable_base objects together.

\tableofcontents

\section tutorial-chaining-continuables-then Using then and results

A \ref continuable_base provides various methods to continue the asynchronous
call hierarchy. The most important method therefor is
\ref continuable_base::then which changes the object through attaching a
result handler:

\code{.cpp}
http_request("github.com")
  .then([] (std::string result) {
    // Do something...
  });
\endcode

A new \ref continuable_base is created which result depends on the return type
of the handler. For instance it is possible to return plain values or the next
\ref continuable_base to continue the call hierarchy.
See \ref continuable_base::then for details.

\code{.cpp}
mysql_query("SELECT `id`, `name` FROM `users`")
  .then([](ResultSet users) {
    // Return the next continuable to process ...
    return mysql_query("SELECT `id` name FROM `sessions`");
  })
  .then([](ResultSet sessions) {
    // ... or pass multiple values to the next callback using tuples or pairs ...
    return std::make_tuple(std::move(sessions), true);
  })
  .then([](ResultSet sessions, bool is_ok) {
    // ... or pass a single value to the next callback ...
    return 10;
  })
  .then([](auto value) {
    //     ^^^^ Templated callbacks are possible too
  })
  // ... you may even pass continuables to the `then` method directly:
  .then(mysql_query("SELECT * `statistics`"))
  .then([](ResultSet result) {
    // ...
  });
\endcode

\section tutorial-chaining-continuables-fail Using fail and errors

\code{.cpp}
http_request("github.com")
  .then([] (std::string result) {
    // Is never called
  })
  .fail([] (std::exception_ptr ptr) {
    try {
      std::rethrow_exception(ptr);
    } catch(std::exception const& e) {
      // Handle the exception or error code here
    }
  });
\endcode

\section tutorial-chaining-continuables-next Using next for everything


The \ref cti::continuable_base \ref cti::when_any \ref cti::promisify

- Continue the continuation using `.then(...)` and `.fail(...)`, exceptions are passed to the first available handler:

  \endcode

- Create connections between the continuables and use its compound result:
  \code{.cpp}
  (http_request("github.com") && (http_request("travis-ci.org") || http_request("atom.io")))
    .then([](std::string github, std::string travis_or_atom) {
      // The promise is called with the response of github and travis or atom.
    });
  \endcode
*/
}