Replace boost by the standalone asio library

1 files changed, 1059 insertions, 0 deletions

diff --git a/lib/asio/connect.hpp b/lib/asio/connect.hpp
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+++ b/lib/asio/connect.hpp
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+//
+// connect.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 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_CONNECT_HPP
+#define ASIO_CONNECT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include "asio/async_result.hpp"
+#include "asio/basic_socket.hpp"
+#include "asio/detail/type_traits.hpp"
+#include "asio/error.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+namespace detail
+{
+  char (&has_iterator_helper(...))[2];
+
+  template <typename T>
+  char has_iterator_helper(T*, typename T::iterator* = 0);
+
+  template <typename T>
+  struct has_iterator_typedef
+  {
+    enum { value = (sizeof((has_iterator_helper)((T*)(0))) == 1) };
+  };
+} // namespace detail
+
+/// Type trait used to determine whether a type is an endpoint sequence that can
+/// be used with with @c connect and @c async_connect.
+template <typename T>
+struct is_endpoint_sequence
+{
+#if defined(GENERATING_DOCUMENTATION)
+  /// The value member is true if the type may be used as an endpoint sequence.
+  static const bool value;
+#else
+  enum
+  {
+    value = detail::has_iterator_typedef<T>::value
+  };
+#endif
+};
+
+/**
+ * @defgroup connect asio::connect
+ *
+ * @brief Establishes a socket connection by trying each endpoint in a sequence.
+ */
+/*@{*/
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @returns The successfully connected endpoint.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @par Example
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ * asio::connect(s, r.resolve(q)); @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, the successfully connected endpoint. Otherwise, a
+ * default-constructed endpoint.
+ *
+ * @par Example
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ * asio::error_code ec;
+ * asio::connect(s, r.resolve(q), ec);
+ * if (ec)
+ * {
+ *   // An error occurred.
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, asio::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(ASIO_NO_DEPRECATED)
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s, Iterator begin,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, asio::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @returns An iterator denoting the successfully connected endpoint.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @par Example
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * asio::connect(s, e.begin(), e.end()); @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, Iterator end);
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @par Example
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * asio::error_code ec;
+ * asio::connect(s, e.begin(), e.end(), ec);
+ * if (ec)
+ * {
+ *   // An error occurred.
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, Iterator end, asio::error_code& ec);
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @returns The successfully connected endpoint.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ * tcp::endpoint e = asio::connect(s,
+ *     r.resolve(q), my_connect_condition());
+ * std::cout << "Connected to: " << e << std::endl; @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, the successfully connected endpoint. Otherwise, a
+ * default-constructed endpoint.
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ * asio::error_code ec;
+ * tcp::endpoint e = asio::connect(s,
+ *     r.resolve(q), my_connect_condition(), ec);
+ * if (ec)
+ * {
+ *   // An error occurred.
+ * }
+ * else
+ * {
+ *   std::cout << "Connected to: " << e << std::endl;
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    asio::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(ASIO_NO_DEPRECATED)
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, ConnectCondition connect_condition,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s, Iterator begin,
+    ConnectCondition connect_condition, asio::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @returns An iterator denoting the successfully connected endpoint.
+ *
+ * @throws asio::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * tcp::resolver::results_type::iterator i = asio::connect(
+ *     s, e.begin(), e.end(), my_connect_condition());
+ * std::cout << "Connected to: " << i->endpoint() << std::endl; @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s, Iterator begin,
+    Iterator end, ConnectCondition connect_condition);
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * asio::error_code ec;
+ * tcp::resolver::results_type::iterator i = asio::connect(
+ *     s, e.begin(), e.end(), my_connect_condition());
+ * if (ec)
+ * {
+ *   // An error occurred.
+ * }
+ * else
+ * {
+ *   std::cout << "Connected to: " << i->endpoint() << std::endl;
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition>
+Iterator connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, Iterator end, ConnectCondition connect_condition,
+    asio::error_code& ec);
+
+/*@}*/
+
+/**
+ * @defgroup async_connect asio::async_connect
+ *
+ * @brief Asynchronously establishes a socket connection by trying each
+ * endpoint in a sequence.
+ */
+/*@{*/
+
+/// Asynchronously establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, the successfully connected endpoint.
+ *   // Otherwise, a default-constructed endpoint.
+ *   const typename Protocol::endpoint& endpoint
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @par Example
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ *
+ * // ...
+ *
+ * r.async_resolve(q, resolve_handler);
+ *
+ * // ...
+ *
+ * void resolve_handler(
+ *     const asio::error_code& ec,
+ *     tcp::resolver::results_type results)
+ * {
+ *   if (!ec)
+ *   {
+ *     asio::async_connect(s, results, connect_handler);
+ *   }
+ * }
+ *
+ * // ...
+ *
+ * void connect_handler(
+ *     const asio::error_code& ec,
+ *     const tcp::endpoint& endpoint)
+ * {
+ *   // ...
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename RangeConnectHandler>
+ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (asio::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(ASIO_NO_DEPRECATED)
+/// (Deprecated.) Asynchronously establishes a socket connection by trying each
+/// endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
+    void (asio::error_code, Iterator))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+/// Asynchronously establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @par Example
+ * @code std::vector<tcp::endpoint> endpoints = ...;
+ * tcp::socket s(io_context);
+ * asio::async_connect(s,
+ *     endpoints.begin(), endpoints.end(),
+ *     connect_handler);
+ *
+ * // ...
+ *
+ * void connect_handler(
+ *     const asio::error_code& ec,
+ *     std::vector<tcp::endpoint>::iterator i)
+ * {
+ *   // ...
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
+    void (asio::error_code, Iterator))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, Iterator end,
+    ASIO_MOVE_ARG(IteratorConnectHandler) handler);
+
+/// Asynchronously establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param endpoints A sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ *
+ * // ...
+ *
+ * r.async_resolve(q, resolve_handler);
+ *
+ * // ...
+ *
+ * void resolve_handler(
+ *     const asio::error_code& ec,
+ *     tcp::resolver::results_type results)
+ * {
+ *   if (!ec)
+ *   {
+ *     asio::async_connect(s, results,
+ *         my_connect_condition(),
+ *         connect_handler);
+ *   }
+ * }
+ *
+ * // ...
+ *
+ * void connect_handler(
+ *     const asio::error_code& ec,
+ *     const tcp::endpoint& endpoint)
+ * {
+ *   if (ec)
+ *   {
+ *     // An error occurred.
+ *   }
+ *   else
+ *   {
+ *     std::cout << "Connected to: " << endpoint << std::endl;
+ *   }
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename EndpointSequence,
+    typename ConnectCondition, typename RangeConnectHandler>
+ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (asio::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(ASIO_NO_DEPRECATED)
+/// (Deprecated.) Asynchronously establishes a socket connection by trying each
+/// endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
+    void (asio::error_code, Iterator))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s, Iterator begin,
+    ConnectCondition connect_condition,
+    ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+/// Asynchronously establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const asio::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const asio::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * asio::io_context::post().
+ *
+ * @par Example
+ * The following connect condition function object can be used to output
+ * information about the individual connection attempts:
+ * @code struct my_connect_condition
+ * {
+ *   bool operator()(
+ *       const asio::error_code& ec,
+ *       const::tcp::endpoint& next)
+ *   {
+ *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
+ *   }
+ * }; @endcode
+ * It would be used with the asio::connect function as follows:
+ * @code tcp::resolver r(io_context);
+ * tcp::resolver::query q("host", "service");
+ * tcp::socket s(io_context);
+ *
+ * // ...
+ *
+ * r.async_resolve(q, resolve_handler);
+ *
+ * // ...
+ *
+ * void resolve_handler(
+ *     const asio::error_code& ec,
+ *     tcp::resolver::iterator i)
+ * {
+ *   if (!ec)
+ *   {
+ *     tcp::resolver::iterator end;
+ *     asio::async_connect(s, i, end,
+ *         my_connect_condition(),
+ *         connect_handler);
+ *   }
+ * }
+ *
+ * // ...
+ *
+ * void connect_handler(
+ *     const asio::error_code& ec,
+ *     tcp::resolver::iterator i)
+ * {
+ *   if (ec)
+ *   {
+ *     // An error occurred.
+ *   }
+ *   else
+ *   {
+ *     std::cout << "Connected to: " << i->endpoint() << std::endl;
+ *   }
+ * } @endcode
+ */
+template <typename Protocol ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
+    void (asio::error_code, Iterator))
+async_connect(basic_socket<Protocol ASIO_SVC_TARG>& s,
+    Iterator begin, Iterator end, ConnectCondition connect_condition,
+    ASIO_MOVE_ARG(IteratorConnectHandler) handler);
+
+/*@}*/
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#include "asio/impl/connect.hpp"
+
+#endif