[/
 / 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:SignalSetService Signal set service requirements]

A signal set service must meet the requirements for an [link
boost_asio.reference.IoObjectService I/O object service], as well as the
additional requirements listed below.

In the table below, `X` denotes a signal set service class, `a` denotes a value
of type `X`, `b` denotes a value of type `X::implementation_type`, `ec` denotes
a value of type `error_code`, `n` denotes a value of type `int`, and `sh`
denotes a value meeting [link boost_asio.reference.SignalHandler `SignalHandler`]
requirements.

[table SignalSetService requirements
  [[expression] [return type] [assertion/note\npre/post-condition]]
  [
    [`a.construct(b);`]
    []
    [
      From [link boost_asio.reference.IoObjectService IoObjectService]
      requirements.\n
    ]
  ]
  [
    [`a.destroy(b);`]
    []
    [
      From [link boost_asio.reference.IoObjectService IoObjectService]
      requirements. Implicitly clears the registered signals as if by calling
      `a.clear(b, ec)`, then implicitly cancels outstanding asynchronous
      operations as if by calling `a.cancel(b, ec)`.
    ]
  ]
  [
    [``
      a.add(b, n, ec);
    ``]
    [`error_code`]
    [
    ]
  ]
  [
    [``
      a.remove(b, n, ec);
    ``]
    [`error_code`]
    [
    ]
  ]
  [
    [``
      a.clear(b, ec);
    ``]
    [`error_code`]
    [
    ]
  ]
  [
    [``
      a.cancel(b, ec);
    ``]
    [`error_code`]
    [
    ]
  ]
  [
    [`a.async_wait(b, sh);`]
    [`void`]
    [
      pre: `a.is_open(b)`.\n
      \n
      Initiates an asynchronous operation to wait for the delivery of one of the
      signals registered for the signal set `b`. The operation is performed via
      the `io_service` object `a.get_io_service()` and behaves according to
      [link boost_asio.reference.asynchronous_operations asynchronous operation]
      requirements.\n
      \n
      If the operation completes successfully, the `SignalHandler` object
      `sh` is invoked with the number identifying the delivered signal. Otherwise
      it is invoked with `0`.
    ]
  ]
]

[endsect]