ceph/src/boost/libs/mpl/doc/src/refmanual/empty_sequence.rst

   1 .. Sequences/Views//empty_sequence
   2
   3 empty_sequence
   4 ==============
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     struct empty_sequence
  12     {
  13         // |unspecified|
  14         // |...|
  15     };
  16
  17
  18 Description
  19 -----------
  20
  21 Represents a sequence containing no elements.
  22
  23
  24 Header
  25 ------
  26
  27 .. parsed-literal::
  28
  29     #include <boost/mpl/empty_sequence.hpp>
  30
  31
  32 Expression semantics
  33 --------------------
  34
  35 |Semantics disclaimer...| |Random Access Sequence|.
  36
  37 In the following table, ``s`` is an instance of ``empty_sequence``.
  38
  39 +-------------------------------+-----------------------------------------------------------+
  40 | Expression                    | Semantics                                                 |
  41 +===============================+===========================================================+
  42 | ``empty_sequence``            | An empty |Random Access Sequence|.                        |
  43 +-------------------------------+-----------------------------------------------------------+
  44 | ``size<s>::type``             | ``size<s>::value == 0``; see |Random Access Sequence|.    |
  45 +-------------------------------+-----------------------------------------------------------+
  46
  47
  48 Example
  49 -------
  50
  51 .. parsed-literal::
  52
  53     typedef begin<empty_sequence>::type first;
  54     typedef end<empty_sequence>::type last;
  55
  56     BOOST_MPL_ASSERT(( is_same<first,last> ));
  57     BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 );
  58
  59     typedef transform_view<
  60           empty_sequence
  61         , add_pointer<_>
  62         > empty_view;
  63
  64     BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 );
  65
  66
  67 See also
  68 --------
  69
  70 |Sequences|, |Views|, |vector|, |list|, |single_view|
  71
  72
  73 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
  74    Distributed under the Boost Software License, Version 1.0. (See accompanying
  75    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)