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

   1 .. Sequences/Intrinsic Metafunctions//is_sequence
   2
   3 is_sequence
   4 ===========
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename X
  13         >
  14     struct is_sequence
  15     {
  16         typedef |unspecified| type;
  17     };
  18
  19
  20
  21 Description
  22 -----------
  23
  24 Returns a boolean |Integral Constant| ``c`` such that ``c::value == true`` if and
  25 only if ``X`` is a model of |Forward Sequence|.
  26
  27
  28 Header
  29 ------
  30
  31 .. parsed-literal::
  32
  33     #include <boost/mpl/is_sequence.hpp>
  34
  35
  36 Parameters
  37 ----------
  38
  39 +---------------+-------------------+-----------------------------------------------+
  40 | Parameter     | Requirement       | Description                                   |
  41 +===============+===================+===============================================+
  42 | ``X``         | Any type          | The type to query.                            |
  43 +---------------+-------------------+-----------------------------------------------+
  44
  45
  46 Expression semantics
  47 --------------------
  48
  49
  50 .. parsed-literal::
  51
  52     typedef is_sequence<X>::type c;
  53
  54 :Return type:
  55     Boolean |Integral Constant|.
  56
  57 :Semantics:
  58     Equivalent to
  59
  60     .. parsed-literal::
  61
  62         typedef not_< is_same< begin<T>::type,void_ > >::type c;
  63
  64
  65
  66 Complexity
  67 ----------
  68
  69 Amortized constant time.
  70
  71
  72 Example
  73 -------
  74
  75 .. parsed-literal::
  76
  77     struct UDT {};
  78
  79     BOOST_MPL_ASSERT_NOT(( is_sequence< std::vector<int> > ));
  80     BOOST_MPL_ASSERT_NOT(( is_sequence< int > ));
  81     BOOST_MPL_ASSERT_NOT(( is_sequence< int& > ));
  82     BOOST_MPL_ASSERT_NOT(( is_sequence< UDT > ));
  83     BOOST_MPL_ASSERT_NOT(( is_sequence< UDT* > ));
  84     BOOST_MPL_ASSERT(( is_sequence< range_c<int,0,0> > ));
  85     BOOST_MPL_ASSERT(( is_sequence< list<> > ));
  86     BOOST_MPL_ASSERT(( is_sequence< list<int> > ));
  87     BOOST_MPL_ASSERT(( is_sequence< vector<> > ));
  88     BOOST_MPL_ASSERT(( is_sequence< vector<int> > ));
  89
  90
  91 See also
  92 --------
  93
  94 |Forward Sequence|, |begin|, |end|, |vector|, |list|, |range_c|
  95
  96
  97 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
  98    Distributed under the Boost Software License, Version 1.0. (See accompanying
  99    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)