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

   1 .. Algorithms/Querying Algorithms//count |40
   2
   3 count
   4 =====
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename Sequence
  13         , typename T
  14         >
  15     struct count
  16     {
  17         typedef |unspecified| type;
  18     };
  19
  20
  21
  22 Description
  23 -----------
  24
  25 Returns the number of elements in a ``Sequence`` that are identical to ``T``.
  26
  27
  28 Header
  29 ------
  30
  31 .. parsed-literal::
  32
  33     #include <boost/mpl/count.hpp>
  34
  35
  36 Parameters
  37 ----------
  38
  39 +---------------+---------------------------+-----------------------------------+
  40 | Parameter     | Requirement               | Description                       |
  41 +===============+===========================+===================================+
  42 | ``Sequence``  | |Forward Sequence|        | A sequence to be examined.        |
  43 +---------------+---------------------------+-----------------------------------+
  44 | ``T``         | Any type                  | A type to search for.             |
  45 +---------------+---------------------------+-----------------------------------+
  46
  47
  48 Expression semantics
  49 --------------------
  50
  51
  52 For any |Forward Sequence| ``s`` and arbitrary type ``t``:
  53
  54
  55 .. parsed-literal::
  56
  57     typedef count<s,t>::type n;
  58
  59 :Return type:
  60     |Integral Constant|.
  61
  62 :Semantics:
  63     Equivalent to
  64
  65     .. parsed-literal::
  66
  67         typedef count_if< s,is_same<_,T> >::type n;
  68
  69
  70 Complexity
  71 ----------
  72
  73 Linear. Exactly ``size<s>::value`` comparisons for identity.
  74
  75
  76 Example
  77 -------
  78
  79 .. parsed-literal::
  80
  81     typedef vector<int,char,long,short,char,short,double,long> types;
  82     typedef count<types, short>::type n;
  83
  84     BOOST_MPL_ASSERT_RELATION( n::value, ==, 2 );
  85
  86
  87 See also
  88 --------
  89
  90 |Querying Algorithms|, |count_if|, |find|, |find_if|, |contains|, |lower_bound|
  91
  92
  93 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
  94    Distributed under the Boost Software License, Version 1.0. (See accompanying
  95    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)