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

   1 .. Metafunctions/Bitwise Operations//shift_right
   2
   3 shift_right
   4 ===========
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename T
  13         , typename Shift
  14         >
  15     struct shift_right
  16     {
  17         typedef |unspecified| type;
  18     };
  19
  20
  21
  22 Description
  23 -----------
  24
  25 Returns the result of bitwise *shift right* (``>>``) operation on ``T``.
  26
  27
  28 Header
  29 ------
  30
  31 .. parsed-literal::
  32
  33     #include <boost/mpl/shift_right.hpp>
  34     #include <boost/mpl/bitwise.hpp>
  35
  36
  37 Model of
  38 --------
  39
  40 |Numeric Metafunction|
  41
  42
  43 Parameters
  44 ----------
  45
  46 +---------------+-------------------------------+---------------------------+
  47 | Parameter     | Requirement                   | Description               |
  48 +===============+===============================+===========================+
  49 | ``T``         | |Integral Constant|           | A value to shift.         |
  50 +---------------+-------------------------------+---------------------------+
  51 | ``Shift``     | Unsigned |Integral Constant|  | A shift distance.         |
  52 +---------------+-------------------------------+---------------------------+
  53
  54 |Note:| |numeric metafunction note| |-- end note|
  55
  56
  57 Expression semantics
  58 --------------------
  59
  60 For arbitrary |Integral Constant| ``c`` and unsigned |Integral Constant| ``shift``:
  61
  62
  63 .. parsed-literal::
  64
  65     typedef shift_right<c,shift>::type r;
  66
  67 :Return type:
  68     |Integral Constant|.
  69
  70 :Semantics:
  71     Equivalent to
  72
  73     .. parsed-literal::
  74
  75         typedef integral_c<
  76               c::value_type
  77             , ( c::value >> shift::value )
  78             > r;
  79
  80 .. ..........................................................................
  81
  82 .. parsed-literal::
  83
  84     typedef shift_right<c,shift> r;
  85
  86 :Return type:
  87     |Integral Constant|.
  88
  89 :Semantics:
  90     Equivalent to
  91
  92     .. parsed-literal::
  93
  94         struct r : shift_right<c,shift>::type {};
  95
  96
  97 Complexity
  98 ----------
  99
 100 Amortized constant time.
 101
 102
 103 Example
 104 -------
 105
 106 .. parsed-literal::
 107
 108     typedef integral_c<unsigned,0> u0;
 109     typedef integral_c<unsigned,1> u1;
 110     typedef integral_c<unsigned,2> u2;
 111     typedef integral_c<unsigned,8> u8;
 112
 113     BOOST_MPL_ASSERT_RELATION( (shift_right<u0,u0>::value), ==, 0 );
 114     BOOST_MPL_ASSERT_RELATION( (shift_right<u1,u0>::value), ==, 1 );
 115     BOOST_MPL_ASSERT_RELATION( (shift_right<u1,u1>::value), ==, 0 );
 116     BOOST_MPL_ASSERT_RELATION( (shift_right<u2,u1>::value), ==, 1 );
 117     BOOST_MPL_ASSERT_RELATION( (shift_right<u8,u1>::value), ==, 4 );
 118
 119
 120 See also
 121 --------
 122
 123 |Bitwise Operations|, |Numeric Metafunction|, |numeric_cast|, |shift_left|, |bitand_|
 124
 125
 126 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 127    Distributed under the Boost Software License, Version 1.0. (See accompanying
 128    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)