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

   1 .. Metafunctions/Comparisons//equal_to |50
   2
   3 equal_to
   4 ========
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename T1
  13         , typename T2
  14         >
  15     struct equal_to
  16     {
  17         typedef |unspecified| type;
  18     };
  19
  20
  21
  22 Description
  23 -----------
  24
  25 Returns a true-valued |Integral Constant| if ``T1`` and ``T2`` are equal.
  26
  27
  28 Header
  29 ------
  30
  31 .. parsed-literal::
  32
  33     #include <boost/mpl/equal_to.hpp>
  34     #include <boost/mpl/comparison.hpp>
  35
  36
  37 Model of
  38 --------
  39
  40 |Numeric Metafunction|
  41
  42
  43 Parameters
  44 ----------
  45
  46 +---------------+---------------------------+-----------------------------------------------+
  47 | Parameter     | Requirement               | Description                                   |
  48 +===============+===========================+===============================================+
  49 | ``T1``, ``T2``| |Integral Constant|       | Operation's arguments.                        |
  50 +---------------+---------------------------+-----------------------------------------------+
  51
  52 |Note:| |numeric metafunction note| |-- end note|
  53
  54
  55 Expression semantics
  56 --------------------
  57
  58
  59 For any |Integral Constant|\ s ``c1`` and ``c2``:
  60
  61 .. parsed-literal::
  62
  63     typedef equal_to<c1,c2>::type r;
  64
  65 :Return type:
  66     |Integral Constant|.
  67
  68 :Semantics:
  69     Equivalent to
  70
  71     .. parsed-literal::
  72
  73         typedef bool_< (c1::value == c2::value) > r;
  74
  75
  76 .. ..........................................................................
  77
  78 .. parsed-literal::
  79
  80     typedef equal_to<c1,c2> r;
  81
  82 :Return type:
  83     |Integral Constant|.
  84
  85 :Semantics:
  86     Equivalent to
  87
  88     .. parsed-literal::
  89
  90         struct r : equal_to<c1,c2>::type {};
  91
  92
  93
  94 Complexity
  95 ----------
  96
  97 Amortized constant time.
  98
  99
 100 Example
 101 -------
 102
 103 .. parsed-literal::
 104
 105     BOOST_MPL_ASSERT_NOT(( equal_to< int_<0>, int_<10> > ));
 106     BOOST_MPL_ASSERT_NOT(( equal_to< long_<10>, int_<0> > ));
 107     BOOST_MPL_ASSERT(( equal_to< long_<10>, int_<10> > ));
 108
 109
 110 See also
 111 --------
 112
 113 |Comparisons|, |Numeric Metafunction|, |numeric_cast|, |not_equal_to|, |less|
 114
 115
 116 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 117    Distributed under the Boost Software License, Version 1.0. (See accompanying
 118    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)