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

   1 .. Algorithms/Runtime Algorithms//for_each |10
   2
   3 for_each
   4 ========
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename Sequence
  13         , typename F
  14         >
  15     void for_each( F f );
  16
  17     template<
  18           typename Sequence
  19         , typename TransformOp
  20         , typename F
  21         >
  22     void for_each( F f );
  23
  24
  25 Description
  26 -----------
  27
  28 ``for_each`` is a family of overloaded function templates:
  29
  30 * ``for_each<Sequence>( f )`` applies the runtime function object
  31   ``f`` to every element in the |begin/end<Sequence>| range.
  32
  33 * ``for_each<Sequence,TransformOp>( f )`` applies the runtime function
  34   object ``f`` to the result of the transformation ``TransformOp`` of
  35   every element in the |begin/end<Sequence>| range.
  36
  37
  38 Header
  39 ------
  40
  41 .. parsed-literal::
  42
  43     #include <boost/mpl/for_each.hpp>
  44
  45
  46 Parameters
  47 ----------
  48
  49 +-------------------+-----------------------------------+-----------------------------------+
  50 | Parameter         | Requirement                       | Description                       |
  51 +===================+===================================+===================================+
  52 | ``Sequence``      | |Forward Sequence|                | A sequence to iterate.            |
  53 +-------------------+-----------------------------------+-----------------------------------+
  54 | ``TransformOp``   | |Lambda Expression|               | A transformation.                 |
  55 +-------------------+-----------------------------------+-----------------------------------+
  56 | ``f``             | An |unary function object|        | A runtime operation to apply.     |
  57 +-------------------+-----------------------------------+-----------------------------------+
  58
  59
  60 Expression semantics
  61 --------------------
  62
  63 For any |Forward Sequence| ``s``, |Lambda Expression| ``op`` , and an
  64 |unary function object| ``f``:
  65
  66 .. parsed-literal::
  67
  68     for_each<s>( f );
  69
  70 :Return type:
  71     ``void``
  72
  73 :Postcondition:
  74     Equivalent to
  75
  76     .. parsed-literal::
  77
  78         typedef begin<Sequence>::type i\ :sub:`1`;
  79         |value_initialized|\ < deref<i\ :sub:`1`>::type > x\ :sub:`1`;
  80         f(boost::get(x\ :sub:`1`));
  81
  82         typedef next<i\ :sub:`1`>::type i\ :sub:`2`;
  83         |value_initialized|\ < deref<i\ :sub:`2`>::type > x\ :sub:`2`;
  84         f(boost::get(x\ :sub:`2`));
  85         |...|
  86         |value_initialized|\ < deref<i\ :sub:`n`>::type > x\ :sub:`n`;
  87         f(boost::get(x\ :sub:`n`));
  88         typedef next<i\ :sub:`n`>::type last;
  89
  90     where ``n == size<s>::value`` and ``last`` is identical to
  91     ``end<s>::type``; no effect if ``empty<s>::value == true``.
  92
  93
  94 .. parsed-literal::
  95
  96     for_each<s,op>( f );
  97
  98 :Return type:
  99     ``void``
 100
 101 :Postcondition:
 102     Equivalent to
 103
 104     .. parsed-literal::
 105
 106         for_each< transform_view<s,op> >( f );
 107
 108
 109 Complexity
 110 ----------
 111
 112 Linear. Exactly ``size<s>::value`` applications of ``op`` and ``f``.
 113
 114
 115 Example
 116 -------
 117
 118 .. parsed-literal::
 119
 120     struct value_printer
 121     {
 122         template< typename U > void operator()(U x)
 123         {
 124             std::cout << x << '\\n';
 125         }
 126     };
 127
 128     int main()
 129     {
 130         for_each< range_c<int,0,10> >( value_printer() );
 131     }
 132
 133
 134 See also
 135 --------
 136
 137 |Runtime Algorithms|, |Views|, |transform_view|
 138
 139 .. |unary function object| replace:: `unary function object <http://www.sgi.com/tech/stl/UnaryFunction.html>`__
 140 .. |value_initialized| replace:: `value_initialized <http://www.boost.org/libs/utility/value_init.htm>`__
 141
 142
 143 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 144    Distributed under the Boost Software License, Version 1.0. (See accompanying
 145    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)