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

   1 .. Algorithms/Transformation Algorithms//stable_partition |90
   2
   3 stable_partition
   4 ================
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename Seq
  13         , typename Pred
  14         , typename In1 = |unspecified|
  15         , typename In2 = |unspecified|
  16         >
  17     struct stable_partition
  18     {
  19         typedef |unspecified| type;
  20     };
  21
  22
  23 Description
  24 -----------
  25
  26 Returns a pair of sequences together containing all elements in the range
  27 |begin/end<Seq>| split into two groups based on the predicate ``Pred``.
  28 ``stable_partition`` is guaranteed to preserve the relative order of the
  29 elements in the resulting sequences.
  30
  31
  32 |transformation algorithm disclaimer|
  33
  34
  35 Header
  36 ------
  37
  38 .. parsed-literal::
  39
  40     #include <boost/mpl/stable_partition.hpp>
  41
  42
  43 Model of
  44 --------
  45
  46 |Reversible Algorithm|
  47
  48
  49 Parameters
  50 ----------
  51
  52 +-------------------+-----------------------------------+-------------------------------+
  53 | Parameter         | Requirement                       | Description                   |
  54 +===================+===================================+===============================+
  55 | ``Seq``           | |Forward Sequence|                | An original sequence.         |
  56 +-------------------+-----------------------------------+-------------------------------+
  57 | ``Pred``          | Unary |Lambda Expression|         | A partitioning predicate.     |
  58 +-------------------+-----------------------------------+-------------------------------+
  59 | ``In1``, ``In2``  | |Inserter|                        | Output inserters.             |
  60 +-------------------+-----------------------------------+-------------------------------+
  61
  62
  63 Expression semantics
  64 --------------------
  65
  66 |Semantics disclaimer...| |Reversible Algorithm|.
  67
  68 For any |Forward Sequence| ``s``, an unary |Lambda Expression| ``pred``, and |Inserter|\ s
  69 ``in1`` and ``in2``:
  70
  71
  72 .. parsed-literal::
  73
  74     typedef stable_partition<s,pred,in1,in2>::type r;
  75
  76 :Return type:
  77     A |pair|.
  78
  79 :Semantics:
  80     Equivalent to
  81
  82     .. parsed-literal::
  83
  84         typedef lambda<pred>::type p;
  85         typedef lambda<in1::operation>::type in1_op;
  86         typedef lambda<in2::operation>::type in2_op;
  87
  88         typedef fold<
  89               s
  90             , pair< in1::state, in2::state >
  91             , if_<
  92                   apply_wrap\ ``1``\<p,_2>
  93                 , pair< apply_wrap\ ``2``\<in1_op,first<_1>,_2>, second<_1> >
  94                 , pair< first<_1>, apply_wrap\ ``2``\<in2_op,second<_1>,_2> >
  95                 >
  96             >::type r;
  97
  98
  99 Complexity
 100 ----------
 101
 102 Linear. Exactly ``size<s>::value`` applications of ``pred``, and ``size<s>::value``
 103 of summarized ``in1::operation`` / ``in2::operation`` applications.
 104
 105
 106 Example
 107 -------
 108
 109 .. parsed-literal::
 110
 111     template< typename N > struct is_odd : bool_<(N::value % 2)> {};
 112
 113     typedef stable_partition<
 114           range_c<int,0,10>
 115         , is_odd<_1>
 116         , back_inserter< vector<> >
 117         , back_inserter< vector<> >
 118         >::type r;
 119
 120     BOOST_MPL_ASSERT(( equal< r::first, vector_c<int,1,3,5,7,9> > ));
 121     BOOST_MPL_ASSERT(( equal< r::second, vector_c<int,0,2,4,6,8> > ));
 122
 123
 124 See also
 125 --------
 126
 127 |Transformation Algorithms|, |Reversible Algorithm|, |reverse_stable_partition|, |partition|, |sort|, |transform|
 128
 129
 130 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 131    Distributed under the Boost Software License, Version 1.0. (See accompanying
 132    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)