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

   1 .. Algorithms/Transformation Algorithms//replace_if |50
   2
   3 replace_if
   4 ==========
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename Sequence
  13         , typename Pred
  14         , typename NewType
  15         , typename In = |unspecified|
  16         >
  17     struct replace_if
  18     {
  19         typedef |unspecified| type;
  20     };
  21
  22
  23
  24 Description
  25 -----------
  26
  27 Returns a copy of the original sequence where every type that satisfies
  28 the predicate ``Pred`` has been replaced with ``NewType``.
  29
  30 |transformation algorithm disclaimer|
  31
  32 Header
  33 ------
  34
  35 .. parsed-literal::
  36
  37     #include <boost/mpl/replace_if.hpp>
  38
  39
  40
  41 Model of
  42 --------
  43
  44 |Reversible Algorithm|
  45
  46
  47 Parameters
  48 ----------
  49
  50 +---------------+-----------------------------------+-------------------------------+
  51 | Parameter     | Requirement                       | Description                   |
  52 +===============+===================================+===============================+
  53 | ``Sequence``  | |Forward Sequence|                | An original sequence.         |
  54 +---------------+-----------------------------------+-------------------------------+
  55 | ``Pred``      | Unary |Lambda Expression|         | A replacement condition.      |
  56 +---------------+-----------------------------------+-------------------------------+
  57 | ``NewType``   | Any type                          | A type to replace with.       |
  58 +---------------+-----------------------------------+-------------------------------+
  59 | ``In``        | |Inserter|                        | An inserter.                  |
  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``,
  69 an |Inserter| ``in``, and arbitrary type ``x``:
  70
  71
  72 .. parsed-literal::
  73
  74     typedef replace_if<s,pred,x,in>::type r;
  75
  76 :Return type:
  77     A type.
  78
  79 :Semantics:
  80     Equivalent to
  81
  82     .. parsed-literal::
  83
  84         typedef lambda<pred>::type p;
  85         typedef transform< s, if_< apply_wrap1<p,_1>,x,_1>, in >::type r;
  86
  87
  88 Complexity
  89 ----------
  90
  91 Linear. Performs exactly ``size<s>::value`` applications of ``pred``, and at most
  92 ``size<s>::value`` insertions.
  93
  94
  95 Example
  96 -------
  97
  98 .. parsed-literal::
  99
 100     typedef vector_c<int,1,4,5,2,7,5,3,5> numbers;
 101     typedef vector_c<int,1,4,0,2,0,0,3,0> expected;
 102     typedef replace_if< numbers, greater<_,int_<4> >, int_<0> >::type result;
 103
 104     BOOST_MPL_ASSERT(( equal< result,expected, equal_to<_,_> > ));
 105
 106
 107 See also
 108 --------
 109
 110 |Transformation Algorithms|, |Reversible Algorithm|, |reverse_replace_if|, |replace|, |remove_if|, |transform|
 111
 112
 113 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 114    Distributed under the Boost Software License, Version 1.0. (See accompanying
 115    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)