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

   1 .. Sequences/Intrinsic Metafunctions//erase
   2
   3 erase
   4 =====
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename Sequence
  13         , typename First
  14         , typename Last = |unspecified|
  15         >
  16     struct erase
  17     {
  18         typedef |unspecified| type;
  19     };
  20
  21
  22
  23 Description
  24 -----------
  25
  26 ``erase`` performs a removal of one or more adjacent elements in the sequence
  27 starting from an arbitrary position.
  28
  29 Header
  30 ------
  31
  32 .. parsed-literal::
  33
  34     #include <boost/mpl/erase.hpp>
  35
  36
  37 Model of
  38 --------
  39
  40 |Tag Dispatched Metafunction|
  41
  42
  43 Parameters
  44 ----------
  45
  46 +---------------+-----------------------------------+-----------------------------------------------+
  47 | Parameter     | Requirement                       | Description                                   |
  48 +===============+===================================+===============================================+
  49 | ``Sequence``  | |Extensible Sequence| or          | A sequence to erase from.                     |
  50 |               | |Extensible Associative Sequence| |                                               |
  51 +---------------+-----------------------------------+-----------------------------------------------+
  52 | ``First``     | |Forward Iterator|                | An iterator to the beginning of the range to  |
  53 |               |                                   | be erased.                                    |
  54 +---------------+-----------------------------------+-----------------------------------------------+
  55 | ``Last``      | |Forward Iterator|                | An iterator past-the-end of the range to be   |
  56 |               |                                   | erased.                                       |
  57 +---------------+-----------------------------------+-----------------------------------------------+
  58
  59
  60 Expression semantics
  61 --------------------
  62
  63 .. compound::
  64     :class: expression-semantics
  65
  66     For any |Extensible Sequence| ``s``, and iterators ``pos``, ``first`` and ``last`` into ``s``:
  67
  68
  69     .. parsed-literal::
  70
  71         typedef erase<s,first,last>::type r;
  72
  73     :Return type:
  74         |Extensible Sequence|.
  75
  76     :Precondition:
  77         ``[first,last)`` is a valid range in ``s``.
  78
  79     :Semantics:
  80         ``r`` is a new sequence, |concept-identical| to ``s``, of the following elements:
  81         [``begin<s>::type``, ``pos``), [``last``, ``end<s>::type``).
  82
  83     :Postcondition:
  84         The relative order of the elements in ``r`` is the same as in ``s``;
  85
  86         .. parsed-literal::
  87
  88            size<r>::value == size<s>::value - distance<first,last>::value
  89
  90
  91     .. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  92
  93     .. parsed-literal::
  94
  95         typedef erase<s,pos>::type r;
  96
  97     :Return type:
  98         |Extensible Sequence|.
  99
 100     :Precondition:
 101         ``pos`` is a dereferenceable iterator in ``s``.
 102
 103     :Semantics:
 104         Equivalent to
 105
 106         .. parsed-literal::
 107
 108            typedef erase< s,pos,next<pos>::type >::type r;
 109
 110
 111
 112 .. compound::
 113     :class: expression-semantics
 114
 115     For any |Extensible Associative Sequence| ``s``, and iterator ``pos`` into ``s``:
 116
 117     .. parsed-literal::
 118
 119         typedef erase<s,pos>::type r;
 120
 121     :Return type:
 122         |Extensible Sequence|.
 123
 124     :Precondition:
 125         ``pos`` is a dereferenceable iterator to ``s``.
 126
 127     :Semantics:
 128         Erases the element at a specific position ``pos``; equivalent to
 129         ``erase_key<s, deref<pos>::type >::type``.
 130
 131     :Postcondition:
 132         ``size<r>::value == size<s>::value - 1``.
 133
 134
 135 Complexity
 136 ----------
 137
 138 +---------------------------------------+-----------------------------------------------+
 139 | Sequence archetype                    | Complexity (the range form)                   |
 140 +=======================================+===============================================+
 141 | |Extensible Associative Sequence|     | Amortized constant time.                      |
 142 +---------------------------------------+-----------------------------------------------+
 143 | |Extensible Sequence|                 | Quadratic in the worst case, linear at best.  |
 144 +---------------------------------------+-----------------------------------------------+
 145
 146
 147 Example
 148 -------
 149
 150 .. parsed-literal::
 151
 152     typedef vector_c<int,1,0,5,1,7,5,0,5> values;
 153     typedef find< values, integral_c<int,7> >::type pos;
 154     typedef erase<values,pos>::type result;
 155
 156     BOOST_MPL_ASSERT_RELATION( size<result>::value, ==, 7 );
 157
 158     typedef find<result, integral_c<int,7> >::type iter;
 159     BOOST_MPL_ASSERT(( is_same< iter, end<result>::type > ));
 160
 161
 162 See also
 163 --------
 164
 165 |Extensible Sequence|, |Extensible Associative Sequence|, |erase_key|, |pop_front|, |pop_back|, |insert|
 166
 167
 168 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 169    Distributed under the Boost Software License, Version 1.0. (See accompanying
 170    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)