projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
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 |