projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Sequences/Intrinsic Metafunctions//pop_back |
| 2 | ||
| 3 | pop_back | |
| 4 | ======== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Sequence | |
| 13 | > | |
| 14 | struct pop_back | |
| 15 | { | |
| 16 | typedef |unspecified| type; | |
| 17 | }; | |
| 18 | ||
| 19 | ||
| 20 | Description | |
| 21 | ----------- | |
| 22 | ||
| 23 | ``pop_back`` performs a removal at the end of the sequence with guaranteed |O(1)| | |
| 24 | complexity. | |
| 25 | ||
| 26 | ||
| 27 | Header | |
| 28 | ------ | |
| 29 | ||
| 30 | .. parsed-literal:: | |
| 31 | ||
| 32 | #include <boost/mpl/pop_back.hpp> | |
| 33 | ||
| 34 | ||
| 35 | Model of | |
| 36 | -------- | |
| 37 | ||
| 38 | |Tag Dispatched Metafunction| | |
| 39 | ||
| 40 | ||
| 41 | Parameters | |
| 42 | ---------- | |
| 43 | ||
| 44 | +---------------+-------------------------------+-----------------------------------------------+ | |
| 45 | | Parameter | Requirement | Description | | |
| 46 | +===============+===============================+===============================================+ | |
| 47 | | ``Sequence`` | |Back Extensible Sequence| | A sequence to erase the last element from. | | |
| 48 | +---------------+-------------------------------+-----------------------------------------------+ | |
| 49 | ||
| 50 | ||
| 51 | Expression semantics | |
| 52 | -------------------- | |
| 53 | ||
| 54 | For any |Back Extensible Sequence| ``s``: | |
| 55 | ||
| 56 | .. parsed-literal:: | |
| 57 | ||
| 58 | typedef pop_back<s>::type r; | |
| 59 | ||
| 60 | :Return type: | |
| 61 | |Back Extensible Sequence|. | |
| 62 | ||
| 63 | :Precondition: | |
| 64 | ``empty<s>::value == false``. | |
| 65 | ||
| 66 | :Semantics: | |
| 67 | Equivalent to ``erase<s,end<s>::type>::type;``. | |
| 68 | ||
| 69 | :Postcondition: | |
| 70 | ``size<r>::value == size<s>::value - 1``. | |
| 71 | ||
| 72 | ||
| 73 | Complexity | |
| 74 | ---------- | |
| 75 | ||
| 76 | Amortized constant time. | |
| 77 | ||
| 78 | ||
| 79 | Example | |
| 80 | ------- | |
| 81 | ||
| 82 | .. parsed-literal:: | |
| 83 | ||
| 84 | typedef vector<long>::type types1; | |
| 85 | typedef vector<long,int>::type types2; | |
| 86 | typedef vector<long,int,char>::type types3; | |
| 87 | ||
| 88 | typedef pop_back<types1>::type result1; | |
| 89 | typedef pop_back<types2>::type result2; | |
| 90 | typedef pop_back<types3>::type result3; | |
| 91 | ||
| 92 | BOOST_MPL_ASSERT_RELATION( size<result1>::value, ==, 0 ); | |
| 93 | BOOST_MPL_ASSERT_RELATION( size<result2>::value, ==, 1 ); | |
| 94 | BOOST_MPL_ASSERT_RELATION( size<result3>::value, ==, 2 ); | |
| 95 | ||
| 96 | BOOST_MPL_ASSERT(( is_same< back<result2>::type, long> )); | |
| 97 | BOOST_MPL_ASSERT(( is_same< back<result3>::type, int > )); | |
| 98 | ||
| 99 | ||
| 100 | See also | |
| 101 | -------- | |
| 102 | ||
| 103 | |Back Extensible Sequence|, |erase|, |push_back|, |back|, |pop_front| | |
| 104 | ||
| 105 | ||
| 106 |