projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Sequences/Intrinsic Metafunctions//pop_front |
| 2 | ||
| 3 | pop_front | |
| 4 | ========= | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Sequence | |
| 13 | > | |
| 14 | struct pop_front | |
| 15 | { | |
| 16 | typedef |unspecified| type; | |
| 17 | }; | |
| 18 | ||
| 19 | ||
| 20 | ||
| 21 | Description | |
| 22 | ----------- | |
| 23 | ||
| 24 | ``pop_front`` performs a removal at the beginning of the sequence with guaranteed |O(1)| | |
| 25 | complexity. | |
| 26 | ||
| 27 | ||
| 28 | Header | |
| 29 | ------ | |
| 30 | ||
| 31 | .. parsed-literal:: | |
| 32 | ||
| 33 | #include <boost/mpl/pop_front.hpp> | |
| 34 | ||
| 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`` | |Front Extensible Sequence| | A sequence to erase the first element from. | | |
| 50 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 51 | ||
| 52 | ||
| 53 | Expression semantics | |
| 54 | -------------------- | |
| 55 | ||
| 56 | For any |Front Extensible Sequence| ``s``: | |
| 57 | ||
| 58 | .. parsed-literal:: | |
| 59 | ||
| 60 | typedef pop_front<s>::type r; | |
| 61 | ||
| 62 | :Return type: | |
| 63 | |Front Extensible Sequence|. | |
| 64 | ||
| 65 | :Precondition: | |
| 66 | ``empty<s>::value == false``. | |
| 67 | ||
| 68 | :Semantics: | |
| 69 | Equivalent to ``erase<s,begin<s>::type>::type;``. | |
| 70 | ||
| 71 | :Postcondition: | |
| 72 | ``size<r>::value == size<s>::value - 1``. | |
| 73 | ||
| 74 | ||
| 75 | Complexity | |
| 76 | ---------- | |
| 77 | ||
| 78 | Amortized constant time. | |
| 79 | ||
| 80 | ||
| 81 | Example | |
| 82 | ------- | |
| 83 | ||
| 84 | .. parsed-literal:: | |
| 85 | ||
| 86 | typedef vector<long>::type types1; | |
| 87 | typedef vector<int,long>::type types2; | |
| 88 | typedef vector<char,int,long>::type types3; | |
| 89 | ||
| 90 | typedef pop_front<types1>::type result1; | |
| 91 | typedef pop_front<types2>::type result2; | |
| 92 | typedef pop_front<types3>::type result3; | |
| 93 | ||
| 94 | BOOST_MPL_ASSERT_RELATION( size<result1>::value, ==, 0 ); | |
| 95 | BOOST_MPL_ASSERT_RELATION( size<result2>::value, ==, 1 ); | |
| 96 | BOOST_MPL_ASSERT_RELATION( size<result3>::value, ==, 2 ); | |
| 97 | ||
| 98 | BOOST_MPL_ASSERT(( is_same< front<result2>::type, long > )); | |
| 99 | BOOST_MPL_ASSERT(( is_same< front<result3>::type, int > )); | |
| 100 | ||
| 101 | ||
| 102 | See also | |
| 103 | -------- | |
| 104 | ||
| 105 | |Front Extensible Sequence|, |erase|, |push_front|, |front|, |pop_back| | |
| 106 | ||
| 107 | ||
| 108 |