projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Sequences/Intrinsic Metafunctions//erase_key |
| 2 | ||
| 3 | erase_key | |
| 4 | ========= | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename AssocSeq | |
| 13 | , typename Key | |
| 14 | > | |
| 15 | struct erase_key | |
| 16 | { | |
| 17 | typedef |unspecified| type; | |
| 18 | }; | |
| 19 | ||
| 20 | ||
| 21 | ||
| 22 | Description | |
| 23 | ----------- | |
| 24 | ||
| 25 | Erases elements associated with the key ``Key`` in the |Extensible Associative Sequence| | |
| 26 | ``AssocSeq`` . | |
| 27 | ||
| 28 | Header | |
| 29 | ------ | |
| 30 | ||
| 31 | .. parsed-literal:: | |
| 32 | ||
| 33 | #include <boost/mpl/erase_key.hpp> | |
| 34 | ||
| 35 | ||
| 36 | Model of | |
| 37 | -------- | |
| 38 | ||
| 39 | |Tag Dispatched Metafunction| | |
| 40 | ||
| 41 | ||
| 42 | Parameters | |
| 43 | ---------- | |
| 44 | ||
| 45 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 46 | | Parameter | Requirement | Description | | |
| 47 | +===============+===================================+===============================================+ | |
| 48 | | ``AssocSeq`` | |Extensible Associative Sequence| | A sequence to erase elements from. | | |
| 49 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 50 | | ``Key`` | Any type | A key for the elements to be removed. | | |
| 51 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 52 | ||
| 53 | ||
| 54 | Expression semantics | |
| 55 | -------------------- | |
| 56 | ||
| 57 | For any |Extensible Associative Sequence| ``s``, and arbitrary type ``key``: | |
| 58 | ||
| 59 | ||
| 60 | .. parsed-literal:: | |
| 61 | ||
| 62 | typedef erase_key<s,key>::type r; | |
| 63 | ||
| 64 | :Return type: | |
| 65 | |Extensible Associative Sequence|. | |
| 66 | ||
| 67 | :Semantics: | |
| 68 | ``r`` is |concept-identical| and equivalent to ``s`` except that | |
| 69 | ``has_key<r,k>::value == false``. | |
| 70 | ||
| 71 | :Postcondition: | |
| 72 | ``size<r>::value == size<s>::value - 1``. | |
| 73 | ||
| 74 | ||
| 75 | ||
| 76 | Complexity | |
| 77 | ---------- | |
| 78 | ||
| 79 | Amortized constant time. | |
| 80 | ||
| 81 | ||
| 82 | Example | |
| 83 | ------- | |
| 84 | ||
| 85 | .. parsed-literal:: | |
| 86 | ||
| 87 | typedef map< pair<int,unsigned>, pair<char,long> > m; | |
| 88 | typedef erase_key<m,char>::type m1; | |
| 89 | ||
| 90 | BOOST_MPL_ASSERT_RELATION( size<m1>::type::value, ==, 1 ); | |
| 91 | BOOST_MPL_ASSERT(( is_same< at<m1,char>::type,void\_ > )); | |
| 92 | BOOST_MPL_ASSERT(( is_same< at<m1,int>::type,unsigned > )); | |
| 93 | ||
| 94 | ||
| 95 | See also | |
| 96 | -------- | |
| 97 | ||
| 98 | |Extensible Associative Sequence|, |erase|, |has_key|, |insert| | |
| 99 | ||
| 100 | ||
| 101 |