projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Iterators/Iterator Metafunctions//deref |50 |
| 2 | ||
| 3 | deref | |
| 4 | ===== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Iterator | |
| 13 | > | |
| 14 | struct deref | |
| 15 | { | |
| 16 | typedef |unspecified| type; | |
| 17 | }; | |
| 18 | ||
| 19 | ||
| 20 | ||
| 21 | Description | |
| 22 | ----------- | |
| 23 | ||
| 24 | Dereferences an iterator. | |
| 25 | ||
| 26 | ||
| 27 | Header | |
| 28 | ------ | |
| 29 | ||
| 30 | .. parsed-literal:: | |
| 31 | ||
| 32 | #include <boost/mpl/deref.hpp> | |
| 33 | ||
| 34 | ||
| 35 | ||
| 36 | Parameters | |
| 37 | ---------- | |
| 38 | ||
| 39 | +---------------+---------------------------+-----------------------------------+ | |
| 40 | | Parameter | Requirement | Description | | |
| 41 | +===============+===========================+===================================+ | |
| 42 | | ``Iterator`` | |Forward Iterator| | The iterator to dereference. | | |
| 43 | +---------------+---------------------------+-----------------------------------+ | |
| 44 | ||
| 45 | ||
| 46 | Expression semantics | |
| 47 | -------------------- | |
| 48 | ||
| 49 | For any |Forward Iterator|\ s ``iter``: | |
| 50 | ||
| 51 | ||
| 52 | .. parsed-literal:: | |
| 53 | ||
| 54 | typedef deref<iter>::type t; | |
| 55 | ||
| 56 | :Return type: | |
| 57 | A type. | |
| 58 | ||
| 59 | :Precondition: | |
| 60 | ``iter`` is dereferenceable. | |
| 61 | ||
| 62 | :Semantics: | |
| 63 | ``t`` is identical to the element referenced by ``iter``. If ``iter`` is | |
| 64 | a user-defined iterator, the library-provided default implementation is | |
| 65 | equivalent to | |
| 66 | ||
| 67 | .. parsed-literal:: | |
| 68 | ||
| 69 | typedef iter::type t; | |
| 70 | ||
| 71 | ||
| 72 | ||
| 73 | ||
| 74 | Complexity | |
| 75 | ---------- | |
| 76 | ||
| 77 | Amortized constant time. | |
| 78 | ||
| 79 | ||
| 80 | Example | |
| 81 | ------- | |
| 82 | ||
| 83 | .. parsed-literal:: | |
| 84 | ||
| 85 | typedef vector<char,short,int,long> types; | |
| 86 | typedef begin<types>::type iter; | |
| 87 | ||
| 88 | BOOST_MPL_ASSERT(( is_same< deref<iter>::type, char > )); | |
| 89 | ||
| 90 | ||
| 91 | See also | |
| 92 | -------- | |
| 93 | ||
| 94 | |Iterators|, |begin| / |end|, |next| | |
| 95 | ||
| 96 | ||
| 97 |