projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Algorithms/Querying Algorithms//count |40 |
| 2 | ||
| 3 | count | |
| 4 | ===== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Sequence | |
| 13 | , typename T | |
| 14 | > | |
| 15 | struct count | |
| 16 | { | |
| 17 | typedef |unspecified| type; | |
| 18 | }; | |
| 19 | ||
| 20 | ||
| 21 | ||
| 22 | Description | |
| 23 | ----------- | |
| 24 | ||
| 25 | Returns the number of elements in a ``Sequence`` that are identical to ``T``. | |
| 26 | ||
| 27 | ||
| 28 | Header | |
| 29 | ------ | |
| 30 | ||
| 31 | .. parsed-literal:: | |
| 32 | ||
| 33 | #include <boost/mpl/count.hpp> | |
| 34 | ||
| 35 | ||
| 36 | Parameters | |
| 37 | ---------- | |
| 38 | ||
| 39 | +---------------+---------------------------+-----------------------------------+ | |
| 40 | | Parameter | Requirement | Description | | |
| 41 | +===============+===========================+===================================+ | |
| 42 | | ``Sequence`` | |Forward Sequence| | A sequence to be examined. | | |
| 43 | +---------------+---------------------------+-----------------------------------+ | |
| 44 | | ``T`` | Any type | A type to search for. | | |
| 45 | +---------------+---------------------------+-----------------------------------+ | |
| 46 | ||
| 47 | ||
| 48 | Expression semantics | |
| 49 | -------------------- | |
| 50 | ||
| 51 | ||
| 52 | For any |Forward Sequence| ``s`` and arbitrary type ``t``: | |
| 53 | ||
| 54 | ||
| 55 | .. parsed-literal:: | |
| 56 | ||
| 57 | typedef count<s,t>::type n; | |
| 58 | ||
| 59 | :Return type: | |
| 60 | |Integral Constant|. | |
| 61 | ||
| 62 | :Semantics: | |
| 63 | Equivalent to | |
| 64 | ||
| 65 | .. parsed-literal:: | |
| 66 | ||
| 67 | typedef count_if< s,is_same<_,T> >::type n; | |
| 68 | ||
| 69 | ||
| 70 | Complexity | |
| 71 | ---------- | |
| 72 | ||
| 73 | Linear. Exactly ``size<s>::value`` comparisons for identity. | |
| 74 | ||
| 75 | ||
| 76 | Example | |
| 77 | ------- | |
| 78 | ||
| 79 | .. parsed-literal:: | |
| 80 | ||
| 81 | typedef vector<int,char,long,short,char,short,double,long> types; | |
| 82 | typedef count<types, short>::type n; | |
| 83 | ||
| 84 | BOOST_MPL_ASSERT_RELATION( n::value, ==, 2 ); | |
| 85 | ||
| 86 | ||
| 87 | See also | |
| 88 | -------- | |
| 89 | ||
| 90 | |Querying Algorithms|, |count_if|, |find|, |find_if|, |contains|, |lower_bound| | |
| 91 | ||
| 92 | ||
| 93 |