projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Algorithms/Querying Algorithms//find_if |20 |
| 2 | ||
| 3 | find_if | |
| 4 | ======= | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Sequence | |
| 13 | , typename Pred | |
| 14 | > | |
| 15 | struct find_if | |
| 16 | { | |
| 17 | typedef |unspecified| type; | |
| 18 | }; | |
| 19 | ||
| 20 | ||
| 21 | ||
| 22 | Description | |
| 23 | ----------- | |
| 24 | ||
| 25 | Returns an iterator to the first element in ``Sequence`` that satisfies | |
| 26 | the predicate ``Pred``. | |
| 27 | ||
| 28 | ||
| 29 | Header | |
| 30 | ------ | |
| 31 | ||
| 32 | .. parsed-literal:: | |
| 33 | ||
| 34 | #include <boost/mpl/find_if.hpp> | |
| 35 | ||
| 36 | ||
| 37 | ||
| 38 | Parameters | |
| 39 | ---------- | |
| 40 | ||
| 41 | +---------------+-------------------------------+-----------------------------------+ | |
| 42 | | Parameter | Requirement | Description | | |
| 43 | +===============+===============================+===================================+ | |
| 44 | | ``Sequence`` | |Forward Sequence| | A sequence to search in. | | |
| 45 | +---------------+-------------------------------+-----------------------------------+ | |
| 46 | | ``Pred`` | Unary |Lambda Expression| | A search condition. | | |
| 47 | +---------------+-------------------------------+-----------------------------------+ | |
| 48 | ||
| 49 | ||
| 50 | Expression semantics | |
| 51 | -------------------- | |
| 52 | ||
| 53 | For any |Forward Sequence| ``s`` and unary |Lambda Expression| ``pred``: | |
| 54 | ||
| 55 | ||
| 56 | .. parsed-literal:: | |
| 57 | ||
| 58 | typedef find_if<s,pred>::type i; | |
| 59 | ||
| 60 | :Return type: | |
| 61 | |Forward Iterator|. | |
| 62 | ||
| 63 | :Semantics: | |
| 64 | ``i`` is the first iterator in the range |begin/end<s>| such that | |
| 65 | ||
| 66 | .. parsed-literal:: | |
| 67 | ||
| 68 | apply< pred,deref<i>::type >::type::value == true | |
| 69 | ||
| 70 | If no such iterator exists, ``i`` is identical to ``end<s>::type``. | |
| 71 | ||
| 72 | ||
| 73 | Complexity | |
| 74 | ---------- | |
| 75 | ||
| 76 | Linear. At most ``size<s>::value`` applications of ``pred``. | |
| 77 | ||
| 78 | ||
| 79 | Example | |
| 80 | ------- | |
| 81 | ||
| 82 | .. parsed-literal:: | |
| 83 | ||
| 84 | typedef vector<char,int,unsigned,long,unsigned long> types; | |
| 85 | typedef find_if<types, is_same<_1,unsigned> >::type iter; | |
| 86 | ||
| 87 | BOOST_MPL_ASSERT(( is_same< deref<iter>::type, unsigned > )); | |
| 88 | BOOST_MPL_ASSERT_RELATION( iter::pos::value, ==, 2 ); | |
| 89 | ||
| 90 | ||
| 91 | See also | |
| 92 | -------- | |
| 93 | ||
| 94 | |Querying Algorithms|, |find|, |count_if|, |lower_bound| | |
| 95 | ||
| 96 | ||
| 97 |