projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Algorithms/Transformation Algorithms//unique |80 |
| 2 | ||
| 3 | unique | |
| 4 | ====== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Seq | |
| 13 | , typename Pred | |
| 14 | , typename In = |unspecified| | |
| 15 | > | |
| 16 | struct unique | |
| 17 | { | |
| 18 | typedef |unspecified| type; | |
| 19 | }; | |
| 20 | ||
| 21 | ||
| 22 | Description | |
| 23 | ----------- | |
| 24 | ||
| 25 | Returns a sequence of the initial elements of every subrange of the | |
| 26 | original sequence ``Seq`` whose elements are all the same. | |
| 27 | ||
| 28 | |transformation algorithm disclaimer| | |
| 29 | ||
| 30 | Header | |
| 31 | ------ | |
| 32 | ||
| 33 | .. parsed-literal:: | |
| 34 | ||
| 35 | #include <boost/mpl/unique.hpp> | |
| 36 | ||
| 37 | ||
| 38 | Model of | |
| 39 | -------- | |
| 40 | ||
| 41 | |Reversible Algorithm| | |
| 42 | ||
| 43 | ||
| 44 | Parameters | |
| 45 | ---------- | |
| 46 | ||
| 47 | +---------------+-----------------------------------+-------------------------------+ | |
| 48 | | Parameter | Requirement | Description | | |
| 49 | +===============+===================================+===============================+ | |
| 50 | | ``Sequence`` | |Forward Sequence| | An original sequence. | | |
| 51 | +---------------+-----------------------------------+-------------------------------+ | |
| 52 | | ``Pred`` | Binary |Lambda Expression| | An equivalence relation. | | |
| 53 | +---------------+-----------------------------------+-------------------------------+ | |
| 54 | | ``In`` | |Inserter| | An inserter. | | |
| 55 | +---------------+-----------------------------------+-------------------------------+ | |
| 56 | ||
| 57 | ||
| 58 | Expression semantics | |
| 59 | -------------------- | |
| 60 | ||
| 61 | |Semantics disclaimer...| |Reversible Algorithm|. | |
| 62 | ||
| 63 | For any |Forward Sequence| ``s``, a binary |Lambda Expression| ``pred``, | |
| 64 | and an |Inserter| ``in``: | |
| 65 | ||
| 66 | ||
| 67 | .. parsed-literal:: | |
| 68 | ||
| 69 | typedef unique<s,pred,in>::type r; | |
| 70 | ||
| 71 | :Return type: | |
| 72 | A type. | |
| 73 | ||
| 74 | :Semantics: | |
| 75 | If ``size<s>::value <= 1``, then equivalent to | |
| 76 | ||
| 77 | .. parsed-literal:: | |
| 78 | ||
| 79 | typedef copy<s,in>::type r; | |
| 80 | ||
| 81 | otherwise equivalent to | |
| 82 | ||
| 83 | .. parsed-literal:: | |
| 84 | ||
| 85 | typedef lambda<pred>::type p; | |
| 86 | typedef lambda<in::operation>::type in_op; | |
| 87 | typedef apply_wrap\ ``2``\< | |
| 88 | in_op | |
| 89 | , in::state | |
| 90 | , front<types>::type | |
| 91 | >::type in_state; | |
| 92 | ||
| 93 | typedef fold< | |
| 94 | s | |
| 95 | , pair< in_state, front<s>::type > | |
| 96 | , eval_if< | |
| 97 | apply_wrap\ ``2``\<p, second<_1>, _2> | |
| 98 | , identity< first<_1> > | |
| 99 | , apply_wrap\ ``2``\<in_op, first<_1>, _2> | |
| 100 | > | |
| 101 | >::type::first r; | |
| 102 | ||
| 103 | ||
| 104 | Complexity | |
| 105 | ---------- | |
| 106 | ||
| 107 | Linear. Performs exactly ``size<s>::value - 1`` applications of ``pred``, and at | |
| 108 | most ``size<s>::value`` insertions. | |
| 109 | ||
| 110 | ||
| 111 | Example | |
| 112 | ------- | |
| 113 | ||
| 114 | .. parsed-literal:: | |
| 115 | ||
| 116 | typedef vector<int,float,float,char,int,int,int,double> types; | |
| 117 | typedef vector<int,float,char,int,double> expected; | |
| 118 | typedef unique< types, is_same<_1,_2> >::type result; | |
| 119 | ||
| 120 | BOOST_MPL_ASSERT(( equal< result,expected > )); | |
| 121 | ||
| 122 | ||
| 123 | See also | |
| 124 | -------- | |
| 125 | ||
| 126 | |Transformation Algorithms|, |Reversible Algorithm|, |reverse_unique|, |remove|, |copy_if|, |replace_if| | |
| 127 | ||
| 128 | ||
| 129 |