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| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Algorithms/Transformation Algorithms//partition |85 |
| 2 | ||
| 3 | partition | |
| 4 | ========= | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename Seq | |
| 13 | , typename Pred | |
| 14 | , typename In1 = |unspecified| | |
| 15 | , typename In2 = |unspecified| | |
| 16 | > | |
| 17 | struct partition | |
| 18 | { | |
| 19 | typedef |unspecified| type; | |
| 20 | }; | |
| 21 | ||
| 22 | ||
| 23 | Description | |
| 24 | ----------- | |
| 25 | ||
| 26 | Returns a pair of sequences together containing all elements in the range | |
| 27 | |begin/end<Seq>| split into two groups based on the predicate ``Pred``. | |
| 28 | ``partition`` is a synonym for |stable_partition|. | |
| 29 | ||
| 30 | |transformation algorithm disclaimer| | |
| 31 | ||
| 32 | ||
| 33 | Header | |
| 34 | ------ | |
| 35 | ||
| 36 | .. parsed-literal:: | |
| 37 | ||
| 38 | #include <boost/mpl/partition.hpp> | |
| 39 | ||
| 40 | ||
| 41 | Model of | |
| 42 | -------- | |
| 43 | ||
| 44 | |Reversible Algorithm| | |
| 45 | ||
| 46 | ||
| 47 | Parameters | |
| 48 | ---------- | |
| 49 | ||
| 50 | +-------------------+-----------------------------------+-------------------------------+ | |
| 51 | | Parameter | Requirement | Description | | |
| 52 | +===================+===================================+===============================+ | |
| 53 | | ``Seq`` | |Forward Sequence| | An original sequence. | | |
| 54 | +-------------------+-----------------------------------+-------------------------------+ | |
| 55 | | ``Pred`` | Unary |Lambda Expression| | A partitioning predicate. | | |
| 56 | +-------------------+-----------------------------------+-------------------------------+ | |
| 57 | | ``In1``, ``In2`` | |Inserter| | Output inserters. | | |
| 58 | +-------------------+-----------------------------------+-------------------------------+ | |
| 59 | ||
| 60 | ||
| 61 | Expression semantics | |
| 62 | -------------------- | |
| 63 | ||
| 64 | |Semantics disclaimer...| |Reversible Algorithm|. | |
| 65 | ||
| 66 | For any |Forward Sequence| ``s``, an unary |Lambda Expression| ``pred``, and |Inserter|\ s | |
| 67 | ``in1`` and ``in2``: | |
| 68 | ||
| 69 | ||
| 70 | .. parsed-literal:: | |
| 71 | ||
| 72 | typedef partition<s,pred,in1,in2>::type r; | |
| 73 | ||
| 74 | :Return type: | |
| 75 | A |pair|. | |
| 76 | ||
| 77 | :Semantics: | |
| 78 | Equivalent to | |
| 79 | ||
| 80 | .. parsed-literal:: | |
| 81 | ||
| 82 | typedef stable_partition<s,pred,in1,in2>::type r; | |
| 83 | ||
| 84 | ||
| 85 | Complexity | |
| 86 | ---------- | |
| 87 | ||
| 88 | Linear. Exactly ``size<s>::value`` applications of ``pred``, and ``size<s>::value`` | |
| 89 | of summarized ``in1::operation`` / ``in2::operation`` applications. | |
| 90 | ||
| 91 | ||
| 92 | Example | |
| 93 | ------- | |
| 94 | ||
| 95 | .. parsed-literal:: | |
| 96 | ||
| 97 | template< typename N > struct is_odd : bool_<(N::value % 2)> {}; | |
| 98 | ||
| 99 | typedef partition< | |
| 100 | range_c<int,0,10> | |
| 101 | , is_odd<_1> | |
| 102 | , back_inserter< vector<> > | |
| 103 | , back_inserter< vector<> > | |
| 104 | >::type r; | |
| 105 | ||
| 106 | BOOST_MPL_ASSERT(( equal< r::first, vector_c<int,1,3,5,7,9> > )); | |
| 107 | BOOST_MPL_ASSERT(( equal< r::second, vector_c<int,0,2,4,6,8> > )); | |
| 108 | ||
| 109 | ||
| 110 | See also | |
| 111 | -------- | |
| 112 | ||
| 113 | |Transformation Algorithms|, |Reversible Algorithm|, |reverse_partition|, |stable_partition|, |sort| | |
| 114 | ||
| 115 | ||
| 116 |