projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Metafunctions/Invocation//apply |10 |
| 2 | ||
| 3 | apply | |
| 4 | ===== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename F | |
| 13 | > | |
| 14 | struct apply0 | |
| 15 | { | |
| 16 | typedef |unspecified| type; | |
| 17 | }; | |
| 18 | ||
| 19 | template< | |
| 20 | typename F, typename A1 | |
| 21 | > | |
| 22 | struct apply1 | |
| 23 | { | |
| 24 | typedef |unspecified| type; | |
| 25 | }; | |
| 26 | ||
| 27 | |...| | |
| 28 | ||
| 29 | template< | |
| 30 | typename F, typename A1,\ |...| typename An | |
| 31 | > | |
| 32 | struct apply\ *n* | |
| 33 | { | |
| 34 | typedef |unspecified| type; | |
| 35 | }; | |
| 36 | ||
| 37 | template< | |
| 38 | typename F | |
| 39 | , typename A1 = |unspecified| | |
| 40 | |...| | |
| 41 | , typename An = |unspecified| | |
| 42 | > | |
| 43 | struct apply | |
| 44 | { | |
| 45 | typedef |unspecified| type; | |
| 46 | }; | |
| 47 | ||
| 48 | ||
| 49 | ||
| 50 | Description | |
| 51 | ----------- | |
| 52 | ||
| 53 | Invokes a |Metafunction Class| or a |Lambda Expression| ``F`` with arguments ``A1``,... ``An``. | |
| 54 | ||
| 55 | ||
| 56 | Header | |
| 57 | ------ | |
| 58 | ||
| 59 | .. parsed-literal:: | |
| 60 | ||
| 61 | #include <boost/mpl/apply.hpp> | |
| 62 | ||
| 63 | ||
| 64 | Parameters | |
| 65 | ---------- | |
| 66 | ||
| 67 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 68 | | Parameter | Requirement | Description | | |
| 69 | +===============+===================================+===============================================+ | |
| 70 | | ``F`` | |Lambda Expression| | An expression to invoke. | | |
| 71 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 72 | | |A1...An| | Any type | Invocation arguments. | | |
| 73 | +---------------+-----------------------------------+-----------------------------------------------+ | |
| 74 | ||
| 75 | ||
| 76 | Expression semantics | |
| 77 | -------------------- | |
| 78 | ||
| 79 | For any |Lambda Expression| ``f`` and arbitrary types ``a1``,... ``an``: | |
| 80 | ||
| 81 | ||
| 82 | .. parsed-literal:: | |
| 83 | ||
| 84 | typedef apply\ *n*\<f,a1,\ |...|\ a\ *n*\>::type t; | |
| 85 | typedef apply<f,a1,\ |...|\ a\ *n*\>::type t; | |
| 86 | ||
| 87 | :Return type: | |
| 88 | Any type. | |
| 89 | ||
| 90 | :Semantics: | |
| 91 | Equivalent to ``typedef apply_wrap``\ *n*\ ``< lambda<f>::type,a1,... an>::type t;``. | |
| 92 | ||
| 93 | ||
| 94 | Example | |
| 95 | ------- | |
| 96 | ||
| 97 | .. parsed-literal:: | |
| 98 | ||
| 99 | template< typename N1, typename N2 > struct int_plus | |
| 100 | : int_<( N1::value + N2::value )> | |
| 101 | { | |
| 102 | }; | |
| 103 | ||
| 104 | typedef apply< int_plus<_1,_2>, int_<2>, int_<3> >::type r1; | |
| 105 | typedef apply< quote\ ``2``\ <int_plus>, int_<2>, int_<3> >::type r2; | |
| 106 | ||
| 107 | BOOST_MPL_ASSERT_RELATION( r1::value, ==, 5 ); | |
| 108 | BOOST_MPL_ASSERT_RELATION( r2::value, ==, 5 ); | |
| 109 | ||
| 110 | ||
| 111 | See also | |
| 112 | -------- | |
| 113 | ||
| 114 | |Metafunctions|, |apply_wrap|, |lambda|, |quote|, |bind| | |
| 115 | ||
| 116 | ||
| 117 |