projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Metafunctions/Miscellaneous//inherit |30 |
| 2 | ||
| 3 | inherit | |
| 4 | ======= | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | template< | |
| 12 | typename T1, typename T2 | |
| 13 | > | |
| 14 | struct inherit\ ``2`` | |
| 15 | { | |
| 16 | typedef |unspecified| type; | |
| 17 | }; | |
| 18 | ||
| 19 | |...| | |
| 20 | ||
| 21 | template< | |
| 22 | typename T1, typename T2,\ |...| typename T\ *n* | |
| 23 | > | |
| 24 | struct inherit\ *n* | |
| 25 | { | |
| 26 | typedef |unspecified| type; | |
| 27 | }; | |
| 28 | ||
| 29 | template< | |
| 30 | typename T1 | |
| 31 | , typename T2 | |
| 32 | |...| | |
| 33 | , typename T\ *n* = |unspecified| | |
| 34 | > | |
| 35 | struct inherit | |
| 36 | { | |
| 37 | typedef |unspecified| type; | |
| 38 | }; | |
| 39 | ||
| 40 | ||
| 41 | Description | |
| 42 | ----------- | |
| 43 | ||
| 44 | Returns an unspecified class type publically derived from |T1...Tn|. | |
| 45 | Guarantees that derivation from |empty_base| is always a no-op, | |
| 46 | regardless of the position and number of |empty_base| classes in | |
| 47 | |T1...Tn|. | |
| 48 | ||
| 49 | ||
| 50 | Header | |
| 51 | ------ | |
| 52 | ||
| 53 | .. parsed-literal:: | |
| 54 | ||
| 55 | #include <boost/mpl/inherit.hpp> | |
| 56 | ||
| 57 | ||
| 58 | Model of | |
| 59 | -------- | |
| 60 | ||
| 61 | |Metafunction| | |
| 62 | ||
| 63 | ||
| 64 | Parameters | |
| 65 | ---------- | |
| 66 | ||
| 67 | +---------------+-------------------+-----------------------------------+ | |
| 68 | | Parameter | Requirement | Description | | |
| 69 | +===============+===================+===================================+ | |
| 70 | | |T1...Tn| | A class type | Classes to derived from. | | |
| 71 | +---------------+-------------------+-----------------------------------+ | |
| 72 | ||
| 73 | ||
| 74 | Expression semantics | |
| 75 | -------------------- | |
| 76 | ||
| 77 | For artibrary class types |t1...tn|: | |
| 78 | ||
| 79 | .. parsed-literal:: | |
| 80 | ||
| 81 | typedef inherit2<t1,t2>::type r; | |
| 82 | ||
| 83 | :Return type: | |
| 84 | A class type. | |
| 85 | ||
| 86 | :Precondition: | |
| 87 | ``t1`` and ``t2`` are complete types. | |
| 88 | ||
| 89 | :Semantics: | |
| 90 | If both ``t1`` and ``t2`` are identical to ``empty_base``, equivalent to | |
| 91 | ||
| 92 | .. parsed-literal:: | |
| 93 | ||
| 94 | typedef empty_base r; | |
| 95 | ||
| 96 | ||
| 97 | otherwise, if ``t1`` is identical to ``empty_base``, equivalent to | |
| 98 | ||
| 99 | .. parsed-literal:: | |
| 100 | ||
| 101 | typedef t2 r; | |
| 102 | ||
| 103 | ||
| 104 | otherwise, if ``t2`` is identical to ``empty_base``, equivalent to | |
| 105 | ||
| 106 | .. parsed-literal:: | |
| 107 | ||
| 108 | typedef t1 r; | |
| 109 | ||
| 110 | ||
| 111 | otherwise equivalent to | |
| 112 | ||
| 113 | .. parsed-literal:: | |
| 114 | ||
| 115 | struct r : t1, t2 {}; | |
| 116 | ||
| 117 | .. ........................................................................... | |
| 118 | ||
| 119 | .. parsed-literal:: | |
| 120 | ||
| 121 | typedef inherit\ *n*\<t1,t2,\ |...|\ t\ *n*\ >::type r; | |
| 122 | ||
| 123 | :Return type: | |
| 124 | A class type. | |
| 125 | ||
| 126 | :Precondition: | |
| 127 | |t1...tn| are complete types. | |
| 128 | ||
| 129 | :Semantics: | |
| 130 | Equivalent to | |
| 131 | ||
| 132 | .. parsed-literal:: | |
| 133 | ||
| 134 | struct r | |
| 135 | : inherit\ ``2``\< | |
| 136 | inherit\ *n-1*\<t1,t2,\ |...|\ t\ *n-1*\>::type | |
| 137 | , t\ *n* | |
| 138 | > | |
| 139 | { | |
| 140 | }; | |
| 141 | ||
| 142 | ||
| 143 | .. ........................................................................... | |
| 144 | ||
| 145 | ||
| 146 | .. parsed-literal:: | |
| 147 | ||
| 148 | typedef inherit<t1,t2,\ |...|\ t\ *n*\ >::type r; | |
| 149 | ||
| 150 | :Precondition: | |
| 151 | |t1...tn| are complete types. | |
| 152 | ||
| 153 | :Return type: | |
| 154 | A class type. | |
| 155 | ||
| 156 | :Semantics: | |
| 157 | Equivalent to | |
| 158 | ||
| 159 | .. parsed-literal:: | |
| 160 | ||
| 161 | typedef inherit\ *n*\<t1,t2,\ |...|\ t\ *n*\ >::type r; | |
| 162 | ||
| 163 | ||
| 164 | ||
| 165 | Complexity | |
| 166 | ---------- | |
| 167 | ||
| 168 | Amortized constant time. | |
| 169 | ||
| 170 | ||
| 171 | Example | |
| 172 | ------- | |
| 173 | ||
| 174 | .. parsed-literal:: | |
| 175 | ||
| 176 | struct udt1 { int n; }; | |
| 177 | struct udt2 {}; | |
| 178 | ||
| 179 | typedef inherit<udt1,udt2>::type r1; | |
| 180 | typedef inherit<empty_base,udt1>::type r2; | |
| 181 | typedef inherit<empty_base,udt1,empty_base,empty_base>::type r3; | |
| 182 | typedef inherit<udt1,empty_base,udt2>::type r4; | |
| 183 | typedef inherit<empty_base,empty_base>::type r5; | |
| 184 | ||
| 185 | BOOST_MPL_ASSERT(( is_base_and_derived< udt1, r1> )); | |
| 186 | BOOST_MPL_ASSERT(( is_base_and_derived< udt2, r1> )); | |
| 187 | BOOST_MPL_ASSERT(( is_same< r2, udt1> )); | |
| 188 | BOOST_MPL_ASSERT(( is_same< r3, udt1 > )); | |
| 189 | BOOST_MPL_ASSERT(( is_base_and_derived< udt1, r4 > )); | |
| 190 | BOOST_MPL_ASSERT(( is_base_and_derived< udt2, r4 > )); | |
| 191 | BOOST_MPL_ASSERT(( is_same< r5, empty_base > )); | |
| 192 | ||
| 193 | ||
| 194 | See also | |
| 195 | -------- | |
| 196 | ||
| 197 | |Metafunctions|, |empty_base|, |inherit_linearly|, |identity| | |
| 198 | ||
| 199 | ||
| 200 |