projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | .. Macros/Broken Compiler Workarounds//BOOST_MPL_AUX_LAMBDA_SUPPORT |
| 2 | ||
| 3 | BOOST_MPL_AUX_LAMBDA_SUPPORT | |
| 4 | ============================ | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | #define BOOST_MPL_AUX_LAMBDA_SUPPORT(arity, fun, params) \\ | |
| 12 | |unspecified-token-seq| \\ | |
| 13 | /\*\*/ | |
| 14 | ||
| 15 | ||
| 16 | ||
| 17 | Description | |
| 18 | ----------- | |
| 19 | ||
| 20 | Enables metafunction ``fun`` for the use in |Lambda Expression|\ s on | |
| 21 | compilers that don't support partial template specialization or/and | |
| 22 | template template parameters. Expands to nothing on conforming compilers. | |
| 23 | ||
| 24 | ||
| 25 | Header | |
| 26 | ------ | |
| 27 | ||
| 28 | .. parsed-literal:: | |
| 29 | ||
| 30 | #include <boost/mpl/aux\_/lambda_support.hpp> | |
| 31 | ||
| 32 | ||
| 33 | Parameters | |
| 34 | ---------- | |
| 35 | ||
| 36 | +---------------+-------------------------------+---------------------------------------------------+ | |
| 37 | | Parameter | Requirement | Description | | |
| 38 | +===============+===============================+===================================================+ | |
| 39 | | ``arity`` | An integral constant | The metafunction's arity, i.e. the number of its | | |
| 40 | | | | template parameters, including the defaults. | | |
| 41 | +---------------+-------------------------------+---------------------------------------------------+ | |
| 42 | | ``fun`` | A legal identifier token | The metafunction's name. | | |
| 43 | +---------------+-------------------------------+---------------------------------------------------+ | |
| 44 | | ``params`` | A |PP-tuple| | A tuple of the metafunction's parameter names, in | | |
| 45 | | | | their original order, including the defaults. | | |
| 46 | +---------------+-------------------------------+---------------------------------------------------+ | |
| 47 | ||
| 48 | ||
| 49 | Expression semantics | |
| 50 | -------------------- | |
| 51 | ||
| 52 | For any integral constant ``n``, a |Metafunction| ``fun``, and arbitrary types |A1...An|: | |
| 53 | ||
| 54 | ||
| 55 | .. parsed-literal:: | |
| 56 | ||
| 57 | template< typename A1,\ |...| typename A\ *n* > struct fun | |
| 58 | { | |
| 59 | // |...| | |
| 60 | ||
| 61 | BOOST_MPL_AUX_LAMBDA_SUPPORT(n, fun, (A1,\ |...|\ A\ *n*\ )) | |
| 62 | }; | |
| 63 | ||
| 64 | :Precondition: | |
| 65 | Appears in ``fun``\ 's scope, immediately followed by the scope-closing | |
| 66 | bracket (``}``). | |
| 67 | ||
| 68 | :Return type: | |
| 69 | None. | |
| 70 | ||
| 71 | :Semantics: | |
| 72 | Expands to nothing and has no effect on conforming compilers. On compilers that | |
| 73 | don't support partial template specialization or/and template template parameters | |
| 74 | expands to an unspecified token sequence enabling ``fun`` to participate in | |
| 75 | |Lambda Expression|\ s with the semantics described in this manual. | |
| 76 | ||
| 77 | ||
| 78 | Example | |
| 79 | ------- | |
| 80 | ||
| 81 | .. parsed-literal:: | |
| 82 | ||
| 83 | template< typename T, typename U = int > struct f | |
| 84 | { | |
| 85 | typedef T type[sizeof(U)]; | |
| 86 | ||
| 87 | BOOST_MPL_AUX_LAMBDA_SUPPORT(2, f, (T,U)) | |
| 88 | }; | |
| 89 | ||
| 90 | typedef apply\ ``1``\< f<char,_1>,long >::type r; | |
| 91 | BOOST_MPL_ASSERT(( is_same< r, char[sizeof(long)] > )); | |
| 92 | ||
| 93 | ||
| 94 | See also | |
| 95 | -------- | |
| 96 | ||
| 97 | |Macros|, |Metafunctions|, |Lambda Expression| | |
| 98 | ||
| 99 | ||
| 100 | .. |PP-tuple| replace:: `PP-tuple <http://www.boost.org/libs/preprocessor/doc/data/tuples.html>`__ | |
| 101 | ||
| 102 | ||
| 103 |