projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Data Types/Concepts//Integral Constant |
| 2 | ||
| 3 | Integral Constant | |
| 4 | ================= | |
| 5 | ||
| 6 | Description | |
| 7 | ----------- | |
| 8 | ||
| 9 | An |Integral Constant| is a holder class for a compile-time value of an | |
| 10 | integral type. Every |Integral Constant| is also a nullary |Metafunction|, | |
| 11 | returning itself. An integral constant *object* is implicitly convertible to the | |
| 12 | corresponding run-time value of the wrapped integral type. | |
| 13 | ||
| 14 | Expression requirements | |
| 15 | ----------------------- | |
| 16 | ||
| 17 | |In the following table...| ``n`` is a model of |Integral Constant|. | |
| 18 | ||
| 19 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 20 | | Expression | Type | Complexity | | |
| 21 | +===================================+=======================================+===========================+ | |
| 22 | | ``n::tag`` | ``integral_c_tag`` | Constant time. | | |
| 23 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 24 | | ``n::value_type`` | An integral type | Constant time. | | |
| 25 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 26 | | ``n::value`` | An integral constant expression | Constant time. | | |
| 27 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 28 | | ``n::type`` | |Integral Constant| | Constant time. | | |
| 29 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 30 | | ``next<n>::type`` | |Integral Constant| | Constant time. | | |
| 31 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 32 | | ``prior<n>::type`` | |Integral Constant| | Constant time. | | |
| 33 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 34 | | ``n::value_type const c = n()`` | | Constant time. | | |
| 35 | +-----------------------------------+---------------------------------------+---------------------------+ | |
| 36 | ||
| 37 | ||
| 38 | Expression semantics | |
| 39 | -------------------- | |
| 40 | ||
| 41 | +---------------------------------------+-----------------------------------------------------------+ | |
| 42 | | Expression | Semantics | | |
| 43 | +=======================================+===========================================================+ | |
| 44 | | ``n::tag`` | ``n``\ 's tag type; ``n::tag::value`` is ``n``\ 's | | |
| 45 | | | *conversion rank*. | | |
| 46 | +---------------------------------------+-----------------------------------------------------------+ | |
| 47 | | ``n::value_type`` | A cv-unqualified type of ``n::value``. | | |
| 48 | +---------------------------------------+-----------------------------------------------------------+ | |
| 49 | | ``n::value`` | The value of the wrapped integral constant. | | |
| 50 | +---------------------------------------+-----------------------------------------------------------+ | |
| 51 | | ``n::type`` | ``is_same<n::type,n>::value == true``. | | |
| 52 | +---------------------------------------+-----------------------------------------------------------+ | |
| 53 | | ``next<n>::type`` | An |Integral Constant| ``c`` of type ``n::value_type`` | | |
| 54 | | | such that ``c::value == n::value + 1``. | | |
| 55 | +---------------------------------------+-----------------------------------------------------------+ | |
| 56 | | ``prior<n>::type`` | An |Integral Constant| ``c`` of type ``n::value_type`` | | |
| 57 | | | such that ``c::value == n::value - 1``. | | |
| 58 | +---------------------------------------+-----------------------------------------------------------+ | |
| 59 | | ``n::value_type const c = n()`` | ``c == n::value``. | | |
| 60 | +---------------------------------------+-----------------------------------------------------------+ | |
| 61 | ||
| 62 | ||
| 63 | Models | |
| 64 | ------ | |
| 65 | ||
| 66 | * |bool_| | |
| 67 | * |int_| | |
| 68 | * |long_| | |
| 69 | * |char_| | |
| 70 | * |integral_c| | |
| 71 | ||
| 72 | ||
| 73 | See also | |
| 74 | -------- | |
| 75 | ||
| 76 | |Data Types|, |Integral Sequence Wrapper|, |integral_c| | |
| 77 | ||
| 78 | ||
| 79 |