projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Sequences/Views//empty_sequence |
| 2 | ||
| 3 | empty_sequence | |
| 4 | ============== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | struct empty_sequence | |
| 12 | { | |
| 13 | // |unspecified| | |
| 14 | // |...| | |
| 15 | }; | |
| 16 | ||
| 17 | ||
| 18 | Description | |
| 19 | ----------- | |
| 20 | ||
| 21 | Represents a sequence containing no elements. | |
| 22 | ||
| 23 | ||
| 24 | Header | |
| 25 | ------ | |
| 26 | ||
| 27 | .. parsed-literal:: | |
| 28 | ||
| 29 | #include <boost/mpl/empty_sequence.hpp> | |
| 30 | ||
| 31 | ||
| 32 | Expression semantics | |
| 33 | -------------------- | |
| 34 | ||
| 35 | |Semantics disclaimer...| |Random Access Sequence|. | |
| 36 | ||
| 37 | In the following table, ``s`` is an instance of ``empty_sequence``. | |
| 38 | ||
| 39 | +-------------------------------+-----------------------------------------------------------+ | |
| 40 | | Expression | Semantics | | |
| 41 | +===============================+===========================================================+ | |
| 42 | | ``empty_sequence`` | An empty |Random Access Sequence|. | | |
| 43 | +-------------------------------+-----------------------------------------------------------+ | |
| 44 | | ``size<s>::type`` | ``size<s>::value == 0``; see |Random Access Sequence|. | | |
| 45 | +-------------------------------+-----------------------------------------------------------+ | |
| 46 | ||
| 47 | ||
| 48 | Example | |
| 49 | ------- | |
| 50 | ||
| 51 | .. parsed-literal:: | |
| 52 | ||
| 53 | typedef begin<empty_sequence>::type first; | |
| 54 | typedef end<empty_sequence>::type last; | |
| 55 | ||
| 56 | BOOST_MPL_ASSERT(( is_same<first,last> )); | |
| 57 | BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 ); | |
| 58 | ||
| 59 | typedef transform_view< | |
| 60 | empty_sequence | |
| 61 | , add_pointer<_> | |
| 62 | > empty_view; | |
| 63 | ||
| 64 | BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 ); | |
| 65 | ||
| 66 | ||
| 67 | See also | |
| 68 | -------- | |
| 69 | ||
| 70 | |Sequences|, |Views|, |vector|, |list|, |single_view| | |
| 71 | ||
| 72 | ||
| 73 |