projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | [#reject] |
| 2 | [section reject] | |
| 3 | ||
| 4 | [h1 Synopsis] | |
| 5 | ||
| 6 | template <class Msg, class Pos> | |
| 7 | struct reject; | |
| 8 | ||
| 9 | This is a [link metaprogramming_value template metaprogramming value]. | |
| 10 | ||
| 11 | [table Arguments | |
| 12 | [[Name] [Type]] | |
| 13 | [[`Msg`] [[link metaprogramming_value template metaprogramming value]]] | |
| 14 | [[`Pos`] [[link source_position source position]]] | |
| 15 | ] | |
| 16 | ||
| 17 | [h1 Description] | |
| 18 | ||
| 19 | Values representing a failed parser application. It behaves as a | |
| 20 | [link lazy_metafunction lazy template metafunction]: when it is evaluated as a | |
| 21 | metafunction, it returns itself with its arguments evaluated. See expression | |
| 22 | semantics for further details. | |
| 23 | ||
| 24 | [note | |
| 25 | Note that for backward compatibility when `Msg::type` is not defined, | |
| 26 | `reject<....>::type` does not evaluate `Msg`. For example | |
| 27 | `reject<int, start>::type` is `reject<int, start::type>`. Using types that are | |
| 28 | not template metaprogramming values as `Msg` is deprecated and will not work | |
| 29 | in future versions of the library. | |
| 30 | ] | |
| 31 | ||
| 32 | [h1 Expressions semantics] | |
| 33 | ||
| 34 | For any `m` template metaprogramming value and `p` source position the following | |
| 35 | are equivalent: | |
| 36 | ||
| 37 | reject<m, p>::type | |
| 38 | ||
| 39 | reject<m, p::type> | |
| 40 | ||
| 41 | [h1 Header] | |
| 42 | ||
| 43 | #include <boost/metaparse/reject.hpp> | |
| 44 | ||
| 45 | [h1 Operations] | |
| 46 | ||
| 47 | * [link get_position `get_position`] | |
| 48 | * [link get_message `get_message`] | |
| 49 | ||
| 50 | [endsect] | |
| 51 |