commit | f840a151064bcff13290b505ce88b097a27a70e9 | [log] [tgz] |
---|---|---|
author | Treehugger Robot <android-test-infra-autosubmit@system.gserviceaccount.com> | Thu Nov 09 01:18:27 2023 +0000 |
committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Thu Nov 09 01:18:27 2023 +0000 |
tree | 4525f9495dff583f2d184efa0e3836da50a8b5e5 | |
parent | c56c6555870dd0e471c77f38aa04513ccb33dab1 [diff] | |
parent | 8b2f4bd94fe4f2201e0c5a96a57ae221f4fc25e2 [diff] |
Merge "Adding autogenerated Trusty makefile rules" into main am: 4b273e2a95 am: 8b2f4bd94f Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/enumn/+/2750956 Change-Id: Id1f6c4acacfdedbccf68c0d6755b516d860850e9 Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This crate provides a derive macro to generate a function for converting a primitive integer into the corresponding variant of an enum.
The generated function is named n
and has the following signature:
impl YourEnum { pub fn n(value: Repr) -> Option<Self>; }
where Repr
is an integer type of the right size as described in more detail below.
use enumn::N; #[derive(PartialEq, Debug, N)] enum Status { LegendaryTriumph, QualifiedSuccess, FortuitousRevival, IndeterminateStalemate, RecoverableSetback, DireMisadventure, AbjectFailure, } fn main() { let s = Status::n(1); assert_eq!(s, Some(Status::QualifiedSuccess)); let s = Status::n(9); assert_eq!(s, None); }
The generated signature depends on whether the enum has a #[repr(..)]
attribute. If a repr
is specified, the input to n
will be required to be of that type.
#[derive(enumn::N)] #[repr(u8)] enum E { /* ... */ } // expands to: impl E { pub fn n(value: u8) -> Option<Self> { /* ... */ } }
On the other hand if no repr
is specified then we get a signature that is generic over a variety of possible types.
impl E { pub fn n<REPR: Into<i64>>(value: REPR) -> Option<Self> { /* ... */ } }
The conversion respects explictly specified enum discriminants. Consider this enum:
#[derive(enumn::N)] enum Letter { A = 65, B = 66, }
Here Letter::n(65)
would return Some(Letter::A)
.