commit | 49a3012dee89afb715c0522baab3c5132d91c53c | [log] [tgz] |
---|---|---|
author | Matthew Maurer <mmaurer@google.com> | Thu Mar 09 18:06:16 2023 +0000 |
committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Thu Mar 09 18:06:16 2023 +0000 |
tree | 8ae195a806078dddb243dd9857481738fdc27cb7 | |
parent | 7cd1272f9094fe6e43e00542b445ab4f081607af [diff] | |
parent | 514dc9e9384d009ed4d3d35ff1d9f178d7ae21c4 [diff] |
Make enumn available to product and vendor am: d40c576a19 am: 022c204831 am: b2857ce51f am: 514dc9e938 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/enumn/+/2476341 Change-Id: Ia74a1c0dc07ff19f9b8dbe645277e4a7881f0380 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)
.