tag | 17b47d00e8f5fa523dc841c9c2247d68ba65253b | |
---|---|---|
tagger | The Android Open Source Project <initial-contribution@android.com> | Mon Apr 29 09:53:44 2024 -0700 |
object | 08f1932986f3064f5aa8c26b160243afe1739d26 |
aml_art_341514450 (11720836,com.google.android.art,com.google.android.go.art)
commit | 08f1932986f3064f5aa8c26b160243afe1739d26 | [log] [tgz] |
---|---|---|
author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Jul 07 04:43:05 2023 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Jul 07 04:43:05 2023 +0000 |
tree | 8ae195a806078dddb243dd9857481738fdc27cb7 | |
parent | 57038662745311c211a8484f68314af288c8adc4 [diff] | |
parent | 49a3012dee89afb715c0522baab3c5132d91c53c [diff] |
Snap for 10453563 from 49a3012dee89afb715c0522baab3c5132d91c53c to mainline-art-release Change-Id: I9cd75647553a30c54a505e2a8e3d70c1502fd540
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)
.