tag | 51857e1845c6753eea357ce9dfafe3140e3d69cd | |
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tagger | The Android Open Source Project <initial-contribution@android.com> | Mon May 06 21:48:02 2024 -0700 |
object | f200e1cc821c715876e5466cc7255c842ef90692 |
Android platform 14.0.0 release 7
commit | f200e1cc821c715876e5466cc7255c842ef90692 | [log] [tgz] |
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author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Mar 10 02:19:53 2023 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Mar 10 02:19:53 2023 +0000 |
tree | 8ae195a806078dddb243dd9857481738fdc27cb7 | |
parent | 8f669db6a87796450c7731e80cd264108fd87535 [diff] | |
parent | 514dc9e9384d009ed4d3d35ff1d9f178d7ae21c4 [diff] |
Snap for 9719949 from 514dc9e9384d009ed4d3d35ff1d9f178d7ae21c4 to udc-release Change-Id: I7d0d5c69cd1c698a7390773aad6b4d8dfe44dbff
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)
.