tag | f01fd9f53507093eaacb9d12079a6af57045f72f | |
---|---|---|
tagger | Xin Li <delphij@google.com> | Wed Apr 24 20:16:33 2024 -0700 |
object | b8406674010aaa52be8febf6d0894a99fe1798ff |
aml_odp_341610000 (11382236,com.google.android.go.ondevicepersonalization,com.google.android.ondevicepersonalization)
commit | b8406674010aaa52be8febf6d0894a99fe1798ff | [log] [tgz] |
---|---|---|
author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Jul 07 07:12:50 2023 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Jul 07 07:12:50 2023 +0000 |
tree | 8ae195a806078dddb243dd9857481738fdc27cb7 | |
parent | bdd16bd5295b58405b179b6c687d761ae01347b7 [diff] | |
parent | 49a3012dee89afb715c0522baab3c5132d91c53c [diff] |
Snap for 10453938 from 49a3012dee89afb715c0522baab3c5132d91c53c to mainline-odp-release Change-Id: If0bf0154816ee8891b6b064f47631488c729c58c
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)
.