tag | 191e73211e24ab8242acae0da0b73bbf2058d6a3 | |
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tagger | The Android Open Source Project <initial-contribution@android.com> | Tue May 07 10:58:35 2024 -0700 |
object | aacdf12a204e973f455dcd71c0d4ee6c8eec67f0 |
Android 14.0.0 release 37
commit | aacdf12a204e973f455dcd71c0d4ee6c8eec67f0 | [log] [tgz] |
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author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Nov 10 00:11:07 2023 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Nov 10 00:11:07 2023 +0000 |
tree | 4525f9495dff583f2d184efa0e3836da50a8b5e5 | |
parent | 8017acfe6fc154298dc19be72b84efb612b4c65e [diff] | |
parent | 040bd3db3c5f4e2e90bcfafce7e5fa3efc48c35c [diff] |
Snap for 11078623 from 040bd3db3c5f4e2e90bcfafce7e5fa3efc48c35c to 24Q1-release Change-Id: I7c5f2f85a71f9d6ad230073140854bc1f5f3f5db
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)
.