tag | d96ec9cda6efeed04d372aa09bfa9fdea02b99a9 | |
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tagger | The Android Open Source Project <initial-contribution@android.com> | Thu May 19 16:14:35 2022 -0700 |
object | e993fb1a1e8ffd7886e1efba6a8f3216bec7ecc2 |
Platform Tools Release 33.0.0 (8141338)
commit | e993fb1a1e8ffd7886e1efba6a8f3216bec7ecc2 | [log] [tgz] |
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author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Thu Jan 13 02:04:43 2022 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Thu Jan 13 02:04:43 2022 +0000 |
tree | df203de1940d8a090d6e47d90d82252c7274f18e | |
parent | 36b38be80948603e539c2f479bfdf7aa2a607c99 [diff] | |
parent | 856ed9a3e6ab64e36a42aa2032a7bbbcc553f66f [diff] |
Snap for 8074123 from 856ed9a3e6ab64e36a42aa2032a7bbbcc553f66f to sdk-release Change-Id: I58152721b6813f2a010b48a48ddbd62e8ed75d8a
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)
.