diff options
Diffstat (limited to 'vendor/generic-array-0.12.4/src/arr.rs')
-rw-r--r-- | vendor/generic-array-0.12.4/src/arr.rs | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/vendor/generic-array-0.12.4/src/arr.rs b/vendor/generic-array-0.12.4/src/arr.rs new file mode 100644 index 000000000..ebe687500 --- /dev/null +++ b/vendor/generic-array-0.12.4/src/arr.rs @@ -0,0 +1,126 @@ +//! Implementation for `arr!` macro. + +use super::ArrayLength; +use core::ops::Add; +use typenum::U1; + +/// Helper trait for `arr!` macro +pub trait AddLength<T, N: ArrayLength<T>>: ArrayLength<T> { + /// Resulting length + type Output: ArrayLength<T>; +} + +impl<T, N1, N2> AddLength<T, N2> for N1 +where + N1: ArrayLength<T> + Add<N2>, + N2: ArrayLength<T>, + <N1 as Add<N2>>::Output: ArrayLength<T>, +{ + type Output = <N1 as Add<N2>>::Output; +} + +/// Helper type for `arr!` macro +pub type Inc<T, U> = <U as AddLength<T, U1>>::Output; + +#[doc(hidden)] +#[macro_export] +macro_rules! arr_impl { + (@replace_expr $e:expr)=>{ + 1 + }; + ($T:ty; $N:ty, [$($x:expr),*], []) => ({ + const __ARR_LENGTH:usize=0 $(+ $crate::arr_impl!(@replace_expr $x) )*; + fn __do_transmute<'a, T, N: $crate::ArrayLength<T>>(arr: [T; __ARR_LENGTH]) -> $crate::GenericArray<T, N> { + unsafe { $crate::transmute(arr) } + } + + let _:[();<$N as $crate::typenum::Unsigned>::USIZE]=[();__ARR_LENGTH]; + + __do_transmute::<$T,$N>([$($x),*]) + }); + ($T:ty; $N:ty, [], [$x1:expr]) => ( + $crate::arr_impl!($T; $crate::arr::Inc<$T, $N>, [$x1], []) + ); + ($T:ty; $N:ty, [], [$x1:expr, $($x:expr),+]) => ( + $crate::arr_impl!($T; $crate::arr::Inc<$T, $N>, [$x1], [$($x),+]) + ); + ($T:ty; $N:ty, [$($y:expr),+], [$x1:expr]) => ( + $crate::arr_impl!($T; $crate::arr::Inc<$T, $N>, [$($y),+, $x1], []) + ); + ($T:ty; $N:ty, [$($y:expr),+], [$x1:expr, $($x:expr),+]) => ( + $crate::arr_impl!($T; $crate::arr::Inc<$T, $N>, [$($y),+, $x1], [$($x),+]) + ); +} + +/// Macro allowing for easy generation of Generic Arrays. +/// Example: `let test = arr![u32; 1, 2, 3];` +#[macro_export] +macro_rules! arr { + ($T:ty; $(,)*) => ({ + unsafe { $crate::transmute::<[$T; 0], $crate::GenericArray<$T, $crate::typenum::U0>>([]) } + }); + ($T:ty; $($x:expr),* $(,)*) => ( + arr_impl!($T; $crate::typenum::U0, [], [$($x),*]) + ); + ($($x:expr,)+) => (arr![$($x),*]); + () => ("""Macro requires a type, e.g. `let array = arr![u32; 1, 2, 3];`") +} + + +mod doctests_only{ + /// + /// # With ellision + /// + /// Testing that lifetimes aren't transmuted when they're ellided. + /// + /// ```compile_fail + /// #[macro_use] extern crate generic_array; + /// fn main() { + /// fn unsound_lifetime_extension<'a, A>(a: &'a A) -> &'static A { + /// arr![&A; a][0] + /// } + /// } + /// ``` + /// + /// ```rust + /// #[macro_use] extern crate generic_array; + /// fn main() { + /// fn unsound_lifetime_extension<'a, A>(a: &'a A) -> &'a A { + /// arr![&A; a][0] + /// } + /// } + /// ``` + /// + /// # Without ellision + /// + /// Testing that lifetimes aren't transmuted when they're specified explicitly. + /// + /// ```compile_fail + /// #[macro_use] extern crate generic_array; + /// fn main() { + /// fn unsound_lifetime_extension<'a, A>(a: &'a A) -> &'static A { + /// arr![&'a A; a][0] + /// } + /// } + /// ``` + /// + /// ```compile_fail + /// #[macro_use] extern crate generic_array; + /// fn main() { + /// fn unsound_lifetime_extension<'a, A>(a: &'a A) -> &'static A { + /// arr![&'static A; a][0] + /// } + /// } + /// ``` + /// + /// ```rust + /// #[macro_use] extern crate generic_array; + /// fn main() { + /// fn unsound_lifetime_extension<'a, A>(a: &'a A) -> &'a A { + /// arr![&'a A; a][0] + /// } + /// } + /// ``` + #[allow(dead_code)] + pub enum DocTests{} +} |