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#![no_std]
#![allow(incomplete_features)]
#![feature(generic_const_exprs, ptr_metadata)]
#![warn(clippy::pedantic, missing_docs)]
mod slice;
pub use slice::*;
pub trait ArrayExt<T, const N: usize>: Sized {
fn array_split_at<const M: usize>(self) -> ([T; M], [T; N - M])
where
[T; N - M]: Sized;
fn truncate<const M: usize>(self) -> [T; M]
where
[T; N - M]: Sized,
{
self.array_split_at().0
}
fn append<const M: usize>(self, other: [T; M]) -> [T; N + M];
}
impl<T, const N: usize> ArrayExt<T, N> for [T; N] {
fn array_split_at<const M: usize>(self) -> ([T; M], [T; N - M])
where
[T; N - M]: Sized,
{
let arr = core::mem::ManuallyDrop::new(self).as_ptr();
unsafe {
(
core::ptr::read(arr.add(0).cast()),
core::ptr::read(arr.add(M).cast()),
)
}
}
fn append<const M: usize>(self, other: [T; M]) -> [T; N + M] {
let arr_a = core::mem::ManuallyDrop::new(self).as_ptr();
let arr_b = core::mem::ManuallyDrop::new(other).as_ptr();
let mut arr_c = core::mem::MaybeUninit::<[T; N + M]>::uninit();
let p = arr_c.as_mut_ptr().cast::<T>();
unsafe {
core::ptr::copy(arr_a, p.add(0), N);
core::ptr::copy(arr_b, p.add(N), M);
core::mem::MaybeUninit::assume_init(arr_c)
}
}
}
#[cfg(test)]
mod tests {
use crate::ArrayExt;
#[test]
fn split_at() {
let (a, b) = [1, 2, 3, 4, 5].array_split_at::<3>();
assert_eq!(a, [1, 2, 3]);
assert_eq!(b, [4, 5]);
}
#[test]
fn append() {
let a = [1, 2, 3].append([4, 5]);
assert_eq!(a, [1, 2, 3, 4, 5]);
}
}