const generic expr based fixed length array manipulation crate
array flatten
| -rw-r--r-- | Cargo.toml | 2 | ||||
| -rw-r--r-- | src/lib.rs | 34 |
2 files changed, 34 insertions, 2 deletions
@@ -1,6 +1,6 @@ [package] name = "atools" -version = "0.1.1" +version = "0.1.2" edition = "2021" description = "const generic expr based fixed length array manipulation" authors = ["bend-n <[email protected]>"] @@ -29,7 +29,7 @@ pub mod prelude { #[doc(inline)] pub use super::{ pervasive::prelude::*, range, splat, Array, ArrayTools, Chunked, CollectArray, Couple, - DropFront, Join, Pop, Trunc, Tuple, + DropFront, Flatten, Join, Pop, Trunc, Tuple, }; #[doc(inline)] pub use core::array::from_fn; @@ -226,6 +226,38 @@ impl<const N: usize, T> Chunked<T, N> for [T; N] { } } +/// Flatten arrays. +pub trait Flatten<T, const N: usize, const N2: usize> { + /// Takes a `[[T; N]; N2]`, and flattens it to a `[T; N * N2]`. + /// + /// # Examples + /// + /// ``` + /// # #![feature(generic_const_exprs)] + /// # use atools::prelude::*; + /// assert_eq!([[1, 2, 3], [4, 5, 6]].flatten(), [1, 2, 3, 4, 5, 6]); + /// + /// assert_eq!( + /// [[1, 2, 3], [4, 5, 6]].flatten(), + /// [[1, 2], [3, 4], [5, 6]].flatten(), + /// ); + /// + /// let array_of_empty_arrays: [[i32; 0]; 5] = [[], [], [], [], []]; + /// assert!(array_of_empty_arrays.flatten().is_empty()); + /// + /// let empty_array_of_arrays: [[u32; 10]; 0] = []; + /// assert!(empty_array_of_arrays.flatten().is_empty()); + /// ``` + fn flatten(self) -> [T; N * N2]; +} + +impl<T, const N: usize, const N2: usize> Flatten<T, N, N2> for [[T; N]; N2] { + fn flatten(self) -> [T; N * N2] { + // SAFETY: layout is the same. + unsafe { core::intrinsics::transmute_unchecked(self) } + } +} + /// Array tools. pub trait ArrayTools<T, const N: usize> { /// Skip `BY` elements. |