ring/polyfill/

slice.rs

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//
// The above copyright notice and this permission notice
// shall be included in all copies or substantial portions
// of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
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// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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mod as_chunks;
mod as_chunks_mut;

pub use as_chunks::{as_chunks, AsChunks};
pub use as_chunks_mut::{as_chunks_mut, AsChunksMut};

// TODO(MSRV feature(split_at_checked)): Use `slice::split_at_checked`.
//
// Note that the libcore version is implemented in terms of
// `slice::split_at_unchecked()`, and `slice::split_at()` was changed to be
// implemented in terms of `split_at_checked`. For now, we implement this in
// terms of `split_at` and rely on the optimizer to eliminate the panic.
#[inline(always)]
pub fn split_at_checked<T>(slice: &[T], i: usize) -> Option<(&[T], &[T])> {
    if slice.len() >= i {
        Some(slice.split_at(i))
    } else {
        None
    }
}

// TODO(MSRV-1.77): Use `slice::split_first_chunk_mut`.
#[inline(always)]
pub fn split_first_chunk_mut<T, const N: usize>(
    slice: &mut [T],
) -> Option<(&mut [T; N], &mut [T])> {
    if slice.len() >= N {
        let (head, tail) = slice.split_at_mut(N);
        head.try_into().ok().map(|head| (head, tail))
    } else {
        None
    }
}