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// devela::sys::mem::view::slice::namespace::bytes
use crate::Slice;
/// # `take*` API methods for subslicing.
impl<T> Slice<T> {
// take_first
/// Returns the first `n` elements of the slice.
///
/// Equivalent to `&slice[..n]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_first(slice: &[T], n: usize) -> &[T] {
slice.split_at(n).0
}
/// Returns the first `n` elements of the slice.
///
/// Equivalent to `&slice[..n]`.
///
/// Returns `None` if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_first_checked(slice: &[T], n: usize) -> Option<&[T]> {
match slice.split_at_checked(n) {
Some((subslice, _)) => Some(subslice),
None => None,
}
}
/// Returns the first `n` elements of the slice.
///
/// Equivalent to `&slice[..n]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const unsafe fn take_first_unchecked(slice: &[T], n: usize) -> &[T] {
unsafe { slice.split_at_unchecked(n).0 }
}
/// Returns the first `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[..n]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_first_mut(slice: &mut [T], n: usize) -> &mut [T] {
slice.split_at_mut(n).0
}
/// Returns the first `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[..n]`.
///
/// Returns `None` if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_first_mut_checked(slice: &mut [T], n: usize) -> Option<&mut [T]> {
match slice.split_at_mut_checked(n) {
Some((subslice, _)) => Some(subslice),
None => None,
}
}
/// Returns the first `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[..n]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const unsafe fn take_first_mut_unchecked(slice: &mut [T], n: usize) -> &mut [T] {
unsafe { slice.split_at_mut_unchecked(n).0 }
}
// take_last
/// Returns the last `n` elements of the slice.
///
/// Equivalent to `&slice[slice.len() - n..]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_last(slice: &[T], n: usize) -> &[T] {
slice.split_at(slice.len() - n).1
}
/// Returns the last `n` elements of the slice.
///
/// Equivalent to `&slice[slice.len() - n..]`.
///
/// Returns `None` if `n` > `slice.len()`.
///
/// # Features
/// This method makes use of of the `unsafe_slice` feature is enabled.
#[must_use]
#[inline(always)]
pub const fn take_last_checked(slice: &[T], n: usize) -> Option<&[T]> {
match slice.len().checked_sub(n) {
Some(index) => {
#[cfg(any(feature = "safe_mem", not(feature = "unsafe_slice")))]
return Some(slice.split_at(index).1);
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
// SAFETY: `n` is checked to be within bounds and valid
return Some(unsafe { slice.split_at_unchecked(index).1 });
}
None => None,
}
}
/// Returns the last `n` elements of the slice.
///
/// Equivalent to `&slice[slice.len() - n..]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const unsafe fn take_last_unchecked(slice: &[T], n: usize) -> &[T] {
unsafe { slice.split_at_unchecked(slice.len() - n).1 }
}
/// Returns the last `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[slice.len() - n..]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_last_mut(slice: &mut [T], n: usize) -> &mut [T] {
slice.split_at_mut(slice.len() - n).1
}
/// Returns the last `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[slice.len() - n..]`.
///
/// Returns `None` if `n` > `slice.len()`.
///
/// # Features
/// This method makes use of of the `unsafe_slice` feature is enabled.
#[must_use]
#[inline(always)]
pub const fn take_last_mut_checked(slice: &mut [T], n: usize) -> Option<&mut [T]> {
match slice.len().checked_sub(n) {
Some(index) => {
#[cfg(any(feature = "safe_mem", not(feature = "unsafe_slice")))]
return Some(slice.split_at_mut(index).1);
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
// SAFETY: `n` is checked to be within bounds and valid
return Some(unsafe { slice.split_at_mut_unchecked(index).1 });
}
None => None,
}
}
/// Returns the last `n` elements of the exclusive slice.
///
/// Equivalent to `&mut slice[slice.len() - n..]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const unsafe fn take_last_mut_unchecked(slice: &mut [T], n: usize) -> &mut [T] {
unsafe { slice.split_at_mut_unchecked(slice.len() - n).1 }
}
// take_omit_last
/// Returns the slice omitting the last `n` elements.
///
/// Equivalent to `&slice[..slice.len() - n]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_omit_last(slice: &[T], n: usize) -> &[T] {
slice.split_at(slice.len() - n).0
}
/// Returns the slice omitting the last `n` elements.
///
/// Equivalent to `&slice[..slice.len() - n]`.
///
/// Returns `None` if `n` > `slice.len()`.
///
/// # Features
/// This method makes use of of the `unsafe_slice` feature is enabled.
#[must_use]
#[inline(always)]
pub const fn take_omit_last_checked(slice: &[T], n: usize) -> Option<&[T]> {
match slice.len().checked_sub(n) {
Some(index) => {
#[cfg(any(feature = "safe_mem", not(feature = "unsafe_slice")))]
return Some(slice.split_at(index).0);
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
// SAFETY: `n` is checked to be within bounds and valid
return Some(unsafe { slice.split_at_unchecked(index).0 });
}
None => None,
}
}
/// Returns the slice omitting the last `n` elements.
///
/// Equivalent to `&slice[..slice.len() - n]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const fn take_omit_last_unchecked(slice: &[T], n: usize) -> &[T] {
unsafe { slice.split_at_unchecked(slice.len() - n).0 }
}
/// Returns the exclusive slice omitting the last `n` elements.
///
/// Equivalent to `&mut slice[..slice.len() - n]`.
///
/// # Panics
/// Panics if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
pub const fn take_omit_last_mut(slice: &mut [T], n: usize) -> &mut [T] {
slice.split_at_mut(slice.len() - n).0
}
/// Returns the exclusive slice omitting the last `n` elements.
///
/// Equivalent to `&mut slice[..slice.len() - n]`.
///
/// Returns `None` if `n` > `slice.len()`.
///
/// # Features
/// This method makes use of of the `unsafe_slice` feature is enabled.
#[must_use]
#[inline(always)]
pub const fn take_omit_last_mut_checked(slice: &mut [T], n: usize) -> Option<&mut [T]> {
match slice.len().checked_sub(n) {
Some(index) => {
#[cfg(any(feature = "safe_mem", not(feature = "unsafe_slice")))]
return Some(slice.split_at_mut(index).0);
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
// SAFETY: `n` is checked to be within bounds and valid
return Some(unsafe { slice.split_at_mut_unchecked(index).0 });
}
None => None,
}
}
/// Returns the exclusive slice omitting the last `n` elements.
///
/// Equivalent to `&mut slice[..slice.len() - n]`.
///
/// # Safety
/// Results in *undefined behavior* if `n` > `slice.len()`.
#[must_use]
#[inline(always)]
#[cfg(all(not(feature = "safe_mem"), feature = "unsafe_slice"))]
#[cfg_attr(nightly_doc, doc(cfg(feature = "unsafe_slice")))]
pub const fn take_omit_last_mut_unchecked(slice: &mut [T], n: usize) -> &mut [T] {
unsafe { slice.split_at_mut_unchecked(slice.len() - n).0 }
}
}