konst/slice/slice_iter_methods.rs
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use crate::{
iter::{IntoIterKind, IsIteratorKind},
option, slice,
};
use konst_macro_rules::iterator_shared;
/// Gets a const iterator over `slice`, const equivalent of
/// [`<[T]>::iter`
/// ](https://doc.rust-lang.org/std/primitive.slice.html#method.iter)
///
/// # Example
///
/// ### Normal
///
/// ```rust
/// use konst::iter::for_each;
/// use konst::slice;
///
/// const ARR: &[usize] = &{
/// let mut arr = [0usize; 3];
/// // the `slice::iter` call here is unnecessary,
/// // you can pass a slice reference to `for_each*`
/// for_each!{(i, elem) in slice::iter(&["foo", "hello", "That box"]), enumerate() =>
/// arr[i] = elem.len();
/// }
/// arr
/// };
///
/// assert_eq!(ARR, [3, 5, 8]);
///
/// ```
///
/// ### Reversed
///
/// ```rust
/// use konst::iter::for_each;
/// use konst::slice;
///
/// const ARR: &[usize] = &{
/// let mut arr = [0usize; 3];
/// for_each!{(i, elem) in slice::iter(&["foo", "hello", "That box"]).rev(),enumerate() =>
/// arr[i] = elem.len();
/// }
/// arr
/// };
///
/// assert_eq!(ARR, [8, 5, 3]);
///
/// ```
pub use konst_macro_rules::into_iter::slice_into_iter::iter;
/// Const equivalent of [`core::slice::Iter`].
///
/// This is constructed in either of these ways:
/// ```rust
/// # let a_slice = &[3];
/// # let _ = (
/// konst::slice::iter(a_slice)
/// # ,
/// konst::iter::into_iter!(a_slice)
/// # );
/// ```
pub use konst_macro_rules::into_iter::slice_into_iter::Iter;
/// Const equivalent of `core::iter::Rev<core::slice::Iter<_>>`
///
/// This is constructed in either of these ways:
/// ```rust
/// # let a_slice = &[3];
/// # let _ = (
/// konst::slice::iter(a_slice).rev()
/// # ,
/// konst::iter::into_iter!(a_slice).rev()
/// # );
/// ```
pub use konst_macro_rules::into_iter::slice_into_iter::IterRev;
/// A const equivalent of `slice.iter().copied()`
///
/// # Version compatibility
///
/// This requires the `"rust_1_61"` feature.
///
/// # Example
///
/// ```rust
/// use konst::{iter, slice};
///
/// const fn find_even(slice: &[u32]) -> Option<u32> {
/// iter::eval!(slice::iter_copied(slice),find(|elem| *elem % 2 == 0))
/// }
///
/// assert_eq!(find_even(&[]), None);
/// assert_eq!(find_even(&[1]), None);
/// assert_eq!(find_even(&[1, 2]), Some(2));
/// assert_eq!(find_even(&[5, 4, 3, 2, 1]), Some(4));
///
/// ```
///
#[cfg(feature = "rust_1_61")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_61")))]
pub use konst_macro_rules::into_iter::slice_into_iter::iter_copied;
/// A const equivalent of `iter::Copied<slice::Iter<'a, T>>`.
///
/// This const iterator can be created with [`iter_copied`].
///
/// # Version compatibility
///
/// This requires the `"rust_1_61"` feature.
///
#[cfg(feature = "rust_1_61")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_61")))]
pub use konst_macro_rules::into_iter::slice_into_iter::IterCopied;
/// A const equivalent of `iter::Rev<iter::Copied<slice::Iter<'a, T>>>`
///
/// This const iterator can be created with
/// ```rust
/// # let slice = &[3, 5, 8];
/// # let _: konst::slice::IterCopiedRev<'_, u32> =
/// konst::slice::iter_copied(slice).rev()
/// # ;
/// ```
///
/// # Version compatibility
///
/// This requires the `"rust_1_61"` feature.
///
/// # Example
///
/// ```rust
/// use konst::iter;
/// use konst::slice::{self, IterCopiedRev};
///
/// const fn rfind_even(slice: &[u32]) -> Option<u32> {
/// let iter: IterCopiedRev<'_, u32> = slice::iter_copied(slice).rev();
/// iter::eval!(iter,find(|&elem| elem % 2 == 0))
/// }
///
/// assert_eq!(rfind_even(&[]), None);
/// assert_eq!(rfind_even(&[1]), None);
/// assert_eq!(rfind_even(&[1, 2]), Some(2));
/// assert_eq!(rfind_even(&[1, 2, 3, 4, 5]), Some(4));
///
/// ```
///
#[cfg(feature = "rust_1_61")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_61")))]
pub use konst_macro_rules::into_iter::slice_into_iter::IterCopiedRev;
///////////////////////////////////////////////////////////////////////////////
#[cfg(feature = "rust_1_64")]
mod requires_rust_1_64 {
use super::*;
#[inline(always)]
pub(crate) const fn some_if_nonempty<T>(slice: &[T]) -> Option<&[T]> {
if let [] = slice {
None
} else {
Some(slice)
}
}
/// Const equivalent of
/// [`<[T]>::windows`
/// ](https://doc.rust-lang.org/std/primitive.slice.html#method.windows)
///
/// # Example
///
/// ```rust
/// use konst::{iter, slice};
///
/// const fn is_sorted(slice: &[u8]) -> bool {
/// iter::eval!(slice::windows(slice, 2),all(|w| w[1] > w[0]))
/// }
///
/// assert!(is_sorted(&[3, 5, 8]));
/// assert!(!is_sorted(&[8, 13, 0]));
///
///
///
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
#[track_caller]
pub const fn windows<T>(slice: &[T], size: usize) -> Windows<'_, T> {
assert!(size != 0, "window size must be non-zero");
Windows { slice, size }
}
macro_rules! windows_shared {
(is_forward = $is_forward:ident) => {
iterator_shared! {
is_forward = $is_forward,
item = &'a [T],
iter_forward = Windows<'a, T>,
iter_reversed = WindowsRev<'a, T>,
next(self){
if self.slice.len() < self.size {
None
} else {
let up_to = slice::slice_up_to(self.slice, self.size);
self.slice = slice::slice_from(self.slice, 1);
Some((up_to, self))
}
},
next_back {
let len = self.slice.len();
if len < self.size {
None
} else {
let up_to = slice::slice_from(self.slice, len - self.size);
self.slice = slice::slice_up_to(self.slice, len - 1);
Some((up_to, self))
}
},
fields = {slice, size},
}
};
}
/// Const equivalent of [`core::slice::Windows`]
///
/// This is constructed with [`windows`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::windows(slice, 1)
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct Windows<'a, T> {
slice: &'a [T],
size: usize,
}
impl<T> IntoIterKind for Windows<'_, T> {
type Kind = IsIteratorKind;
}
/// Const equivalent of `core::iter::Rev<core::slice::Windows>`
///
/// This is constructed with [`windows`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::windows(slice, 1).rev()
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct WindowsRev<'a, T> {
slice: &'a [T],
size: usize,
}
impl<T> IntoIterKind for WindowsRev<'_, T> {
type Kind = IsIteratorKind;
}
impl<'a, T> Windows<'a, T> {
windows_shared! {is_forward = true}
}
impl<'a, T> WindowsRev<'a, T> {
windows_shared! {is_forward = false}
}
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
/// Const equivalent of
/// [`<[T]>::chunks`](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks)
///
/// # Example
///
/// ```rust
/// use konst::iter::for_each;
/// use konst::slice;
///
/// const CHUNKS: &[&[u8]] = &{
/// let mut out = [&[] as &[u8]; 3] ;
/// let fibb = &[3, 5, 8, 13, 21, 34, 55, 89];
/// for_each!{(i, chunk) in slice::chunks(fibb, 3),enumerate() =>
/// out[i] = chunk;
/// }
/// out
/// };
///
/// let expected: &[&[u8]] = &[&[3, 5, 8], &[13, 21, 34], &[55, 89]];
///
/// assert_eq!(CHUNKS, expected)
///
/// ```
///
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
#[track_caller]
pub const fn chunks<T>(slice: &[T], size: usize) -> Chunks<'_, T> {
assert!(size != 0, "chunk size must be non-zero");
Chunks {
slice: some_if_nonempty(slice),
size,
}
}
macro_rules! chunks_shared {
(is_forward = $is_forward:ident) => {
iterator_shared! {
is_forward = $is_forward,
item = &'a [T],
iter_forward = Chunks<'a, T>,
iter_reversed = ChunksRev<'a, T>,
next(self) {
option::map!(self.slice, |slice| {
let (ret, next) = slice::split_at(slice, self.size);
self.slice = some_if_nonempty(next);
(ret, self)
})
},
next_back{
option::map!(self.slice, |slice| {
let at = (slice.len() - 1) / self.size * self.size;
let (next, ret) = slice::split_at(slice, at);
self.slice = some_if_nonempty(next);
(ret, self)
})
},
fields = {slice, size},
}
};
}
/// Const equivalent of [`core::slice::Chunks`]
///
/// This is constructed with [`chunks`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::chunks(slice, 1)
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct Chunks<'a, T> {
slice: Option<&'a [T]>,
size: usize,
}
impl<T> IntoIterKind for Chunks<'_, T> {
type Kind = IsIteratorKind;
}
/// Const equivalent of `core::iter::Rev<core::slice::Chunks>`
///
/// This is constructed with [`chunks`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::chunks(slice, 1).rev()
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct ChunksRev<'a, T> {
slice: Option<&'a [T]>,
size: usize,
}
impl<T> IntoIterKind for ChunksRev<'_, T> {
type Kind = IsIteratorKind;
}
impl<'a, T> Chunks<'a, T> {
chunks_shared! {is_forward = true}
}
impl<'a, T> ChunksRev<'a, T> {
chunks_shared! {is_forward = false}
}
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
/// Const equivalent of
/// [`<[T]>::chunks_exact`
/// ](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks_exact)
///
/// # Example
///
/// ```rust
/// use konst::{for_range, option, slice};
///
/// const FOUND: [&[u8]; 3] = {
/// let iter = slice::chunks_exact(&[3, 5, 8, 13, 21, 34, 55, 89], 3);
/// let (elem0, iter) = option::unwrap!(iter.next());
/// let (elem1, iter) = option::unwrap!(iter.next());
/// [elem0, elem1, iter.remainder()]
/// };
///
/// let expected: [&[u8]; 3] = [&[3u8, 5, 8], &[13, 21, 34], &[55, 89]];
///
/// assert_eq!(FOUND, expected);
///
/// ```
///
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
#[track_caller]
pub const fn chunks_exact<T>(slice: &[T], size: usize) -> ChunksExact<'_, T> {
assert!(size != 0, "chunk size must be non-zero");
ChunksExact { slice, size }
}
macro_rules! chunks_exact_shared {
(is_forward = $is_forward:ident) => {
iterator_shared! {
is_forward = $is_forward,
item = &'a [T],
iter_forward = ChunksExact<'a, T>,
iter_reversed = ChunksExactRev<'a, T>,
next(self) {
if self.slice.len() < self.size {
None
} else {
let (ret, next) = slice::split_at(self.slice, self.size);
self.slice = next;
Some((ret, self))
}
},
next_back {
if let Some(mut at) = self.slice.len().checked_sub(self.size) {
at = at / self.size * self.size;
let (next, ret) = slice::split_at(self.slice, at);
self.slice = next;
Some((slice::slice_up_to(ret, self.size), self))
} else {
None
}
},
fields = {slice, size},
}
/// Returns the remainder of the slice that not returned by [`next`](Self::next),
/// because it is shorter than the chunk size.
pub const fn remainder(&self) -> &'a [T] {
self.slice
}
};
}
/// Const equivalent of [`core::slice::ChunksExact`]
///
/// This is constructed with [`chunks_exact`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::chunks_exact(slice, 1)
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct ChunksExact<'a, T> {
slice: &'a [T],
size: usize,
}
impl<T> IntoIterKind for ChunksExact<'_, T> {
type Kind = IsIteratorKind;
}
/// Const equivalent of `core::iter::Rev<core::slice::ChunksExact>`
///
/// This is constructed with [`chunks_exact`] like this:
/// ```rust
/// # let slice = &[3];
/// # let _ =
/// konst::slice::chunks_exact(slice, 1).rev()
/// # ;
/// ```
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "rust_1_64")))]
pub struct ChunksExactRev<'a, T> {
slice: &'a [T],
size: usize,
}
impl<T> IntoIterKind for ChunksExactRev<'_, T> {
type Kind = IsIteratorKind;
}
impl<'a, T> ChunksExact<'a, T> {
chunks_exact_shared! {is_forward = true}
}
impl<'a, T> ChunksExactRev<'a, T> {
chunks_exact_shared! {is_forward = false}
}
}
#[cfg(feature = "rust_1_64")]
pub use requires_rust_1_64::*;