| use crate::iter::adapters::{ |
| zip::try_get_unchecked, TrustedRandomAccess, TrustedRandomAccessNoCoerce, |
| }; |
| use crate::iter::{FusedIterator, TrustedLen}; |
| use crate::mem::MaybeUninit; |
| use crate::mem::SizedTypeProperties; |
| use crate::ops::Try; |
| use crate::{array, ptr}; |
| |
| /// An iterator that copies the elements of an underlying iterator. |
| /// |
| /// This `struct` is created by the [`copied`] method on [`Iterator`]. See its |
| /// documentation for more. |
| /// |
| /// [`copied`]: Iterator::copied |
| /// [`Iterator`]: trait.Iterator.html |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| #[must_use = "iterators are lazy and do nothing unless consumed"] |
| #[derive(Clone, Debug)] |
| pub struct Copied<I> { |
| it: I, |
| } |
| |
| impl<I> Copied<I> { |
| pub(in crate::iter) fn new(it: I) -> Copied<I> { |
| Copied { it } |
| } |
| } |
| |
| fn copy_fold<T: Copy, Acc>(mut f: impl FnMut(Acc, T) -> Acc) -> impl FnMut(Acc, &T) -> Acc { |
| move |acc, &elt| f(acc, elt) |
| } |
| |
| fn copy_try_fold<T: Copy, Acc, R>(mut f: impl FnMut(Acc, T) -> R) -> impl FnMut(Acc, &T) -> R { |
| move |acc, &elt| f(acc, elt) |
| } |
| |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| impl<'a, I, T: 'a> Iterator for Copied<I> |
| where |
| I: Iterator<Item = &'a T>, |
| T: Copy, |
| { |
| type Item = T; |
| |
| fn next(&mut self) -> Option<T> { |
| self.it.next().copied() |
| } |
| |
| fn next_chunk<const N: usize>( |
| &mut self, |
| ) -> Result<[Self::Item; N], array::IntoIter<Self::Item, N>> |
| where |
| Self: Sized, |
| { |
| <I as SpecNextChunk<'_, N, T>>::spec_next_chunk(&mut self.it) |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.it.size_hint() |
| } |
| |
| fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R |
| where |
| Self: Sized, |
| F: FnMut(B, Self::Item) -> R, |
| R: Try<Output = B>, |
| { |
| self.it.try_fold(init, copy_try_fold(f)) |
| } |
| |
| fn fold<Acc, F>(self, init: Acc, f: F) -> Acc |
| where |
| F: FnMut(Acc, Self::Item) -> Acc, |
| { |
| self.it.fold(init, copy_fold(f)) |
| } |
| |
| fn nth(&mut self, n: usize) -> Option<T> { |
| self.it.nth(n).copied() |
| } |
| |
| fn last(self) -> Option<T> { |
| self.it.last().copied() |
| } |
| |
| fn count(self) -> usize { |
| self.it.count() |
| } |
| |
| #[inline] |
| fn advance_by(&mut self, n: usize) -> Result<(), usize> { |
| self.it.advance_by(n) |
| } |
| |
| unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T |
| where |
| Self: TrustedRandomAccessNoCoerce, |
| { |
| // SAFETY: the caller must uphold the contract for |
| // `Iterator::__iterator_get_unchecked`. |
| *unsafe { try_get_unchecked(&mut self.it, idx) } |
| } |
| } |
| |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| impl<'a, I, T: 'a> DoubleEndedIterator for Copied<I> |
| where |
| I: DoubleEndedIterator<Item = &'a T>, |
| T: Copy, |
| { |
| fn next_back(&mut self) -> Option<T> { |
| self.it.next_back().copied() |
| } |
| |
| fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R |
| where |
| Self: Sized, |
| F: FnMut(B, Self::Item) -> R, |
| R: Try<Output = B>, |
| { |
| self.it.try_rfold(init, copy_try_fold(f)) |
| } |
| |
| fn rfold<Acc, F>(self, init: Acc, f: F) -> Acc |
| where |
| F: FnMut(Acc, Self::Item) -> Acc, |
| { |
| self.it.rfold(init, copy_fold(f)) |
| } |
| |
| #[inline] |
| fn advance_back_by(&mut self, n: usize) -> Result<(), usize> { |
| self.it.advance_back_by(n) |
| } |
| } |
| |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| impl<'a, I, T: 'a> ExactSizeIterator for Copied<I> |
| where |
| I: ExactSizeIterator<Item = &'a T>, |
| T: Copy, |
| { |
| fn len(&self) -> usize { |
| self.it.len() |
| } |
| |
| fn is_empty(&self) -> bool { |
| self.it.is_empty() |
| } |
| } |
| |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| impl<'a, I, T: 'a> FusedIterator for Copied<I> |
| where |
| I: FusedIterator<Item = &'a T>, |
| T: Copy, |
| { |
| } |
| |
| #[doc(hidden)] |
| #[unstable(feature = "trusted_random_access", issue = "none")] |
| unsafe impl<I> TrustedRandomAccess for Copied<I> where I: TrustedRandomAccess {} |
| |
| #[doc(hidden)] |
| #[unstable(feature = "trusted_random_access", issue = "none")] |
| unsafe impl<I> TrustedRandomAccessNoCoerce for Copied<I> |
| where |
| I: TrustedRandomAccessNoCoerce, |
| { |
| const MAY_HAVE_SIDE_EFFECT: bool = I::MAY_HAVE_SIDE_EFFECT; |
| } |
| |
| #[stable(feature = "iter_copied", since = "1.36.0")] |
| unsafe impl<'a, I, T: 'a> TrustedLen for Copied<I> |
| where |
| I: TrustedLen<Item = &'a T>, |
| T: Copy, |
| { |
| } |
| |
| trait SpecNextChunk<'a, const N: usize, T: 'a>: Iterator<Item = &'a T> |
| where |
| T: Copy, |
| { |
| fn spec_next_chunk(&mut self) -> Result<[T; N], array::IntoIter<T, N>>; |
| } |
| |
| impl<'a, const N: usize, I, T: 'a> SpecNextChunk<'a, N, T> for I |
| where |
| I: Iterator<Item = &'a T>, |
| T: Copy, |
| { |
| default fn spec_next_chunk(&mut self) -> Result<[T; N], array::IntoIter<T, N>> { |
| array::iter_next_chunk(&mut self.map(|e| *e)) |
| } |
| } |
| |
| impl<'a, const N: usize, T: 'a> SpecNextChunk<'a, N, T> for crate::slice::Iter<'a, T> |
| where |
| T: Copy, |
| { |
| fn spec_next_chunk(&mut self) -> Result<[T; N], array::IntoIter<T, N>> { |
| let mut raw_array = MaybeUninit::uninit_array(); |
| |
| let len = self.len(); |
| |
| if T::IS_ZST { |
| if len < N { |
| let _ = self.advance_by(len); |
| // SAFETY: ZSTs can be conjured ex nihilo; only the amount has to be correct |
| return Err(unsafe { array::IntoIter::new_unchecked(raw_array, 0..len) }); |
| } |
| |
| let _ = self.advance_by(N); |
| // SAFETY: ditto |
| return Ok(unsafe { MaybeUninit::array_assume_init(raw_array) }); |
| } |
| |
| if len < N { |
| // SAFETY: `len` indicates that this many elements are available and we just checked that |
| // it fits into the array. |
| unsafe { |
| ptr::copy_nonoverlapping( |
| self.as_ref().as_ptr(), |
| raw_array.as_mut_ptr() as *mut T, |
| len, |
| ); |
| let _ = self.advance_by(len); |
| return Err(array::IntoIter::new_unchecked(raw_array, 0..len)); |
| } |
| } |
| |
| // SAFETY: `len` is larger than the array size. Copy a fixed amount here to fully initialize |
| // the array. |
| unsafe { |
| ptr::copy_nonoverlapping(self.as_ref().as_ptr(), raw_array.as_mut_ptr() as *mut T, N); |
| let _ = self.advance_by(N); |
| Ok(MaybeUninit::array_assume_init(raw_array)) |
| } |
| } |
| } |