| use crate::iter::adapters::{ |
| zip::try_get_unchecked, SourceIter, TrustedRandomAccess, TrustedRandomAccessNoCoerce, |
| }; |
| use crate::iter::{FusedIterator, InPlaceIterable, TrustedLen, UncheckedIterator}; |
| use crate::ops::Try; |
| use core::num::NonZeroUsize; |
| |
| /// An iterator that clones the elements of an underlying iterator. |
| /// |
| /// This `struct` is created by the [`cloned`] method on [`Iterator`]. See its |
| /// documentation for more. |
| /// |
| /// [`cloned`]: Iterator::cloned |
| /// [`Iterator`]: trait.Iterator.html |
| #[stable(feature = "iter_cloned", since = "1.1.0")] |
| #[must_use = "iterators are lazy and do nothing unless consumed"] |
| #[derive(Clone, Debug)] |
| pub struct Cloned<I> { |
| it: I, |
| } |
| |
| impl<I> Cloned<I> { |
| pub(in crate::iter) fn new(it: I) -> Cloned<I> { |
| Cloned { it } |
| } |
| } |
| |
| fn clone_try_fold<T: Clone, Acc, R>(mut f: impl FnMut(Acc, T) -> R) -> impl FnMut(Acc, &T) -> R { |
| move |acc, elt| f(acc, elt.clone()) |
| } |
| |
| #[stable(feature = "iter_cloned", since = "1.1.0")] |
| impl<'a, I, T: 'a> Iterator for Cloned<I> |
| where |
| I: Iterator<Item = &'a T>, |
| T: Clone, |
| { |
| type Item = T; |
| |
| fn next(&mut self) -> Option<T> { |
| self.it.next().cloned() |
| } |
| |
| 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, clone_try_fold(f)) |
| } |
| |
| fn fold<Acc, F>(self, init: Acc, f: F) -> Acc |
| where |
| F: FnMut(Acc, Self::Item) -> Acc, |
| { |
| self.it.map(T::clone).fold(init, f) |
| } |
| |
| 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).clone() } |
| } |
| } |
| |
| #[stable(feature = "iter_cloned", since = "1.1.0")] |
| impl<'a, I, T: 'a> DoubleEndedIterator for Cloned<I> |
| where |
| I: DoubleEndedIterator<Item = &'a T>, |
| T: Clone, |
| { |
| fn next_back(&mut self) -> Option<T> { |
| self.it.next_back().cloned() |
| } |
| |
| 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, clone_try_fold(f)) |
| } |
| |
| fn rfold<Acc, F>(self, init: Acc, f: F) -> Acc |
| where |
| F: FnMut(Acc, Self::Item) -> Acc, |
| { |
| self.it.map(T::clone).rfold(init, f) |
| } |
| } |
| |
| #[stable(feature = "iter_cloned", since = "1.1.0")] |
| impl<'a, I, T: 'a> ExactSizeIterator for Cloned<I> |
| where |
| I: ExactSizeIterator<Item = &'a T>, |
| T: Clone, |
| { |
| fn len(&self) -> usize { |
| self.it.len() |
| } |
| |
| fn is_empty(&self) -> bool { |
| self.it.is_empty() |
| } |
| } |
| |
| #[stable(feature = "fused", since = "1.26.0")] |
| impl<'a, I, T: 'a> FusedIterator for Cloned<I> |
| where |
| I: FusedIterator<Item = &'a T>, |
| T: Clone, |
| { |
| } |
| |
| #[doc(hidden)] |
| #[unstable(feature = "trusted_random_access", issue = "none")] |
| unsafe impl<I> TrustedRandomAccess for Cloned<I> where I: TrustedRandomAccess {} |
| |
| #[doc(hidden)] |
| #[unstable(feature = "trusted_random_access", issue = "none")] |
| unsafe impl<I> TrustedRandomAccessNoCoerce for Cloned<I> |
| where |
| I: TrustedRandomAccessNoCoerce, |
| { |
| const MAY_HAVE_SIDE_EFFECT: bool = true; |
| } |
| |
| #[unstable(feature = "trusted_len", issue = "37572")] |
| unsafe impl<'a, I, T: 'a> TrustedLen for Cloned<I> |
| where |
| I: TrustedLen<Item = &'a T>, |
| T: Clone, |
| { |
| } |
| |
| impl<'a, I, T: 'a> UncheckedIterator for Cloned<I> |
| where |
| I: UncheckedIterator<Item = &'a T>, |
| T: Clone, |
| { |
| unsafe fn next_unchecked(&mut self) -> T { |
| // SAFETY: `Cloned` is 1:1 with the inner iterator, so if the caller promised |
| // that there's an element left, the inner iterator has one too. |
| let item = unsafe { self.it.next_unchecked() }; |
| item.clone() |
| } |
| } |
| |
| #[stable(feature = "default_iters", since = "1.70.0")] |
| impl<I: Default> Default for Cloned<I> { |
| /// Creates a `Cloned` iterator from the default value of `I` |
| /// ``` |
| /// # use core::slice; |
| /// # use core::iter::Cloned; |
| /// let iter: Cloned<slice::Iter<'_, u8>> = Default::default(); |
| /// assert_eq!(iter.len(), 0); |
| /// ``` |
| fn default() -> Self { |
| Self::new(Default::default()) |
| } |
| } |
| |
| #[unstable(issue = "none", feature = "inplace_iteration")] |
| unsafe impl<I> SourceIter for Cloned<I> |
| where |
| I: SourceIter, |
| { |
| type Source = I::Source; |
| |
| #[inline] |
| unsafe fn as_inner(&mut self) -> &mut I::Source { |
| // SAFETY: unsafe function forwarding to unsafe function with the same requirements |
| unsafe { SourceIter::as_inner(&mut self.it) } |
| } |
| } |
| |
| #[unstable(issue = "none", feature = "inplace_iteration")] |
| unsafe impl<I: InPlaceIterable> InPlaceIterable for Cloned<I> { |
| const EXPAND_BY: Option<NonZeroUsize> = I::EXPAND_BY; |
| const MERGE_BY: Option<NonZeroUsize> = I::MERGE_BY; |
| } |