| use super::plumbing::*; |
| use super::*; |
| use std::iter; |
| use std::ops::Range; |
| use std::usize; |
| |
| /// `Enumerate` is an iterator that returns the current count along with the element. |
| /// This struct is created by the [`enumerate()`] method on [`IndexedParallelIterator`] |
| /// |
| /// [`enumerate()`]: trait.IndexedParallelIterator.html#method.enumerate |
| /// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html |
| #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] |
| #[derive(Debug, Clone)] |
| pub struct Enumerate<I: IndexedParallelIterator> { |
| base: I, |
| } |
| |
| impl<I> Enumerate<I> |
| where |
| I: IndexedParallelIterator, |
| { |
| /// Create a new `Enumerate` iterator. |
| pub(super) fn new(base: I) -> Self { |
| Enumerate { base } |
| } |
| } |
| |
| impl<I> ParallelIterator for Enumerate<I> |
| where |
| I: IndexedParallelIterator, |
| { |
| type Item = (usize, I::Item); |
| |
| fn drive_unindexed<C>(self, consumer: C) -> C::Result |
| where |
| C: UnindexedConsumer<Self::Item>, |
| { |
| bridge(self, consumer) |
| } |
| |
| fn opt_len(&self) -> Option<usize> { |
| Some(self.len()) |
| } |
| } |
| |
| impl<I> IndexedParallelIterator for Enumerate<I> |
| where |
| I: IndexedParallelIterator, |
| { |
| fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result { |
| bridge(self, consumer) |
| } |
| |
| fn len(&self) -> usize { |
| self.base.len() |
| } |
| |
| fn with_producer<CB>(self, callback: CB) -> CB::Output |
| where |
| CB: ProducerCallback<Self::Item>, |
| { |
| return self.base.with_producer(Callback { callback }); |
| |
| struct Callback<CB> { |
| callback: CB, |
| } |
| |
| impl<I, CB> ProducerCallback<I> for Callback<CB> |
| where |
| CB: ProducerCallback<(usize, I)>, |
| { |
| type Output = CB::Output; |
| fn callback<P>(self, base: P) -> CB::Output |
| where |
| P: Producer<Item = I>, |
| { |
| let producer = EnumerateProducer { base, offset: 0 }; |
| self.callback.callback(producer) |
| } |
| } |
| } |
| } |
| |
| /// //////////////////////////////////////////////////////////////////////// |
| /// Producer implementation |
| |
| struct EnumerateProducer<P> { |
| base: P, |
| offset: usize, |
| } |
| |
| impl<P> Producer for EnumerateProducer<P> |
| where |
| P: Producer, |
| { |
| type Item = (usize, P::Item); |
| type IntoIter = iter::Zip<Range<usize>, P::IntoIter>; |
| |
| fn into_iter(self) -> Self::IntoIter { |
| // Enumerate only works for IndexedParallelIterators. Since those |
| // have a max length of usize::MAX, their max index is |
| // usize::MAX - 1, so the range 0..usize::MAX includes all |
| // possible indices. |
| // |
| // However, we should to use a precise end to the range, otherwise |
| // reversing the iterator may have to walk back a long ways before |
| // `Zip::next_back` can produce anything. |
| let base = self.base.into_iter(); |
| let end = self.offset + base.len(); |
| (self.offset..end).zip(base) |
| } |
| |
| fn min_len(&self) -> usize { |
| self.base.min_len() |
| } |
| fn max_len(&self) -> usize { |
| self.base.max_len() |
| } |
| |
| fn split_at(self, index: usize) -> (Self, Self) { |
| let (left, right) = self.base.split_at(index); |
| ( |
| EnumerateProducer { |
| base: left, |
| offset: self.offset, |
| }, |
| EnumerateProducer { |
| base: right, |
| offset: self.offset + index, |
| }, |
| ) |
| } |
| } |