120 lines
2.6 KiB
Rust
120 lines
2.6 KiB
Rust
use super::plumbing::*;
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use super::*;
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use std::iter;
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/// `Rev` is an iterator that produces elements in reverse order. This struct
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/// is created by the [`rev()`] method on [`IndexedParallelIterator`]
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///
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/// [`rev()`]: IndexedParallelIterator::rev()
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#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
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#[derive(Debug, Clone)]
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pub struct Rev<I> {
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base: I,
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}
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impl<I> Rev<I> {
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/// Creates a new `Rev` iterator.
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pub(super) fn new(base: I) -> Self {
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Rev { base }
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}
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}
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impl<I> ParallelIterator for Rev<I>
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where
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I: IndexedParallelIterator,
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{
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type Item = I::Item;
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fn drive_unindexed<C>(self, consumer: C) -> C::Result
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where
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C: UnindexedConsumer<Self::Item>,
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{
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bridge(self, consumer)
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}
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fn opt_len(&self) -> Option<usize> {
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Some(self.len())
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}
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}
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impl<I> IndexedParallelIterator for Rev<I>
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where
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I: IndexedParallelIterator,
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{
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fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result {
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bridge(self, consumer)
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}
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fn len(&self) -> usize {
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self.base.len()
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}
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fn with_producer<CB>(self, callback: CB) -> CB::Output
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where
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CB: ProducerCallback<Self::Item>,
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{
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let len = self.base.len();
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return self.base.with_producer(Callback { callback, len });
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struct Callback<CB> {
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callback: CB,
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len: usize,
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}
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impl<T, CB> ProducerCallback<T> for Callback<CB>
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where
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CB: ProducerCallback<T>,
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{
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type Output = CB::Output;
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fn callback<P>(self, base: P) -> CB::Output
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where
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P: Producer<Item = T>,
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{
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let producer = RevProducer {
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base,
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len: self.len,
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};
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self.callback.callback(producer)
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}
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}
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}
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}
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struct RevProducer<P> {
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base: P,
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len: usize,
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}
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impl<P> Producer for RevProducer<P>
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where
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P: Producer,
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{
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type Item = P::Item;
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type IntoIter = iter::Rev<P::IntoIter>;
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fn into_iter(self) -> Self::IntoIter {
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self.base.into_iter().rev()
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}
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fn min_len(&self) -> usize {
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self.base.min_len()
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}
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fn max_len(&self) -> usize {
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self.base.max_len()
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}
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fn split_at(self, index: usize) -> (Self, Self) {
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let (left, right) = self.base.split_at(self.len - index);
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(
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RevProducer {
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base: right,
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len: index,
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},
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RevProducer {
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base: left,
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len: self.len - index,
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},
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)
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}
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}
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