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+use super::plumbing::*;
+use super::*;
+
+/// `InterleaveShortest` is an iterator that works similarly to
+/// `Interleave`, but this version stops returning elements once one
+/// of the iterators run out.
+///
+/// This struct is created by the [`interleave_shortest()`] method on
+/// [`IndexedParallelIterator`].
+///
+/// [`interleave_shortest()`]: trait.IndexedParallelIterator.html#method.interleave_shortest
+/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug, Clone)]
+pub struct InterleaveShortest<I, J>
+where
+ I: IndexedParallelIterator,
+ J: IndexedParallelIterator<Item = I::Item>,
+{
+ interleave: Interleave<Take<I>, Take<J>>,
+}
+
+impl<I, J> InterleaveShortest<I, J>
+where
+ I: IndexedParallelIterator,
+ J: IndexedParallelIterator<Item = I::Item>,
+{
+ /// Creates a new `InterleaveShortest` iterator
+ pub(super) fn new(i: I, j: J) -> Self {
+ InterleaveShortest {
+ interleave: if i.len() <= j.len() {
+ // take equal lengths from both iterators
+ let n = i.len();
+ i.take(n).interleave(j.take(n))
+ } else {
+ // take one extra item from the first iterator
+ let n = j.len();
+ i.take(n + 1).interleave(j.take(n))
+ },
+ }
+ }
+}
+
+impl<I, J> ParallelIterator for InterleaveShortest<I, J>
+where
+ I: IndexedParallelIterator,
+ J: IndexedParallelIterator<Item = I::Item>,
+{
+ type Item = I::Item;
+
+ fn drive_unindexed<C>(self, consumer: C) -> C::Result
+ where
+ C: Consumer<I::Item>,
+ {
+ bridge(self, consumer)
+ }
+
+ fn opt_len(&self) -> Option<usize> {
+ Some(self.len())
+ }
+}
+
+impl<I, J> IndexedParallelIterator for InterleaveShortest<I, J>
+where
+ I: IndexedParallelIterator,
+ J: IndexedParallelIterator<Item = I::Item>,
+{
+ fn drive<C>(self, consumer: C) -> C::Result
+ where
+ C: Consumer<Self::Item>,
+ {
+ bridge(self, consumer)
+ }
+
+ fn len(&self) -> usize {
+ self.interleave.len()
+ }
+
+ fn with_producer<CB>(self, callback: CB) -> CB::Output
+ where
+ CB: ProducerCallback<Self::Item>,
+ {
+ self.interleave.with_producer(callback)
+ }
+}