1 files changed, 139 insertions, 0 deletions
diff --git a/vendor/itertools/src/zip_longest.rs b/vendor/itertools/src/zip_longest.rs
new file mode 100644
index 00000000..d4eb9a88
--- /dev/null
+++ b/vendor/itertools/src/zip_longest.rs
@@ -0,0 +1,139 @@
+use super::size_hint;
+use std::cmp::Ordering::{Equal, Greater, Less};
+use std::iter::{Fuse, FusedIterator};
+
+use crate::either_or_both::EitherOrBoth;
+
+// ZipLongest originally written by SimonSapin,
+// and dedicated to itertools https://github.com/rust-lang/rust/pull/19283
+
+/// An iterator which iterates two other iterators simultaneously
+/// and wraps the elements in [`EitherOrBoth`].
+///
+/// This iterator is *fused*.
+///
+/// See [`.zip_longest()`](crate::Itertools::zip_longest) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct ZipLongest<T, U> {
+    a: Fuse<T>,
+    b: Fuse<U>,
+}
+
+/// Create a new `ZipLongest` iterator.
+pub fn zip_longest<T, U>(a: T, b: U) -> ZipLongest<T, U>
+where
+    T: Iterator,
+    U: Iterator,
+{
+    ZipLongest {
+        a: a.fuse(),
+        b: b.fuse(),
+    }
+}
+
+impl<T, U> Iterator for ZipLongest<T, U>
+where
+    T: Iterator,
+    U: Iterator,
+{
+    type Item = EitherOrBoth<T::Item, U::Item>;
+
+    #[inline]
+    fn next(&mut self) -> Option<Self::Item> {
+        match (self.a.next(), self.b.next()) {
+            (None, None) => None,
+            (Some(a), None) => Some(EitherOrBoth::Left(a)),
+            (None, Some(b)) => Some(EitherOrBoth::Right(b)),
+            (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)),
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        size_hint::max(self.a.size_hint(), self.b.size_hint())
+    }
+
+    #[inline]
+    fn fold<B, F>(self, init: B, mut f: F) -> B
+    where
+        Self: Sized,
+        F: FnMut(B, Self::Item) -> B,
+    {
+        let Self { mut a, mut b } = self;
+        let res = a.try_fold(init, |init, a| match b.next() {
+            Some(b) => Ok(f(init, EitherOrBoth::Both(a, b))),
+            None => Err(f(init, EitherOrBoth::Left(a))),
+        });
+        match res {
+            Ok(acc) => b.map(EitherOrBoth::Right).fold(acc, f),
+            Err(acc) => a.map(EitherOrBoth::Left).fold(acc, f),
+        }
+    }
+}
+
+impl<T, U> DoubleEndedIterator for ZipLongest<T, U>
+where
+    T: DoubleEndedIterator + ExactSizeIterator,
+    U: DoubleEndedIterator + ExactSizeIterator,
+{
+    #[inline]
+    fn next_back(&mut self) -> Option<Self::Item> {
+        match self.a.len().cmp(&self.b.len()) {
+            Equal => match (self.a.next_back(), self.b.next_back()) {
+                (None, None) => None,
+                (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)),
+                // These can only happen if .len() is inconsistent with .next_back()
+                (Some(a), None) => Some(EitherOrBoth::Left(a)),
+                (None, Some(b)) => Some(EitherOrBoth::Right(b)),
+            },
+            Greater => self.a.next_back().map(EitherOrBoth::Left),
+            Less => self.b.next_back().map(EitherOrBoth::Right),
+        }
+    }
+
+    fn rfold<B, F>(self, mut init: B, mut f: F) -> B
+    where
+        F: FnMut(B, Self::Item) -> B,
+    {
+        let Self { mut a, mut b } = self;
+        let a_len = a.len();
+        let b_len = b.len();
+        match a_len.cmp(&b_len) {
+            Equal => {}
+            Greater => {
+                init = a
+                    .by_ref()
+                    .rev()
+                    .take(a_len - b_len)
+                    .map(EitherOrBoth::Left)
+                    .fold(init, &mut f)
+            }
+            Less => {
+                init = b
+                    .by_ref()
+                    .rev()
+                    .take(b_len - a_len)
+                    .map(EitherOrBoth::Right)
+                    .fold(init, &mut f)
+            }
+        }
+        a.rfold(init, |acc, item_a| {
+            f(acc, EitherOrBoth::Both(item_a, b.next_back().unwrap()))
+        })
+    }
+}
+
+impl<T, U> ExactSizeIterator for ZipLongest<T, U>
+where
+    T: ExactSizeIterator,
+    U: ExactSizeIterator,
+{
+}
+
+impl<T, U> FusedIterator for ZipLongest<T, U>
+where
+    T: Iterator,
+    U: Iterator,
+{
+}