1 files changed, 124 insertions, 0 deletions
diff --git a/vendor/itertools/src/pad_tail.rs b/vendor/itertools/src/pad_tail.rs
new file mode 100644
index 00000000..5595b42b
--- /dev/null
+++ b/vendor/itertools/src/pad_tail.rs
@@ -0,0 +1,124 @@
+use crate::size_hint;
+use std::iter::{Fuse, FusedIterator};
+
+/// An iterator adaptor that pads a sequence to a minimum length by filling
+/// missing elements using a closure.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.pad_using()`](crate::Itertools::pad_using) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct PadUsing<I, F> {
+    iter: Fuse<I>,
+    min: usize,
+    pos: usize,
+    filler: F,
+}
+
+impl<I, F> std::fmt::Debug for PadUsing<I, F>
+where
+    I: std::fmt::Debug,
+{
+    debug_fmt_fields!(PadUsing, iter, min, pos);
+}
+
+/// Create a new `PadUsing` iterator.
+pub fn pad_using<I, F>(iter: I, min: usize, filler: F) -> PadUsing<I, F>
+where
+    I: Iterator,
+    F: FnMut(usize) -> I::Item,
+{
+    PadUsing {
+        iter: iter.fuse(),
+        min,
+        pos: 0,
+        filler,
+    }
+}
+
+impl<I, F> Iterator for PadUsing<I, F>
+where
+    I: Iterator,
+    F: FnMut(usize) -> I::Item,
+{
+    type Item = I::Item;
+
+    #[inline]
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.iter.next() {
+            None => {
+                if self.pos < self.min {
+                    let e = Some((self.filler)(self.pos));
+                    self.pos += 1;
+                    e
+                } else {
+                    None
+                }
+            }
+            e => {
+                self.pos += 1;
+                e
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let tail = self.min.saturating_sub(self.pos);
+        size_hint::max(self.iter.size_hint(), (tail, Some(tail)))
+    }
+
+    fn fold<B, G>(self, mut init: B, mut f: G) -> B
+    where
+        G: FnMut(B, Self::Item) -> B,
+    {
+        let mut pos = self.pos;
+        init = self.iter.fold(init, |acc, item| {
+            pos += 1;
+            f(acc, item)
+        });
+        (pos..self.min).map(self.filler).fold(init, f)
+    }
+}
+
+impl<I, F> DoubleEndedIterator for PadUsing<I, F>
+where
+    I: DoubleEndedIterator + ExactSizeIterator,
+    F: FnMut(usize) -> I::Item,
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        if self.min == 0 {
+            self.iter.next_back()
+        } else if self.iter.len() >= self.min {
+            self.min -= 1;
+            self.iter.next_back()
+        } else {
+            self.min -= 1;
+            Some((self.filler)(self.min))
+        }
+    }
+
+    fn rfold<B, G>(self, mut init: B, mut f: G) -> B
+    where
+        G: FnMut(B, Self::Item) -> B,
+    {
+        init = (self.iter.len()..self.min)
+            .map(self.filler)
+            .rfold(init, &mut f);
+        self.iter.rfold(init, f)
+    }
+}
+
+impl<I, F> ExactSizeIterator for PadUsing<I, F>
+where
+    I: ExactSizeIterator,
+    F: FnMut(usize) -> I::Item,
+{
+}
+
+impl<I, F> FusedIterator for PadUsing<I, F>
+where
+    I: FusedIterator,
+    F: FnMut(usize) -> I::Item,
+{
+}