fn next_back(&mut self) -> Option<<I as Iterator>::Item> { self.iter.next_back() }
}
+#[stable]
+impl<'a, I> ExactSizeIterator for ByRef<'a, I> where I: 'a + ExactSizeIterator {
+ #[inline]
+ fn len(&self) -> uint { self.iter.len() }
+}
+
/// A trait for iterators over elements which can be added together
#[unstable = "needs to be re-evaluated as part of numerics reform"]
pub trait AdditiveIterator<A> {
}
}
+#[stable]
+impl<T, I> ExactSizeIterator for Peekable<T, I> where I: ExactSizeIterator<Item = T> {
+ #[inline]
+ fn len(&self) -> usize {
+ // This is guarenteed to not overflow because `len()` must have been able to return a valid
+ // value before we peeked.
+ self.iter.len() + if self.peeked.is_some() { 1 } else { 0 }
+ }
+}
+
#[stable]
impl<T, I> Peekable<T, I> where I: Iterator<Item=T> {
/// Return a reference to the next element of the iterator with out advancing it,
}
}
+#[stable]
+impl<I> ExactSizeIterator for Skip<I> where I: ExactSizeIterator {
+ #[inline]
+ fn len(&self) -> uint { self.iter.len().saturating_sub(self.n) }
+}
+
/// An iterator that only iterates over the first `n` iterations of `iter`.
#[derive(Clone)]
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
}
}
+#[stable]
+impl<I> ExactSizeIterator for Take<I> where I: ExactSizeIterator {
+ #[inline]
+ fn len(&self) -> uint { cmp::min(self.iter.len(), self.n) }
+}
+
/// An iterator to maintain state while iterating another iterator
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
}
}
+#[stable]
+impl<I> ExactSizeIterator for Fuse<I> where I: ExactSizeIterator {
+ #[inline]
+ fn len(&self) -> uint { self.iter.len() }
+}
+
impl<I> Fuse<I> {
/// Resets the fuse such that the next call to .next() or .next_back() will
/// call the underlying iterator again even if it previously returned None.