Implement missing specializations on the MergeJoinBy Iterator
@@ -84,4 +84,70 @@ impl<I, J, F> Iterator for MergeJoinBy<I, J, F>
(lower, upper)
}
+
+ fn count(mut self) -> usize {
+ let mut count = 0;
+ loop {
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break count,
+ (Some(_left), None) => break count + 1 + self.left.count(),
+ (None, Some(_right)) => break count + 1 + self.right.count(),
+ (Some(left), Some(right)) => {
+ count += 1;
+ match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => {}
+ Ordering::Less => self.right.put_back(right),
+ Ordering::Greater => self.left.put_back(left),
+ }
+ }
+ }
+ }
+ }
+
+ fn last(mut self) -> Option<Self::Item> {
+ let mut previous_element = None;
+ loop {
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break previous_element,
+ (Some(left), None) => {
+ break Some(EitherOrBoth::Left(self.left.last().unwrap_or(left)))
+ }
+ (None, Some(right)) => {
+ break Some(EitherOrBoth::Right(self.right.last().unwrap_or(right)))
+ }
+ (Some(left), Some(right)) => {
+ previous_element = match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => Some(EitherOrBoth::Both(left, right)),
+ Ordering::Less => {
+ self.right.put_back(right);
+ Some(EitherOrBoth::Left(left))
+ }
+ Ordering::Greater => {
+ self.left.put_back(left);
+ Some(EitherOrBoth::Right(right))
+ }
+ }
+ }
+ }
+ }
+ }
+
+ fn nth(&mut self, mut n: usize) -> Option<Self::Item> {
+ loop {
+ if n == 0 {
+ break self.next();
+ }
+ n -= 1;
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break None,
+ (Some(_left), None) => break self.left.nth(n).map(EitherOrBoth::Left),
+ (None, Some(_right)) => break self.right.nth(n).map(EitherOrBoth::Right),
+ (Some(left), Some(right)) => match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => {}
+ Ordering::Less => self.right.put_back(right),
+ Ordering::Greater => self.left.put_back(left),
+ },
+ }
+ }
+ }
}
