Jakub Kotur | a425e55 | 2020-12-21 17:28:15 +0100 | [diff] [blame] | 1 | |
| 2 | macro_rules! impl_cons_iter( |
| 3 | ($_A:ident, $_B:ident, ) => (); // stop |
| 4 | |
| 5 | ($A:ident, $($B:ident,)*) => ( |
| 6 | impl_cons_iter!($($B,)*); |
| 7 | #[allow(non_snake_case)] |
| 8 | impl<X, Iter, $($B),*> Iterator for ConsTuples<Iter, (($($B,)*), X)> |
| 9 | where Iter: Iterator<Item = (($($B,)*), X)>, |
| 10 | { |
| 11 | type Item = ($($B,)* X, ); |
| 12 | fn next(&mut self) -> Option<Self::Item> { |
| 13 | self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, )) |
| 14 | } |
| 15 | |
| 16 | fn size_hint(&self) -> (usize, Option<usize>) { |
| 17 | self.iter.size_hint() |
| 18 | } |
| 19 | fn fold<Acc, Fold>(self, accum: Acc, mut f: Fold) -> Acc |
| 20 | where Fold: FnMut(Acc, Self::Item) -> Acc, |
| 21 | { |
| 22 | self.iter.fold(accum, move |acc, (($($B,)*), x)| f(acc, ($($B,)* x, ))) |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | #[allow(non_snake_case)] |
| 27 | impl<X, Iter, $($B),*> DoubleEndedIterator for ConsTuples<Iter, (($($B,)*), X)> |
| 28 | where Iter: DoubleEndedIterator<Item = (($($B,)*), X)>, |
| 29 | { |
| 30 | fn next_back(&mut self) -> Option<Self::Item> { |
| 31 | self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, )) |
| 32 | } |
| 33 | } |
| 34 | |
| 35 | ); |
| 36 | ); |
| 37 | |
Joel Galenson | 6f79871 | 2021-04-01 17:03:06 -0700 | [diff] [blame] | 38 | impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,); |
Jakub Kotur | a425e55 | 2020-12-21 17:28:15 +0100 | [diff] [blame] | 39 | |
| 40 | /// An iterator that maps an iterator of tuples like |
| 41 | /// `((A, B), C)` to an iterator of `(A, B, C)`. |
| 42 | /// |
| 43 | /// Used by the `iproduct!()` macro. |
| 44 | #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] |
| 45 | #[derive(Debug)] |
| 46 | pub struct ConsTuples<I, J> |
| 47 | where I: Iterator<Item=J>, |
| 48 | { |
| 49 | iter: I, |
| 50 | } |
| 51 | |
| 52 | impl<I, J> Clone for ConsTuples<I, J> |
| 53 | where I: Clone + Iterator<Item=J>, |
| 54 | { |
| 55 | clone_fields!(iter); |
| 56 | } |
| 57 | |
| 58 | /// Create an iterator that maps for example iterators of |
| 59 | /// `((A, B), C)` to `(A, B, C)`. |
Joel Galenson | 6f79871 | 2021-04-01 17:03:06 -0700 | [diff] [blame] | 60 | pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I::IntoIter, J> |
| 61 | where I: IntoIterator<Item=J> |
Jakub Kotur | a425e55 | 2020-12-21 17:28:15 +0100 | [diff] [blame] | 62 | { |
| 63 | ConsTuples { iter: iterable.into_iter() } |
| 64 | } |