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
38 impl_cons_iter!(A, B, C, D, E, F, G, H,);
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)`.
cons_tuples<I, J>(iterable: I) -> ConsTuples<I, J> where I: Iterator<Item=J>60 pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I, J>
61 where I: Iterator<Item=J>
62 {
63 ConsTuples { iter: iterable.into_iter() }
64 }
65