ConsTuples is a MapSpecialCase

Author: phimuemue

src/cons_tuples_impl.rs

@@ -1,58 +1,39 @@
+use crate::adaptors::map::{MapSpecialCase, MapSpecialCaseFn};
+
 macro_rules! impl_cons_iter(
     ($_A:ident, $_B:ident, ) => (); // stop
 
     ($A:ident, $($B:ident,)*) => (
         impl_cons_iter!($($B,)*);
         #[allow(non_snake_case)]
-        impl<X, Iter, $($B),*> Iterator for ConsTuples<Iter, (($($B,)*), X)>
-            where Iter: Iterator<Item = (($($B,)*), X)>,
-        {
-            type Item = ($($B,)* X, );
-            fn next(&mut self) -> Option<Self::Item> {
-                self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, ))
-            }
-
-            fn size_hint(&self) -> (usize, Option<usize>) {
-                self.iter.size_hint()
-            }
-            fn fold<Acc, Fold>(self, accum: Acc, mut f: Fold) -> Acc
-                where Fold: FnMut(Acc, Self::Item) -> Acc,
-            {
-                self.iter.fold(accum, move |acc, (($($B,)*), x)| f(acc, ($($B,)* x, )))
+        impl<$($B),*, X> MapSpecialCaseFn<(($($B,)*), X)> for ConsTuplesFn {
+            type Out = ($($B,)* X, );
+            fn call(&mut self, (($($B,)*), X): (($($B,)*), X)) -> Self::Out {
+                ($($B,)* X, )
             }
         }
     );
 );
 
 impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,);
 
+#[derive(Debug, Clone)]
+pub struct ConsTuplesFn;
+
 /// An iterator that maps an iterator of tuples like
 /// `((A, B), C)` to an iterator of `(A, B, C)`.
 ///
 /// Used by the `iproduct!()` macro.
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-#[derive(Debug)]
-pub struct ConsTuples<I, J>
-where
-    I: Iterator<Item = J>,
-{
-    iter: I,
-}
-
-impl<I, J> Clone for ConsTuples<I, J>
-where
-    I: Clone + Iterator<Item = J>,
-{
-    clone_fields!(iter);
-}
+pub type ConsTuples<I> = MapSpecialCase<I, ConsTuplesFn>;
 
 /// Create an iterator that maps for example iterators of
 /// `((A, B), C)` to `(A, B, C)`.
-pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I::IntoIter, J>
+pub fn cons_tuples<I>(iterable: I) -> ConsTuples<I::IntoIter>
 where
-    I: IntoIterator<Item = J>,
+    I: IntoIterator,
 {
     ConsTuples {
         iter: iterable.into_iter(),
+        f: ConsTuplesFn,
     }
 }