Avoid redundant macro arguments

Author: phimuemue

src/adaptors/mod.rs

@@ -737,7 +737,7 @@ impl<I: Iterator> HasCombination<I> for (I::Item,) {
 }
 
 macro_rules! impl_tuple_combination {
-    ($C:ident $P:ident ; $A:ident, $($I:ident),* ; $($X:ident)*) => (
+    ($C:ident $P:ident ; $($X:ident)*) => (
         #[derive(Clone, Debug)]
         pub struct $C<I: Iterator> {
             item: Option<I::Item>,
@@ -766,11 +766,11 @@ macro_rules! impl_tuple_combination {
             }
         }
 
-        impl<I, $A> Iterator for $C<I>
-            where I: Iterator<Item = $A> + Clone,
+        impl<I, A> Iterator for $C<I>
+            where I: Iterator<Item = A> + Clone,
                   I::Item: Clone
         {
-            type Item = ($($I),*);
+            type Item = (A, $(ignore_ident!($X, A)),*);
 
             fn next(&mut self) -> Option<Self::Item> {
                 if let Some(($($X),*,)) = self.c.next() {
@@ -786,8 +786,8 @@ macro_rules! impl_tuple_combination {
             }
         }
 
-        impl<I, $A> HasCombination<I> for ($($I),*)
-            where I: Iterator<Item = $A> + Clone,
+        impl<I, A> HasCombination<I> for (A, $(ignore_ident!($X, A)),*)
+            where I: Iterator<Item = A> + Clone,
                   I::Item: Clone
         {
             type Combination = $C<Fuse<I>>;
@@ -800,25 +800,24 @@ macro_rules! impl_tuple_combination {
 //    use itertools::Itertools;
 //
 //    for i in 2..=12 {
-//        println!("impl_tuple_combination!(Tuple{arity}Combination Tuple{prev}Combination; {tys}; {idents});",
+//        println!("impl_tuple_combination!(Tuple{arity}Combination Tuple{prev}Combination; {idents});",
 //            arity = i,
 //            prev = i - 1,
-//            tys = iter::repeat("A").take(i + 1).join(", "),
 //            idents = ('a'..'z').take(i - 1).join(" "),
 //        );
 //    }
 // It could probably be replaced by a bit more macro cleverness.
-impl_tuple_combination!(Tuple2Combination Tuple1Combination; A, A, A; a);
-impl_tuple_combination!(Tuple3Combination Tuple2Combination; A, A, A, A; a b);
-impl_tuple_combination!(Tuple4Combination Tuple3Combination; A, A, A, A, A; a b c);
-impl_tuple_combination!(Tuple5Combination Tuple4Combination; A, A, A, A, A, A; a b c d);
-impl_tuple_combination!(Tuple6Combination Tuple5Combination; A, A, A, A, A, A, A; a b c d e);
-impl_tuple_combination!(Tuple7Combination Tuple6Combination; A, A, A, A, A, A, A, A; a b c d e f);
-impl_tuple_combination!(Tuple8Combination Tuple7Combination; A, A, A, A, A, A, A, A, A; a b c d e f g);
-impl_tuple_combination!(Tuple9Combination Tuple8Combination; A, A, A, A, A, A, A, A, A, A; a b c d e f g h);
-impl_tuple_combination!(Tuple10Combination Tuple9Combination; A, A, A, A, A, A, A, A, A, A, A; a b c d e f g h i);
-impl_tuple_combination!(Tuple11Combination Tuple10Combination; A, A, A, A, A, A, A, A, A, A, A, A; a b c d e f g h i j);
-impl_tuple_combination!(Tuple12Combination Tuple11Combination; A, A, A, A, A, A, A, A, A, A, A, A, A; a b c d e f g h i j k);
+impl_tuple_combination!(Tuple2Combination Tuple1Combination; a);
+impl_tuple_combination!(Tuple3Combination Tuple2Combination; a b);
+impl_tuple_combination!(Tuple4Combination Tuple3Combination; a b c);
+impl_tuple_combination!(Tuple5Combination Tuple4Combination; a b c d);
+impl_tuple_combination!(Tuple6Combination Tuple5Combination; a b c d e);
+impl_tuple_combination!(Tuple7Combination Tuple6Combination; a b c d e f);
+impl_tuple_combination!(Tuple8Combination Tuple7Combination; a b c d e f g);
+impl_tuple_combination!(Tuple9Combination Tuple8Combination; a b c d e f g h);
+impl_tuple_combination!(Tuple10Combination Tuple9Combination; a b c d e f g h i);
+impl_tuple_combination!(Tuple11Combination Tuple10Combination; a b c d e f g h i j);
+impl_tuple_combination!(Tuple12Combination Tuple11Combination; a b c d e f g h i j k);
 
 /// An iterator adapter to filter values within a nested `Result::Ok`.
 ///