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Trait impls for tuples of arity <= 12 #475

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merged 1 commit into from Sep 22, 2020
Merged

Trait impls for tuples of arity <= 12 #475

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27 changes: 24 additions & 3 deletions src/adaptors/mod.rs
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Expand Up @@ -806,9 +806,30 @@ macro_rules! impl_tuple_combination {
)
}

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);
// This snippet generates the twelve `impl_tuple_combination!` invocations:
// use core::iter;
// use itertools::Itertools;
//
// for i in 2..=12 {
// println!("impl_tuple_combination!(Tuple{arity}Combination Tuple{prev}Combination; {tys}; {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);

/// An iterator adapter to filter values within a nested `Result::Ok`.
///
Expand Down
2 changes: 1 addition & 1 deletion src/cons_tuples_impl.rs
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Expand Up @@ -35,7 +35,7 @@ macro_rules! impl_cons_iter(
);
);

impl_cons_iter!(A, B, C, D, E, F, G, H,);
impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,);

/// An iterator that maps an iterator of tuples like
/// `((A, B), C)` to an iterator of `(A, B, C)`.
Expand Down
6 changes: 3 additions & 3 deletions src/lib.rs
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Expand Up @@ -1250,7 +1250,7 @@ pub trait Itertools : Iterator {
/// elements from an iterator.
///
/// Iterator element can be any homogeneous tuple of type `Self::Item` with
/// size up to 4.
/// size up to 12.
///
/// ```
/// use itertools::Itertools;
Expand Down Expand Up @@ -1485,7 +1485,7 @@ pub trait Itertools : Iterator {

// non-adaptor methods
/// Advances the iterator and returns the next items grouped in a tuple of
/// a specific size (up to 4).
/// a specific size (up to 12).
///
/// If there are enough elements to be grouped in a tuple, then the tuple is
/// returned inside `Some`, otherwise `None` is returned.
Expand All @@ -1505,7 +1505,7 @@ pub trait Itertools : Iterator {
}

/// Collects all items from the iterator into a tuple of a specific size
/// (up to 4).
/// (up to 12).
///
/// If the number of elements inside the iterator is **exactly** equal to
/// the tuple size, then the tuple is returned inside `Some`, otherwise
Expand Down
41 changes: 26 additions & 15 deletions src/tuple_impl.rs
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Expand Up @@ -280,23 +280,14 @@ macro_rules! impl_tuple_collect {
return None;
}

#[allow(unused_assignments)]
fn collect_from_iter_no_buf<I>(iter: I) -> Option<Self>
where I: IntoIterator<Item = $A>
{
let mut iter = iter.into_iter();
loop {
$(
let $Y = if let Some($Y) = iter.next() {
$Y
} else {
break;
};
)*
return Some(($($Y),*,))
}

return None;
Some(($(
{ let $Y = iter.next()?; $Y },
)*))
Comment on lines -288 to +290
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I think this modification is semantically equivalent, but I'd love if someone else could check it over before I merge.

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@phimuemue phimuemue Sep 14, 2020 •
edited

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Looks good to me. Godbolt even seems to generate very similar code in --release.

off-topic: I do not have much time to spare at the moment, so I will be slow to respond.

}

fn num_items() -> usize {
Expand All @@ -307,17 +298,37 @@ macro_rules! impl_tuple_collect {
use std::mem::replace;

let &mut ($(ref mut $Y),*,) = self;
let tmp = item;
$(
let tmp = replace($Y_rev, tmp);
let item = replace($Y_rev, item);
)*
drop(tmp);
drop(item);
}
}
)
}

// This snippet generates the twelve `impl_tuple_collect!` invocations:
// use core::iter;
// use itertools::Itertools;
//
// for i in 1..=12 {
// println!("impl_tuple_collect!({arity}; A; {ty}; {idents}; {rev_idents});",
// arity=i,
// ty=iter::repeat("A").take(i).join(", "),
// idents=('a'..='z').take(i).join(", "),
// rev_idents=('a'..='z').take(i).collect_vec().into_iter().rev().join(", ")
// );
// }
// It could probably be replaced by a bit more macro cleverness.
impl_tuple_collect!(1; A; A; a; a);
impl_tuple_collect!(2; A; A, A; a, b; b, a);
impl_tuple_collect!(3; A; A, A, A; a, b, c; c, b, a);
impl_tuple_collect!(4; A; A, A, A, A; a, b, c, d; d, c, b, a);
impl_tuple_collect!(5; A; A, A, A, A, A; a, b, c, d, e; e, d, c, b, a);
impl_tuple_collect!(6; A; A, A, A, A, A, A; a, b, c, d, e, f; f, e, d, c, b, a);
impl_tuple_collect!(7; A; A, A, A, A, A, A, A; a, b, c, d, e, f, g; g, f, e, d, c, b, a);
impl_tuple_collect!(8; A; A, A, A, A, A, A, A, A; a, b, c, d, e, f, g, h; h, g, f, e, d, c, b, a);
impl_tuple_collect!(9; A; A, A, A, A, A, A, A, A, A; a, b, c, d, e, f, g, h, i; i, h, g, f, e, d, c, b, a);
impl_tuple_collect!(10; A; A, A, A, A, A, A, A, A, A, A; a, b, c, d, e, f, g, h, i, j; j, i, h, g, f, e, d, c, b, a);
impl_tuple_collect!(11; A; A, A, A, A, A, A, A, A, A, A, A; a, b, c, d, e, f, g, h, i, j, k; k, j, i, h, g, f, e, d, c, b, a);
impl_tuple_collect!(12; A; A, A, A, A, A, A, A, A, A, A, A, A; a, b, c, d, e, f, g, h, i, j, k, l; l, k, j, i, h, g, f, e, d, c, b, a);
4 changes: 4 additions & 0 deletions src/ziptuple.rs
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Expand Up @@ -109,3 +109,7 @@ impl_zip_iter!(A, B, C, D, E);
impl_zip_iter!(A, B, C, D, E, F);
impl_zip_iter!(A, B, C, D, E, F, G);
impl_zip_iter!(A, B, C, D, E, F, G, H);
impl_zip_iter!(A, B, C, D, E, F, G, H, I);
impl_zip_iter!(A, B, C, D, E, F, G, H, I, J);
impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K);
impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K, L);