From 87e641a2a50aa52d44a8972a7d5371e3ac5b391a Mon Sep 17 00:00:00 2001 From: Sebastian Hahn Date: Thu, 26 Dec 2024 08:30:51 +0100 Subject: [PATCH 1/2] Fix formatting --- library/core/src/iter/traits/collect.rs | 38 ++++++++++++------------- 1 file changed, 19 insertions(+), 19 deletions(-) diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs index 8ab1c26f95e32..de090d2a50fad 100644 --- a/library/core/src/iter/traits/collect.rs +++ b/library/core/src/iter/traits/collect.rs @@ -629,7 +629,7 @@ macro_rules! spec_tuple_impl { } impl<$($ty_names,)* $($extend_ty_names,)* Iter> $trait_name<$($extend_ty_names),*> for Iter - where + where $($extend_ty_names: Extend<$ty_names>,)* Iter: Iterator, { @@ -639,7 +639,7 @@ macro_rules! spec_tuple_impl { } impl<$($ty_names,)* $($extend_ty_names,)* Iter> $trait_name<$($extend_ty_names),*> for Iter - where + where $($extend_ty_names: Extend<$ty_names>,)* Iter: TrustedLen, { @@ -647,29 +647,29 @@ macro_rules! spec_tuple_impl { fn extend<'a, $($ty_names,)*>( $($var_names: &'a mut impl Extend<$ty_names>,)* ) -> impl FnMut((), ($($ty_names,)*)) + 'a { - #[allow(non_snake_case)] - // SAFETY: We reserve enough space for the `size_hint`, and the iterator is `TrustedLen` - // so its `size_hint` is exact. - move |(), ($($extend_ty_names,)*)| unsafe { - $($var_names.extend_one_unchecked($extend_ty_names);)* + #[allow(non_snake_case)] + // SAFETY: We reserve enough space for the `size_hint`, and the iterator is + // `TrustedLen` so its `size_hint` is exact. + move |(), ($($extend_ty_names,)*)| unsafe { + $($var_names.extend_one_unchecked($extend_ty_names);)* + } } - } - let (lower_bound, upper_bound) = self.size_hint(); + let (lower_bound, upper_bound) = self.size_hint(); - if upper_bound.is_none() { - // We cannot reserve more than `usize::MAX` items, and this is likely to go out of memory anyway. - $default_fn_name(self, $($var_names,)*); - return; - } + if upper_bound.is_none() { + // We cannot reserve more than `usize::MAX` items, and this is likely to go out of memory anyway. + $default_fn_name(self, $($var_names,)*); + return; + } - if lower_bound > 0 { - $($var_names.extend_reserve(lower_bound);)* - } + if lower_bound > 0 { + $($var_names.extend_reserve(lower_bound);)* + } - self.fold((), extend($($var_names,)*)); + self.fold((), extend($($var_names,)*)); + } } - } }; } From 10b23518c1f632f67a9a7c47e742d07c4579242a Mon Sep 17 00:00:00 2001 From: Sebastian Hahn Date: Thu, 26 Dec 2024 08:38:08 +0100 Subject: [PATCH 2/2] Impl FromIterator for tuples with arity 1-12 --- library/core/src/iter/traits/collect.rs | 68 +++++++++++----------- library/core/tests/iter/traits/iterator.rs | 12 ++++ 2 files changed, 47 insertions(+), 33 deletions(-) diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs index de090d2a50fad..73e6d93106096 100644 --- a/library/core/src/iter/traits/collect.rs +++ b/library/core/src/iter/traits/collect.rs @@ -152,39 +152,6 @@ pub trait FromIterator: Sized { fn from_iter>(iter: T) -> Self; } -/// This implementation turns an iterator of tuples into a tuple of types which implement -/// [`Default`] and [`Extend`]. -/// -/// This is similar to [`Iterator::unzip`], but is also composable with other [`FromIterator`] -/// implementations: -/// -/// ```rust -/// # fn main() -> Result<(), core::num::ParseIntError> { -/// let string = "1,2,123,4"; -/// -/// let (numbers, lengths): (Vec<_>, Vec<_>) = string -/// .split(',') -/// .map(|s| s.parse().map(|n: u32| (n, s.len()))) -/// .collect::>()?; -/// -/// assert_eq!(numbers, [1, 2, 123, 4]); -/// assert_eq!(lengths, [1, 1, 3, 1]); -/// # Ok(()) } -/// ``` -#[stable(feature = "from_iterator_for_tuple", since = "1.79.0")] -impl FromIterator<(AE, BE)> for (A, B) -where - A: Default + Extend, - B: Default + Extend, -{ - fn from_iter>(iter: I) -> Self { - let mut res = <(A, B)>::default(); - res.extend(iter); - - res - } -} - /// Conversion into an [`Iterator`]. /// /// By implementing `IntoIterator` for a type, you define how it will be @@ -671,6 +638,41 @@ macro_rules! spec_tuple_impl { } } + /// This implementation turns an iterator of tuples into a tuple of types which implement + /// [`Default`] and [`Extend`]. + /// + /// This is similar to [`Iterator::unzip`], but is also composable with other [`FromIterator`] + /// implementations: + /// + /// ```rust + /// # fn main() -> Result<(), core::num::ParseIntError> { + /// let string = "1,2,123,4"; + /// + /// // Example given for a 2-tuple, but 1- through 12-tuples are supported + /// let (numbers, lengths): (Vec<_>, Vec<_>) = string + /// .split(',') + /// .map(|s| s.parse().map(|n: u32| (n, s.len()))) + /// .collect::>()?; + /// + /// assert_eq!(numbers, [1, 2, 123, 4]); + /// assert_eq!(lengths, [1, 1, 3, 1]); + /// # Ok(()) } + /// ``` + #[$meta] + $(#[$doctext])? + #[stable(feature = "from_iterator_for_tuple", since = "1.79.0")] + impl<$($ty_names,)* $($extend_ty_names,)*> FromIterator<($($extend_ty_names,)*)> for ($($ty_names,)*) + where + $($ty_names: Default + Extend<$extend_ty_names>,)* + { + fn from_iter>(iter: Iter) -> Self { + let mut res = <($($ty_names,)*)>::default(); + res.extend(iter); + + res + } + } + }; } diff --git a/library/core/tests/iter/traits/iterator.rs b/library/core/tests/iter/traits/iterator.rs index 76f1e3319d42e..e31d2e15b6d7e 100644 --- a/library/core/tests/iter/traits/iterator.rs +++ b/library/core/tests/iter/traits/iterator.rs @@ -630,6 +630,18 @@ fn test_collect_into_tuples() { assert!(e.2 == d); } +#[test] +fn test_collect_for_tuples() { + let a = vec![(1, 2, 3), (4, 5, 6), (7, 8, 9)]; + let b = vec![1, 4, 7]; + let c = vec![2, 5, 8]; + let d = vec![3, 6, 9]; + let e: (Vec<_>, Vec<_>, Vec<_>) = a.into_iter().collect(); + assert!(e.0 == b); + assert!(e.1 == c); + assert!(e.2 == d); +} + // just tests by whether or not this compiles fn _empty_impl_all_auto_traits() { use std::panic::{RefUnwindSafe, UnwindSafe};