diff options
Diffstat (limited to 'library/core/src/iter')
-rw-r--r-- | library/core/src/iter/range.rs | 2 | ||||
-rw-r--r-- | library/core/src/iter/sources/empty.rs | 7 | ||||
-rw-r--r-- | library/core/src/iter/sources/from_generator.rs | 23 | ||||
-rw-r--r-- | library/core/src/iter/sources/once_with.rs | 14 | ||||
-rw-r--r-- | library/core/src/iter/sources/repeat_n.rs | 2 | ||||
-rw-r--r-- | library/core/src/iter/sources/repeat_with.rs | 10 | ||||
-rw-r--r-- | library/core/src/iter/traits/accum.rs | 8 | ||||
-rw-r--r-- | library/core/src/iter/traits/iterator.rs | 43 |
8 files changed, 87 insertions, 22 deletions
diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs index ac7b389b1..b5739f2f3 100644 --- a/library/core/src/iter/range.rs +++ b/library/core/src/iter/range.rs @@ -756,7 +756,7 @@ impl<A: Step> Iterator for ops::Range<A> { where Self: TrustedRandomAccessNoCoerce, { - // SAFETY: The TrustedRandomAccess contract requires that callers only pass an index + // SAFETY: The TrustedRandomAccess contract requires that callers only pass an index // that is in bounds. // Additionally Self: TrustedRandomAccess is only implemented for Copy types // which means even repeated reads of the same index would be safe. diff --git a/library/core/src/iter/sources/empty.rs b/library/core/src/iter/sources/empty.rs index 98734c527..617dfd123 100644 --- a/library/core/src/iter/sources/empty.rs +++ b/library/core/src/iter/sources/empty.rs @@ -22,17 +22,12 @@ pub const fn empty<T>() -> Empty<T> { Empty(marker::PhantomData) } -// Newtype for use in `PhantomData` to avoid -// > error: const-stable function cannot use `#[feature(const_fn_fn_ptr_basics)]` -// in `const fn empty<T>()` above. -struct FnReturning<T>(fn() -> T); - /// An iterator that yields nothing. /// /// This `struct` is created by the [`empty()`] function. See its documentation for more. #[must_use = "iterators are lazy and do nothing unless consumed"] #[stable(feature = "iter_empty", since = "1.2.0")] -pub struct Empty<T>(marker::PhantomData<FnReturning<T>>); +pub struct Empty<T>(marker::PhantomData<fn() -> T>); #[stable(feature = "core_impl_debug", since = "1.9.0")] impl<T> fmt::Debug for Empty<T> { diff --git a/library/core/src/iter/sources/from_generator.rs b/library/core/src/iter/sources/from_generator.rs index 8e7cbd34a..4cbe731b2 100644 --- a/library/core/src/iter/sources/from_generator.rs +++ b/library/core/src/iter/sources/from_generator.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::ops::{Generator, GeneratorState}; use crate::pin::Pin; @@ -23,14 +24,21 @@ use crate::pin::Pin; /// ``` #[inline] #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] -pub fn from_generator<G: Generator<Return = ()> + Unpin>( - generator: G, -) -> impl Iterator<Item = G::Yield> { +pub fn from_generator<G: Generator<Return = ()> + Unpin>(generator: G) -> FromGenerator<G> { FromGenerator(generator) } -struct FromGenerator<G>(G); +/// An iterator over the values yielded by an underlying generator. +/// +/// This `struct` is created by the [`iter::from_generator()`] function. See its documentation for +/// more. +/// +/// [`iter::from_generator()`]: from_generator +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] +#[derive(Clone)] +pub struct FromGenerator<G>(G); +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] impl<G: Generator<Return = ()> + Unpin> Iterator for FromGenerator<G> { type Item = G::Yield; @@ -41,3 +49,10 @@ impl<G: Generator<Return = ()> + Unpin> Iterator for FromGenerator<G> { } } } + +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] +impl<G> fmt::Debug for FromGenerator<G> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("FromGenerator").finish() + } +} diff --git a/library/core/src/iter/sources/once_with.rs b/library/core/src/iter/sources/once_with.rs index d79f85c25..9309a06c8 100644 --- a/library/core/src/iter/sources/once_with.rs +++ b/library/core/src/iter/sources/once_with.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::iter::{FusedIterator, TrustedLen}; /// Creates an iterator that lazily generates a value exactly once by invoking @@ -66,12 +67,23 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> { /// /// This `struct` is created by the [`once_with()`] function. /// See its documentation for more. -#[derive(Clone, Debug)] +#[derive(Clone)] #[stable(feature = "iter_once_with", since = "1.43.0")] pub struct OnceWith<F> { gen: Option<F>, } +#[stable(feature = "iter_once_with_debug", since = "1.68.0")] +impl<F> fmt::Debug for OnceWith<F> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.gen.is_some() { + f.write_str("OnceWith(Some(_))") + } else { + f.write_str("OnceWith(None)") + } + } +} + #[stable(feature = "iter_once_with", since = "1.43.0")] impl<A, F: FnOnce() -> A> Iterator for OnceWith<F> { type Item = A; diff --git a/library/core/src/iter/sources/repeat_n.rs b/library/core/src/iter/sources/repeat_n.rs index fd8d25ce1..dc61d6065 100644 --- a/library/core/src/iter/sources/repeat_n.rs +++ b/library/core/src/iter/sources/repeat_n.rs @@ -126,7 +126,7 @@ impl<A: Clone> Iterator for RepeatN<A> { // zero so it won't be dropped later, and thus it's okay to take it here. unsafe { ManuallyDrop::take(&mut self.element) } } else { - A::clone(&mut self.element) + A::clone(&self.element) }) } diff --git a/library/core/src/iter/sources/repeat_with.rs b/library/core/src/iter/sources/repeat_with.rs index ab2d0472b..3f34105a3 100644 --- a/library/core/src/iter/sources/repeat_with.rs +++ b/library/core/src/iter/sources/repeat_with.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::iter::{FusedIterator, TrustedLen}; use crate::ops::Try; @@ -71,12 +72,19 @@ pub fn repeat_with<A, F: FnMut() -> A>(repeater: F) -> RepeatWith<F> { /// /// This `struct` is created by the [`repeat_with()`] function. /// See its documentation for more. -#[derive(Copy, Clone, Debug)] +#[derive(Copy, Clone)] #[stable(feature = "iterator_repeat_with", since = "1.28.0")] pub struct RepeatWith<F> { repeater: F, } +#[stable(feature = "iterator_repeat_with_debug", since = "1.68.0")] +impl<F> fmt::Debug for RepeatWith<F> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RepeatWith").finish_non_exhaustive() + } +} + #[stable(feature = "iterator_repeat_with", since = "1.28.0")] impl<A, F: FnMut() -> A> Iterator for RepeatWith<F> { type Item = A; diff --git a/library/core/src/iter/traits/accum.rs b/library/core/src/iter/traits/accum.rs index 84d83ee39..e31669b39 100644 --- a/library/core/src/iter/traits/accum.rs +++ b/library/core/src/iter/traits/accum.rs @@ -10,6 +10,10 @@ use crate::num::Wrapping; /// [`sum()`]: Iterator::sum /// [`FromIterator`]: iter::FromIterator #[stable(feature = "iter_arith_traits", since = "1.12.0")] +#[rustc_on_unimplemented( + message = "a value of type `{Self}` cannot be made by summing an iterator over elements of type `{A}`", + label = "value of type `{Self}` cannot be made by summing a `std::iter::Iterator<Item={A}>`" +)] pub trait Sum<A = Self>: Sized { /// Method which takes an iterator and generates `Self` from the elements by /// "summing up" the items. @@ -27,6 +31,10 @@ pub trait Sum<A = Self>: Sized { /// [`product()`]: Iterator::product /// [`FromIterator`]: iter::FromIterator #[stable(feature = "iter_arith_traits", since = "1.12.0")] +#[rustc_on_unimplemented( + message = "a value of type `{Self}` cannot be made by multiplying all elements of type `{A}` from an iterator", + label = "value of type `{Self}` cannot be made by multiplying all elements from a `std::iter::Iterator<Item={A}>`" +)] pub trait Product<A = Self>: Sized { /// Method which takes an iterator and generates `Self` from the elements by /// multiplying the items. diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index 83c7e8977..a4a665d48 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -58,6 +58,11 @@ fn _assert_is_object_safe(_: &dyn Iterator<Item = ()>) {} note = "if you want to iterate between `start` until a value `end`, use the exclusive range \ syntax `start..end` or the inclusive range syntax `start..=end`" ), + on( + _Self = "{float}", + note = "if you want to iterate between `start` until a value `end`, use the exclusive range \ + syntax `start..end` or the inclusive range syntax `start..=end`" + ), label = "`{Self}` is not an iterator", message = "`{Self}` is not an iterator" )] @@ -66,6 +71,7 @@ fn _assert_is_object_safe(_: &dyn Iterator<Item = ()>) {} #[must_use = "iterators are lazy and do nothing unless consumed"] pub trait Iterator { /// The type of the elements being iterated over. + #[rustc_diagnostic_item = "IteratorItem"] #[stable(feature = "rust1", since = "1.0.0")] type Item; @@ -803,7 +809,7 @@ pub trait Iterator { /// (0..5).map(|x| x * 2 + 1) /// .for_each(move |x| tx.send(x).unwrap()); /// - /// let v: Vec<_> = rx.iter().collect(); + /// let v: Vec<_> = rx.iter().collect(); /// assert_eq!(v, vec![1, 3, 5, 7, 9]); /// ``` /// @@ -1380,8 +1386,8 @@ pub trait Iterator { Take::new(self, n) } - /// An iterator adapter similar to [`fold`] that holds internal state and - /// produces a new iterator. + /// An iterator adapter which, like [`fold`], holds internal state, but + /// unlike [`fold`], produces a new iterator. /// /// [`fold`]: Iterator::fold /// @@ -1393,20 +1399,25 @@ pub trait Iterator { /// /// On iteration, the closure will be applied to each element of the /// iterator and the return value from the closure, an [`Option`], is - /// yielded by the iterator. + /// returned by the `next` method. Thus the closure can return + /// `Some(value)` to yield `value`, or `None` to end the iteration. /// /// # Examples /// /// Basic usage: /// /// ``` - /// let a = [1, 2, 3]; + /// let a = [1, 2, 3, 4]; /// /// let mut iter = a.iter().scan(1, |state, &x| { - /// // each iteration, we'll multiply the state by the element + /// // each iteration, we'll multiply the state by the element ... /// *state = *state * x; /// - /// // then, we'll yield the negation of the state + /// // ... and terminate if the state exceeds 6 + /// if *state > 6 { + /// return None; + /// } + /// // ... else yield the negation of the state /// Some(-*state) /// }); /// @@ -1508,6 +1519,18 @@ pub trait Iterator { /// assert_eq!(merged, "alphabetagamma"); /// ``` /// + /// Flattening works on any `IntoIterator` type, including `Option` and `Result`: + /// + /// ``` + /// let options = vec![Some(123), Some(321), None, Some(231)]; + /// let flattened_options: Vec<_> = options.into_iter().flatten().collect(); + /// assert_eq!(flattened_options, vec![123, 321, 231]); + /// + /// let results = vec![Ok(123), Ok(321), Err(456), Ok(231)]; + /// let flattened_results: Vec<_> = results.into_iter().flatten().collect(); + /// assert_eq!(flattened_results, vec![123, 321, 231]); + /// ``` + /// /// Flattening only removes one level of nesting at a time: /// /// ``` @@ -1829,6 +1852,7 @@ pub trait Iterator { #[inline] #[stable(feature = "rust1", since = "1.0.0")] #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"] + #[cfg_attr(not(test), rustc_diagnostic_item = "iterator_collect_fn")] fn collect<B: FromIterator<Self::Item>>(self) -> B where Self: Sized, @@ -2652,7 +2676,10 @@ pub trait Iterator { /// argument is a double reference. You can see this effect in the /// examples below, with `&&x`. /// + /// If you need the index of the element, see [`position()`]. + /// /// [`Some(element)`]: Some + /// [`position()`]: Iterator::position /// /// # Examples /// @@ -2733,7 +2760,7 @@ pub trait Iterator { /// the first true result or the first error. /// /// The return type of this method depends on the return type of the closure. - /// If you return `Result<bool, E>` from the closure, you'll get a `Result<Option<Self::Item>; E>`. + /// If you return `Result<bool, E>` from the closure, you'll get a `Result<Option<Self::Item>, E>`. /// If you return `Option<bool>` from the closure, you'll get an `Option<Option<Self::Item>>`. /// /// # Examples |