| //! Implementations of things like `Eq` for fixed-length arrays |
| //! up to a certain length. Eventually, we should be able to generalize |
| //! to all lengths. |
| //! |
| //! *[See also the array primitive type](../../std/primitive.array.html).* |
| |
| #![stable(feature = "core_array", since = "1.36.0")] |
| |
| use crate::borrow::{Borrow, BorrowMut}; |
| use crate::cmp::Ordering; |
| use crate::convert::{Infallible, TryFrom}; |
| use crate::fmt; |
| use crate::hash::{self, Hash}; |
| use crate::marker::Unsize; |
| use crate::slice::{Iter, IterMut}; |
| |
| mod iter; |
| |
| #[unstable(feature = "array_value_iter", issue = "65798")] |
| pub use iter::IntoIter; |
| |
| /// Utility trait implemented only on arrays of fixed size |
| /// |
| /// This trait can be used to implement other traits on fixed-size arrays |
| /// without causing much metadata bloat. |
| /// |
| /// The trait is marked unsafe in order to restrict implementors to fixed-size |
| /// arrays. User of this trait can assume that implementors have the exact |
| /// layout in memory of a fixed size array (for example, for unsafe |
| /// initialization). |
| /// |
| /// Note that the traits [`AsRef`] and [`AsMut`] provide similar methods for types that |
| /// may not be fixed-size arrays. Implementors should prefer those traits |
| /// instead. |
| /// |
| /// [`AsRef`]: ../convert/trait.AsRef.html |
| /// [`AsMut`]: ../convert/trait.AsMut.html |
| #[unstable(feature = "fixed_size_array", issue = "27778")] |
| pub unsafe trait FixedSizeArray<T> { |
| /// Converts the array to immutable slice |
| #[unstable(feature = "fixed_size_array", issue = "27778")] |
| fn as_slice(&self) -> &[T]; |
| /// Converts the array to mutable slice |
| #[unstable(feature = "fixed_size_array", issue = "27778")] |
| fn as_mut_slice(&mut self) -> &mut [T]; |
| } |
| |
| #[unstable(feature = "fixed_size_array", issue = "27778")] |
| unsafe impl<T, A: Unsize<[T]>> FixedSizeArray<T> for A { |
| #[inline] |
| fn as_slice(&self) -> &[T] { |
| self |
| } |
| #[inline] |
| fn as_mut_slice(&mut self) -> &mut [T] { |
| self |
| } |
| } |
| |
| /// The error type returned when a conversion from a slice to an array fails. |
| #[stable(feature = "try_from", since = "1.34.0")] |
| #[derive(Debug, Copy, Clone)] |
| pub struct TryFromSliceError(()); |
| |
| #[stable(feature = "core_array", since = "1.36.0")] |
| impl fmt::Display for TryFromSliceError { |
| #[inline] |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Display::fmt(self.__description(), f) |
| } |
| } |
| |
| impl TryFromSliceError { |
| #[unstable( |
| feature = "array_error_internals", |
| reason = "available through Error trait and this method should not \ |
| be exposed publicly", |
| issue = "none" |
| )] |
| #[inline] |
| #[doc(hidden)] |
| pub fn __description(&self) -> &str { |
| "could not convert slice to array" |
| } |
| } |
| |
| #[stable(feature = "try_from_slice_error", since = "1.36.0")] |
| impl From<Infallible> for TryFromSliceError { |
| fn from(x: Infallible) -> TryFromSliceError { |
| match x {} |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T, const N: usize> AsRef<[T]> for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn as_ref(&self) -> &[T] { |
| &self[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T, const N: usize> AsMut<[T]> for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn as_mut(&mut self) -> &mut [T] { |
| &mut self[..] |
| } |
| } |
| |
| #[stable(feature = "array_borrow", since = "1.4.0")] |
| impl<T, const N: usize> Borrow<[T]> for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| fn borrow(&self) -> &[T] { |
| self |
| } |
| } |
| |
| #[stable(feature = "array_borrow", since = "1.4.0")] |
| impl<T, const N: usize> BorrowMut<[T]> for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| fn borrow_mut(&mut self) -> &mut [T] { |
| self |
| } |
| } |
| |
| #[stable(feature = "try_from", since = "1.34.0")] |
| impl<T, const N: usize> TryFrom<&[T]> for [T; N] |
| where |
| T: Copy, |
| [T; N]: LengthAtMost32, |
| { |
| type Error = TryFromSliceError; |
| |
| fn try_from(slice: &[T]) -> Result<[T; N], TryFromSliceError> { |
| <&Self>::try_from(slice).map(|r| *r) |
| } |
| } |
| |
| #[stable(feature = "try_from", since = "1.34.0")] |
| impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| type Error = TryFromSliceError; |
| |
| fn try_from(slice: &[T]) -> Result<&[T; N], TryFromSliceError> { |
| if slice.len() == N { |
| let ptr = slice.as_ptr() as *const [T; N]; |
| // SAFETY: ok because we just checked that the length fits |
| unsafe { Ok(&*ptr) } |
| } else { |
| Err(TryFromSliceError(())) |
| } |
| } |
| } |
| |
| #[stable(feature = "try_from", since = "1.34.0")] |
| impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| type Error = TryFromSliceError; |
| |
| fn try_from(slice: &mut [T]) -> Result<&mut [T; N], TryFromSliceError> { |
| if slice.len() == N { |
| let ptr = slice.as_mut_ptr() as *mut [T; N]; |
| // SAFETY: ok because we just checked that the length fits |
| unsafe { Ok(&mut *ptr) } |
| } else { |
| Err(TryFromSliceError(())) |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Hash, const N: usize> Hash for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| fn hash<H: hash::Hasher>(&self, state: &mut H) { |
| Hash::hash(&self[..], state) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: fmt::Debug, const N: usize> fmt::Debug for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Debug::fmt(&&self[..], f) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T, const N: usize> IntoIterator for &'a [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| type Item = &'a T; |
| type IntoIter = Iter<'a, T>; |
| |
| fn into_iter(self) -> Iter<'a, T> { |
| self.iter() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T, const N: usize> IntoIterator for &'a mut [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| type Item = &'a mut T; |
| type IntoIter = IterMut<'a, T>; |
| |
| fn into_iter(self) -> IterMut<'a, T> { |
| self.iter_mut() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<A, B, const N: usize> PartialEq<[B; N]> for [A; N] |
| where |
| A: PartialEq<B>, |
| [A; N]: LengthAtMost32, |
| [B; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &[B; N]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &[B; N]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<A, B, const N: usize> PartialEq<[B]> for [A; N] |
| where |
| A: PartialEq<B>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &[B]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &[B]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<A, B, const N: usize> PartialEq<[A; N]> for [B] |
| where |
| B: PartialEq<A>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &[A; N]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &[A; N]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'b, A, B, const N: usize> PartialEq<&'b [B]> for [A; N] |
| where |
| A: PartialEq<B>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &&'b [B]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &&'b [B]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b [B] |
| where |
| B: PartialEq<A>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &[A; N]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &[A; N]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'b, A, B, const N: usize> PartialEq<&'b mut [B]> for [A; N] |
| where |
| A: PartialEq<B>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &&'b mut [B]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &&'b mut [B]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b mut [B] |
| where |
| B: PartialEq<A>, |
| [A; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn eq(&self, other: &[A; N]) -> bool { |
| self[..] == other[..] |
| } |
| #[inline] |
| fn ne(&self, other: &[A; N]) -> bool { |
| self[..] != other[..] |
| } |
| } |
| |
| // NOTE: some less important impls are omitted to reduce code bloat |
| // __impl_slice_eq2! { [A; $N], &'b [B; $N] } |
| // __impl_slice_eq2! { [A; $N], &'b mut [B; $N] } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Eq, const N: usize> Eq for [T; N] where [T; N]: LengthAtMost32 {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: PartialOrd, const N: usize> PartialOrd for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn partial_cmp(&self, other: &[T; N]) -> Option<Ordering> { |
| PartialOrd::partial_cmp(&&self[..], &&other[..]) |
| } |
| #[inline] |
| fn lt(&self, other: &[T; N]) -> bool { |
| PartialOrd::lt(&&self[..], &&other[..]) |
| } |
| #[inline] |
| fn le(&self, other: &[T; N]) -> bool { |
| PartialOrd::le(&&self[..], &&other[..]) |
| } |
| #[inline] |
| fn ge(&self, other: &[T; N]) -> bool { |
| PartialOrd::ge(&&self[..], &&other[..]) |
| } |
| #[inline] |
| fn gt(&self, other: &[T; N]) -> bool { |
| PartialOrd::gt(&&self[..], &&other[..]) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Ord, const N: usize> Ord for [T; N] |
| where |
| [T; N]: LengthAtMost32, |
| { |
| #[inline] |
| fn cmp(&self, other: &[T; N]) -> Ordering { |
| Ord::cmp(&&self[..], &&other[..]) |
| } |
| } |
| |
| /// Implemented for lengths where trait impls are allowed on arrays in core/std |
| #[rustc_on_unimplemented(message = "arrays only have std trait implementations for lengths 0..=32")] |
| #[unstable( |
| feature = "const_generic_impls_guard", |
| issue = "none", |
| reason = "will never be stable, just a temporary step until const generics are stable" |
| )] |
| pub trait LengthAtMost32 {} |
| |
| macro_rules! array_impls { |
| ($($N:literal)+) => { |
| $( |
| #[unstable(feature = "const_generic_impls_guard", issue = "none")] |
| impl<T> LengthAtMost32 for [T; $N] {} |
| )+ |
| } |
| } |
| |
| array_impls! { |
| 0 1 2 3 4 5 6 7 8 9 |
| 10 11 12 13 14 15 16 17 18 19 |
| 20 21 22 23 24 25 26 27 28 29 |
| 30 31 32 |
| } |
| |
| // The Default impls cannot be generated using the array_impls! macro because |
| // they require array literals. |
| |
| macro_rules! array_impl_default { |
| {$n:expr, $t:ident $($ts:ident)*} => { |
| #[stable(since = "1.4.0", feature = "array_default")] |
| impl<T> Default for [T; $n] where T: Default { |
| fn default() -> [T; $n] { |
| [$t::default(), $($ts::default()),*] |
| } |
| } |
| array_impl_default!{($n - 1), $($ts)*} |
| }; |
| {$n:expr,} => { |
| #[stable(since = "1.4.0", feature = "array_default")] |
| impl<T> Default for [T; $n] { |
| fn default() -> [T; $n] { [] } |
| } |
| }; |
| } |
| |
| array_impl_default! {32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T} |