diff options
Diffstat (limited to 'src/libcore/array')
| -rw-r--r-- | src/libcore/array/iter.rs | 236 | ||||
| -rw-r--r-- | src/libcore/array/mod.rs | 366 |
2 files changed, 0 insertions, 602 deletions
diff --git a/src/libcore/array/iter.rs b/src/libcore/array/iter.rs deleted file mode 100644 index 174f7e26efb..00000000000 --- a/src/libcore/array/iter.rs +++ /dev/null @@ -1,236 +0,0 @@ -//! Defines the `IntoIter` owned iterator for arrays. - -use crate::{ - fmt, - iter::{ExactSizeIterator, FusedIterator, TrustedLen}, - mem::{self, MaybeUninit}, - ops::Range, - ptr, -}; - -/// A by-value [array] iterator. -/// -/// [array]: ../../std/primitive.array.html -#[unstable(feature = "array_value_iter", issue = "65798")] -pub struct IntoIter<T, const N: usize> { - /// This is the array we are iterating over. - /// - /// Elements with index `i` where `alive.start <= i < alive.end` have not - /// been yielded yet and are valid array entries. Elements with indices `i - /// < alive.start` or `i >= alive.end` have been yielded already and must - /// not be accessed anymore! Those dead elements might even be in a - /// completely uninitialized state! - /// - /// So the invariants are: - /// - `data[alive]` is alive (i.e. contains valid elements) - /// - `data[..alive.start]` and `data[alive.end..]` are dead (i.e. the - /// elements were already read and must not be touched anymore!) - data: [MaybeUninit<T>; N], - - /// The elements in `data` that have not been yielded yet. - /// - /// Invariants: - /// - `alive.start <= alive.end` - /// - `alive.end <= N` - alive: Range<usize>, -} - -impl<T, const N: usize> IntoIter<T, N> { - /// Creates a new iterator over the given `array`. - /// - /// *Note*: this method might never get stabilized and/or removed in the - /// future as there will likely be another, preferred way of obtaining this - /// iterator (either via `IntoIterator` for arrays or via another way). - #[unstable(feature = "array_value_iter", issue = "65798")] - pub fn new(array: [T; N]) -> Self { - // SAFETY: The transmute here is actually safe. The docs of `MaybeUninit` - // promise: - // - // > `MaybeUninit<T>` is guaranteed to have the same size and alignment - // > as `T`. - // - // The docs even show a transmute from an array of `MaybeUninit<T>` to - // an array of `T`. - // - // With that, this initialization satisfies the invariants. - - // FIXME(LukasKalbertodt): actually use `mem::transmute` here, once it - // works with const generics: - // `mem::transmute::<[T; {N}], [MaybeUninit<T>; {N}]>(array)` - // - // Until then, we do it manually here. We first create a bitwise copy - // but cast the pointer so that it is treated as a different type. Then - // we forget `array` so that it is not dropped. - let data = unsafe { - let data = ptr::read(&array as *const [T; N] as *const [MaybeUninit<T>; N]); - mem::forget(array); - data - }; - - Self { data, alive: 0..N } - } - - /// Returns an immutable slice of all elements that have not been yielded - /// yet. - fn as_slice(&self) -> &[T] { - let slice = &self.data[self.alive.clone()]; - // SAFETY: This transmute is safe. As mentioned in `new`, `MaybeUninit` retains - // the size and alignment of `T`. Furthermore, we know that all - // elements within `alive` are properly initialized. - unsafe { mem::transmute::<&[MaybeUninit<T>], &[T]>(slice) } - } - - /// Returns a mutable slice of all elements that have not been yielded yet. - fn as_mut_slice(&mut self) -> &mut [T] { - // This transmute is safe, same as in `as_slice` above. - let slice = &mut self.data[self.alive.clone()]; - // SAFETY: This transmute is safe. As mentioned in `new`, `MaybeUninit` retains - // the size and alignment of `T`. Furthermore, we know that all - // elements within `alive` are properly initialized. - unsafe { mem::transmute::<&mut [MaybeUninit<T>], &mut [T]>(slice) } - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T, const N: usize> Iterator for IntoIter<T, N> { - type Item = T; - fn next(&mut self) -> Option<Self::Item> { - if self.alive.start == self.alive.end { - return None; - } - - // Bump start index. - // - // From the check above we know that `alive.start != alive.end`. - // Combine this with the invariant `alive.start <= alive.end`, we know - // that `alive.start < alive.end`. Increasing `alive.start` by 1 - // maintains the invariant regarding `alive`. However, due to this - // change, for a short time, the alive zone is not `data[alive]` - // anymore, but `data[idx..alive.end]`. - let idx = self.alive.start; - self.alive.start += 1; - - // Read the element from the array. - // SAFETY: This is safe: `idx` is an index - // into the "alive" region of the array. Reading this element means - // that `data[idx]` is regarded as dead now (i.e. do not touch). As - // `idx` was the start of the alive-zone, the alive zone is now - // `data[alive]` again, restoring all invariants. - let out = unsafe { self.data.get_unchecked(idx).read() }; - - Some(out) - } - - fn size_hint(&self) -> (usize, Option<usize>) { - let len = self.len(); - (len, Some(len)) - } - - fn count(self) -> usize { - self.len() - } - - fn last(mut self) -> Option<Self::Item> { - self.next_back() - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T, const N: usize> DoubleEndedIterator for IntoIter<T, N> { - fn next_back(&mut self) -> Option<Self::Item> { - if self.alive.start == self.alive.end { - return None; - } - - // Decrease end index. - // - // From the check above we know that `alive.start != alive.end`. - // Combine this with the invariant `alive.start <= alive.end`, we know - // that `alive.start < alive.end`. As `alive.start` cannot be negative, - // `alive.end` is at least 1, meaning that we can safely decrement it - // by one. This also maintains the invariant `alive.start <= - // alive.end`. However, due to this change, for a short time, the alive - // zone is not `data[alive]` anymore, but `data[alive.start..alive.end - // + 1]`. - self.alive.end -= 1; - - // Read the element from the array. - // SAFETY: This is safe: `alive.end` is an - // index into the "alive" region of the array. Compare the previous - // comment that states that the alive region is - // `data[alive.start..alive.end + 1]`. Reading this element means that - // `data[alive.end]` is regarded as dead now (i.e. do not touch). As - // `alive.end` was the end of the alive-zone, the alive zone is now - // `data[alive]` again, restoring all invariants. - let out = unsafe { self.data.get_unchecked(self.alive.end).read() }; - - Some(out) - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T, const N: usize> Drop for IntoIter<T, N> { - fn drop(&mut self) { - // SAFETY: This is safe: `as_mut_slice` returns exactly the sub-slice - // of elements that have not been moved out yet and that remain - // to be dropped. - unsafe { ptr::drop_in_place(self.as_mut_slice()) } - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T, const N: usize> ExactSizeIterator for IntoIter<T, N> { - fn len(&self) -> usize { - // Will never underflow due to the invariant `alive.start <= - // alive.end`. - self.alive.end - self.alive.start - } - fn is_empty(&self) -> bool { - self.alive.is_empty() - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T, const N: usize> FusedIterator for IntoIter<T, N> {} - -// The iterator indeed reports the correct length. The number of "alive" -// elements (that will still be yielded) is the length of the range `alive`. -// This range is decremented in length in either `next` or `next_back`. It is -// always decremented by 1 in those methods, but only if `Some(_)` is returned. -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -unsafe impl<T, const N: usize> TrustedLen for IntoIter<T, N> {} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T: Clone, const N: usize> Clone for IntoIter<T, N> { - fn clone(&self) -> Self { - // SAFETY: each point of unsafety is documented inside the unsafe block - unsafe { - // This creates a new uninitialized array. Note that the `assume_init` - // refers to the array, not the individual elements. And it is Ok if - // the array is in an uninitialized state as all elements may be - // uninitialized (all bit patterns are valid). Compare the - // `MaybeUninit` docs for more information. - let mut new_data: [MaybeUninit<T>; N] = MaybeUninit::uninit().assume_init(); - - // Clone all alive elements. - for idx in self.alive.clone() { - // The element at `idx` in the old array is alive, so we can - // safely call `get_ref()`. We then clone it, and write the - // clone into the new array. - let clone = self.data.get_unchecked(idx).get_ref().clone(); - new_data.get_unchecked_mut(idx).write(clone); - } - - Self { data: new_data, alive: self.alive.clone() } - } - } -} - -#[stable(feature = "array_value_iter_impls", since = "1.40.0")] -impl<T: fmt::Debug, const N: usize> fmt::Debug for IntoIter<T, N> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - // Only print the elements that were not yielded yet: we cannot - // access the yielded elements anymore. - f.debug_tuple("IntoIter").field(&self.as_slice()).finish() - } -} diff --git a/src/libcore/array/mod.rs b/src/libcore/array/mod.rs deleted file mode 100644 index c0bf3833b9c..00000000000 --- a/src/libcore/array/mod.rs +++ /dev/null @@ -1,366 +0,0 @@ -//! 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] { - #[inline] - fn as_ref(&self) -> &[T] { - &self[..] - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, const N: usize> AsMut<[T]> for [T; N] { - #[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] { - fn borrow(&self) -> &[T] { - self - } -} - -#[stable(feature = "array_borrow", since = "1.4.0")] -impl<T, const N: usize> BorrowMut<[T]> for [T; N] { - 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, -{ - 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] { - 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] { - 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] { - 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] { - 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] { - 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] { - 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>, -{ - #[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>, -{ - #[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>, -{ - #[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>, -{ - #[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>, -{ - #[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>, -{ - #[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>, -{ - #[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; $N] } - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Eq, const N: usize> Eq for [T; N] {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: PartialOrd, const N: usize> PartialOrd for [T; N] { - #[inline] - fn partial_cmp(&self, other: &[T; N]) -> Option<Ordering> { - PartialOrd::partial_cmp(&&self[..], &&other[..]) - } - #[inline] - fn lt(&self, other: &[T; N]) -> bool { - PartialOrd::lt(&&self[..], &&other[..]) - } - #[inline] - fn le(&self, other: &[T; N]) -> bool { - PartialOrd::le(&&self[..], &&other[..]) - } - #[inline] - fn ge(&self, other: &[T; N]) -> bool { - PartialOrd::ge(&&self[..], &&other[..]) - } - #[inline] - fn gt(&self, other: &[T; N]) -> bool { - PartialOrd::gt(&&self[..], &&other[..]) - } -} - -/// Implements comparison of arrays lexicographically. -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Ord, const N: usize> Ord for [T; N] { - #[inline] - fn cmp(&self, other: &[T; N]) -> Ordering { - Ord::cmp(&&self[..], &&other[..]) - } -} - -// The Default impls cannot be generated using the array_impls! macro because -// they require array literals. - -macro_rules! array_impl_default { - {$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} |