diff options
Diffstat (limited to 'third_party/rust/generic-array/src/lib.rs')
| -rw-r--r-- | third_party/rust/generic-array/src/lib.rs | 679 |
1 files changed, 679 insertions, 0 deletions
diff --git a/third_party/rust/generic-array/src/lib.rs b/third_party/rust/generic-array/src/lib.rs new file mode 100644 index 0000000000..43ab26ff56 --- /dev/null +++ b/third_party/rust/generic-array/src/lib.rs @@ -0,0 +1,679 @@ +//! This crate implements a structure that can be used as a generic array type.
+//! Core Rust array types `[T; N]` can't be used generically with
+//! respect to `N`, so for example this:
+//!
+//! ```rust{compile_fail}
+//! struct Foo<T, N> {
+//! data: [T; N]
+//! }
+//! ```
+//!
+//! won't work.
+//!
+//! **generic-array** exports a `GenericArray<T,N>` type, which lets
+//! the above be implemented as:
+//!
+//! ```rust
+//! use generic_array::{ArrayLength, GenericArray};
+//!
+//! struct Foo<T, N: ArrayLength<T>> {
+//! data: GenericArray<T,N>
+//! }
+//! ```
+//!
+//! The `ArrayLength<T>` trait is implemented by default for
+//! [unsigned integer types](../typenum/uint/index.html) from
+//! [typenum](../typenum/index.html):
+//!
+//! ```rust
+//! # use generic_array::{ArrayLength, GenericArray};
+//! use generic_array::typenum::U5;
+//!
+//! struct Foo<N: ArrayLength<i32>> {
+//! data: GenericArray<i32, N>
+//! }
+//!
+//! # fn main() {
+//! let foo = Foo::<U5>{data: GenericArray::default()};
+//! # }
+//! ```
+//!
+//! For example, `GenericArray<T, U5>` would work almost like `[T; 5]`:
+//!
+//! ```rust
+//! # use generic_array::{ArrayLength, GenericArray};
+//! use generic_array::typenum::U5;
+//!
+//! struct Foo<T, N: ArrayLength<T>> {
+//! data: GenericArray<T, N>
+//! }
+//!
+//! # fn main() {
+//! let foo = Foo::<i32, U5>{data: GenericArray::default()};
+//! # }
+//! ```
+//!
+//! For ease of use, an `arr!` macro is provided - example below:
+//!
+//! ```
+//! # #[macro_use]
+//! # extern crate generic_array;
+//! # extern crate typenum;
+//! # fn main() {
+//! let array = arr![u32; 1, 2, 3];
+//! assert_eq!(array[2], 3);
+//! # }
+//! ```
+
+#![deny(missing_docs)]
+#![deny(meta_variable_misuse)]
+#![no_std]
+
+#[cfg(feature = "serde")]
+extern crate serde;
+
+#[cfg(feature = "zeroize")]
+extern crate zeroize;
+
+#[cfg(test)]
+extern crate bincode;
+
+pub extern crate typenum;
+
+mod hex;
+mod impls;
+
+#[cfg(feature = "serde")]
+mod impl_serde;
+
+#[cfg(feature = "zeroize")]
+mod impl_zeroize;
+
+use core::iter::FromIterator;
+use core::marker::PhantomData;
+use core::mem::{MaybeUninit, ManuallyDrop};
+use core::ops::{Deref, DerefMut};
+use core::{mem, ptr, slice};
+use typenum::bit::{B0, B1};
+use typenum::uint::{UInt, UTerm, Unsigned};
+
+#[cfg_attr(test, macro_use)]
+pub mod arr;
+pub mod functional;
+pub mod iter;
+pub mod sequence;
+
+use self::functional::*;
+pub use self::iter::GenericArrayIter;
+use self::sequence::*;
+
+/// Trait making `GenericArray` work, marking types to be used as length of an array
+pub unsafe trait ArrayLength<T>: Unsigned {
+ /// Associated type representing the array type for the number
+ type ArrayType;
+}
+
+unsafe impl<T> ArrayLength<T> for UTerm {
+ #[doc(hidden)]
+ type ArrayType = [T; 0];
+}
+
+/// Internal type used to generate a struct of appropriate size
+#[allow(dead_code)]
+#[repr(C)]
+#[doc(hidden)]
+pub struct GenericArrayImplEven<T, U> {
+ parent1: U,
+ parent2: U,
+ _marker: PhantomData<T>,
+}
+
+impl<T: Clone, U: Clone> Clone for GenericArrayImplEven<T, U> {
+ fn clone(&self) -> GenericArrayImplEven<T, U> {
+ GenericArrayImplEven {
+ parent1: self.parent1.clone(),
+ parent2: self.parent2.clone(),
+ _marker: PhantomData,
+ }
+ }
+}
+
+impl<T: Copy, U: Copy> Copy for GenericArrayImplEven<T, U> {}
+
+/// Internal type used to generate a struct of appropriate size
+#[allow(dead_code)]
+#[repr(C)]
+#[doc(hidden)]
+pub struct GenericArrayImplOdd<T, U> {
+ parent1: U,
+ parent2: U,
+ data: T,
+}
+
+impl<T: Clone, U: Clone> Clone for GenericArrayImplOdd<T, U> {
+ fn clone(&self) -> GenericArrayImplOdd<T, U> {
+ GenericArrayImplOdd {
+ parent1: self.parent1.clone(),
+ parent2: self.parent2.clone(),
+ data: self.data.clone(),
+ }
+ }
+}
+
+impl<T: Copy, U: Copy> Copy for GenericArrayImplOdd<T, U> {}
+
+unsafe impl<T, N: ArrayLength<T>> ArrayLength<T> for UInt<N, B0> {
+ #[doc(hidden)]
+ type ArrayType = GenericArrayImplEven<T, N::ArrayType>;
+}
+
+unsafe impl<T, N: ArrayLength<T>> ArrayLength<T> for UInt<N, B1> {
+ #[doc(hidden)]
+ type ArrayType = GenericArrayImplOdd<T, N::ArrayType>;
+}
+
+/// Struct representing a generic array - `GenericArray<T, N>` works like [T; N]
+#[allow(dead_code)]
+#[repr(transparent)]
+pub struct GenericArray<T, U: ArrayLength<T>> {
+ data: U::ArrayType,
+}
+
+unsafe impl<T: Send, N: ArrayLength<T>> Send for GenericArray<T, N> {}
+unsafe impl<T: Sync, N: ArrayLength<T>> Sync for GenericArray<T, N> {}
+
+impl<T, N> Deref for GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ type Target = [T];
+
+ #[inline(always)]
+ fn deref(&self) -> &[T] {
+ unsafe { slice::from_raw_parts(self as *const Self as *const T, N::USIZE) }
+ }
+}
+
+impl<T, N> DerefMut for GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ #[inline(always)]
+ fn deref_mut(&mut self) -> &mut [T] {
+ unsafe { slice::from_raw_parts_mut(self as *mut Self as *mut T, N::USIZE) }
+ }
+}
+
+/// Creates an array one element at a time using a mutable iterator
+/// you can write to with `ptr::write`.
+///
+/// Increment the position while iterating to mark off created elements,
+/// which will be dropped if `into_inner` is not called.
+#[doc(hidden)]
+pub struct ArrayBuilder<T, N: ArrayLength<T>> {
+ array: MaybeUninit<GenericArray<T, N>>,
+ position: usize,
+}
+
+impl<T, N: ArrayLength<T>> ArrayBuilder<T, N> {
+ #[doc(hidden)]
+ #[inline]
+ pub unsafe fn new() -> ArrayBuilder<T, N> {
+ ArrayBuilder {
+ array: MaybeUninit::uninit(),
+ position: 0,
+ }
+ }
+
+ /// Creates a mutable iterator for writing to the array using `ptr::write`.
+ ///
+ /// Increment the position value given as a mutable reference as you iterate
+ /// to mark how many elements have been created.
+ #[doc(hidden)]
+ #[inline]
+ pub unsafe fn iter_position(&mut self) -> (slice::IterMut<T>, &mut usize) {
+ ((&mut *self.array.as_mut_ptr()).iter_mut(), &mut self.position)
+ }
+
+ /// When done writing (assuming all elements have been written to),
+ /// get the inner array.
+ #[doc(hidden)]
+ #[inline]
+ pub unsafe fn into_inner(self) -> GenericArray<T, N> {
+ let array = ptr::read(&self.array);
+
+ mem::forget(self);
+
+ array.assume_init()
+ }
+}
+
+impl<T, N: ArrayLength<T>> Drop for ArrayBuilder<T, N> {
+ fn drop(&mut self) {
+ if mem::needs_drop::<T>() {
+ unsafe {
+ for value in &mut (&mut *self.array.as_mut_ptr())[..self.position] {
+ ptr::drop_in_place(value);
+ }
+ }
+ }
+ }
+}
+
+/// Consumes an array.
+///
+/// Increment the position while iterating and any leftover elements
+/// will be dropped if position does not go to N
+#[doc(hidden)]
+pub struct ArrayConsumer<T, N: ArrayLength<T>> {
+ array: ManuallyDrop<GenericArray<T, N>>,
+ position: usize,
+}
+
+impl<T, N: ArrayLength<T>> ArrayConsumer<T, N> {
+ #[doc(hidden)]
+ #[inline]
+ pub unsafe fn new(array: GenericArray<T, N>) -> ArrayConsumer<T, N> {
+ ArrayConsumer {
+ array: ManuallyDrop::new(array),
+ position: 0,
+ }
+ }
+
+ /// Creates an iterator and mutable reference to the internal position
+ /// to keep track of consumed elements.
+ ///
+ /// Increment the position as you iterate to mark off consumed elements
+ #[doc(hidden)]
+ #[inline]
+ pub unsafe fn iter_position(&mut self) -> (slice::Iter<T>, &mut usize) {
+ (self.array.iter(), &mut self.position)
+ }
+}
+
+impl<T, N: ArrayLength<T>> Drop for ArrayConsumer<T, N> {
+ fn drop(&mut self) {
+ if mem::needs_drop::<T>() {
+ for value in &mut self.array[self.position..N::USIZE] {
+ unsafe {
+ ptr::drop_in_place(value);
+ }
+ }
+ }
+ }
+}
+
+impl<'a, T: 'a, N> IntoIterator for &'a GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ type IntoIter = slice::Iter<'a, T>;
+ type Item = &'a T;
+
+ fn into_iter(self: &'a GenericArray<T, N>) -> Self::IntoIter {
+ self.as_slice().iter()
+ }
+}
+
+impl<'a, T: 'a, N> IntoIterator for &'a mut GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ type IntoIter = slice::IterMut<'a, T>;
+ type Item = &'a mut T;
+
+ fn into_iter(self: &'a mut GenericArray<T, N>) -> Self::IntoIter {
+ self.as_mut_slice().iter_mut()
+ }
+}
+
+impl<T, N> FromIterator<T> for GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ fn from_iter<I>(iter: I) -> GenericArray<T, N>
+ where
+ I: IntoIterator<Item = T>,
+ {
+ unsafe {
+ let mut destination = ArrayBuilder::new();
+
+ {
+ let (destination_iter, position) = destination.iter_position();
+
+ iter.into_iter()
+ .zip(destination_iter)
+ .for_each(|(src, dst)| {
+ ptr::write(dst, src);
+
+ *position += 1;
+ });
+ }
+
+ if destination.position < N::USIZE {
+ from_iter_length_fail(destination.position, N::USIZE);
+ }
+
+ destination.into_inner()
+ }
+ }
+}
+
+#[inline(never)]
+#[cold]
+fn from_iter_length_fail(length: usize, expected: usize) -> ! {
+ panic!(
+ "GenericArray::from_iter received {} elements but expected {}",
+ length, expected
+ );
+}
+
+unsafe impl<T, N> GenericSequence<T> for GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+ Self: IntoIterator<Item = T>,
+{
+ type Length = N;
+ type Sequence = Self;
+
+ fn generate<F>(mut f: F) -> GenericArray<T, N>
+ where
+ F: FnMut(usize) -> T,
+ {
+ unsafe {
+ let mut destination = ArrayBuilder::new();
+
+ {
+ let (destination_iter, position) = destination.iter_position();
+
+ destination_iter.enumerate().for_each(|(i, dst)| {
+ ptr::write(dst, f(i));
+
+ *position += 1;
+ });
+ }
+
+ destination.into_inner()
+ }
+ }
+
+ #[doc(hidden)]
+ fn inverted_zip<B, U, F>(
+ self,
+ lhs: GenericArray<B, Self::Length>,
+ mut f: F,
+ ) -> MappedSequence<GenericArray<B, Self::Length>, B, U>
+ where
+ GenericArray<B, Self::Length>:
+ GenericSequence<B, Length = Self::Length> + MappedGenericSequence<B, U>,
+ Self: MappedGenericSequence<T, U>,
+ Self::Length: ArrayLength<B> + ArrayLength<U>,
+ F: FnMut(B, Self::Item) -> U,
+ {
+ unsafe {
+ let mut left = ArrayConsumer::new(lhs);
+ let mut right = ArrayConsumer::new(self);
+
+ let (left_array_iter, left_position) = left.iter_position();
+ let (right_array_iter, right_position) = right.iter_position();
+
+ FromIterator::from_iter(left_array_iter.zip(right_array_iter).map(|(l, r)| {
+ let left_value = ptr::read(l);
+ let right_value = ptr::read(r);
+
+ *left_position += 1;
+ *right_position += 1;
+
+ f(left_value, right_value)
+ }))
+ }
+ }
+
+ #[doc(hidden)]
+ fn inverted_zip2<B, Lhs, U, F>(self, lhs: Lhs, mut f: F) -> MappedSequence<Lhs, B, U>
+ where
+ Lhs: GenericSequence<B, Length = Self::Length> + MappedGenericSequence<B, U>,
+ Self: MappedGenericSequence<T, U>,
+ Self::Length: ArrayLength<B> + ArrayLength<U>,
+ F: FnMut(Lhs::Item, Self::Item) -> U,
+ {
+ unsafe {
+ let mut right = ArrayConsumer::new(self);
+
+ let (right_array_iter, right_position) = right.iter_position();
+
+ FromIterator::from_iter(
+ lhs.into_iter()
+ .zip(right_array_iter)
+ .map(|(left_value, r)| {
+ let right_value = ptr::read(r);
+
+ *right_position += 1;
+
+ f(left_value, right_value)
+ }),
+ )
+ }
+ }
+}
+
+unsafe impl<T, U, N> MappedGenericSequence<T, U> for GenericArray<T, N>
+where
+ N: ArrayLength<T> + ArrayLength<U>,
+ GenericArray<U, N>: GenericSequence<U, Length = N>,
+{
+ type Mapped = GenericArray<U, N>;
+}
+
+unsafe impl<T, N> FunctionalSequence<T> for GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+ Self: GenericSequence<T, Item = T, Length = N>,
+{
+ fn map<U, F>(self, mut f: F) -> MappedSequence<Self, T, U>
+ where
+ Self::Length: ArrayLength<U>,
+ Self: MappedGenericSequence<T, U>,
+ F: FnMut(T) -> U,
+ {
+ unsafe {
+ let mut source = ArrayConsumer::new(self);
+
+ let (array_iter, position) = source.iter_position();
+
+ FromIterator::from_iter(array_iter.map(|src| {
+ let value = ptr::read(src);
+
+ *position += 1;
+
+ f(value)
+ }))
+ }
+ }
+
+ #[inline]
+ fn zip<B, Rhs, U, F>(self, rhs: Rhs, f: F) -> MappedSequence<Self, T, U>
+ where
+ Self: MappedGenericSequence<T, U>,
+ Rhs: MappedGenericSequence<B, U, Mapped = MappedSequence<Self, T, U>>,
+ Self::Length: ArrayLength<B> + ArrayLength<U>,
+ Rhs: GenericSequence<B, Length = Self::Length>,
+ F: FnMut(T, Rhs::Item) -> U,
+ {
+ rhs.inverted_zip(self, f)
+ }
+
+ fn fold<U, F>(self, init: U, mut f: F) -> U
+ where
+ F: FnMut(U, T) -> U,
+ {
+ unsafe {
+ let mut source = ArrayConsumer::new(self);
+
+ let (array_iter, position) = source.iter_position();
+
+ array_iter.fold(init, |acc, src| {
+ let value = ptr::read(src);
+
+ *position += 1;
+
+ f(acc, value)
+ })
+ }
+ }
+}
+
+impl<T, N> GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ /// Extracts a slice containing the entire array.
+ #[inline]
+ pub fn as_slice(&self) -> &[T] {
+ self.deref()
+ }
+
+ /// Extracts a mutable slice containing the entire array.
+ #[inline]
+ pub fn as_mut_slice(&mut self) -> &mut [T] {
+ self.deref_mut()
+ }
+
+ /// Converts slice to a generic array reference with inferred length;
+ ///
+ /// Length of the slice must be equal to the length of the array.
+ #[inline]
+ pub fn from_slice(slice: &[T]) -> &GenericArray<T, N> {
+ slice.into()
+ }
+
+ /// Converts mutable slice to a mutable generic array reference
+ ///
+ /// Length of the slice must be equal to the length of the array.
+ #[inline]
+ pub fn from_mut_slice(slice: &mut [T]) -> &mut GenericArray<T, N> {
+ slice.into()
+ }
+}
+
+impl<'a, T, N: ArrayLength<T>> From<&'a [T]> for &'a GenericArray<T, N> {
+ /// Converts slice to a generic array reference with inferred length;
+ ///
+ /// Length of the slice must be equal to the length of the array.
+ #[inline]
+ fn from(slice: &[T]) -> &GenericArray<T, N> {
+ assert_eq!(slice.len(), N::USIZE);
+
+ unsafe { &*(slice.as_ptr() as *const GenericArray<T, N>) }
+ }
+}
+
+impl<'a, T, N: ArrayLength<T>> From<&'a mut [T]> for &'a mut GenericArray<T, N> {
+ /// Converts mutable slice to a mutable generic array reference
+ ///
+ /// Length of the slice must be equal to the length of the array.
+ #[inline]
+ fn from(slice: &mut [T]) -> &mut GenericArray<T, N> {
+ assert_eq!(slice.len(), N::USIZE);
+
+ unsafe { &mut *(slice.as_mut_ptr() as *mut GenericArray<T, N>) }
+ }
+}
+
+impl<T: Clone, N> GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ /// Construct a `GenericArray` from a slice by cloning its content
+ ///
+ /// Length of the slice must be equal to the length of the array
+ #[inline]
+ pub fn clone_from_slice(list: &[T]) -> GenericArray<T, N> {
+ Self::from_exact_iter(list.iter().cloned())
+ .expect("Slice must be the same length as the array")
+ }
+}
+
+impl<T, N> GenericArray<T, N>
+where
+ N: ArrayLength<T>,
+{
+ /// Creates a new `GenericArray` instance from an iterator with a specific size.
+ ///
+ /// Returns `None` if the size is not equal to the number of elements in the `GenericArray`.
+ pub fn from_exact_iter<I>(iter: I) -> Option<Self>
+ where
+ I: IntoIterator<Item = T>,
+ {
+ let mut iter = iter.into_iter();
+
+ unsafe {
+ let mut destination = ArrayBuilder::new();
+
+ {
+ let (destination_iter, position) = destination.iter_position();
+
+ destination_iter.zip(&mut iter).for_each(|(dst, src)| {
+ ptr::write(dst, src);
+
+ *position += 1;
+ });
+
+ // The iterator produced fewer than `N` elements.
+ if *position != N::USIZE {
+ return None;
+ }
+
+ // The iterator produced more than `N` elements.
+ if iter.next().is_some() {
+ return None;
+ }
+ }
+
+ Some(destination.into_inner())
+ }
+ }
+}
+
+/// A reimplementation of the `transmute` function, avoiding problems
+/// when the compiler can't prove equal sizes.
+#[inline]
+#[doc(hidden)]
+pub unsafe fn transmute<A, B>(a: A) -> B {
+ let a = ManuallyDrop::new(a);
+ ::core::ptr::read(&*a as *const A as *const B)
+}
+
+#[cfg(test)]
+mod test {
+ // Compile with:
+ // cargo rustc --lib --profile test --release --
+ // -C target-cpu=native -C opt-level=3 --emit asm
+ // and view the assembly to make sure test_assembly generates
+ // SIMD instructions instead of a naive loop.
+
+ #[inline(never)]
+ pub fn black_box<T>(val: T) -> T {
+ use core::{mem, ptr};
+
+ let ret = unsafe { ptr::read_volatile(&val) };
+ mem::forget(val);
+ ret
+ }
+
+ #[test]
+ fn test_assembly() {
+ use crate::functional::*;
+
+ let a = black_box(arr![i32; 1, 3, 5, 7]);
+ let b = black_box(arr![i32; 2, 4, 6, 8]);
+
+ let c = (&a).zip(b, |l, r| l + r);
+
+ let d = a.fold(0, |a, x| a + x);
+
+ assert_eq!(c, arr![i32; 3, 7, 11, 15]);
+
+ assert_eq!(d, 16);
+ }
+}
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