674 lines
18 KiB
Rust
674 lines
18 KiB
Rust
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//! This crate implements a structure that can be used as a generic array type.
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//! Core Rust array types `[T; N]` can't be used generically with
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//! respect to `N`, so for example this:
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//!
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//! ```rust{compile_fail}
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//! struct Foo<T, N> {
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//! data: [T; N]
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//! }
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//! ```
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//!
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//! won't work.
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//!
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//! **generic-array** exports a `GenericArray<T,N>` type, which lets
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//! the above be implemented as:
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//!
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//! ```rust
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//! use generic_array::{ArrayLength, GenericArray};
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//!
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//! struct Foo<T, N: ArrayLength<T>> {
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//! data: GenericArray<T,N>
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//! }
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//! ```
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//!
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//! The `ArrayLength<T>` trait is implemented by default for
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//! [unsigned integer types](../typenum/uint/index.html) from
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//! [typenum](../typenum/index.html):
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//!
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//! ```rust
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//! # use generic_array::{ArrayLength, GenericArray};
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//! use generic_array::typenum::U5;
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//!
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//! struct Foo<N: ArrayLength<i32>> {
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//! data: GenericArray<i32, N>
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//! }
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//!
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//! # fn main() {
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//! let foo = Foo::<U5>{data: GenericArray::default()};
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//! # }
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//! ```
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//!
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//! For example, `GenericArray<T, U5>` would work almost like `[T; 5]`:
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//!
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//! ```rust
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//! # use generic_array::{ArrayLength, GenericArray};
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//! use generic_array::typenum::U5;
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//!
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//! struct Foo<T, N: ArrayLength<T>> {
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//! data: GenericArray<T, N>
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//! }
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//!
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//! # fn main() {
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//! let foo = Foo::<i32, U5>{data: GenericArray::default()};
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//! # }
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//! ```
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//!
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//! For ease of use, an `arr!` macro is provided - example below:
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//!
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//! ```
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//! # #[macro_use]
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//! # extern crate generic_array;
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//! # extern crate typenum;
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//! # fn main() {
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//! let array = arr![u32; 1, 2, 3];
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//! assert_eq!(array[2], 3);
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//! # }
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//! ```
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#![deny(missing_docs)]
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#![deny(meta_variable_misuse)]
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#![no_std]
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#[cfg(feature = "serde")]
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extern crate serde;
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#[cfg(test)]
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extern crate bincode;
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pub extern crate typenum;
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mod hex;
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mod impls;
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#[cfg(feature = "serde")]
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mod impl_serde;
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use core::iter::FromIterator;
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use core::marker::PhantomData;
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use core::mem::{MaybeUninit, ManuallyDrop};
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use core::ops::{Deref, DerefMut};
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use core::{mem, ptr, slice};
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use typenum::bit::{B0, B1};
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use typenum::uint::{UInt, UTerm, Unsigned};
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#[cfg_attr(test, macro_use)]
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pub mod arr;
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pub mod functional;
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pub mod iter;
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pub mod sequence;
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use self::functional::*;
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pub use self::iter::GenericArrayIter;
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use self::sequence::*;
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/// Trait making `GenericArray` work, marking types to be used as length of an array
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pub unsafe trait ArrayLength<T>: Unsigned {
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/// Associated type representing the array type for the number
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type ArrayType;
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}
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unsafe impl<T> ArrayLength<T> for UTerm {
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#[doc(hidden)]
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type ArrayType = [T; 0];
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}
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/// Internal type used to generate a struct of appropriate size
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#[allow(dead_code)]
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#[repr(C)]
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#[doc(hidden)]
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pub struct GenericArrayImplEven<T, U> {
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parent1: U,
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parent2: U,
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_marker: PhantomData<T>,
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}
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impl<T: Clone, U: Clone> Clone for GenericArrayImplEven<T, U> {
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fn clone(&self) -> GenericArrayImplEven<T, U> {
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GenericArrayImplEven {
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parent1: self.parent1.clone(),
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parent2: self.parent2.clone(),
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_marker: PhantomData,
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}
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}
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}
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impl<T: Copy, U: Copy> Copy for GenericArrayImplEven<T, U> {}
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/// Internal type used to generate a struct of appropriate size
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#[allow(dead_code)]
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#[repr(C)]
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#[doc(hidden)]
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pub struct GenericArrayImplOdd<T, U> {
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parent1: U,
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parent2: U,
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data: T,
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}
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impl<T: Clone, U: Clone> Clone for GenericArrayImplOdd<T, U> {
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fn clone(&self) -> GenericArrayImplOdd<T, U> {
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GenericArrayImplOdd {
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parent1: self.parent1.clone(),
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parent2: self.parent2.clone(),
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data: self.data.clone(),
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}
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}
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}
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impl<T: Copy, U: Copy> Copy for GenericArrayImplOdd<T, U> {}
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unsafe impl<T, N: ArrayLength<T>> ArrayLength<T> for UInt<N, B0> {
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#[doc(hidden)]
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type ArrayType = GenericArrayImplEven<T, N::ArrayType>;
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}
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unsafe impl<T, N: ArrayLength<T>> ArrayLength<T> for UInt<N, B1> {
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#[doc(hidden)]
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type ArrayType = GenericArrayImplOdd<T, N::ArrayType>;
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}
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/// Struct representing a generic array - `GenericArray<T, N>` works like [T; N]
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#[allow(dead_code)]
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#[repr(transparent)]
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pub struct GenericArray<T, U: ArrayLength<T>> {
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data: U::ArrayType,
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}
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unsafe impl<T: Send, N: ArrayLength<T>> Send for GenericArray<T, N> {}
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unsafe impl<T: Sync, N: ArrayLength<T>> Sync for GenericArray<T, N> {}
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impl<T, N> Deref for GenericArray<T, N>
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where
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N: ArrayLength<T>,
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{
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type Target = [T];
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#[inline(always)]
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fn deref(&self) -> &[T] {
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unsafe { slice::from_raw_parts(self as *const Self as *const T, N::USIZE) }
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}
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}
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impl<T, N> DerefMut for GenericArray<T, N>
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where
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N: ArrayLength<T>,
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{
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#[inline(always)]
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fn deref_mut(&mut self) -> &mut [T] {
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unsafe { slice::from_raw_parts_mut(self as *mut Self as *mut T, N::USIZE) }
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}
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}
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/// Creates an array one element at a time using a mutable iterator
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/// you can write to with `ptr::write`.
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///
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/// Incremenent the position while iterating to mark off created elements,
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/// which will be dropped if `into_inner` is not called.
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#[doc(hidden)]
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pub struct ArrayBuilder<T, N: ArrayLength<T>> {
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array: MaybeUninit<GenericArray<T, N>>,
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position: usize,
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}
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impl<T, N: ArrayLength<T>> ArrayBuilder<T, N> {
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#[doc(hidden)]
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#[inline]
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pub unsafe fn new() -> ArrayBuilder<T, N> {
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ArrayBuilder {
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array: MaybeUninit::uninit(),
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position: 0,
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}
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}
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/// Creates a mutable iterator for writing to the array using `ptr::write`.
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///
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/// Increment the position value given as a mutable reference as you iterate
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/// to mark how many elements have been created.
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#[doc(hidden)]
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#[inline]
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pub unsafe fn iter_position(&mut self) -> (slice::IterMut<T>, &mut usize) {
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((&mut *self.array.as_mut_ptr()).iter_mut(), &mut self.position)
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}
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/// When done writing (assuming all elements have been written to),
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/// get the inner array.
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#[doc(hidden)]
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#[inline]
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pub unsafe fn into_inner(self) -> GenericArray<T, N> {
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let array = ptr::read(&self.array);
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mem::forget(self);
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array.assume_init()
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}
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}
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impl<T, N: ArrayLength<T>> Drop for ArrayBuilder<T, N> {
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fn drop(&mut self) {
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if mem::needs_drop::<T>() {
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unsafe {
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for value in &mut (&mut *self.array.as_mut_ptr())[..self.position] {
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ptr::drop_in_place(value);
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}
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}
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}
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}
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}
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/// Consumes an array.
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///
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/// Increment the position while iterating and any leftover elements
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/// will be dropped if position does not go to N
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#[doc(hidden)]
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pub struct ArrayConsumer<T, N: ArrayLength<T>> {
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array: ManuallyDrop<GenericArray<T, N>>,
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position: usize,
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}
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impl<T, N: ArrayLength<T>> ArrayConsumer<T, N> {
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#[doc(hidden)]
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#[inline]
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pub unsafe fn new(array: GenericArray<T, N>) -> ArrayConsumer<T, N> {
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ArrayConsumer {
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array: ManuallyDrop::new(array),
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position: 0,
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}
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}
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/// Creates an iterator and mutable reference to the internal position
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/// to keep track of consumed elements.
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///
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/// Increment the position as you iterate to mark off consumed elements
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#[doc(hidden)]
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#[inline]
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pub unsafe fn iter_position(&mut self) -> (slice::Iter<T>, &mut usize) {
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(self.array.iter(), &mut self.position)
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}
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}
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impl<T, N: ArrayLength<T>> Drop for ArrayConsumer<T, N> {
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fn drop(&mut self) {
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if mem::needs_drop::<T>() {
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for value in &mut self.array[self.position..N::USIZE] {
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unsafe {
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ptr::drop_in_place(value);
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}
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}
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}
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}
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}
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impl<'a, T: 'a, N> IntoIterator for &'a GenericArray<T, N>
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where
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N: ArrayLength<T>,
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{
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type IntoIter = slice::Iter<'a, T>;
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type Item = &'a T;
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fn into_iter(self: &'a GenericArray<T, N>) -> Self::IntoIter {
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self.as_slice().iter()
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}
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}
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impl<'a, T: 'a, N> IntoIterator for &'a mut GenericArray<T, N>
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where
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N: ArrayLength<T>,
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{
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type IntoIter = slice::IterMut<'a, T>;
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type Item = &'a mut T;
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fn into_iter(self: &'a mut GenericArray<T, N>) -> Self::IntoIter {
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self.as_mut_slice().iter_mut()
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}
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}
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impl<T, N> FromIterator<T> for GenericArray<T, N>
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where
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N: ArrayLength<T>,
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{
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fn from_iter<I>(iter: I) -> GenericArray<T, N>
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where
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I: IntoIterator<Item = T>,
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{
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unsafe {
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let mut destination = ArrayBuilder::new();
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{
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let (destination_iter, position) = destination.iter_position();
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iter.into_iter()
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.zip(destination_iter)
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.for_each(|(src, dst)| {
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ptr::write(dst, src);
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*position += 1;
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});
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}
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if destination.position < N::USIZE {
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from_iter_length_fail(destination.position, N::USIZE);
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}
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destination.into_inner()
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}
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}
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}
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#[inline(never)]
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#[cold]
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fn from_iter_length_fail(length: usize, expected: usize) -> ! {
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panic!(
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"GenericArray::from_iter received {} elements but expected {}",
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length, expected
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);
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}
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unsafe impl<T, N> GenericSequence<T> for GenericArray<T, N>
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|
where
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N: ArrayLength<T>,
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Self: IntoIterator<Item = T>,
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{
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type Length = N;
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type Sequence = Self;
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fn generate<F>(mut f: F) -> GenericArray<T, N>
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where
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F: FnMut(usize) -> T,
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{
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unsafe {
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let mut destination = ArrayBuilder::new();
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{
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let (destination_iter, position) = destination.iter_position();
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destination_iter.enumerate().for_each(|(i, dst)| {
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ptr::write(dst, f(i));
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*position += 1;
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});
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}
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destination.into_inner()
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}
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}
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#[doc(hidden)]
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|
|
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 niave 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);
|
||
|
|
}
|
||
|
|
}
|