| //! This crate implements a structure that can be used as a generic array type.use |
| //! Core Rust array types `[T; N]` can't be used generically with |
| //! respect to `N`, so for example this: |
| //! |
| //! ```{should_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: |
| //! |
| //! ``` |
| //! # 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). |
| //! |
| //! 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)] |
| #![no_std] |
| |
| pub extern crate typenum; |
| #[cfg(feature = "serde")] |
| extern crate serde; |
| |
| mod hex; |
| mod impls; |
| |
| #[cfg(feature = "serde")] |
| pub mod impl_serde; |
| |
| use core::{mem, ptr, slice}; |
| |
| use core::marker::PhantomData; |
| use core::mem::ManuallyDrop; |
| pub use core::mem::transmute; |
| use core::ops::{Deref, DerefMut}; |
| |
| use typenum::bit::{B0, B1}; |
| use typenum::uint::{UInt, UTerm, Unsigned}; |
| |
| #[cfg_attr(test, macro_use)] |
| pub mod arr; |
| pub mod iter; |
| pub use iter::GenericArrayIter; |
| |
| /// 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 = (); |
| } |
| |
| /// 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)] |
| pub struct GenericArray<T, U: ArrayLength<T>> { |
| data: U::ArrayType, |
| } |
| |
| impl<T, N> Deref for GenericArray<T, N> |
| where |
| N: ArrayLength<T>, |
| { |
| type Target = [T]; |
| |
| fn deref(&self) -> &[T] { |
| unsafe { slice::from_raw_parts(self as *const Self as *const T, N::to_usize()) } |
| } |
| } |
| |
| impl<T, N> DerefMut for GenericArray<T, N> |
| where |
| N: ArrayLength<T>, |
| { |
| fn deref_mut(&mut self) -> &mut [T] { |
| unsafe { slice::from_raw_parts_mut(self as *mut Self as *mut T, N::to_usize()) } |
| } |
| } |
| |
| struct ArrayBuilder<T, N: ArrayLength<T>> { |
| array: ManuallyDrop<GenericArray<T, N>>, |
| position: usize, |
| } |
| |
| impl<T, N: ArrayLength<T>> ArrayBuilder<T, N> { |
| fn new() -> ArrayBuilder<T, N> { |
| ArrayBuilder { |
| array: ManuallyDrop::new(unsafe { mem::uninitialized() }), |
| position: 0, |
| } |
| } |
| |
| fn into_inner(self) -> GenericArray<T, N> { |
| let array = unsafe { ptr::read(&self.array) }; |
| |
| mem::forget(self); |
| |
| ManuallyDrop::into_inner(array) |
| } |
| } |
| |
| impl<T, N: ArrayLength<T>> Drop for ArrayBuilder<T, N> { |
| fn drop(&mut self) { |
| for value in self.array.iter_mut().take(self.position) { |
| unsafe { |
| ptr::drop_in_place(value); |
| } |
| } |
| } |
| } |
| |
| struct ArrayConsumer<T, N: ArrayLength<T>> { |
| array: ManuallyDrop<GenericArray<T, N>>, |
| position: usize, |
| } |
| |
| impl<T, N: ArrayLength<T>> ArrayConsumer<T, N> { |
| fn new(array: GenericArray<T, N>) -> ArrayConsumer<T, N> { |
| ArrayConsumer { |
| array: ManuallyDrop::new(array), |
| position: 0, |
| } |
| } |
| } |
| |
| impl<T, N: ArrayLength<T>> Drop for ArrayConsumer<T, N> { |
| fn drop(&mut self) { |
| for i in self.position..N::to_usize() { |
| unsafe { |
| ptr::drop_in_place(self.array.get_unchecked_mut(i)); |
| } |
| } |
| } |
| } |
| |
| impl<T, N> GenericArray<T, N> |
| where |
| N: ArrayLength<T>, |
| { |
| /// Initializes a new `GenericArray` instance using the given function. |
| /// |
| /// If the generator function panics while initializing the array, |
| /// any already initialized elements will be dropped. |
| pub fn generate<F>(f: F) -> GenericArray<T, N> |
| where |
| F: Fn(usize) -> T, |
| { |
| let mut destination = ArrayBuilder::new(); |
| |
| for (i, dst) in destination.array.iter_mut().enumerate() { |
| unsafe { |
| ptr::write(dst, f(i)); |
| } |
| |
| destination.position += 1; |
| } |
| |
| destination.into_inner() |
| } |
| |
| /// Map a function over a slice to a `GenericArray`. |
| /// |
| /// The length of the slice *must* be equal to the length of the array. |
| #[inline] |
| pub fn map_slice<S, F: Fn(&S) -> T>(s: &[S], f: F) -> GenericArray<T, N> { |
| assert_eq!(s.len(), N::to_usize()); |
| |
| Self::generate(|i| f(unsafe { s.get_unchecked(i) })) |
| } |
| |
| /// Maps a `GenericArray` to another `GenericArray`. |
| /// |
| /// If the mapping function panics, any already initialized elements in the new array |
| /// will be dropped, AND any unused elements in the source array will also be dropped. |
| pub fn map<U, F>(self, f: F) -> GenericArray<U, N> |
| where |
| F: Fn(T) -> U, |
| N: ArrayLength<U>, |
| { |
| let mut source = ArrayConsumer::new(self); |
| let mut destination = ArrayBuilder::new(); |
| |
| for (dst, src) in destination.array.iter_mut().zip(source.array.iter()) { |
| unsafe { |
| ptr::write(dst, f(ptr::read(src))); |
| } |
| |
| source.position += 1; |
| destination.position += 1; |
| } |
| |
| destination.into_inner() |
| } |
| |
| /// Maps a `GenericArray` to another `GenericArray` by reference. |
| /// |
| /// If the mapping function panics, any already initialized elements will be dropped. |
| #[inline] |
| pub fn map_ref<U, F>(&self, f: F) -> GenericArray<U, N> |
| where |
| F: Fn(&T) -> U, |
| N: ArrayLength<U>, |
| { |
| GenericArray::generate(|i| f(unsafe { self.get_unchecked(i) })) |
| } |
| |
| /// Combines two `GenericArray` instances and iterates through both of them, |
| /// initializing a new `GenericArray` with the result of the zipped mapping function. |
| /// |
| /// If the mapping function panics, any already initialized elements in the new array |
| /// will be dropped, AND any unused elements in the source arrays will also be dropped. |
| pub fn zip<B, U, F>(self, rhs: GenericArray<B, N>, f: F) -> GenericArray<U, N> |
| where |
| F: Fn(T, B) -> U, |
| N: ArrayLength<B> + ArrayLength<U>, |
| { |
| let mut left = ArrayConsumer::new(self); |
| let mut right = ArrayConsumer::new(rhs); |
| |
| let mut destination = ArrayBuilder::new(); |
| |
| for (dst, (lhs, rhs)) in |
| destination.array.iter_mut().zip(left.array.iter().zip( |
| right.array.iter(), |
| )) |
| { |
| unsafe { |
| ptr::write(dst, f(ptr::read(lhs), ptr::read(rhs))); |
| } |
| |
| destination.position += 1; |
| left.position += 1; |
| right.position += 1; |
| } |
| |
| destination.into_inner() |
| } |
| |
| /// Combines two `GenericArray` instances and iterates through both of them by reference, |
| /// initializing a new `GenericArray` with the result of the zipped mapping function. |
| /// |
| /// If the mapping function panics, any already initialized elements will be dropped. |
| pub fn zip_ref<B, U, F>(&self, rhs: &GenericArray<B, N>, f: F) -> GenericArray<U, N> |
| where |
| F: Fn(&T, &B) -> U, |
| N: ArrayLength<B> + ArrayLength<U>, |
| { |
| GenericArray::generate(|i| unsafe { |
| f(self.get_unchecked(i), rhs.get_unchecked(i)) |
| }) |
| } |
| |
| /// 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> { |
| assert_eq!(slice.len(), N::to_usize()); |
| |
| unsafe { &*(slice.as_ptr() as *const 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] |
| pub fn from_mut_slice(slice: &mut [T]) -> &mut GenericArray<T, N> { |
| assert_eq!(slice.len(), N::to_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>, |
| { |
| pub fn from_exact_iter<I>(iter: I) -> Option<Self> |
| where |
| I: IntoIterator<Item = T>, |
| <I as IntoIterator>::IntoIter: ExactSizeIterator, |
| { |
| let iter = iter.into_iter(); |
| |
| if iter.len() == N::to_usize() { |
| let mut destination = ArrayBuilder::new(); |
| |
| for (dst, src) in destination.array.iter_mut().zip(iter.into_iter()) { |
| unsafe { |
| ptr::write(dst, src); |
| } |
| |
| destination.position += 1; |
| } |
| |
| let array = unsafe { ptr::read(&destination.array) }; |
| |
| mem::forget(destination); |
| |
| Some(ManuallyDrop::into_inner(array)) |
| } else { |
| None |
| } |
| } |
| } |
| |
| impl<T, N> ::core::iter::FromIterator<T> for GenericArray<T, N> |
| where |
| N: ArrayLength<T>, |
| T: Default, |
| { |
| fn from_iter<I>(iter: I) -> GenericArray<T, N> |
| where |
| I: IntoIterator<Item = T>, |
| { |
| let mut destination = ArrayBuilder::new(); |
| |
| let defaults = ::core::iter::repeat(()).map(|_| T::default()); |
| |
| for (dst, src) in destination.array.iter_mut().zip( |
| iter.into_iter().chain(defaults), |
| ) |
| { |
| unsafe { |
| ptr::write(dst, src); |
| } |
| } |
| |
| destination.into_inner() |
| } |
| } |
| |
| #[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() { |
| let a = black_box(arr![i32; 1, 3, 5, 7]); |
| let b = black_box(arr![i32; 2, 4, 6, 8]); |
| |
| let c = a.zip_ref(&b, |l, r| l + r); |
| |
| assert_eq!(c, arr![i32; 3, 7, 11, 15]); |
| } |
| } |