New upstream version 1.51.0+dfsg1

[rustc.git] / vendor / generic-array-0.12.3 / src / lib.rs

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