root
523 lines
13 KiB
Rust
523 lines
13 KiB
Rust
extern crate nodrop;
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use nodrop::NoDrop;
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use std::iter;
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use std::mem;
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use std::ptr;
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use std::ops::{
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Deref,
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DerefMut,
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};
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use std::slice;
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// extra traits
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use std::borrow::{Borrow, BorrowMut};
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use std::hash::{Hash, Hasher};
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use std::fmt;
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mod array;
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pub use array::Array;
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unsafe fn new_array<A: Array>() -> A {
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// Note: Returning an uninitialized value here only works
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// if we can be sure the data is never used. The nullable pointer
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// inside enum optimization conflicts with this this for example,
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// so we need to be extra careful. See `Flag` enum.
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mem::uninitialized()
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}
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/// A vector with a fixed capacity.
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///
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/// The **ArrayVec** is a vector backed by a fixed size array. It keeps track of
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/// the number of initialized elements.
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///
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/// The vector is a contiguous value that you can store directly on the stack
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/// if needed.
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///
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/// It offers a simple API but also dereferences to a slice, so
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/// that the full slice API is available.
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///
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/// ArrayVec can be converted into a by value iterator.
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pub struct ArrayVec<A: Array> {
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xs: NoDrop<A>,
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len: u8,
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}
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impl<A: Array> Drop for ArrayVec<A> {
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fn drop(&mut self) {
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// clear all elements, then NoDrop inhibits drop of inner array
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while let Some(_) = self.pop() { }
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}
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}
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impl<A: Array> ArrayVec<A> {
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/// Create a new empty **ArrayVec**.
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///
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/// Capacity is inferred from the type parameter.
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///
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/// ## Examples
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///
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::<[_; 16]>::new();
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/// array.push(1);
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/// array.push(2);
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/// assert_eq!(&array[..], &[1, 2]);
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/// assert_eq!(array.capacity(), 16);
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/// ```
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pub fn new() -> ArrayVec<A> {
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unsafe {
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ArrayVec { xs: NoDrop::new(new_array()), len: 0 }
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}
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}
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/// Return the number of elements in the **ArrayVec**.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::from([1, 2, 3]);
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/// array.pop();
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/// assert_eq!(array.len(), 2);
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/// ```
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#[inline]
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pub fn len(&self) -> usize { self.len as usize }
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/// Return the capacity of the **ArrayVec**.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let array = ArrayVec::from([1, 2, 3]);
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/// assert_eq!(array.capacity(), 3);
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/// ```
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#[inline]
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pub fn capacity(&self) -> usize { A::capacity() }
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/// Push **element** to the end of the vector.
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///
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/// Return **None** if the push succeeds, or and return **Some(** *element* **)**
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/// if the vector is full.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::<[_; 2]>::new();
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///
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/// array.push(1);
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/// array.push(2);
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/// let overflow = array.push(3);
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///
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/// assert_eq!(&array[..], &[1, 2]);
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/// assert_eq!(overflow, Some(3));
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/// ```
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pub fn push(&mut self, element: A::Item) -> Option<A::Item> {
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if self.len() < A::capacity() {
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unsafe {
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let len = self.len();
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ptr::write(self.get_unchecked_mut(len), element);
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}
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self.len += 1;
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None
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} else {
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Some(element)
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}
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}
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/// Remove the last element in the vector.
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///
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/// Return **Some(** *element* **)** if the vector is non-empty, else **None**.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::<[_; 2]>::new();
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///
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/// array.push(1);
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///
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/// assert_eq!(array.pop(), Some(1));
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/// assert_eq!(array.pop(), None);
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/// ```
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pub fn pop(&mut self) -> Option<A::Item> {
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if self.len == 0 {
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return None
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}
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unsafe {
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self.len -= 1;
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let len = self.len();
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Some(ptr::read(self.get_unchecked_mut(len)))
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}
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}
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/// Remove the element at **index** and swap the last element into its place.
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///
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/// This operation is O(1).
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///
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/// Return **Some(** *element* **)** if the index is in bounds, else **None**.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::from([1, 2, 3]);
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///
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/// let elt = array.swap_remove(0);
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///
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/// assert_eq!(elt, Some(1));
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/// assert_eq!(&array[..], &[3, 2]);
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///
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/// assert_eq!(array.swap_remove(10), None);
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/// ```
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pub fn swap_remove(&mut self, index: usize) -> Option<A::Item> {
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let len = self.len();
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if index >= len {
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return None
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}
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self.swap(index, len - 1);
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self.pop()
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}
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}
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impl<A: Array> Deref for ArrayVec<A> {
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type Target = [A::Item];
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#[inline]
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fn deref(&self) -> &[A::Item] {
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unsafe {
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slice::from_raw_parts(self.xs.as_ptr(), self.len())
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}
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}
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}
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impl<A: Array> DerefMut for ArrayVec<A> {
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#[inline]
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fn deref_mut(&mut self) -> &mut [A::Item] {
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let len = self.len();
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unsafe {
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slice::from_raw_parts_mut(self.xs.as_mut_ptr(), len)
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}
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}
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}
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/// Create an **ArrayVec** from an array.
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///
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/// ## Examples
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::from([1, 2, 3]);
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/// assert_eq!(array.len(), 3);
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/// assert_eq!(array.capacity(), 3);
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/// ```
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impl<A: Array> From<A> for ArrayVec<A> {
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fn from(array: A) -> Self {
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ArrayVec { xs: NoDrop::new(array), len: A::capacity() as u8 }
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}
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}
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/// Iterate the **ArrayVec** with references to each element.
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///
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/// ## Examples
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///
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let array = ArrayVec::from([1, 2, 3]);
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///
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/// for elt in &array {
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/// // ...
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/// }
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/// ```
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impl<'a, A: Array> IntoIterator for &'a ArrayVec<A> {
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type Item = &'a A::Item;
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type IntoIter = slice::Iter<'a, A::Item>;
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fn into_iter(self) -> Self::IntoIter { self.iter() }
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}
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/// Iterate the **ArrayVec** with mutable references to each element.
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///
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/// ## Examples
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///
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// let mut array = ArrayVec::from([1, 2, 3]);
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///
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/// for elt in &mut array {
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/// // ...
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/// }
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/// ```
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impl<'a, A: Array> IntoIterator for &'a mut ArrayVec<A> {
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type Item = &'a mut A::Item;
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type IntoIter = slice::IterMut<'a, A::Item>;
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fn into_iter(self) -> Self::IntoIter { self.iter_mut() }
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}
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/// Iterate the **ArrayVec** with each element by value.
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///
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/// The vector is consumed by this operation.
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///
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/// ## Examples
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///
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/// ```
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/// use arrayvec::ArrayVec;
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///
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/// for elt in ArrayVec::from([1, 2, 3]) {
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/// // ...
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/// }
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/// ```
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impl<A: Array> IntoIterator for ArrayVec<A> {
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type Item = A::Item;
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type IntoIter = IntoIter<A>;
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fn into_iter(self) -> IntoIter<A> {
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IntoIter { index: 0, v: self, }
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}
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}
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/// By-value iterator for ArrayVec.
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pub struct IntoIter<A: Array> {
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index: u8,
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v: ArrayVec<A>,
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}
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impl<A: Array> Iterator for IntoIter<A> {
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type Item = A::Item;
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#[inline]
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fn next(&mut self) -> Option<A::Item> {
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if self.index == self.v.len {
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None
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} else {
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unsafe {
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let ptr = self.v.get_unchecked_mut(self.index as usize);
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let elt = ptr::read(ptr);
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self.index += 1;
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Some(elt)
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}
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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let len = self.v.len() - self.index as usize;
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(len, Some(len))
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}
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}
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impl<A: Array> DoubleEndedIterator for IntoIter<A> {
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#[inline]
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fn next_back(&mut self) -> Option<A::Item> {
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if self.index == self.v.len {
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None
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} else {
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unsafe {
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self.v.len -= 1;
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let len = self.v.len();
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let elt = ptr::read(self.v.get_unchecked_mut(len));
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Some(elt)
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}
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}
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}
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}
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impl<A: Array> ExactSizeIterator for IntoIter<A> { }
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impl<A: Array> Drop for IntoIter<A> {
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fn drop(&mut self) {
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// exhaust iterator and clear the vector
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while let Some(_) = self.next() { }
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self.v.len = 0;
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}
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}
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/// Extend the **ArrayVec** with an iterator.
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///
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/// Does not extract more items than there is space for. No error
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/// occurs if there are more iterator elements.
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impl<A: Array> Extend<A::Item> for ArrayVec<A> {
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fn extend<T: IntoIterator<Item=A::Item>>(&mut self, iter: T) {
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let take = self.capacity() - self.len();
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for elt in iter.into_iter().take(take) {
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self.push(elt);
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}
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}
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}
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/// Create an **ArrayVec** from an iterator.
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///
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/// Does not extract more items than there is space for. No error
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/// occurs if there are more iterator elements.
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impl<A: Array> iter::FromIterator<A::Item> for ArrayVec<A> {
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fn from_iter<T: IntoIterator<Item=A::Item>>(iter: T) -> Self {
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let mut array = ArrayVec::new();
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array.extend(iter);
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array
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}
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}
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impl<A: Array> Clone for ArrayVec<A>
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where A::Item: Clone
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{
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fn clone(&self) -> Self {
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self.iter().cloned().collect()
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}
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}
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impl<A: Array> Hash for ArrayVec<A>
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where A::Item: Hash
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{
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fn hash<H: Hasher>(&self, state: &mut H) {
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Hash::hash(&**self, state)
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}
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}
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impl<A: Array> PartialEq for ArrayVec<A>
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where A::Item: PartialEq
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{
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fn eq(&self, other: &Self) -> bool {
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**self == **other
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}
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}
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impl<A: Array> Eq for ArrayVec<A> where A::Item: Eq { }
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impl<A: Array> Borrow<[A::Item]> for ArrayVec<A> {
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fn borrow(&self) -> &[A::Item] { self }
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}
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impl<A: Array> BorrowMut<[A::Item]> for ArrayVec<A> {
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fn borrow_mut(&mut self) -> &mut [A::Item] { self }
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}
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impl<A: Array> AsRef<[A::Item]> for ArrayVec<A> {
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fn as_ref(&self) -> &[A::Item] { self }
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}
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impl<A: Array> AsMut<[A::Item]> for ArrayVec<A> {
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fn as_mut(&mut self) -> &mut [A::Item] { self }
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}
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impl<A: Array> fmt::Debug for ArrayVec<A> where A::Item: fmt::Debug {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }
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}
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#[test]
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fn test_simple() {
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use std::ops::Add;
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let mut vec: ArrayVec<[Vec<i32>; 3]> = ArrayVec::new();
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vec.push(vec![1,2,3,4]);
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vec.push(vec![3]);
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vec.push(vec![-1, 90, -2]);
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for elt in &vec {
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println!("{:?}", elt);
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}
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println!("{:?}", vec);
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let sum = vec.iter().map(|x| x.iter().fold(0, Add::add)).fold(0, Add::add);
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assert_eq!(sum, 13 + 87);
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let sum_len = vec.into_iter().map(|x| x.len()).fold(0, Add::add);
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assert_eq!(sum_len, 8);
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}
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#[test]
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fn test_iter() {
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let mut iter = ArrayVec::from([1, 2, 3]).into_iter();
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assert_eq!(iter.size_hint(), (3, Some(3)));
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assert_eq!(iter.next_back(), Some(3));
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assert_eq!(iter.next(), Some(1));
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assert_eq!(iter.next_back(), Some(2));
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assert_eq!(iter.size_hint(), (0, Some(0)));
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assert_eq!(iter.next_back(), None);
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}
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#[test]
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fn test_drop() {
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use std::cell::Cell;
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let flag = &Cell::new(0);
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struct Bump<'a>(&'a Cell<i32>);
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impl<'a> Drop for Bump<'a> {
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fn drop(&mut self) {
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let n = self.0.get();
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self.0.set(n + 1);
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}
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}
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{
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let mut array = ArrayVec::<[Bump; 128]>::new();
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array.push(Bump(flag));
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array.push(Bump(flag));
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}
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assert_eq!(flag.get(), 2);
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// test something with the nullable pointer optimization
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flag.set(0);
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{
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let mut array = ArrayVec::<[_; 3]>::new();
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array.push(vec![Bump(flag)]);
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array.push(vec![Bump(flag), Bump(flag)]);
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array.push(vec![]);
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array.push(vec![Bump(flag)]);
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assert_eq!(flag.get(), 1);
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drop(array.pop());
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assert_eq!(flag.get(), 1);
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drop(array.pop());
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assert_eq!(flag.get(), 3);
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}
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assert_eq!(flag.get(), 4);
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}
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#[test]
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fn test_extend() {
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let mut range = 0..10;
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let mut array: ArrayVec<[_; 5]> = range.by_ref().collect();
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assert_eq!(&array[..], &[0, 1, 2, 3, 4]);
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assert_eq!(range.next(), Some(5));
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array.extend(range.by_ref());
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assert_eq!(range.next(), Some(6));
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let mut array: ArrayVec<[_; 10]> = (0..3).collect();
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assert_eq!(&array[..], &[0, 1, 2]);
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array.extend(3..5);
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assert_eq!(&array[..], &[0, 1, 2, 3, 4]);
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}
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#[test]
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fn test_is_send_sync() {
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let data = ArrayVec::<[Vec<i32>; 5]>::new();
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&data as &Send;
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&data as &Sync;
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}
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#[test]
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fn test_compact_size() {
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// Future rust will kill these drop flags!
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// 4 elements size + 1 len + 1 enum tag + [1 drop flag] + [1 drop flag nodrop]
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type ByteArray = ArrayVec<[u8; 4]>;
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println!("{}", mem::size_of::<ByteArray>());
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assert!(mem::size_of::<ByteArray>() <= 8);
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// 12 element size + 1 len + 1 drop flag + 2 padding + 1 enum tag + 3 padding
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type QuadArray = ArrayVec<[u32; 3]>;
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println!("{}", mem::size_of::<QuadArray>());
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assert!(mem::size_of::<QuadArray>() <= 24);
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}
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