1 use {
2 crate::{size_hint, Arbitrary, Result, Unstructured},
3 core::{
4 array,
5 mem::{self, MaybeUninit},
6 ptr,
7 },
8 };
9
10 /// Helper to safely create arrays since the standard library doesn't
11 /// provide one yet. Shouldn't be necessary in the future.
12 struct ArrayGuard<T, const N: usize> {
13 dst: *mut T,
14 initialized: usize,
15 }
16
17 impl<T, const N: usize> Drop for ArrayGuard<T, N> {
drop(&mut self)18 fn drop(&mut self) {
19 debug_assert!(self.initialized <= N);
20 let initialized_part = ptr::slice_from_raw_parts_mut(self.dst, self.initialized);
21 unsafe {
22 ptr::drop_in_place(initialized_part);
23 }
24 }
25 }
26
try_create_array<F, T, const N: usize>(mut cb: F) -> Result<[T; N]> where F: FnMut(usize) -> Result<T>,27 fn try_create_array<F, T, const N: usize>(mut cb: F) -> Result<[T; N]>
28 where
29 F: FnMut(usize) -> Result<T>,
30 {
31 let mut array: MaybeUninit<[T; N]> = MaybeUninit::uninit();
32 let array_ptr = array.as_mut_ptr();
33 let dst = array_ptr as _;
34 let mut guard: ArrayGuard<T, N> = ArrayGuard {
35 dst,
36 initialized: 0,
37 };
38 unsafe {
39 for (idx, value_ptr) in (*array.as_mut_ptr()).iter_mut().enumerate() {
40 ptr::write(value_ptr, cb(idx)?);
41 guard.initialized += 1;
42 }
43 mem::forget(guard);
44 Ok(array.assume_init())
45 }
46 }
47
48 impl<'a, T, const N: usize> Arbitrary<'a> for [T; N]
49 where
50 T: Arbitrary<'a>,
51 {
52 #[inline]
arbitrary(u: &mut Unstructured<'a>) -> Result<Self>53 fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> {
54 try_create_array(|_| <T as Arbitrary<'a>>::arbitrary(u))
55 }
56
57 #[inline]
arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<Self>58 fn arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<Self> {
59 let mut array = Self::arbitrary(&mut u)?;
60 if let Some(last) = array.last_mut() {
61 *last = Arbitrary::arbitrary_take_rest(u)?;
62 }
63 Ok(array)
64 }
65
66 #[inline]
size_hint(depth: usize) -> (usize, Option<usize>)67 fn size_hint(depth: usize) -> (usize, Option<usize>) {
68 Self::try_size_hint(depth).unwrap_or_default()
69 }
70
71 #[inline]
try_size_hint(depth: usize) -> Result<(usize, Option<usize>), crate::MaxRecursionReached>72 fn try_size_hint(depth: usize) -> Result<(usize, Option<usize>), crate::MaxRecursionReached> {
73 let hint = <T as Arbitrary>::try_size_hint(depth)?;
74 Ok(size_hint::and_all(&array::from_fn::<_, N, _>(|_| hint)))
75 }
76 }
77