1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5// In this case consistency between impls is more important
6// than using pointer casts
7#![allow(clippy::transmute_ptr_to_ptr)]
8
9use crate::Yokeable;
10use core::{mem, ptr};
11
12macro_rules! copy_yoke_impl {
13 () => {
14 #[inline]
15 fn transform(&self) -> &Self::Output {
16 self
17 }
18 #[inline]
19 fn transform_owned(self) -> Self::Output {
20 self
21 }
22 #[inline]
23 unsafe fn make(this: Self::Output) -> Self {
24 this
25 }
26 #[inline]
27 fn transform_mut<F>(&'a mut self, f: F)
28 where
29 F: 'static + for<'b> FnOnce(&'b mut Self::Output),
30 {
31 f(self)
32 }
33 };
34}
35macro_rules! impl_copy_type {
36 ($ty:ident) => {
37 unsafe impl<'a> Yokeable<'a> for $ty {
38 type Output = Self;
39 copy_yoke_impl!();
40 }
41 };
42}
43
44impl_copy_type!(u8);
45impl_copy_type!(u16);
46impl_copy_type!(u32);
47impl_copy_type!(u64);
48impl_copy_type!(u128);
49impl_copy_type!(usize);
50impl_copy_type!(i8);
51impl_copy_type!(i16);
52impl_copy_type!(i32);
53impl_copy_type!(i64);
54impl_copy_type!(i128);
55impl_copy_type!(isize);
56impl_copy_type!(char);
57impl_copy_type!(bool);
58
59// This is for when we're implementing Yoke on a complex type such that it's not
60// obvious to the compiler that the lifetime is covariant
61macro_rules! unsafe_complex_yoke_impl {
62 () => {
63 fn transform(&'a self) -> &'a Self::Output {
64 unsafe { mem::transmute(self) }
65 }
66
67 fn transform_owned(self) -> Self::Output {
68 debug_assert!(mem::size_of::<Self::Output>() == mem::size_of::<Self>());
69 unsafe {
70 let ptr: *const Self::Output = (&self as *const Self).cast();
71 mem::forget(self);
72 ptr::read(ptr)
73 }
74 }
75
76 unsafe fn make(from: Self::Output) -> Self {
77 debug_assert!(mem::size_of::<Self::Output>() == mem::size_of::<Self>());
78 let ptr: *const Self = (&from as *const Self::Output).cast();
79 mem::forget(from);
80 ptr::read(ptr)
81 }
82
83 fn transform_mut<F>(&'a mut self, f: F)
84 where
85 F: 'static + for<'b> FnOnce(&'b mut Self::Output),
86 {
87 // Cast away the lifetime of Self
88 unsafe { f(mem::transmute::<&'a mut Self, &'a mut Self::Output>(self)) }
89 }
90 };
91}
92
93unsafe impl<'a, T: 'static + for<'b> Yokeable<'b>> Yokeable<'a> for Option<T> {
94 type Output = Option<<T as Yokeable<'a>>::Output>;
95 unsafe_complex_yoke_impl!();
96}
97
98unsafe impl<'a, T1: 'static + for<'b> Yokeable<'b>, T2: 'static + for<'b> Yokeable<'b>> Yokeable<'a>
99 for (T1, T2)
100{
101 type Output = (<T1 as Yokeable<'a>>::Output, <T2 as Yokeable<'a>>::Output);
102 unsafe_complex_yoke_impl!();
103}
104
105unsafe impl<'a, T: Yokeable<'a>, const N: usize> Yokeable<'a> for [T; N] {
106 type Output = [<T as Yokeable<'a>>::Output; N];
107 unsafe_complex_yoke_impl!();
108}
109