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use core::mem;
use core::ptr;
use crate::ghost_cell::*;
pub trait GhostBorrow<'a, 'brand> {
type Result;
fn borrow(self, token: &'a GhostToken<'brand>) -> Self::Result;
}
impl<'a, 'brand, T> GhostBorrow<'a, 'brand> for &'a [GhostCell<'brand, T>] {
type Result = &'a [T];
fn borrow(self, _: &'a GhostToken<'brand>) -> Self::Result {
unsafe { mem::transmute::<Self, Self::Result>(self) }
}
}
impl<'a, 'brand, T, const N: usize> GhostBorrow<'a, 'brand> for &'a [GhostCell<'brand, T>; N] {
type Result = &'a [T; N];
fn borrow(self, _: &'a GhostToken<'brand>) -> Self::Result {
unsafe { mem::transmute::<Self, Self::Result>(self) }
}
}
impl<'a, 'brand, T: ?Sized, const N: usize> GhostBorrow<'a, 'brand> for [&'a GhostCell<'brand, T>; N] {
type Result = [&'a T; N];
fn borrow(self, _: &'a GhostToken<'brand>) -> Self::Result {
unsafe { ptr::read(&self as *const _ as *const Self::Result) }
}
}
macro_rules! last {
() => {};
($head:ident $(,)?) => {
$head
};
($head:ident, $($tail:ident),+ $(,)?) => {
last!($($tail),+)
};
}
macro_rules! generate_public_instance {
( $($name:ident),* ; $($type_letter:ident),* ) => {
impl<'a, 'brand, $($type_letter: ?Sized,)*> GhostBorrow<'a, 'brand>
for ( $(&'a GhostCell<'brand, $type_letter>, )* )
{
type Result = ( $(&'a $type_letter, )* );
fn borrow(self, token: &'a GhostToken<'brand>) -> Self::Result {
let ($($name,)*) = self;
( $( $name.borrow(token),)* )
}
}
impl<'a, 'brand, $($type_letter,)*> GhostBorrow<'a, 'brand>
for &'a ( $(GhostCell<'brand, $type_letter>, )* )
where
last!( $($type_letter),* ): ?Sized
{
type Result = &'a ( $($type_letter, )* );
fn borrow(self, _: &'a GhostToken<'brand>) -> Self::Result {
unsafe { core::mem::transmute::<Self, Self::Result>(self) }
}
}
};
}
generate_public_instance!(a ; T0);
generate_public_instance!(a, b ; T0, T1);
generate_public_instance!(a, b, c ; T0, T1, T2);
generate_public_instance!(a, b, c, d ; T0, T1, T2, T3);
generate_public_instance!(a, b, c, d, e ; T0, T1, T2, T3, T4);
generate_public_instance!(a, b, c, d, e, f ; T0, T1, T2, T3, T4, T5);
generate_public_instance!(a, b, c, d, e, f, g ; T0, T1, T2, T3, T4, T5, T6);
generate_public_instance!(a, b, c, d, e, f, g, h ; T0, T1, T2, T3, T4, T5, T6, T7);
generate_public_instance!(a, b, c, d, e, f, g, h, i ; T0, T1, T2, T3, T4, T5, T6, T7, T8);
generate_public_instance!(a, b, c, d, e, f, g, h, i, j ; T0, T1, T2, T3, T4, T5, T6, T7, T8, T9);
generate_public_instance!(a, b, c, d, e, f, g, h, i, j, k ; T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, TA);
generate_public_instance!(a, b, c, d, e, f, g, h, i, j, k, l ; T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, TA, TB);
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn multiple_borrows_tuple() {
let value = GhostToken::new(|token| {
let cell1 = GhostCell::new(42);
let cell2 = GhostCell::new(47);
let cell3 = GhostCell::new(7);
let cell4 = GhostCell::new(9);
let (reference1, reference2, reference3, reference4): (&i32, &i32, &i32, &i32)
= (&cell1, &cell2, &cell3, &cell4).borrow(&token);
(*reference1, *reference2, *reference3, *reference4)
});
assert_eq!((42, 47, 7, 9), value);
}
#[test]
fn multiple_borrows_tuple_ref() {
let value = GhostToken::new(|token| {
let cell1 = GhostCell::new(42);
let cell2 = GhostCell::new(47);
let cell3 = GhostCell::new(7);
let cell4 = GhostCell::new(9);
let tuple = (cell1, cell2, cell3, cell4);
let reference: &(i32, i32, i32, i32) = tuple.borrow(&token);
(reference.0, reference.1, reference.2, reference.3)
});
assert_eq!((42, 47, 7, 9), value);
}
#[test]
fn multiple_borrows_array_ref() {
let value = GhostToken::new(|token| {
let cell1 = GhostCell::new(42);
let cell2 = GhostCell::new(47);
let cell3 = GhostCell::new(7);
let cell4 = GhostCell::new(9);
let array = [cell1, cell2, cell3, cell4];
let reference: &[i32; 4] = array.borrow(&token);
(reference[0], reference[1], reference[2], reference[3])
});
assert_eq!((42, 47, 7, 9), value);
}
#[test]
fn multiple_borrows_tuple_unsized() {
let value = GhostToken::new(|token| {
let mut data1 = 42;
let mut data2 = [47];
let mut data3 = 7;
let mut data4 = [9];
let cell1 = &*GhostCell::from_mut(&mut data1 as &mut dyn ToString);
let cell2 = &*GhostCell::from_mut(&mut data2 as &mut [i32]);
let cell3 = &*GhostCell::from_mut(&mut data3 as &mut dyn ToString);
let cell4 = &*GhostCell::from_mut(&mut data4 as &mut [i32]);
let (reference1, reference2, reference3, reference4) = (cell1, cell2, cell3, cell4).borrow(&token);
(reference1.to_string(), reference2[0], reference3.to_string(), reference4[0])
});
assert_eq!(("42".to_owned(), 47, "7".to_owned(), 9), value);
}
#[test]
fn multiple_borrows_array_unsized_slice() {
let value = GhostToken::new(|token| {
let mut data1 = [42];
let mut data2 = [47];
let mut data3 = [7];
let mut data4 = [9];
let cell1 = &*GhostCell::from_mut(&mut data1 as &mut [i32]);
let cell2 = &*GhostCell::from_mut(&mut data2 as &mut [i32]);
let cell3 = &*GhostCell::from_mut(&mut data3 as &mut [i32]);
let cell4 = &*GhostCell::from_mut(&mut data4 as &mut [i32]);
let array = [cell1, cell2, cell3, cell4];
let reference: [&[i32]; 4] = array.borrow(&token);
reference.map(|slice| slice[0])
});
assert_eq!([42, 47, 7, 9], value);
}
#[test]
fn multiple_borrows_array_unsized_dyn_trait() {
let value = GhostToken::new(|token| {
let mut data1 = 42;
let mut data2 = 47;
let mut data3 = 7;
let mut data4 = 9;
let cell1 = &*GhostCell::from_mut(&mut data1 as &mut dyn ToString);
let cell2 = &*GhostCell::from_mut(&mut data2 as &mut dyn ToString);
let cell3 = &*GhostCell::from_mut(&mut data3 as &mut dyn ToString);
let cell4 = &*GhostCell::from_mut(&mut data4 as &mut dyn ToString);
let array = [cell1, cell2, cell3, cell4];
let reference: [&dyn ToString; 4] = array.borrow(&token);
reference.map(ToString::to_string)
});
assert_eq!(["42".to_owned(), "47".to_owned(), "7".to_owned(), "9".to_owned()], value);
}
}