abi_stable/std_types/map/
map_query.rs

1use super::*;
2
3/// A trait object used in method that access map entries without replacing them.
4#[derive(StableAbi)]
5#[repr(C)]
6pub struct MapQuery<'a, K> {
7    _marker: NotCopyNotClone,
8    is_equal: extern "C" fn(&K, RRef<'_, ErasedObject>) -> bool,
9    hash: extern "C" fn(RRef<'_, ErasedObject>, HasherObject<'_>),
10    query: RRef<'a, ErasedObject>,
11}
12
13impl<'a, K> MapQuery<'a, K> {
14    #[inline]
15    pub(super) fn new<Q>(query: &'a &'a Q) -> Self
16    where
17        K: Borrow<Q>,
18        Q: Hash + Eq + 'a + ?Sized,
19    {
20        MapQuery {
21            _marker: NotCopyNotClone,
22            is_equal: is_equal::<K, Q>,
23            hash: hash::<Q>,
24            query: unsafe { RRef::new(query).transmute() },
25        }
26    }
27
28    #[inline]
29    pub(super) unsafe fn as_static(&self) -> &MapQuery<'static, K> {
30        unsafe { crate::utils::transmute_reference(self) }
31    }
32}
33
34impl<'a, K> MapQuery<'a, K> {
35    #[inline]
36    pub(super) fn is_equal(&self, other: &K) -> bool {
37        (self.is_equal)(other, self.query)
38    }
39
40    #[inline]
41    pub(super) unsafe fn as_mapkey(&self) -> MapKey<K> {
42        MapKey::Query(NonNull::from(unsafe { self.as_static() }))
43    }
44}
45
46impl<'a, K> Hash for MapQuery<'a, K> {
47    #[inline]
48    fn hash<H>(&self, hasher: &mut H)
49    where
50        H: Hasher,
51    {
52        (self.hash)(self.query, HasherObject::new(hasher))
53    }
54}
55
56extern "C" fn is_equal<K, Q>(key: &K, query: RRef<'_, ErasedObject>) -> bool
57where
58    K: Borrow<Q>,
59    Q: Eq + ?Sized,
60{
61    extern_fn_panic_handling! {
62        let query = unsafe{ query.transmute_into_ref::<&Q>() };
63        key.borrow() == *query
64    }
65}
66
67extern "C" fn hash<Q>(query: RRef<'_, ErasedObject>, mut hasher: HasherObject<'_>)
68where
69    Q: Hash + ?Sized,
70{
71    extern_fn_panic_handling! {
72        let query = unsafe{ query.transmute_into_ref::<&Q>() };
73        query.hash(&mut hasher);
74    }
75}
abi_stable/std_types/map/map_query.rs

abi_stable/std_types/map/
map_query.rs
