musli_core/
no_std.rs

Help
1//! Trait fills for `#[no_std]` environments.
2//!
3//! * [`ToOwned`] - if the `alloc` feature is enabled, this is an alias for
4//!   `alloc::borrow::ToOwned`.
5
6#[cfg(feature = "alloc")]
7pub use rust_alloc::borrow::ToOwned;
8
9#[cfg(not(feature = "alloc"))]
10pub use self::to_owned::ToOwned;
11
12#[cfg(not(feature = "alloc"))]
13mod to_owned {
14    use core::borrow::Borrow;
15
16    /// Never type for [ToOwned] so that `Owned` can reference some type even if
17    /// it's uninhabitable.
18    pub enum NeverOwned {}
19
20    impl<T> Borrow<[T]> for NeverOwned
21    where
22        T: Clone,
23    {
24        fn borrow(&self) -> &[T] {
25            match *self {}
26        }
27    }
28
29    impl<T> Borrow<T> for NeverOwned
30    where
31        T: Clone,
32    {
33        fn borrow(&self) -> &T {
34            match *self {}
35        }
36    }
37
38    impl Borrow<str> for NeverOwned {
39        fn borrow(&self) -> &str {
40            match *self {}
41        }
42    }
43
44    /// Trait fill for ToOwned when we're in a `#[no_std]` environment.
45    pub trait ToOwned {
46        /// The value borrowed.
47        type Owned: Borrow<Self>;
48    }
49
50    impl<T> ToOwned for [T]
51    where
52        T: Clone,
53    {
54        type Owned = NeverOwned;
55    }
56
57    impl<T> ToOwned for T
58    where
59        T: Clone,
60    {
61        type Owned = NeverOwned;
62    }
63
64    impl ToOwned for str {
65        type Owned = NeverOwned;
66    }
67}
musli_core/no_std.rs

musli_core/
no_std.rs
