facet_core/_trait/
mod.rs

1#![warn(missing_docs)]
2#![doc = include_str!("../../README.md")]
3
4pub use crate::types::*;
5
6mod impls;
7
8mod macros;
9pub use macros::*;
10
11/// Allows querying the [`Shape`] of a type, which in turn lets us inspect any fields, build a value of
12/// this type progressively, etc.
13///
14/// # Safety
15///
16/// If you implement this wrong, all the safe abstractions in `facet-peek`, `facet-poke`,
17/// all the serializers, deserializers, the entire ecosystem is unsafe.
18///
19/// You're responsible for describing the type layout properly, and annotating all the invariants.
20pub unsafe trait Facet: Sized {
21    /// The shape of this type
22    const SHAPE: &'static Shape;
23
24    /// Returns true if the type of `self` is equal to the type of `other`
25    fn type_eq<Other: Facet>() -> bool {
26        Self::SHAPE == Other::SHAPE
27    }
28}
29
30/// Extension trait to provide `is_type` and `assert_type`
31pub trait ShapeExt {
32    /// Check if this shape is of the given type
33    fn is_type<Other: Facet>(&'static self) -> bool;
34
35    /// Assert that this shape is of the given type, panicking if it's not
36    fn assert_type<Other: Facet>(&'static self);
37}
38
39impl ShapeExt for Shape {
40    /// Check if this shape is of the given type
41    fn is_type<Other: Facet>(&'static self) -> bool {
42        self == Other::SHAPE
43    }
44
45    /// Assert that this shape is of the given type, panicking if it's not
46    fn assert_type<Other: Facet>(&'static self) {
47        assert!(
48            self.is_type::<Other>(),
49            "Type mismatch: expected {}, found {self}",
50            Other::SHAPE,
51        );
52    }
53}
facet_core/_trait/mod.rs

facet_core/_trait/
mod.rs
