Trait Facet

pub unsafe trait Facet: Sized {
    const SHAPE: &'static Shape;
    const DUMMY: Self;

    // Provided method
    fn type_eq<Other: Facet>() -> bool { ... }
}

Allows querying the Shape of a type, which in turn lets us inspect any fields, build a value of this type progressively, etc.

Safety

If you implement this wrong, all the safe abstractions in facet-peek, facet-poke, all the serializers, deserializers, the entire ecosystem is unsafe.

You’re responsible for describing the type layout properly, and annotating all the invariants.

Required Associated Constants

const SHAPE: &'static Shape

The shape of this type

const DUMMY: Self

An instance of this type — which doesn’t have to be valid, but it has to “not be UB”. We never actually read from it, or even actually use it for dynamic dispatch, we only use it for inference tricks.

Provided Methods

fn type_eq<Other: Facet>() -> bool

Returns true if the type of self is equal to the type of other

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl Facet for &str

const DUMMY: Self = ""

const SHAPE: &'static Shape

impl Facet for Cow<'_, str>

const DUMMY: Self

const SHAPE: &'static Shape

impl Facet for bool

const DUMMY: Self = false

const SHAPE: &'static Shape

impl Facet for f32

const DUMMY: Self = 0f32

const SHAPE: &'static Shape

impl Facet for f64

const DUMMY: Self = 0f64

const SHAPE: &'static Shape

impl Facet for i8

const DUMMY: Self = 0i8

const SHAPE: &'static Shape

impl Facet for i16

const DUMMY: Self = 0i16

const SHAPE: &'static Shape

impl Facet for i32

const DUMMY: Self = 0i32

const SHAPE: &'static Shape

impl Facet for i64

const DUMMY: Self = 0i64

const SHAPE: &'static Shape

impl Facet for i128

const DUMMY: Self = 0i128

const SHAPE: &'static Shape

impl Facet for u8

const DUMMY: Self = 0u8

const SHAPE: &'static Shape

impl Facet for u16

const DUMMY: Self = 0u16

const SHAPE: &'static Shape

impl Facet for u32

const DUMMY: Self = 0u32

const SHAPE: &'static Shape

impl Facet for u64

const DUMMY: Self = 0u64

const SHAPE: &'static Shape

impl Facet for u128

const DUMMY: Self = 0u128

const SHAPE: &'static Shape

impl Facet for ()

const DUMMY: Self = ()

const SHAPE: &'static Shape

impl Facet for String

const DUMMY: Self

const SHAPE: &'static Shape

impl Facet for RandomState

const DUMMY: Self

const SHAPE: &'static Shape

impl<K, V, S> Facet for HashMap<K, V, S>

where K: Facet + Eq + Hash + 'static, V: Facet + 'static, S: Facet + Default,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0> Facet for (T0,)

where T0: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1> Facet for (T0, T1)

where T0: Facet, T1: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2> Facet for (T0, T1, T2)

where T0: Facet, T1: Facet, T2: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3> Facet for (T0, T1, T2, T3)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4> Facet for (T0, T1, T2, T3, T4)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5> Facet for (T0, T1, T2, T3, T4, T5)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6> Facet for (T0, T1, T2, T3, T4, T5, T6)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6, T7> Facet for (T0, T1, T2, T3, T4, T5, T6, T7)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet, T7: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6, T7, T8> Facet for (T0, T1, T2, T3, T4, T5, T6, T7, T8)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet, T7: Facet, T8: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9> Facet for (T0, T1, T2, T3, T4, T5, T6, T7, T8, T9)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet, T7: Facet, T8: Facet, T9: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> Facet for (T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet, T7: Facet, T8: Facet, T9: Facet, T10: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> Facet for (T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11)

where T0: Facet, T1: Facet, T2: Facet, T3: Facet, T4: Facet, T5: Facet, T6: Facet, T7: Facet, T8: Facet, T9: Facet, T10: Facet, T11: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T> Facet for &[T]

where T: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T> Facet for [T; 1]

where T: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

impl<T> Facet for Vec<T>

where T: Facet,

const DUMMY: Self

const SHAPE: &'static Shape

Implementors