facet-trait 0.2.5

Core traits for the facet ecosystem
Documentation
use core::{alloc::Layout, hash::Hash};
use std::collections::{HashMap, VecDeque};
use std::hash::RandomState;

use facet_opaque::{Opaque, OpaqueConst};

use crate::{
    Def, Facet, MapDef, MapIterVTable, MapVTable, MarkerTraits, ScalarDef, Shape, ValueVTable,
    value_vtable,
};

struct HashMapIterator<'mem, K> {
    map: OpaqueConst<'mem>,
    keys: VecDeque<&'mem K>,
}

unsafe impl<K, V, S> Facet for HashMap<K, V, S>
where
    K: Facet + core::cmp::Eq + core::hash::Hash + 'static,
    V: Facet + 'static,
    S: Facet + Default,
{
    const ARCHETYPE: Self = HashMap::with_hasher(S::ARCHETYPE);
    const SHAPE: &'static Shape = &const {
        Shape::builder()
            .layout(Layout::new::<HashMap<K, V>>())
            .vtable(
                &const {
                    let mut builder = ValueVTable::builder()
                        .marker_traits({
                            let mut traits = MarkerTraits::empty();
                            if K::SHAPE.vtable.marker_traits.contains(MarkerTraits::SEND)
                                && V::SHAPE.vtable.marker_traits.contains(MarkerTraits::SEND)
                            {
                                traits = traits.union(MarkerTraits::SEND);
                            }
                            if K::SHAPE.vtable.marker_traits.contains(MarkerTraits::SYNC)
                                && V::SHAPE.vtable.marker_traits.contains(MarkerTraits::SYNC)
                            {
                                traits = traits.union(MarkerTraits::SYNC);
                            }
                            if K::SHAPE.vtable.marker_traits.contains(MarkerTraits::EQ)
                                && V::SHAPE.vtable.marker_traits.contains(MarkerTraits::EQ)
                            {
                                traits = traits.union(MarkerTraits::EQ);
                            }
                            traits
                        })
                        .type_name(|f, opts| {
                            if let Some(opts) = opts.for_children() {
                                write!(f, "HashMap<")?;
                                (K::SHAPE.vtable.type_name)(f, opts)?;
                                write!(f, ", ")?;
                                (V::SHAPE.vtable.type_name)(f, opts)?;
                                write!(f, ">")
                            } else {
                                write!(f, "HashMap<⋯>")
                            }
                        })
                        .drop_in_place(|value| unsafe {
                            core::ptr::drop_in_place(value.as_mut::<HashMap<K, V>>());
                        });

                    if K::SHAPE.vtable.debug.is_some() && V::SHAPE.vtable.debug.is_some() {
                        builder = builder.debug(|value, f| unsafe {
                            let value = value.as_ref::<HashMap<K, V>>();
                            let k_debug = K::SHAPE.vtable.debug.unwrap_unchecked();
                            let v_debug = V::SHAPE.vtable.debug.unwrap_unchecked();
                            write!(f, "{{")?;
                            for (i, (key, val)) in value.iter().enumerate() {
                                if i > 0 {
                                    write!(f, ", ")?;
                                }
                                (k_debug)(OpaqueConst::from_ref(key), f)?;
                                write!(f, ": ")?;
                                (v_debug)(OpaqueConst::from_ref(val), f)?;
                            }
                            write!(f, "}}")
                        });
                    }

                    builder =
                        builder.default_in_place(|target| unsafe { target.write(Self::default()) });

                    builder = builder
                        .clone_into(|src, dst| unsafe { dst.write(src.as_ref::<HashMap<K, V>>()) });

                    if K::SHAPE.vtable.eq.is_some() && V::SHAPE.vtable.eq.is_some() {
                        builder = builder.eq(|a, b| unsafe {
                            let a = a.as_ref::<HashMap<K, V>>();
                            let b = b.as_ref::<HashMap<K, V>>();
                            let k_eq = K::SHAPE.vtable.eq.unwrap_unchecked();
                            let v_eq = V::SHAPE.vtable.eq.unwrap_unchecked();
                            a.len() == b.len()
                                && a.iter().all(|(key_a, val_a)| {
                                    b.get(key_a).is_some_and(|val_b| {
                                        (k_eq)(
                                            OpaqueConst::from_ref(key_a),
                                            OpaqueConst::from_ref(key_a),
                                        ) && (v_eq)(
                                            OpaqueConst::from_ref(val_a),
                                            OpaqueConst::from_ref(val_b),
                                        )
                                    })
                                })
                        });
                    }

                    if K::SHAPE.vtable.hash.is_some() && V::SHAPE.vtable.hash.is_some() {
                        builder = builder.hash(|value, hasher_this, hasher_write_fn| unsafe {
                            use crate::HasherProxy;
                            let map = value.as_ref::<HashMap<K, V>>();
                            let k_hash = K::SHAPE.vtable.hash.unwrap_unchecked();
                            let v_hash = V::SHAPE.vtable.hash.unwrap_unchecked();
                            let mut hasher = HasherProxy::new(hasher_this, hasher_write_fn);
                            map.len().hash(&mut hasher);
                            for (k, v) in map {
                                (k_hash)(OpaqueConst::from_ref(k), hasher_this, hasher_write_fn);
                                (v_hash)(OpaqueConst::from_ref(v), hasher_this, hasher_write_fn);
                            }
                        });
                    }

                    builder.build()
                },
            )
            .def(Def::Map(
                MapDef::builder()
                    .k(K::SHAPE)
                    .v(V::SHAPE)
                    .vtable(
                        &const {
                            MapVTable::builder()
                                .init_in_place_with_capacity(|uninit, capacity| unsafe {
                                    Ok(uninit.write(Self::with_capacity_and_hasher(
                                        capacity,
                                        S::default(),
                                    )))
                                })
                                .insert(|ptr, key, value| unsafe {
                                    let map = ptr.as_mut::<HashMap<K, V>>();
                                    let key = key.read::<K>();
                                    let value = value.read::<V>();
                                    map.insert(key, value);
                                })
                                .len(|ptr| unsafe {
                                    let map = ptr.as_ref::<HashMap<K, V>>();
                                    map.len()
                                })
                                .contains_key(|ptr, key| unsafe {
                                    let map = ptr.as_ref::<HashMap<K, V>>();
                                    map.contains_key(key.as_ref())
                                })
                                .get_value_ptr(|ptr, key| unsafe {
                                    let map = ptr.as_ref::<HashMap<K, V>>();
                                    map.get(key.as_ref())
                                        .map(|v| OpaqueConst::new_unchecked(v as *const _))
                                })
                                .iter(|ptr| unsafe {
                                    let map = ptr.as_ref::<HashMap<K, V>>();
                                    let keys: VecDeque<&K> = map.keys().collect();
                                    let iter_state = Box::new(HashMapIterator { map: ptr, keys });
                                    Opaque::new_unchecked(Box::into_raw(iter_state) as *mut u8)
                                })
                                .iter_vtable(
                                    MapIterVTable::builder()
                                        .next(|iter_ptr| unsafe {
                                            let state = iter_ptr.as_mut::<HashMapIterator<'_, K>>();
                                            let map = state.map.as_ref::<HashMap<K, V>>();
                                            while let Some(key) = state.keys.pop_front() {
                                                if let Some(value) = map.get(key) {
                                                    return Some((
                                                        OpaqueConst::new_unchecked(key as *const K),
                                                        OpaqueConst::new_unchecked(
                                                            value as *const V,
                                                        ),
                                                    ));
                                                }
                                            }

                                            None
                                        })
                                        .dealloc(|iter_ptr| unsafe {
                                            drop(Box::from_raw(
                                                iter_ptr.as_ptr::<HashMapIterator<'_, K>>()
                                                    as *mut HashMapIterator<'_, K>,
                                            ));
                                        })
                                        .build(),
                                )
                                .build()
                        },
                    )
                    .build(),
            ))
            .build()
    };
}

#[allow(dead_code)]
struct RandomStateInnards {
    k0: u64,
    k1: u64,
}

unsafe impl Facet for RandomState {
    const ARCHETYPE: Self = unsafe { core::mem::transmute(RandomStateInnards { k0: 0, k1: 0 }) };
    const SHAPE: &'static Shape = &const {
        Shape::builder()
            .layout(Layout::new::<Self>())
            .def(Def::Scalar(ScalarDef::of::<Self>()))
            .vtable(value_vtable!((), |f, _opts| write!(f, "RandomState")))
            .build()
    };
}