rune/core/object/
cell.rs

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1use super::{Object, WithLifetime};
2use crate::core::gc::{GcMoveable, Trace};
3use std::{cell::Cell, fmt};
4
5/// This type represents and immutable view into an Object. The reason we have
6/// an additional type is because there could be other references to this same
7/// cell that can change the underlying data, so this is wrapper around
8/// `std::cell::Cell` type. It is not valid to mutate the data under a reference
9/// unless it is inside an `Unsafe` Cell. However because this struct could also
10/// be used in an immutable data structure (function constants), we need to
11/// ensure that this cell cannot be mutated by default. This type is not safe to
12/// be copy or clone.
13#[derive(PartialEq, Eq)]
14#[repr(transparent)]
15pub(crate) struct ObjCell(Cell<Object<'static>>);
16
17impl std::hash::Hash for ObjCell {
18    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
19        self.0.get().hash(state);
20    }
21}
22
23impl ObjCell {
24    pub(crate) fn get(&self) -> Object<'_> {
25        unsafe { self.0.get().with_lifetime() }
26    }
27
28    pub(in crate::core) unsafe fn new(obj: Object) -> Self {
29        Self(Cell::new(obj.with_lifetime()))
30    }
31
32    /// Casts to a `MutObjCell`. Caller must ensure that the data structure is
33    /// mutable.
34    pub(in crate::core) unsafe fn as_mut(&self) -> &MutObjCell {
35        &*(self as *const Self).cast()
36    }
37}
38
39impl fmt::Display for ObjCell {
40    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
41        fmt::Display::fmt(&self.0.get(), f)
42    }
43}
44
45impl fmt::Debug for ObjCell {
46    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
47        write!(f, "{self}")
48    }
49}
50
51impl Trace for ObjCell {
52    fn trace(&self, state: &mut crate::core::gc::GcState) {
53        let cell = unsafe { self.as_mut() };
54        if let Some((new, moved)) = cell.get().move_value(&state.to_space) {
55            cell.set(new);
56            if moved {
57                state.push(new);
58            }
59        }
60    }
61}
62
63/// This represents a mutable view into an Object. See [`ObjCell`] for a more
64/// detailed explanation. Holding this type means that we confirmed that the
65/// data stucture is mutable, and we can use the [`MutObjCell::set`] method update this
66/// cell.
67#[derive(PartialEq)]
68#[repr(transparent)]
69pub(crate) struct MutObjCell(ObjCell);
70
71impl std::ops::Deref for MutObjCell {
72    type Target = ObjCell;
73
74    fn deref(&self) -> &Self::Target {
75        &self.0
76    }
77}
78
79impl MutObjCell {
80    pub(crate) fn set(&self, value: Object) {
81        unsafe {
82            self.0.0.set(value.with_lifetime());
83        }
84    }
85}
rune/core/object/cell.rs

rune/core/object/
cell.rs
