pyodide_webassembly_runtime_layer/
externref.rs

1use std::{any::Any, sync::Arc};
2
3use pyo3::prelude::*;
4use wasm_runtime_layer::backend::{AsContextMut, WasmExternRef};
5
6use crate::{
7    conversion::{py_to_js_proxy, ToPy},
8    store::StoreContext,
9    Engine,
10};
11
12/// Extern host reference type.
13#[derive(Debug)]
14pub struct ExternRef {
15    /// The inner extern ref object, for host access, optional
16    host: Option<Arc<AnyExternRef>>,
17    /// The inner extern ref object, for guest access, opaque
18    guest: Py<PyAny>,
19}
20
21impl Clone for ExternRef {
22    fn clone(&self) -> Self {
23        Python::with_gil(|py| Self {
24            host: self.host.clone(),
25            guest: self.guest.clone_ref(py),
26        })
27    }
28}
29
30impl WasmExternRef<Engine> for ExternRef {
31    fn new<T: 'static + Send + Sync>(_ctx: impl AsContextMut<Engine>, object: T) -> Self {
32        Python::with_gil(|py| -> Result<Self, PyErr> {
33            let object: Arc<AnyExternRef> = Arc::new(object);
34
35            let guest = Bound::new(
36                py,
37                PyExternRef {
38                    object: Arc::clone(&object),
39                },
40            )?;
41            let guest = py_to_js_proxy(guest)?;
42
43            Ok(Self {
44                host: Some(object),
45                guest: guest.unbind(),
46            })
47        })
48        .expect("ExternRef::new should not fail")
49    }
50
51    fn downcast<'a, 's: 'a, T: 'static, S: 's>(
52        &'a self,
53        _ctx: StoreContext<'s, S>,
54    ) -> anyhow::Result<&'a T> {
55        // Check if we have a host-accessible non-opaque reference to the data
56        let Some(object) = self.host.as_ref() else {
57            anyhow::bail!("extern ref is from a different source");
58        };
59
60        let Some(object) = object.downcast_ref() else {
61            anyhow::bail!("incorrect extern ref type");
62        };
63
64        Ok(object)
65    }
66}
67
68impl ToPy for ExternRef {
69    fn to_py(&self, py: Python) -> Py<PyAny> {
70        self.guest.clone_ref(py)
71    }
72}
73
74impl ExternRef {
75    /// Creates a new extern ref from a Python value
76    pub(crate) fn from_exported_externref(object: Bound<PyAny>) -> Self {
77        // Check if this ExternRef comes from this source,
78        //  if not, return an opaque ExternRef
79        let Ok(host): Result<Bound<PyExternRef>, _> = object.extract() else {
80            return Self {
81                host: None,
82                guest: object.unbind(),
83            };
84        };
85
86        let host = Arc::clone(&host.get().object);
87
88        Self {
89            host: Some(host),
90            guest: object.unbind(),
91        }
92    }
93}
94
95type AnyExternRef = dyn 'static + Any + Send + Sync;
96
97#[pyclass(frozen)]
98struct PyExternRef {
99    /// The inner extern ref data
100    object: Arc<AnyExternRef>,
101}
pyodide_webassembly_runtime_layer/externref.rs

pyodide_webassembly_runtime_layer/
externref.rs
