pyodide_webassembly_runtime_layer/
global.rs

1use pyo3::{intern, prelude::*, sync::PyOnceLock};
2use wasm_runtime_layer::{
3    backend::{AsContext, AsContextMut, Val, WasmGlobal},
4    GlobalType,
5};
6
7use crate::{
8    conversion::{create_js_object, instanceof, ToPy, ValExt, ValTypeExt},
9    Engine,
10};
11
12/// A global variable accesible as an import or export in a module.
13///
14/// This type wraps a [`WebAssembly.Global`] from the JavaScript API.
15///
16/// [`WebAssembly.Global`]: https://developer.mozilla.org/en-US/docs/WebAssembly/JavaScript_interface/Global
17#[derive(Debug)]
18pub struct Global {
19    /// The global value
20    global: Py<PyAny>,
21    /// The global type
22    ty: GlobalType,
23}
24
25impl Clone for Global {
26    fn clone(&self) -> Self {
27        Python::attach(|py| Self {
28            global: self.global.clone_ref(py),
29            ty: self.ty,
30        })
31    }
32}
33
34impl WasmGlobal<Engine> for Global {
35    fn new(_ctx: impl AsContextMut<Engine>, value: Val<Engine>, mutable: bool) -> Self {
36        Python::attach(|py| -> Result<Self, PyErr> {
37            #[cfg(feature = "tracing")]
38            tracing::debug!(?value, mutable, "Global::new");
39
40            let ty = GlobalType::new(value.ty(), mutable);
41
42            let desc = create_js_object(py)?;
43            desc.setattr(intern!(py, "value"), value.ty().as_js_descriptor())?;
44            desc.setattr(intern!(py, "mutable"), mutable)?;
45
46            let value = value.to_py(py)?;
47
48            let global = web_assembly_global_new(py)?.call1((desc, value))?;
49
50            Ok(Self {
51                global: global.unbind(),
52                ty,
53            })
54        })
55        .expect("Global::new should not fail")
56    }
57
58    fn ty(&self, _ctx: impl AsContext<Engine>) -> GlobalType {
59        self.ty
60    }
61
62    fn set(&self, _ctx: impl AsContextMut<Engine>, new_value: Val<Engine>) -> anyhow::Result<()> {
63        if !self.ty.mutable() {
64            return Err(anyhow::anyhow!("Global is not mutable"));
65        }
66
67        Python::attach(|py| {
68            let global = self.global.bind(py);
69
70            #[cfg(feature = "tracing")]
71            tracing::debug!(global = %global, ?self.ty, ?new_value, "Global::set");
72
73            let new_value = new_value.to_py(py)?;
74
75            global.setattr(intern!(py, "value"), new_value)?;
76
77            Ok(())
78        })
79    }
80
81    fn get(&self, _ctx: impl AsContextMut<Engine>) -> Val<Engine> {
82        Python::attach(|py| {
83            let global = self.global.bind(py);
84
85            #[cfg(feature = "tracing")]
86            tracing::debug!(global = %global, ?self.ty, "Global::get");
87
88            let value = global.getattr(intern!(py, "value"))?;
89
90            Val::from_py_typed(value, self.ty.content())
91        })
92        .expect("Global::get should not fail")
93    }
94}
95
96impl ToPy for Global {
97    fn to_py(&self, py: Python) -> Result<Py<PyAny>, PyErr> {
98        #[cfg(feature = "tracing")]
99        tracing::trace!(value = %self.global, ?self.ty, "Global::to_py");
100
101        Ok(self.global.clone_ref(py))
102    }
103}
104
105impl Global {
106    /// Creates a new global from a Python value
107    pub(crate) fn from_exported_global(
108        global: Bound<PyAny>,
109        ty: GlobalType,
110    ) -> anyhow::Result<Self> {
111        if !instanceof(&global, web_assembly_global(global.py())?)? {
112            anyhow::bail!("expected WebAssembly.Global but found {global}");
113        }
114
115        #[cfg(feature = "tracing")]
116        tracing::debug!(global = %global, ?ty, "Global::from_exported_global");
117
118        Ok(Self {
119            global: global.unbind(),
120            ty,
121        })
122    }
123}
124
125fn web_assembly_global(py: Python<'_>) -> Result<&Bound<'_, PyAny>, PyErr> {
126    static WEB_ASSEMBLY_GLOBAL: PyOnceLock<Py<PyAny>> = PyOnceLock::new();
127    WEB_ASSEMBLY_GLOBAL.import(py, "js.WebAssembly", "Global")
128}
129
130fn web_assembly_global_new(py: Python<'_>) -> Result<&Bound<'_, PyAny>, PyErr> {
131    static WEB_ASSEMBLY_GLOBAL_NEW: PyOnceLock<Py<PyAny>> = PyOnceLock::new();
132    WEB_ASSEMBLY_GLOBAL_NEW.import(py, "js.WebAssembly.Global", "new")
133}
pyodide_webassembly_runtime_layer/global.rs

pyodide_webassembly_runtime_layer/
global.rs
