mirror of https://github.com/boa-dev/boa.git
Haled Odat
1 year ago
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GitHub
29 changed files with 512 additions and 123 deletions
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use std::any::TypeId; |
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use boa_gc::{GcRef, GcRefCell, GcRefMut}; |
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use boa_macros::{Finalize, Trace}; |
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use rustc_hash::FxHashMap; |
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use crate::object::NativeObject; |
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/// Map used to store the host defined objects.
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#[doc(hidden)] |
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type HostDefinedMap = FxHashMap<TypeId, Box<dyn NativeObject>>; |
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/// This represents a `ECMASCript` specification \[`HostDefined`\] field.
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///
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/// This allows storing types which are mapped by their [`TypeId`].
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#[derive(Default, Trace, Finalize)] |
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#[allow(missing_debug_implementations)] |
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pub struct HostDefined { |
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state: GcRefCell<HostDefinedMap>, |
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} |
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impl HostDefined { |
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/// Insert a type into the [`HostDefined`].
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn insert_default<T: NativeObject + Default>(&self) -> Option<Box<dyn NativeObject>> { |
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self.state |
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.borrow_mut() |
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.insert(TypeId::of::<T>(), Box::<T>::default()) |
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} |
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/// Insert a type into the [`HostDefined`].
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn insert<T: NativeObject>(&self, value: T) -> Option<Box<dyn NativeObject>> { |
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self.state |
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.borrow_mut() |
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.insert(TypeId::of::<T>(), Box::new(value)) |
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} |
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/// Check if the [`HostDefined`] has type T.
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed mutably.
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#[track_caller] |
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pub fn has<T: NativeObject>(&self) -> bool { |
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self.state.borrow().contains_key(&TypeId::of::<T>()) |
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} |
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/// Remove type T from [`HostDefined`], if it exists.
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///
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/// Returns [`Some`] with the object if it exits, [`None`] otherwise.
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn remove<T: NativeObject>(&self) -> Option<Box<dyn NativeObject>> { |
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self.state.borrow_mut().remove(&TypeId::of::<T>()) |
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} |
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/// Get type T from [`HostDefined`], if it exits.
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn get<T: NativeObject>(&self) -> Option<GcRef<'_, T>> { |
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let state = self.state.borrow(); |
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state |
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.get(&TypeId::of::<T>()) |
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.map(Box::as_ref) |
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.and_then(<dyn NativeObject>::downcast_ref::<T>)?; |
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Some(GcRef::map(state, |state| { |
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state |
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.get(&TypeId::of::<T>()) |
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.map(Box::as_ref) |
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.and_then(<dyn NativeObject>::downcast_ref::<T>) |
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.expect("Should not fail") |
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})) |
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} |
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/// Get type T from [`HostDefined`], if it exits.
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn get_mut<T: NativeObject>(&self) -> Option<GcRefMut<'_, HostDefinedMap, T>> { |
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let mut state = self.state.borrow_mut(); |
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state |
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.get_mut(&TypeId::of::<T>()) |
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.map(Box::as_mut) |
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.and_then(<dyn NativeObject>::downcast_mut::<T>)?; |
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Some(GcRefMut::map( |
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state, |
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|state: &mut FxHashMap<TypeId, Box<dyn NativeObject>>| { |
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state |
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.get_mut(&TypeId::of::<T>()) |
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.map(Box::as_mut) |
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.and_then(<dyn NativeObject>::downcast_mut::<T>) |
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.expect("Should not fail") |
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}, |
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)) |
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} |
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/// Clears all the objects.
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///
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/// # Panics
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///
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/// Panics if [`HostDefined`] field is borrowed.
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#[track_caller] |
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pub fn clear(&self) { |
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self.state.borrow_mut().clear(); |
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} |
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} |
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@ -0,0 +1,135 @@
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// This example goes into the details on how to store user defined structs/state that is shared.
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use boa_engine::{ |
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native_function::NativeFunction, Context, JsArgs, JsError, JsNativeError, Source, |
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}; |
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use boa_gc::{Finalize, Trace}; |
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/// Custom host-defined struct that has some state, and can be shared between JavaScript and rust.
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#[derive(Default, Trace, Finalize)] |
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struct CustomHostDefinedStruct { |
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#[unsafe_ignore_trace] |
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counter: usize, |
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} |
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/// Custom host-defined struct that has some state, and can be shared between JavaScript and rust.
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#[derive(Trace, Finalize)] |
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struct AnotherCustomHostDefinedStruct { |
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#[unsafe_ignore_trace] |
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counter: usize, |
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} |
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impl AnotherCustomHostDefinedStruct { |
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fn new(value: usize) -> Self { |
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Self { counter: value } |
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} |
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} |
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fn main() -> Result<(), JsError> { |
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// We create a new `Context` to create a new Javascript executor..
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let mut context = Context::default(); |
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// Get the realm from the context.
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let realm = context.realm().clone(); |
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// Insert a default CustomHostDefinedStruct.
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realm |
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.host_defined() |
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.insert_default::<CustomHostDefinedStruct>(); |
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{ |
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assert!(realm.host_defined().has::<CustomHostDefinedStruct>()); |
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// Get the [[HostDefined]] field from the realm and downcast it to our concrete type.
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let Some(host_defined) = realm.host_defined().get::<CustomHostDefinedStruct>() else { |
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return Err(JsNativeError::typ() |
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.with_message("Realm does not have HostDefined field") |
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.into()); |
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}; |
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// Assert that the [[HostDefined]] field is in it's initial state.
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assert_eq!(host_defined.counter, 0); |
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} |
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// Insert another struct with state into [[HostDefined]] field.
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realm |
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.host_defined() |
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.insert(AnotherCustomHostDefinedStruct::new(10)); |
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{ |
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assert!(realm.host_defined().has::<AnotherCustomHostDefinedStruct>()); |
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// Get the [[HostDefined]] field from the realm and downcast it to our concrete type.
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let Some(host_defined) = realm.host_defined().get::<AnotherCustomHostDefinedStruct>() |
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else { |
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return Err(JsNativeError::typ() |
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.with_message("Realm does not have HostDefined field") |
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.into()); |
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}; |
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// Assert that the [[HostDefined]] field is in it's initial state.
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assert_eq!(host_defined.counter, 10); |
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} |
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// Remove a type from the [[HostDefined]] field.
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assert!(realm |
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.host_defined() |
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.remove::<AnotherCustomHostDefinedStruct>() |
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.is_some()); |
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// Create and register function for getting and setting the realm value.
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//
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// The funtion lives in the context's realm and has access to the host-defined field.
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context.register_global_builtin_callable( |
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"setRealmValue", |
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1, |
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NativeFunction::from_fn_ptr(|_, args, context| { |
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let value: usize = args.get_or_undefined(0).try_js_into(context)?; |
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let host_defined = context.realm().host_defined(); |
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let Some(mut host_defined) = host_defined.get_mut::<CustomHostDefinedStruct>() else { |
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return Err(JsNativeError::typ() |
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.with_message("Realm does not have HostDefined field") |
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.into()); |
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}; |
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host_defined.counter = value; |
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Ok(value.into()) |
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}), |
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)?; |
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context.register_global_builtin_callable( |
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"getRealmValue", |
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0, |
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NativeFunction::from_fn_ptr(|_, _, context| { |
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let host_defined = context.realm().host_defined(); |
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let Some(host_defined) = host_defined.get::<CustomHostDefinedStruct>() else { |
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return Err(JsNativeError::typ() |
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.with_message("Realm does not have HostDefined field") |
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.into()); |
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}; |
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Ok(host_defined.counter.into()) |
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}), |
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)?; |
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// Run code in JavaScript that mutates the host-defined field on the Realm.
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context.eval(Source::from_bytes( |
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r" |
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setRealmValue(50); |
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setRealmValue(getRealmValue() * 2); |
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", |
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))?; |
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let Some(host_defined) = realm.host_defined().get::<CustomHostDefinedStruct>() else { |
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return Err(JsNativeError::typ() |
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.with_message("Realm does not have HostDefined field") |
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.into()); |
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}; |
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// Assert that the host-defined field changed.
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assert_eq!(host_defined.counter, 100); |
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Ok(()) |
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} |
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