/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use js::conversions::ToJSValConvertible;
use js::jsapi::Heap;
use js::jsval::JSVal;
use js::rust::MutableHandleValue;
use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::utils::to_frozen_array;
use crate::script_runtime::JSContext;
#[derive(JSTraceable)]
pub(crate) struct CachedFrozenArray {
frozen_value: DomRefCell<Option<Heap<JSVal>>>,
}
impl CachedFrozenArray {
pub(crate) fn new() -> CachedFrozenArray {
CachedFrozenArray {
frozen_value: DomRefCell::new(None),
}
}
pub(crate) fn get_or_init<F: FnOnce() -> Vec<T>, T: ToJSValConvertible>(
&self,
f: F,
cx: JSContext,
mut retval: MutableHandleValue,
) {
if let Some(inner) = &*self.frozen_value.borrow() {
retval.set(inner.get());
return;
}
let array = f();
to_frozen_array(array.as_slice(), cx, retval);
// Safety: need to create the Heap value in its final memory location before setting it.
*self.frozen_value.borrow_mut() = Some(Heap::default());
self.frozen_value
.borrow()
.as_ref()
.unwrap()
.set(retval.get());
}
pub(crate) fn clear(&self) {
*self.frozen_value.borrow_mut() = None;
}
}