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Move more bindings types to script_bindings (#35620)
* Move weak references implementation to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Move maplike/setlike definitions to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Move base error types to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Formatting. Signed-off-by: Josh Matthews <josh@joshmatthews.net> --------- Signed-off-by: Josh Matthews <josh@joshmatthews.net>
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Josh Matthews
GitHub
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21 changed files with 435 additions and 391 deletions
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@ -2,169 +2,18 @@
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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//! Weak-referenceable JS-managed DOM objects.
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//!
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//! IDL interfaces marked as `weakReferenceable` in `Bindings.conf`
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//! automatically implement the `WeakReferenceable` trait in codegen.
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//! The instance object is responsible for setting `None` in its own
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//! own `WeakBox` when it is collected, through the `DOM_WEAK_SLOT`
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//! slot. When all associated `WeakRef` values are dropped, the
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//! `WeakBox` itself is dropped too.
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use std::cell::{Cell, UnsafeCell};
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use std::cell::UnsafeCell;
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use std::mem;
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use std::ops::{Deref, DerefMut, Drop};
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use std::{mem, ptr};
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use js::glue::JS_GetReservedSlot;
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use js::jsapi::{JSTracer, JS_SetReservedSlot};
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use js::jsval::{PrivateValue, UndefinedValue};
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use libc::c_void;
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use js::jsapi::JSTracer;
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use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
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pub use script_bindings::weakref::*;
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use crate::dom::bindings::cell::DomRefCell;
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use crate::dom::bindings::reflector::DomObject;
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use crate::dom::bindings::root::DomRoot;
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use crate::dom::bindings::trace::JSTraceable;
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/// The index of the slot wherein a pointer to the weak holder cell is
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/// stored for weak-referenceable bindings. We use slot 1 for holding it,
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/// this is unsafe for globals, we disallow weak-referenceable globals
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/// directly in codegen.
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pub(crate) const DOM_WEAK_SLOT: u32 = 1;
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/// A weak reference to a JS-managed DOM object.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::allow_unrooted_interior)]
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pub(crate) struct WeakRef<T: WeakReferenceable> {
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ptr: ptr::NonNull<WeakBox<T>>,
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}
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/// The inner box of weak references, public for the finalization in codegen.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
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pub(crate) struct WeakBox<T: WeakReferenceable> {
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/// The reference count. When it reaches zero, the `value` field should
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/// have already been set to `None`. The pointee contributes one to the count.
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pub(crate) count: Cell<usize>,
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/// The pointer to the JS-managed object, set to None when it is collected.
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pub(crate) value: Cell<Option<ptr::NonNull<T>>>,
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}
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/// Trait implemented by weak-referenceable interfaces.
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pub(crate) trait WeakReferenceable: DomObject + Sized {
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/// Downgrade a DOM object reference to a weak one.
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fn downgrade(&self) -> WeakRef<Self> {
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unsafe {
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let object = self.reflector().get_jsobject().get();
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let mut slot = UndefinedValue();
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JS_GetReservedSlot(object, DOM_WEAK_SLOT, &mut slot);
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let mut ptr = slot.to_private() as *mut WeakBox<Self>;
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if ptr.is_null() {
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trace!("Creating new WeakBox holder for {:p}.", self);
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ptr = Box::into_raw(Box::new(WeakBox {
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count: Cell::new(1),
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value: Cell::new(Some(ptr::NonNull::from(self))),
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}));
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let val = PrivateValue(ptr as *const c_void);
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JS_SetReservedSlot(object, DOM_WEAK_SLOT, &val);
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}
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let box_ = &*ptr;
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assert!(box_.value.get().is_some());
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let new_count = box_.count.get() + 1;
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trace!(
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"Incrementing WeakBox refcount for {:p} to {}.",
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self,
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new_count
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);
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box_.count.set(new_count);
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WeakRef {
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ptr: ptr::NonNull::new_unchecked(ptr),
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}
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}
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}
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}
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impl<T: WeakReferenceable> WeakRef<T> {
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/// Create a new weak reference from a `WeakReferenceable` interface instance.
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/// This is just a convenience wrapper around `<T as WeakReferenceable>::downgrade`
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/// to not have to import `WeakReferenceable`.
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pub(crate) fn new(value: &T) -> Self {
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value.downgrade()
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}
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/// DomRoot a weak reference. Returns `None` if the object was already collected.
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pub(crate) fn root(&self) -> Option<DomRoot<T>> {
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unsafe { &*self.ptr.as_ptr() }
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.value
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.get()
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.map(|ptr| unsafe { DomRoot::from_ref(&*ptr.as_ptr()) })
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}
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/// Return whether the weakly-referenced object is still alive.
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pub(crate) fn is_alive(&self) -> bool {
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unsafe { &*self.ptr.as_ptr() }.value.get().is_some()
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}
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}
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impl<T: WeakReferenceable> Clone for WeakRef<T> {
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fn clone(&self) -> WeakRef<T> {
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unsafe {
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let box_ = &*self.ptr.as_ptr();
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let new_count = box_.count.get() + 1;
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box_.count.set(new_count);
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WeakRef { ptr: self.ptr }
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}
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}
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}
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impl<T: WeakReferenceable> MallocSizeOf for WeakRef<T> {
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fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
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0
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}
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}
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impl<T: WeakReferenceable> PartialEq for WeakRef<T> {
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fn eq(&self, other: &Self) -> bool {
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unsafe {
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(*self.ptr.as_ptr()).value.get().map(ptr::NonNull::as_ptr) ==
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(*other.ptr.as_ptr()).value.get().map(ptr::NonNull::as_ptr)
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}
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}
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}
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impl<T: WeakReferenceable> PartialEq<T> for WeakRef<T> {
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fn eq(&self, other: &T) -> bool {
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unsafe {
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match self.ptr.as_ref().value.get() {
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Some(ptr) => ptr::eq(ptr.as_ptr(), other),
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None => false,
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}
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}
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}
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}
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unsafe impl<T: WeakReferenceable> JSTraceable for WeakRef<T> {
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unsafe fn trace(&self, _: *mut JSTracer) {
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// Do nothing.
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}
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}
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impl<T: WeakReferenceable> Drop for WeakRef<T> {
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fn drop(&mut self) {
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unsafe {
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let (count, value) = {
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let weak_box = &*self.ptr.as_ptr();
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assert!(weak_box.count.get() > 0);
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let count = weak_box.count.get() - 1;
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weak_box.count.set(count);
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(count, weak_box.value.get())
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};
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if count == 0 {
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assert!(value.is_none());
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mem::drop(Box::from_raw(self.ptr.as_ptr()));
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}
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}
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}
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}
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/// A mutable weak reference to a JS-managed DOM object. On tracing,
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/// the contained weak reference is dropped if the pointee was already
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/// collected.
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