mirror of
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Move more bindings code to script_bindings (#35578)
* Move JSContext wrapper to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Move webidl constant bindings to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Move CanGc to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Move Dom<T> and Root<T> types to script_bindings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Formatting. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Extra docs for new traits. Signed-off-by: Josh Matthews <josh@joshmatthews.net> * Fix clippy warnings. Signed-off-by: Josh Matthews <josh@joshmatthews.net> --------- Signed-off-by: Josh Matthews <josh@joshmatthews.net>
This commit is contained in:
Josh Matthews
GitHub
parent
54286229ea
commit
35f21e426b
23 changed files with 788 additions and 641 deletions
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@ -24,232 +24,24 @@
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//! originating `DomRoot<T>`.
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//!
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use std::cell::{Cell, OnceCell, UnsafeCell};
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use std::cell::{OnceCell, UnsafeCell};
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use std::default::Default;
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use std::hash::{Hash, Hasher};
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use std::marker::PhantomData;
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use std::ops::Deref;
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use std::{mem, ptr};
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use js::jsapi::{JSObject, JSTracer};
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use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
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pub(crate) use script_bindings::root::*;
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use script_layout_interface::TrustedNodeAddress;
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use style::thread_state;
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use crate::dom::bindings::conversions::DerivedFrom;
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use crate::dom::bindings::inheritance::Castable;
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use crate::dom::bindings::reflector::{DomObject, MutDomObject, Reflector};
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use crate::dom::bindings::trace::{trace_reflector, JSTraceable};
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use crate::dom::bindings::reflector::DomObject;
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use crate::dom::bindings::trace::JSTraceable;
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use crate::dom::node::Node;
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/// A rooted value.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::allow_unrooted_interior)]
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pub(crate) struct Root<T: StableTraceObject> {
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/// The value to root.
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value: T,
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/// List that ensures correct dynamic root ordering
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root_list: *const RootCollection,
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}
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impl<T> Root<T>
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where
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T: StableTraceObject + 'static,
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{
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/// Create a new stack-bounded root for the provided value.
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/// It cannot outlive its associated `RootCollection`, and it gives
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/// out references which cannot outlive this new `Root`.
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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pub(crate) unsafe fn new(value: T) -> Self {
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unsafe fn add_to_root_list(object: *const dyn JSTraceable) -> *const RootCollection {
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assert_in_script();
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STACK_ROOTS.with(|root_list| {
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let root_list = &*root_list.get().unwrap();
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root_list.root(object);
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root_list
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})
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}
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let root_list = add_to_root_list(value.stable_trace_object());
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Root { value, root_list }
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}
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}
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/// `StableTraceObject` represents values that can be rooted through a stable address that will
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/// not change for their whole lifetime.
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/// It is an unsafe trait that requires implementors to ensure certain safety guarantees.
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///
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/// # Safety
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///
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/// Implementors of this trait must ensure that the `trace` method correctly accounts for all
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/// owned and referenced objects, so that the garbage collector can accurately determine which
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/// objects are still in use. Failing to adhere to this contract may result in undefined behavior,
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/// such as use-after-free errors.
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pub(crate) unsafe trait StableTraceObject {
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/// Returns a stable trace object which address won't change for the whole
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/// lifetime of the value.
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fn stable_trace_object(&self) -> *const dyn JSTraceable;
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}
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unsafe impl<T> StableTraceObject for Dom<T>
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where
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T: DomObject,
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{
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fn stable_trace_object(&self) -> *const dyn JSTraceable {
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// The JSTraceable impl for Reflector doesn't actually do anything,
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// so we need this shenanigan to actually trace the reflector of the
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// T pointer in Dom<T>.
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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struct ReflectorStackRoot(Reflector);
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unsafe impl JSTraceable for ReflectorStackRoot {
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unsafe fn trace(&self, tracer: *mut JSTracer) {
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trace_reflector(tracer, "on stack", &self.0);
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}
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}
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unsafe { &*(self.reflector() as *const Reflector as *const ReflectorStackRoot) }
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}
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}
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unsafe impl<T> StableTraceObject for MaybeUnreflectedDom<T>
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where
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T: DomObject,
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{
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fn stable_trace_object(&self) -> *const dyn JSTraceable {
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// The JSTraceable impl for Reflector doesn't actually do anything,
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// so we need this shenanigan to actually trace the reflector of the
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// T pointer in Dom<T>.
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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struct MaybeUnreflectedStackRoot<T>(T);
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unsafe impl<T> JSTraceable for MaybeUnreflectedStackRoot<T>
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where
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T: DomObject,
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{
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unsafe fn trace(&self, tracer: *mut JSTracer) {
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if self.0.reflector().get_jsobject().is_null() {
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self.0.trace(tracer);
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} else {
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trace_reflector(tracer, "on stack", self.0.reflector());
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}
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}
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}
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unsafe { &*(self.ptr.as_ptr() as *const T as *const MaybeUnreflectedStackRoot<T>) }
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}
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}
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impl<T> Deref for Root<T>
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where
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T: Deref + StableTraceObject,
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{
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type Target = <T as Deref>::Target;
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fn deref(&self) -> &Self::Target {
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assert_in_script();
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&self.value
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}
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}
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impl<T> Drop for Root<T>
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where
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T: StableTraceObject,
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{
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fn drop(&mut self) {
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unsafe {
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(*self.root_list).unroot(self.value.stable_trace_object());
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}
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}
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}
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/// A rooted reference to a DOM object.
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pub(crate) type DomRoot<T> = Root<Dom<T>>;
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impl<T: Castable> DomRoot<T> {
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/// Cast a DOM object root upwards to one of the interfaces it derives from.
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pub(crate) fn upcast<U>(root: DomRoot<T>) -> DomRoot<U>
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where
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U: Castable,
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T: DerivedFrom<U>,
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{
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unsafe { mem::transmute::<DomRoot<T>, DomRoot<U>>(root) }
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}
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/// Cast a DOM object root downwards to one of the interfaces it might implement.
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pub(crate) fn downcast<U>(root: DomRoot<T>) -> Option<DomRoot<U>>
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where
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U: DerivedFrom<T>,
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{
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if root.is::<U>() {
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Some(unsafe { mem::transmute::<DomRoot<T>, DomRoot<U>>(root) })
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} else {
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None
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}
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}
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}
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impl<T: DomObject> DomRoot<T> {
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/// Generate a new root from a reference
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pub(crate) fn from_ref(unrooted: &T) -> DomRoot<T> {
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unsafe { DomRoot::new(Dom::from_ref(unrooted)) }
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}
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/// Create a traced version of this rooted object.
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///
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/// # Safety
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///
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/// This should never be used to create on-stack values. Instead these values should always
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/// end up as members of other DOM objects.
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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pub(crate) fn as_traced(&self) -> Dom<T> {
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Dom::from_ref(self)
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}
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}
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impl<T> MallocSizeOf for DomRoot<T>
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where
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T: DomObject + MallocSizeOf,
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{
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fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
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(**self).size_of(ops)
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}
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}
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impl<T> PartialEq for DomRoot<T>
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where
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T: DomObject,
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{
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fn eq(&self, other: &Self) -> bool {
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self.value == other.value
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}
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}
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impl<T> Clone for DomRoot<T>
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where
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T: DomObject,
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{
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fn clone(&self) -> DomRoot<T> {
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DomRoot::from_ref(self)
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}
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}
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unsafe impl<T> JSTraceable for DomRoot<T>
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where
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T: DomObject,
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{
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unsafe fn trace(&self, _: *mut JSTracer) {
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// Already traced.
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}
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}
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/// A rooting mechanism for reflectors on the stack.
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/// LIFO is not required.
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///
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/// See also [*Exact Stack Rooting - Storing a GCPointer on the CStack*][cstack].
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///
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/// [cstack]: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Internals/GC/Exact_Stack_Rooting
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pub(crate) struct RootCollection {
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roots: UnsafeCell<Vec<*const dyn JSTraceable>>,
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}
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thread_local!(static STACK_ROOTS: Cell<Option<*const RootCollection>> = const { Cell::new(None) });
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pub(crate) struct ThreadLocalStackRoots<'a>(PhantomData<&'a u32>);
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impl<'a> ThreadLocalStackRoots<'a> {
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@ -265,48 +57,6 @@ impl Drop for ThreadLocalStackRoots<'_> {
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}
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}
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impl RootCollection {
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/// Create an empty collection of roots
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pub(crate) fn new() -> RootCollection {
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assert_in_script();
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RootCollection {
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roots: UnsafeCell::new(vec![]),
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}
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}
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/// Starts tracking a trace object.
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unsafe fn root(&self, object: *const dyn JSTraceable) {
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assert_in_script();
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(*self.roots.get()).push(object);
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}
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/// Stops tracking a trace object, asserting if it isn't found.
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unsafe fn unroot(&self, object: *const dyn JSTraceable) {
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assert_in_script();
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let roots = &mut *self.roots.get();
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match roots
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.iter()
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.rposition(|r| std::ptr::addr_eq(*r as *const (), object as *const ()))
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{
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Some(idx) => {
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roots.remove(idx);
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},
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None => panic!("Can't remove a root that was never rooted!"),
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}
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}
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}
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/// SM Callback that traces the rooted reflectors
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pub(crate) unsafe fn trace_roots(tracer: *mut JSTracer) {
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trace!("tracing stack roots");
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STACK_ROOTS.with(|collection| {
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let collection = &*(*collection.get().unwrap()).roots.get();
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for root in collection {
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(**root).trace(tracer);
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}
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});
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}
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/// Get a slice of references to DOM objects.
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pub(crate) trait DomSlice<T>
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where
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@ -327,121 +77,24 @@ where
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}
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}
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/// A traced reference to a DOM object
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///
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/// This type is critical to making garbage collection work with the DOM,
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/// but it is very dangerous; if garbage collection happens with a `Dom<T>`
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/// on the stack, the `Dom<T>` can point to freed memory.
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///
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/// This should only be used as a field in other DOM objects.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
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#[repr(transparent)]
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pub(crate) struct Dom<T> {
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ptr: ptr::NonNull<T>,
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}
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// Dom<T> is similar to Rc<T>, in that it's not always clear how to avoid double-counting.
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// For now, we choose not to follow any such pointers.
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impl<T> MallocSizeOf for Dom<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> Dom<T> {
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pub(crate) trait ToLayout<T> {
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/// Returns `LayoutDom<T>` containing the same pointer.
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///
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/// # Safety
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///
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/// The `self` parameter to this method must meet all the requirements of [`ptr::NonNull::as_ref`].
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pub(crate) unsafe fn to_layout(&self) -> LayoutDom<T> {
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unsafe fn to_layout(&self) -> LayoutDom<T>;
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}
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impl<T: DomObject> ToLayout<T> for Dom<T> {
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unsafe fn to_layout(&self) -> LayoutDom<T> {
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assert_in_layout();
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LayoutDom {
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value: self.ptr.as_ref(),
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value: self.as_ptr().as_ref().unwrap(),
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}
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}
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}
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impl<T: DomObject> Dom<T> {
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/// Create a `Dom<T>` from a `&T`
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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pub(crate) fn from_ref(obj: &T) -> Dom<T> {
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assert_in_script();
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Dom {
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ptr: ptr::NonNull::from(obj),
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}
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}
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/// Return a rooted version of this DOM object ([`DomRoot<T>`]) suitable for use on the stack.
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pub(crate) fn as_rooted(&self) -> DomRoot<T> {
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DomRoot::from_ref(self)
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}
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}
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impl<T: DomObject> Deref for Dom<T> {
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type Target = T;
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fn deref(&self) -> &T {
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assert_in_script();
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// We can only have &Dom<T> from a rooted thing, so it's safe to deref
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// it to &T.
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unsafe { &*self.ptr.as_ptr() }
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}
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}
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unsafe impl<T: DomObject> JSTraceable for Dom<T> {
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unsafe fn trace(&self, trc: *mut JSTracer) {
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let trace_string;
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let trace_info = if cfg!(debug_assertions) {
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trace_string = format!("for {} on heap", ::std::any::type_name::<T>());
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&trace_string[..]
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} else {
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"for DOM object on heap"
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};
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trace_reflector(trc, trace_info, (*self.ptr.as_ptr()).reflector());
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}
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}
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/// A traced reference to a DOM object that may not be reflected yet.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
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pub(crate) struct MaybeUnreflectedDom<T> {
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ptr: ptr::NonNull<T>,
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}
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impl<T> MaybeUnreflectedDom<T>
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where
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T: DomObject,
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{
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
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pub(crate) unsafe fn from_box(value: Box<T>) -> Self {
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Self {
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ptr: Box::leak(value).into(),
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}
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}
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}
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impl<T> Root<MaybeUnreflectedDom<T>>
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where
|
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T: DomObject,
|
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{
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pub(crate) fn as_ptr(&self) -> *const T {
|
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self.value.ptr.as_ptr()
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}
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}
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|
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impl<T> Root<MaybeUnreflectedDom<T>>
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where
|
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T: MutDomObject,
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{
|
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pub(crate) unsafe fn reflect_with(self, obj: *mut JSObject) -> DomRoot<T> {
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let ptr = self.as_ptr();
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drop(self);
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let root = DomRoot::from_ref(&*ptr);
|
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root.init_reflector(obj);
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root
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}
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}
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|
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/// An unrooted reference to a DOM object for use in layout. `Layout*Helpers`
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/// traits must be implemented on this.
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#[cfg_attr(crown, crown::unrooted_must_root_lint::allow_unrooted_interior)]
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|
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@ -498,20 +151,6 @@ where
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|
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impl<T> Copy for LayoutDom<'_, T> {}
|
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|
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impl<T> PartialEq for Dom<T> {
|
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fn eq(&self, other: &Dom<T>) -> bool {
|
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self.ptr.as_ptr() == other.ptr.as_ptr()
|
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}
|
||||
}
|
||||
|
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impl<'a, T: DomObject> PartialEq<&'a T> for Dom<T> {
|
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fn eq(&self, other: &&'a T) -> bool {
|
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*self == Dom::from_ref(*other)
|
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}
|
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}
|
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|
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impl<T> Eq for Dom<T> {}
|
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|
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impl<T> PartialEq for LayoutDom<'_, T> {
|
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fn eq(&self, other: &Self) -> bool {
|
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std::ptr::eq(self.value, other.value)
|
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|
|
@ -520,27 +159,12 @@ impl<T> PartialEq for LayoutDom<'_, T> {
|
|||
|
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impl<T> Eq for LayoutDom<'_, T> {}
|
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|
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impl<T> Hash for Dom<T> {
|
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fn hash<H: Hasher>(&self, state: &mut H) {
|
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self.ptr.as_ptr().hash(state)
|
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}
|
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}
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|
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impl<T> Hash for LayoutDom<'_, T> {
|
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fn hash<H: Hasher>(&self, state: &mut H) {
|
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(self.value as *const T).hash(state)
|
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}
|
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}
|
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|
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impl<T> Clone for Dom<T> {
|
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#[inline]
|
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#[cfg_attr(crown, allow(crown::unrooted_must_root))]
|
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fn clone(&self) -> Self {
|
||||
assert_in_script();
|
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Dom { ptr: self.ptr }
|
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}
|
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}
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||||
|
||||
impl<T> Clone for LayoutDom<'_, T> {
|
||||
#[inline]
|
||||
#[allow(clippy::non_canonical_clone_impl)]
|
||||
|
|
@ -616,10 +240,6 @@ impl<T: DomObject + PartialEq> PartialEq<T> for MutDom<T> {
|
|||
}
|
||||
}
|
||||
|
||||
pub(crate) fn assert_in_script() {
|
||||
debug_assert!(thread_state::get().is_script());
|
||||
}
|
||||
|
||||
pub(crate) fn assert_in_layout() {
|
||||
debug_assert!(thread_state::get().is_layout());
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue