Move CustomTraceable to script_bindings. (#35988)

* script: Move CustomTraceable to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* script: Move record binding support to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Address clippy warnings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

---------

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

6 files changed, 501 insertions, 5 deletions

diff --git a/components/script_bindings/Cargo.toml b/components/script_bindings/Cargo.toml
index 3f022f74480..c911a0d4730 100644
--- a/components/script_bindings/Cargo.toml
+++ b/components/script_bindings/Cargo.toml
@@ -22,8 +22,10 @@ serde_json = { workspace = true }
 
 [dependencies]
 bitflags = { workspace = true }
+crossbeam-channel = { workspace = true }
 cssparser = { workspace = true }
 html5ever = { workspace = true }
+indexmap = { workspace = true }
 js = { workspace = true }
 jstraceable_derive = { path = "../jstraceable_derive" }
 libc = { workspace = true }
@@ -31,15 +33,21 @@ log = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 num-traits = { workspace = true }
+parking_lot = { workspace = true }
 regex = { workspace = true }
+servo_arc = { workspace = true }
+smallvec = { workspace = true }
 stylo_atoms = { workspace = true }
 servo_config = { path = "../config" }
 style = { workspace = true }
+tendril = { version = "0.4.1", features = ["encoding_rs"] }
+webxr-api = { workspace = true, optional = true }
+xml5ever = { workspace = true }
 
 [features]
 bluetooth = []
 webgpu = []
-webxr = []
+webxr = ["webxr-api"]
 
 [lints.rust]
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(crown)'] }
diff --git a/components/script_bindings/codegen/CodegenRust.py b/components/script_bindings/codegen/CodegenRust.py
index e77709918f4..6b5c77c2c20 100644
--- a/components/script_bindings/codegen/CodegenRust.py
+++ b/components/script_bindings/codegen/CodegenRust.py
@@ -2287,7 +2287,7 @@ class CGImports(CGWrapper):
                     extras += [descriptor.path, descriptor.bindingPath]
                     parentName = descriptor.getParentName()
             elif t.isType() and t.isRecord():
-                extras += ['crate::dom::bindings::record::Record']
+                extras += ['script_bindings::record::Record']
             elif isinstance(t, IDLPromiseType):
                 extras += ['crate::dom::promise::Promise']
             else:
@@ -2643,7 +2643,7 @@ def UnionTypes(descriptors, dictionaries, callbacks, typedefs, config):
         'crate::dom::bindings::import::base::*',
         'crate::dom::bindings::codegen::DomTypes::DomTypes',
         'crate::dom::bindings::conversions::windowproxy_from_handlevalue',
-        'crate::dom::bindings::record::Record',
+        'script_bindings::record::Record',
         'crate::dom::types::*',
         'crate::dom::windowproxy::WindowProxy',
         'js::typedarray',
diff --git a/components/script_bindings/conversions.rs b/components/script_bindings/conversions.rs
index 98998e170da..6e0ce7adee0 100644
--- a/components/script_bindings/conversions.rs
+++ b/components/script_bindings/conversions.rs
@@ -18,8 +18,8 @@ use js::jsapi::{
 };
 use js::jsval::{ObjectValue, StringValue, UndefinedValue};
 use js::rust::{
-    HandleValue, MutableHandleValue, ToString, get_object_class, is_dom_class, is_dom_object,
-    maybe_wrap_value,
+    HandleId, HandleValue, MutableHandleValue, ToString, get_object_class, is_dom_class,
+    is_dom_object, maybe_wrap_value,
 };
 
 use crate::inheritance::Castable;
@@ -387,3 +387,24 @@ where
     }
     root_from_object(v.get().to_object(), cx)
 }
+
+/// Convert `id` to a `DOMString`. Returns `None` if `id` is not a string or
+/// integer.
+///
+/// Handling of invalid UTF-16 in strings depends on the relevant option.
+///
+/// # Safety
+/// - cx must point to a non-null, valid JSContext instance.
+pub unsafe fn jsid_to_string(cx: *mut JSContext, id: HandleId) -> Option<DOMString> {
+    let id_raw = *id;
+    if id_raw.is_string() {
+        let jsstr = std::ptr::NonNull::new(id_raw.to_string()).unwrap();
+        return Some(jsstring_to_str(cx, jsstr));
+    }
+
+    if id_raw.is_int() {
+        return Some(id_raw.to_int().to_string().into());
+    }
+
+    None
+}
diff --git a/components/script_bindings/lib.rs b/components/script_bindings/lib.rs
index 8090144b73b..e857a2289f8 100644
--- a/components/script_bindings/lib.rs
+++ b/components/script_bindings/lib.rs
@@ -24,6 +24,7 @@ pub mod error;
 pub mod inheritance;
 pub mod iterable;
 pub mod like;
+pub mod record;
 pub mod reflector;
 pub mod root;
 pub mod script_runtime;
@@ -51,3 +52,5 @@ pub mod codegen {
 // Since they are used in derive macros,
 // it is useful that they are accessible at the root of the crate.
 pub(crate) use js::gc::Traceable as JSTraceable;
+
+pub(crate) use crate::trace::CustomTraceable;
diff --git a/components/script_bindings/record.rs b/components/script_bindings/record.rs
new file mode 100644
index 00000000000..2668a84f42c
--- /dev/null
+++ b/components/script_bindings/record.rs
@@ -0,0 +1,209 @@
+/* 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/. */
+
+//! The `Record` (open-ended dictionary) type.
+
+use std::cmp::Eq;
+use std::hash::Hash;
+use std::marker::Sized;
+use std::ops::Deref;
+
+use indexmap::IndexMap;
+use js::conversions::{ConversionResult, FromJSValConvertible, ToJSValConvertible};
+use js::jsapi::glue::JS_GetOwnPropertyDescriptorById;
+use js::jsapi::{
+    HandleId as RawHandleId, JS_NewPlainObject, JSContext, JSITER_HIDDEN, JSITER_OWNONLY,
+    JSITER_SYMBOLS, JSPROP_ENUMERATE, PropertyDescriptor,
+};
+use js::jsval::{ObjectValue, UndefinedValue};
+use js::rooted;
+use js::rust::wrappers::{GetPropertyKeys, JS_DefineUCProperty2, JS_GetPropertyById, JS_IdToValue};
+use js::rust::{HandleId, HandleValue, IdVector, MutableHandleValue};
+
+use crate::conversions::jsid_to_string;
+use crate::str::{ByteString, DOMString, USVString};
+
+pub trait RecordKey: Eq + Hash + Sized {
+    fn to_utf16_vec(&self) -> Vec<u16>;
+
+    /// Attempt to extract a key from a JS id.
+    /// # Safety
+    /// - cx must point to a non-null, valid JSContext.
+    #[allow(clippy::result_unit_err)]
+    unsafe fn from_id(cx: *mut JSContext, id: HandleId) -> Result<ConversionResult<Self>, ()>;
+}
+
+impl RecordKey for DOMString {
+    fn to_utf16_vec(&self) -> Vec<u16> {
+        self.encode_utf16().collect::<Vec<_>>()
+    }
+
+    unsafe fn from_id(cx: *mut JSContext, id: HandleId) -> Result<ConversionResult<Self>, ()> {
+        match jsid_to_string(cx, id) {
+            Some(s) => Ok(ConversionResult::Success(s)),
+            None => Ok(ConversionResult::Failure("Failed to get DOMString".into())),
+        }
+    }
+}
+
+impl RecordKey for USVString {
+    fn to_utf16_vec(&self) -> Vec<u16> {
+        self.0.encode_utf16().collect::<Vec<_>>()
+    }
+
+    unsafe fn from_id(cx: *mut JSContext, id: HandleId) -> Result<ConversionResult<Self>, ()> {
+        rooted!(in(cx) let mut jsid_value = UndefinedValue());
+        let raw_id: RawHandleId = id.into();
+        JS_IdToValue(cx, *raw_id.ptr, jsid_value.handle_mut());
+
+        USVString::from_jsval(cx, jsid_value.handle(), ())
+    }
+}
+
+impl RecordKey for ByteString {
+    fn to_utf16_vec(&self) -> Vec<u16> {
+        self.iter().map(|&x| x as u16).collect::<Vec<u16>>()
+    }
+
+    unsafe fn from_id(cx: *mut JSContext, id: HandleId) -> Result<ConversionResult<Self>, ()> {
+        rooted!(in(cx) let mut jsid_value = UndefinedValue());
+        let raw_id: RawHandleId = id.into();
+        JS_IdToValue(cx, *raw_id.ptr, jsid_value.handle_mut());
+
+        ByteString::from_jsval(cx, jsid_value.handle(), ())
+    }
+}
+
+/// The `Record` (open-ended dictionary) type.
+#[derive(Clone, JSTraceable)]
+pub struct Record<K: RecordKey, V> {
+    #[custom_trace]
+    map: IndexMap<K, V>,
+}
+
+impl<K: RecordKey, V> Record<K, V> {
+    /// Create an empty `Record`.
+    pub fn new() -> Self {
+        Record {
+            map: IndexMap::new(),
+        }
+    }
+}
+
+impl<K: RecordKey, V> Deref for Record<K, V> {
+    type Target = IndexMap<K, V>;
+
+    fn deref(&self) -> &IndexMap<K, V> {
+        &self.map
+    }
+}
+
+impl<K, V, C> FromJSValConvertible for Record<K, V>
+where
+    K: RecordKey,
+    V: FromJSValConvertible<Config = C>,
+    C: Clone,
+{
+    type Config = C;
+    unsafe fn from_jsval(
+        cx: *mut JSContext,
+        value: HandleValue,
+        config: C,
+    ) -> Result<ConversionResult<Self>, ()> {
+        if !value.is_object() {
+            return Ok(ConversionResult::Failure(
+                "Record value was not an object".into(),
+            ));
+        }
+
+        rooted!(in(cx) let object = value.to_object());
+        let mut ids = IdVector::new(cx);
+        if !GetPropertyKeys(
+            cx,
+            object.handle(),
+            JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS,
+            ids.handle_mut(),
+        ) {
+            return Err(());
+        }
+
+        let mut map = IndexMap::new();
+        for id in &*ids {
+            rooted!(in(cx) let id = *id);
+            rooted!(in(cx) let mut desc = PropertyDescriptor::default());
+
+            let mut is_none = false;
+            if !JS_GetOwnPropertyDescriptorById(
+                cx,
+                object.handle().into(),
+                id.handle().into(),
+                desc.handle_mut().into(),
+                &mut is_none,
+            ) {
+                return Err(());
+            }
+
+            if !desc.enumerable_() {
+                continue;
+            }
+
+            let key = match K::from_id(cx, id.handle())? {
+                ConversionResult::Success(key) => key,
+                ConversionResult::Failure(message) => {
+                    return Ok(ConversionResult::Failure(message));
+                },
+            };
+
+            rooted!(in(cx) let mut property = UndefinedValue());
+            if !JS_GetPropertyById(cx, object.handle(), id.handle(), property.handle_mut()) {
+                return Err(());
+            }
+
+            let property = match V::from_jsval(cx, property.handle(), config.clone())? {
+                ConversionResult::Success(property) => property,
+                ConversionResult::Failure(message) => {
+                    return Ok(ConversionResult::Failure(message));
+                },
+            };
+            map.insert(key, property);
+        }
+
+        Ok(ConversionResult::Success(Record { map }))
+    }
+}
+
+impl<K, V> ToJSValConvertible for Record<K, V>
+where
+    K: RecordKey,
+    V: ToJSValConvertible,
+{
+    #[inline]
+    unsafe fn to_jsval(&self, cx: *mut JSContext, mut rval: MutableHandleValue) {
+        rooted!(in(cx) let js_object = JS_NewPlainObject(cx));
+        assert!(!js_object.handle().is_null());
+
+        rooted!(in(cx) let mut js_value = UndefinedValue());
+        for (key, value) in &self.map {
+            let key = key.to_utf16_vec();
+            value.to_jsval(cx, js_value.handle_mut());
+
+            assert!(JS_DefineUCProperty2(
+                cx,
+                js_object.handle(),
+                key.as_ptr(),
+                key.len(),
+                js_value.handle(),
+                JSPROP_ENUMERATE as u32
+            ));
+        }
+
+        rval.set(ObjectValue(js_object.handle().get()));
+    }
+}
+
+impl<K: RecordKey, V> Default for Record<K, V> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
diff --git a/components/script_bindings/trace.rs b/components/script_bindings/trace.rs
index 04819803d33..3248fbfc67c 100644
--- a/components/script_bindings/trace.rs
+++ b/components/script_bindings/trace.rs
@@ -2,9 +2,32 @@
  * 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 std::cell::OnceCell;
+use std::hash::{BuildHasher, Hash};
+use std::marker::PhantomData;
+
+use crossbeam_channel::Sender;
+use html5ever::interface::{Tracer as HtmlTracer, TreeSink};
+use html5ever::tokenizer::{TokenSink, Tokenizer};
+use html5ever::tree_builder::TreeBuilder;
+use indexmap::IndexMap;
 use js::glue::CallObjectTracer;
 use js::jsapi::{GCTraceKindToAscii, Heap, JSObject, JSTracer, TraceKind};
+use parking_lot::RwLock;
+use servo_arc::Arc as ServoArc;
+use smallvec::SmallVec;
+use style::author_styles::AuthorStyles;
+use style::stylesheet_set::{AuthorStylesheetSet, DocumentStylesheetSet};
+use tendril::TendrilSink;
+use tendril::fmt::UTF8;
+use tendril::stream::LossyDecoder;
+#[cfg(feature = "webxr")]
+use webxr_api::{Finger, Hand};
+use xml5ever::interface::TreeSink as XmlTreeSink;
+use xml5ever::tokenizer::XmlTokenizer;
+use xml5ever::tree_builder::{Tracer as XmlTracer, XmlTreeBuilder};
 
+use crate::JSTraceable;
 use crate::error::Error;
 use crate::reflector::Reflector;
 use crate::str::{DOMString, USVString};
@@ -53,3 +76,235 @@ macro_rules! unsafe_no_jsmanaged_fields(
 unsafe_no_jsmanaged_fields!(DOMString);
 unsafe_no_jsmanaged_fields!(USVString);
 unsafe_no_jsmanaged_fields!(Error);
+
+/// A trait to allow tracing only DOM sub-objects.
+///
+/// # Safety
+///
+/// This trait is unsafe; if it is implemented incorrectly, the GC may end up collecting objects
+/// that are still reachable.
+pub unsafe trait CustomTraceable {
+    /// Trace `self`.
+    ///
+    /// # Safety
+    ///
+    /// The `JSTracer` argument must point to a valid `JSTracer` in memory. In addition,
+    /// implementors of this method must ensure that all active objects are properly traced
+    /// or else the garbage collector may end up collecting objects that are still reachable.
+    unsafe fn trace(&self, trc: *mut JSTracer);
+}
+
+unsafe impl<T: CustomTraceable> CustomTraceable for Box<T> {
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        (**self).trace(trc);
+    }
+}
+
+unsafe impl<T: JSTraceable> CustomTraceable for OnceCell<T> {
+    unsafe fn trace(&self, tracer: *mut JSTracer) {
+        if let Some(value) = self.get() {
+            value.trace(tracer)
+        }
+    }
+}
+
+unsafe impl<T> CustomTraceable for Sender<T> {
+    unsafe fn trace(&self, _: *mut JSTracer) {}
+}
+
+unsafe impl<T: JSTraceable> CustomTraceable for ServoArc<T> {
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        (**self).trace(trc)
+    }
+}
+
+unsafe impl<T: JSTraceable> CustomTraceable for RwLock<T> {
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        self.read().trace(trc)
+    }
+}
+
+unsafe impl<T: JSTraceable + Eq + Hash> CustomTraceable for indexmap::IndexSet<T> {
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        for e in self.iter() {
+            e.trace(trc);
+        }
+    }
+}
+
+// XXXManishearth Check if the following three are optimized to no-ops
+// if e.trace() is a no-op (e.g it is an unsafe_no_jsmanaged_fields type)
+unsafe impl<T: JSTraceable + 'static> CustomTraceable for SmallVec<[T; 1]> {
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        for e in self.iter() {
+            e.trace(trc);
+        }
+    }
+}
+
+unsafe impl<K, V, S> CustomTraceable for IndexMap<K, V, S>
+where
+    K: Hash + Eq + JSTraceable,
+    V: JSTraceable,
+    S: BuildHasher,
+{
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        for (k, v) in self {
+            k.trace(trc);
+            v.trace(trc);
+        }
+    }
+}
+
+unsafe impl<S> CustomTraceable for DocumentStylesheetSet<S>
+where
+    S: JSTraceable + ::style::stylesheets::StylesheetInDocument + PartialEq + 'static,
+{
+    unsafe fn trace(&self, tracer: *mut JSTracer) {
+        for (s, _origin) in self.iter() {
+            s.trace(tracer)
+        }
+    }
+}
+
+unsafe impl<S> CustomTraceable for AuthorStylesheetSet<S>
+where
+    S: JSTraceable + ::style::stylesheets::StylesheetInDocument + PartialEq + 'static,
+{
+    unsafe fn trace(&self, tracer: *mut JSTracer) {
+        for s in self.iter() {
+            s.trace(tracer)
+        }
+    }
+}
+
+unsafe impl<S> CustomTraceable for AuthorStyles<S>
+where
+    S: JSTraceable + ::style::stylesheets::StylesheetInDocument + PartialEq + 'static,
+{
+    unsafe fn trace(&self, tracer: *mut JSTracer) {
+        self.stylesheets.trace(tracer)
+    }
+}
+
+unsafe impl<Sink> CustomTraceable for LossyDecoder<Sink>
+where
+    Sink: JSTraceable + TendrilSink<UTF8>,
+{
+    unsafe fn trace(&self, tracer: *mut JSTracer) {
+        self.inner_sink().trace(tracer);
+    }
+}
+
+#[cfg(feature = "webxr")]
+unsafe impl<J> CustomTraceable for Hand<J>
+where
+    J: JSTraceable,
+{
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        // exhaustive match so we don't miss new fields
+        let Hand {
+            ref wrist,
+            ref thumb_metacarpal,
+            ref thumb_phalanx_proximal,
+            ref thumb_phalanx_distal,
+            ref thumb_phalanx_tip,
+            ref index,
+            ref middle,
+            ref ring,
+            ref little,
+        } = *self;
+        wrist.trace(trc);
+        thumb_metacarpal.trace(trc);
+        thumb_phalanx_proximal.trace(trc);
+        thumb_phalanx_distal.trace(trc);
+        thumb_phalanx_tip.trace(trc);
+        index.trace(trc);
+        middle.trace(trc);
+        ring.trace(trc);
+        little.trace(trc);
+    }
+}
+
+#[cfg(feature = "webxr")]
+unsafe impl<J> CustomTraceable for Finger<J>
+where
+    J: JSTraceable,
+{
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        // exhaustive match so we don't miss new fields
+        let Finger {
+            ref metacarpal,
+            ref phalanx_proximal,
+            ref phalanx_intermediate,
+            ref phalanx_distal,
+            ref phalanx_tip,
+        } = *self;
+        metacarpal.trace(trc);
+        phalanx_proximal.trace(trc);
+        phalanx_intermediate.trace(trc);
+        phalanx_distal.trace(trc);
+        phalanx_tip.trace(trc);
+    }
+}
+
+unsafe impl<Handle: JSTraceable + Clone, Sink: TreeSink<Handle = Handle> + JSTraceable>
+    CustomTraceable for TreeBuilder<Handle, Sink>
+{
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        struct Tracer<Handle>(*mut JSTracer, PhantomData<Handle>);
+        let tracer = Tracer::<Handle>(trc, PhantomData);
+
+        impl<Handle: JSTraceable> HtmlTracer for Tracer<Handle> {
+            type Handle = Handle;
+            #[cfg_attr(crown, allow(crown::unrooted_must_root))]
+            fn trace_handle(&self, node: &Handle) {
+                unsafe {
+                    node.trace(self.0);
+                }
+            }
+        }
+
+        self.trace_handles(&tracer);
+        self.sink.trace(trc);
+    }
+}
+
+#[allow(unsafe_code)]
+unsafe impl<Handle: JSTraceable + Clone, Sink: TokenSink<Handle = Handle> + CustomTraceable>
+    CustomTraceable for Tokenizer<Sink>
+{
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        self.sink.trace(trc);
+    }
+}
+
+#[allow(unsafe_code)]
+unsafe impl<Handle: JSTraceable + Clone, Sink: JSTraceable + XmlTreeSink<Handle = Handle>>
+    CustomTraceable for XmlTokenizer<XmlTreeBuilder<Handle, Sink>>
+{
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        struct Tracer<Handle>(*mut JSTracer, PhantomData<Handle>);
+        let tracer = Tracer(trc, PhantomData);
+
+        impl<Handle: JSTraceable> XmlTracer for Tracer<Handle> {
+            type Handle = Handle;
+            #[cfg_attr(crown, allow(crown::unrooted_must_root))]
+            fn trace_handle(&self, node: &Handle) {
+                unsafe {
+                    node.trace(self.0);
+                }
+            }
+        }
+
+        let tree_builder = &self.sink;
+        tree_builder.trace_handles(&tracer);
+        tree_builder.sink.trace(trc);
+    }
+}