ladybird/Libraries/LibWeb/WebIDL/ObservableArray.h
Andreas Kling 614713ed08 LibJS: Replace IndexedProperties with inline Packed/Holey/Dictionary
Replace the OwnPtr<IndexedPropertyStorage> indirection with inline
indexed element storage directly on Object. This eliminates virtual
dispatch and reduces indirection for indexed property access.

The new system uses three storage kinds tracked by IndexedStorageKind:

- Packed: Dense array, no holes. Elements stored in a malloced Value*
  array with capacity header (same layout as named properties).
- Holey: Dense array with possible holes marked by empty sentinel.
  Same physical layout as Packed.
- Dictionary: Sparse storage using GenericIndexedPropertyStorage,
  type-punned into the m_indexed_elements pointer.

Transitions: None->Packed->Holey->Dictionary (mostly monotonic).
Dictionary mode triggers on non-default attributes or sparse arrays.

Object keeps the same 48-byte size since m_indexed_elements (8 bytes)
replaces IndexedProperties (8 bytes), and the storage kind + array
size fit in existing padding alongside m_flags.

The asm interpreter benefits from one fewer indirection: it now reads
the element pointer and array size directly from Object fields instead
of chasing through OwnPtr -> IndexedPropertyStorage -> Vector.

Removes: IndexedProperties, SimpleIndexedPropertyStorage,
IndexedPropertyStorage, IndexedPropertyIterator.
Keeps: GenericIndexedPropertyStorage (for Dictionary mode).
2026-03-17 22:28:35 -05:00

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2.2 KiB
C++

/*
* Copyright (c) 2024, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibJS/Runtime/Array.h>
#include <LibWeb/Export.h>
#include <LibWeb/WebIDL/ExceptionOr.h>
namespace Web::WebIDL {
// https://webidl.spec.whatwg.org/#idl-observable-array
class WEB_API ObservableArray final : public JS::Array {
JS_OBJECT(ObservableArray, JS::Array);
GC_DECLARE_ALLOCATOR(ObservableArray);
public:
static GC::Ref<ObservableArray> create(JS::Realm& realm);
virtual JS::ThrowCompletionOr<bool> internal_set(JS::PropertyKey const& property_key, JS::Value value, JS::Value receiver, JS::CacheableSetPropertyMetadata* metadata = nullptr, PropertyLookupPhase = PropertyLookupPhase::OwnProperty) override;
virtual JS::ThrowCompletionOr<bool> internal_delete(JS::PropertyKey const& property_key) override;
using SetAnIndexedValueCallbackFunction = Function<ExceptionOr<void>(JS::Value&)>;
using DeleteAnIndexedValueCallbackFunction = Function<ExceptionOr<void>(JS::Value)>;
void set_on_set_an_indexed_value_callback(SetAnIndexedValueCallbackFunction&& callback);
void set_on_delete_an_indexed_value_callback(DeleteAnIndexedValueCallbackFunction&& callback);
JS::ThrowCompletionOr<void> append(JS::Value value);
void clear();
template<typename T, typename Callback>
void for_each(Callback callback)
{
for (u32 i = 0; i < indexed_array_like_size(); ++i) {
auto value_and_attributes = indexed_get(i);
if (value_and_attributes.has_value()) {
auto& style_sheet = as<T>(value_and_attributes->value.as_object());
callback(style_sheet);
}
}
}
explicit ObservableArray(JS::Realm&, Object& prototype);
virtual void visit_edges(JS::Cell::Visitor&) override;
private:
using SetAnIndexedValueCallbackHeapFunction = GC::Function<SetAnIndexedValueCallbackFunction::FunctionType>;
using DeleteAnIndexedValueCallbackHeapFunction = GC::Function<DeleteAnIndexedValueCallbackFunction::FunctionType>;
GC::Ptr<SetAnIndexedValueCallbackHeapFunction> m_on_set_an_indexed_value;
GC::Ptr<DeleteAnIndexedValueCallbackHeapFunction> m_on_delete_an_indexed_value;
};
}