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https://github.com/LadybirdBrowser/ladybird.git
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451c947c3f
Before this change, PropertyNameIterator (used by for..in) and `Object::enumerable_own_property_names()` (used by `Object.keys()`, `Object.values()`, and `Object.entries()`) enumerated an object's own enumerable properties exactly as the spec prescribes: - Call `internal_own_property_keys()`, allocating a list of JS::Value keys. - For each key, call internal_get_own_property() to obtain a descriptor and check `[[Enumerable]]`. While that is required in the general case (e.g. for Proxy objects or platform/exotic objects that override `[[OwnPropertyKeys]]`), it's overkill for ordinary JS objects that store their own properties in the shape table and indexed-properties storage. This change introduces `for_each_own_property_with_enumerability()`, which, for objects where `eligible_for_own_property_enumeration_fast_path()` is `true`, lets us read the enumerability directly from shape metadata (and from indexed-properties storage) without a per-property descriptor lookup. When we cannot avoid `internal_get_own_property()`, we still benefit by skipping the temporary `Vector<Value>` of keys and avoiding the unnecessary round-trip between PropertyKey and Value.
45 lines
1.5 KiB
C++
45 lines
1.5 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <LibJS/Export.h>
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#include <LibJS/Runtime/Object.h>
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namespace JS {
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class JS_API StringObject : public Object {
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JS_OBJECT(StringObject, Object);
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GC_DECLARE_ALLOCATOR(StringObject);
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public:
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[[nodiscard]] static GC::Ref<StringObject> create(Realm&, PrimitiveString&, Object& prototype);
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virtual void initialize(Realm&) override;
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virtual ~StringObject() override = default;
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PrimitiveString const& primitive_string() const { return m_string; }
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PrimitiveString& primitive_string() { return m_string; }
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protected:
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StringObject(PrimitiveString&, Object& prototype);
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private:
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virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyKey const&) const override;
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virtual ThrowCompletionOr<bool> internal_define_own_property(PropertyKey const&, PropertyDescriptor&, Optional<PropertyDescriptor>* precomputed_get_own_property = nullptr) override;
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virtual ThrowCompletionOr<GC::RootVector<Value>> internal_own_property_keys() const override;
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virtual bool is_string_object() const final { return true; }
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virtual bool eligible_for_own_property_enumeration_fast_path() const override final { return false; }
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virtual void visit_edges(Visitor&) override;
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GC::Ref<PrimitiveString> m_string;
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};
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template<>
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inline bool Object::fast_is<StringObject>() const { return is_string_object(); }
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}
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