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https://github.com/RGBCube/serenity
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b84f8fb55b
Some of these are allocated upon initialization of the intrinsics, and some lazily, but in neither case the getters actually return a nullptr. This saves us a whole bunch of pointer dereferences (as NonnullGCPtr has an `operator T&()`), and also has the interesting side effect of forcing us to explicitly use the FunctionObject& overload of call(), as passing a NonnullGCPtr is ambigous - it could implicitly be turned into a Value _or_ a FunctionObject& (so we have to dereference manually).
58 lines
1.9 KiB
C++
58 lines
1.9 KiB
C++
/*
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* Copyright (c) 2021-2022, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Runtime/WeakRef.h>
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namespace JS {
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NonnullGCPtr<WeakRef> WeakRef::create(Realm& realm, Object& value)
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{
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return realm.heap().allocate<WeakRef>(realm, value, realm.intrinsics().weak_ref_prototype()).release_allocated_value_but_fixme_should_propagate_errors();
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}
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NonnullGCPtr<WeakRef> WeakRef::create(Realm& realm, Symbol& value)
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{
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return realm.heap().allocate<WeakRef>(realm, value, realm.intrinsics().weak_ref_prototype()).release_allocated_value_but_fixme_should_propagate_errors();
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}
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WeakRef::WeakRef(Object& value, Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, WeakContainer(heap())
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, m_value(&value)
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, m_last_execution_generation(vm().execution_generation())
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{
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}
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WeakRef::WeakRef(Symbol& value, Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, WeakContainer(heap())
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, m_value(&value)
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, m_last_execution_generation(vm().execution_generation())
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{
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}
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void WeakRef::remove_dead_cells(Badge<Heap>)
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{
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if (m_value.visit([](Cell* cell) -> bool { return cell->state() == Cell::State::Live; }, [](Empty) -> bool { VERIFY_NOT_REACHED(); }))
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return;
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m_value = Empty {};
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// This is an optimization, we deregister from the garbage collector early (even if we were not garbage collected ourself yet)
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// to reduce the garbage collection overhead, which we can do because a cleared weak ref cannot be reused.
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WeakContainer::deregister();
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}
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void WeakRef::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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if (vm().execution_generation() == m_last_execution_generation) {
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auto* cell = m_value.visit([](Cell* cell) -> Cell* { return cell; }, [](Empty) -> Cell* { return nullptr; });
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visitor.visit(cell);
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}
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}
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}
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