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Expose a method on built-in iterators that allows retrieving the next iteration result without allocating a JS::Object. This change is a preparation for optimizing for..of and for..in loops.
60 lines
1.4 KiB
C++
60 lines
1.4 KiB
C++
/*
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* Copyright (c) 2021, 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/Array.h>
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#include <LibJS/Runtime/SetIterator.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(SetIterator);
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GC::Ref<SetIterator> SetIterator::create(Realm& realm, Set& set, Object::PropertyKind iteration_kind)
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{
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return realm.create<SetIterator>(set, iteration_kind, realm.intrinsics().set_iterator_prototype());
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}
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SetIterator::SetIterator(Set& set, Object::PropertyKind iteration_kind, Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, m_set(set)
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, m_iteration_kind(iteration_kind)
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, m_iterator(static_cast<Set const&>(set).begin())
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{
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}
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void SetIterator::visit_edges(Cell::Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_set);
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}
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ThrowCompletionOr<void> SetIterator::next(VM& vm, bool& done, Value& value)
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{
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if (m_done) {
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done = true;
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value = js_undefined();
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return {};
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}
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if (m_iterator == m_set->end()) {
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m_done = true;
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done = true;
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value = js_undefined();
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return {};
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}
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VERIFY(m_iteration_kind != Object::PropertyKind::Key);
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value = (*m_iterator).key;
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++m_iterator;
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if (m_iteration_kind == Object::PropertyKind::Value) {
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return {};
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}
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value = Array::create_from(*vm.current_realm(), { value, value });
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return {};
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}
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}
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